Long & Short Interruptions: Interruptions – Definition – Difference between failures,
outage, Interruptions – causes of Long Interruptions – Origin of Interruptions – Limits for the
Interruption frequency – Limits for the interruption duration – costs of Interruption –
Overview of Reliability evaluation to power quality, comparison of observations and
reliability evaluation.Short interruptions: definition, origin of short interruptions, basic principle, fuse saving,
voltage magnitude events due to re-closing, voltage during the interruption, monitoring of
short interruptions, difference between medium and low voltage systems. Multiple events,
single phase tripping – voltage and current during fault period, voltage and current at post
fault period
This document is a final year project presentation on Static VAR Compensator (SVC). It discusses Flexible AC Transmission Systems (FACTS) which use power electronics to control power flow and increase transmission capacity. SVCs in particular provide fast reactive power support to control voltage and improve stability. Different types of SVC are described including series and shunt compensators using thyristor controlled capacitors and reactors. Mechanically Switched Capacitors are also discussed as a type of shunt compensator. The project layout and applications of SVC systems for transmission systems are outlined.
This document discusses different methods of load frequency control and voltage control in power systems. It provides introductions and explanations of various load frequency control concepts including reasons for constant frequency, methods of load frequency control for single and two area power systems, and automatic generation control. For voltage control, it describes the importance of maintaining constant voltage and several methods used including shunt compensation, series capacitors, synchronous condensers, tap changing transformers, and auto transformers.
This document provides an introduction to Flexible AC Transmission Systems (FACTS). It discusses why transmission interconnections are needed, including to minimize generation and fuel costs and supply electricity at minimum cost. It also explores if the full potential of interconnections can be used and describes opportunities for FACTS technology to control power flow and enhance transmission line usage. Some key limitations on transmission line loading capability like thermal, dielectric, and stability limits are also summarized.
Series compensation is used to improve the performance of extra high voltage transmission lines by connecting capacitors in series with the line. It allows for increased transmission capacity and improved system stability by reducing the phase angle between sending and receiving end voltages for the same power transfer. Shunt compensation controls the receiving end voltage by connecting shunt capacitors or reactors to meet reactive power demand and prevent voltage drops or rises. Flexible AC transmission systems use high-speed thyristors to switch transmission line components like capacitors and reactors to control parameters like voltages and reactances to optimize power transfer.
This document discusses active and reactive power flow control using a Static Synchronous Series Compensator (SSSC). The SSSC injects a controllable voltage in series with a transmission line to regulate power flow. It can control both real and reactive power flow to improve transmission efficiency. The SSSC consists of a voltage source converter connected to the line via a transformer. It provides advantages like power factor correction, load balancing, and reducing harmonic distortion.
1. HVDC transmission systems use direct current for electricity transmission over long distances or through underwater cables. This became practical with the development of thyristors and solid state valves.
2. DC transmission has advantages over AC transmission for long distance transmission, as power transfer in DC lines is unaffected by distance. It also allows asynchronous interconnection between grids and monopolar operation.
3. While DC transmission has higher upfront equipment costs, it has better technical performance than AC transmission for long distance or underwater cables, making it economical beyond the break-even distance.
This presentation provides an overview of Flexible AC Transmission Systems (FACTS) and power system stability. It defines FACTS as using power electronics to control power flow and enhance transmission system capacity and stability. The document outlines different types of FACTS controllers including series compensation and shunt compensation. It also classifies power system stability into rotor angle stability, voltage stability, and frequency stability and discusses factors that can lead to losses of each type of stability.
concept of resilience and self healing in smart grid
The document discusses concepts related to resilience and self-healing in smart grids. It defines a smart grid as an electrical grid using communications technologies to improve efficiency. Key functions include enabling customer participation and accommodating different generation options. Self-healing is the ability of a system to automatically restore itself without human intervention. For the electrical grid, this means timely detection of issues and minimizing loss of service through reconfiguring resources. The transmission and distribution components can be modeled using graph theory to analyze resilience. Automatic meter reading is one approach for distribution grids.
The document discusses Thyristor Controlled Series Compensation (TCSC), a FACTS device that uses thyristors to control the capacitive reactance of transmission lines. TCSC can enhance power flow, limit fault current, improve stability and transients. It introduces benefits like mitigating subsynchronous resonance risks, damping power oscillations, and improving post-contingency stability. TCSC operates in modes like blocking, bypass, capacitive boost and inductive boost to accurately regulate power flow and damp oscillations while increasing transmission capacity and stability.
POWER QUALITY ISSUES (POWER SYSTEM AND POWER ELECTRONICS)
This document discusses power quality issues, specifically voltage sags. It defines voltage sags as decreases in voltage between 10-90% of nominal voltage lasting from half a cycle to one minute. Common causes of voltage sags include motor starting, faults in the power system, and sudden increases in load. The document discusses various methods for mitigating voltage sags, including power conditioning equipment like static VAR compensators, UPS systems, and custom devices like dynamic voltage regulators and D-STATCOMs. It also describes using an auto-transformer controlled by an IGBT switch as a method for mitigating voltage sags.
The document discusses distributed generation (DG) technologies. It describes several technologies used in DG, including reciprocating engine gen-sets, combustion turbines, fuel cells of various types (phosphoric acid, proton exchange membrane, molten carbonate, solid oxide, alkaline), and direct methanol fuel cells. For each technology, it provides details on operating principles, typical power ranges, advantages and disadvantages. The goal is to explain the different options for distributed power generation on low voltage distribution networks.
The document discusses the design and components of electrical power grids. It begins with an introduction to power grids, noting their three main components: power stations, transmission lines, and transformers. It then covers various topics related to designing a power grid substation including selecting the site, layout designs, busbar schemes, safety clearances, earth mat design, and control rooms. Key equipment for grids are also discussed such as lighting arrestors, current and potential transformers, circuit breakers, and isolators. The presentation concludes that grids are important for supplying reliable and economic power from sources to loads and maintaining efficiency, though their design and components make them costly.
Protection against overvoltage
overvoltage
causes of overvoltage
lightning
types of lightning strokes
harmful effect of lightning
protection against lightning
This document discusses power quality monitoring. It defines power quality as the properties of the power supply delivered to users. Power quality can be affected by various steady state variations and events that cause deviations from the ideal voltage waveform. The document describes different types of power quality disturbances and how automatic classifiers are used to classify disturbances. It discusses power quality monitoring objectives and the types of commercially available power quality monitors used to identify and analyze power quality problems.
This document discusses the digital control of DC drives using microcomputers. It describes how microcomputers can be used to control the speed and current of DC motors through programs that implement constant torque and constant horsepower operations. The microcomputer provides reliable control, flexibility to change control strategies, and can incorporate additional features like diagnostics and protections. Microcomputers reduce costs and size compared to analog controls while improving control performance and reliability. Speed is detected and current sensed to provide feedback for the inner current and speed control loops implemented through the microcomputer.
Power quality conditioners are devices used in smart grids to improve the quality of power delivered to loads. They ensure efficient power transfer, isolate grids from disturbances, convert DC to AC, and integrate with energy storage. Common types include distribution static compensators (DSTATCOMs), active power filters, and unified power quality conditioners (UPQCs). DSTATCOMs regulate voltage and compensate for reactive power. Active power filters compensate for harmonics and reactive power. UPQCs combine series and shunt filters to compensate for both voltage and current issues. Power quality conditioners are important for integrating renewable energy and ensuring loads function properly in smart grids.
Emergency Power Supplies: Electrical Distribution Design, Installation and Co...
This manual will enable you to understand the level of failure-proofing that specific equipment may require, evaluate available options objectively, specify the best and most economical solution, and manage the installation, commissioning and maintenance of the distribution system.
FOR MORE INFORMATION: http://www.idc-online.com/content/emergency-power-supplies-electrical-distribution-design-installation-and-commissioning-24?id=39
Adaptability of Distribution Automation System to Electric Power Quality Moni...
This document discusses adapting distribution automation systems for electric power quality monitoring in Nigeria's power distribution network. It reviews power quality problems like voltage sags, swells, interruptions and harmonics. It proposes using sensors at substations to measure voltages and currents, with an embedded system to coordinate sensors and communicate data to a central server. Initial results found some substations did not comply with power quality regulations. The study aims to help operators improve power delivery through monitoring and planning based on power quality data.
This document discusses power quality and defines it as any deviation from the normal sinusoidal voltage or current waveform. It covers various power quality issues like voltage sags, swells, fluctuations, harmonics, interruptions and more. It explains the causes and impacts of different power quality problems. The document also discusses classification of issues, measurement and evaluation of power quality as well as relevant standards from organizations like IEEE.
Voltage sags and interruptions are short-duration reductions or losses of voltage caused by faults in the power system. They can negatively impact sensitive equipment like computers and motor drives. Solutions exist at multiple levels, from protecting individual small loads to implementing power conditioning technologies or backup power sources for entire facilities. The best approach depends on the critical equipment and process requirements.
Application Note – Resilience, Reliability and Redundancy
This Application Note introduces the concepts of Resilience, Reliability and Redundancy, all of which are required to achieve high availability. It focuses on important system design issues, such as identifying and eliminating single points of failure and establishing good maintenance procedures to maintain high availability.
1) Voltage sags and interruptions are usually caused by faults on the power system and switching events to isolate faults. They are characterized by reductions in RMS voltage outside normal operating ranges.
2) A voltage sag is a short-term reduction in voltage lasting 0.5 to 30 cycles. A momentary interruption causes a complete loss of voltage for 2 to 5 seconds. Sustained interruptions last over 1 minute.
3) Utilities face more complaints about power quality due to sensitive electronic loads in customers' facilities. Sags and interruptions can cause processes and equipment to malfunction or restart, costing industries productivity.
Modeling Analysis& Solution of Power Quality Problems Using DVR & DSTATCOM
A Power quality problem is an occurrence manifested as a nonstandard voltage, current or frequency that results in a failure or a disoperation of end use equipment. Utility distribution networks, sensitive industrial loads, and critical commercial operations all suffer from various types of outages and service interruptions which can cost significant financial loss per incident based on process down-time, lost production, idle work forces, and other factors. With the restructuring of Power Systems and with shifting trend towards Distributed and Dispersed Generation, the issue of Power Quality is going to take newer dimensions. The aim therefore, in this work, is to identify the prominent concerns in the area and thereby to recommend measures that can enhance the quality of the power, keeping in mind their economic viability and technical repercussions. In this paper electromagnetic transient studies are presented for the following two custom power controllers: the distribution static compensator (DSTATCOM), and the dynamic voltage restorer (DVR). Comprehensive results are presented to assess the performance of each device as a potential custom power solution.
This document discusses power system faults and protection. It defines faults as defects in electrical circuits that divert current from its intended path. The most common faults are short circuits caused by insulation or conducting path failures. Switchgear such as circuit breakers, fuses and relays are used to isolate faulty elements and ensure continuity of power supply. Protective relays detect faults using changes in current, voltage, phase angle or frequency and must clear faults within fractions of a second to prevent equipment damage. Common faults include short circuits, over/under voltage/frequency, and overheating.
The document discusses voltage sags and interruptions. It covers sources of sags and interruptions such as faults in the distribution system. Methods to estimate voltage sag performance and mitigate sags are described, including reducing faults, improving fault clearing time, modifying the supply system, and using voltage stabilizers. Active series compensators and static transfer switches are discussed as technologies to improve power quality during sags. Ferroresonant transformers can handle most sag conditions by maintaining nearly constant output voltage.
This document provides an overview of power system reliability. It discusses key topics such as:
1. Definitions of power system reliability including adequacy, security, and reliability measures.
2. Factors that influence reliability such as transmission planning, reliability perspectives from different stakeholders, and measuring reliability through various indices.
3. Optimizing reliability by balancing higher reliability through improved equipment and redundancy against increased capital and operating costs.
4. Causes of outages and the "bathtub curve" model of failure rates over the life of equipment.
5. The importance of conducting power supply quality surveys to understand reliability issues before new connections.
Surge protection can improve reliability, availability, and return on assets (ROA) for process plants. Surges are a leading cause of up to 30% of premature electronics failures. While techniques like lightning protection, bonding, and UPS systems help mitigate surges, they do not eliminate the risk. Strategically applying surge protection, especially for critical assets or those at high risk, can directly reduce failures and increase availability. This improves ROA by minimizing downtime and maintenance costs. Prioritizing protection based on asset impact and risk exposure maximizes the financial benefits of surge protection.
Mantenimiento en los sistemas Eléctricos de distribución
1. The document discusses the importance of continuous electrical maintenance for companies to ensure facilities and equipment are operating safely and efficiently. It describes how maintenance activities help companies adapt to changes in electricity markets by meeting customer needs through globalization, competition, cost reduction, and quality service.
2. It provides details on CNEL EP, an Ecuadorian electricity corporation, and its annual preventative and predictive maintenance programs for its distribution networks and substations. This is done to identify and address issues before they impact the physical or electrical characteristics needed to provide continuous service.
3. Key parameters for evaluating service quality include reliability standards, safety, timely response to requests, accurate billing, restoration timelines, emergency response, customer information and service
The document summarizes power quality issues including defects like under voltage, over voltage, dips, surges, blackouts, harmonics, and transients. It discusses who is responsible for ensuring power quality and some typical problems caused by defects. Solutions mentioned include surge protection, UPS systems, generators, filters, proper wiring, and load zoning. Assuring high quality power is challenging as electricity must flow continuously from generators to consumers via a shared infrastructure.
Power quality is important for reliable operations and avoiding downtime. It refers to maintaining steady voltage and frequency levels. Poor power quality can cause equipment damage and failure through issues like harmonics, sags, swells, transients, unbalance, and flicker. Power quality monitoring involves continuous measurement and analysis to diagnose problems, improve reliability, and optimize maintenance. Janitza offers complete solutions for power quality monitoring and energy management that help facilities meet standards, protect assets, and reduce costs.
This document summarizes a research paper that models the performance of different types of Dynamic Voltage Restorers (DVRs) in mitigating balanced and unbalanced voltage sags on distribution systems. The paper presents modeling aspects of several DVR configurations and analyzes their effectiveness in compensating for various voltage sag scenarios through detailed simulation results. It also discusses the capability of DVRs to regulate voltage quality at load terminals during power quality issues like sags, swells and harmonics.
IRJET-Review on Power Quality Enhancement in weak Power Grids by Integration ...
Prathmesh Mayekar, Mahesh Wagh, Nilkanth Shinde "Review on Power Quality Enhancement in weak Power Grids by Integration of Renewable Energy Technologies", International Research Journal of Engineering and Technology (IRJET), Volume2,issue-01 April 2015.e-ISSN:2395-0056, p-ISSN:2395-0072. www.irjet.net
Abstract
During Last decade power quality problems has become more complex at all level of power system. With the increased use of sophisticated electronics, high efficiency variable speed drive, power electronic controllers and also more & more non-linear loads, Power Quality has become an increasing concern to utilities and customers. The modern sensitive, Non-linear and sophisticated load affects the power quality. This paper deals with the issues of low power quality in weak power grids. Initially the various power quality issues are discussed with their definition or occurrence and then finally the solution to mitigate this power quality issues are discussed. The innovative solutions like integration of renewable energy systems along with energy storage to enhance power quality by interfacing with custom power devices are explained in detail. Nearly all sorts of solution for mitigating power quality issue require some sort of DC source for providing active power, which can be supplied by renewable energy source. Also the various energy storage systems are studied.
A Review on Basic Concepts and Important Standards of Power Quality in Power ...
This paper deals with the basic of Power quality in power system. In addition basic definition and important concepts was
discussed in simple way. This paper also covers the important power quality standards. In addition IEEE, IEC, SEMI and UIE Power
quality standards are listed. This paper would be helpful for the UG and PG students to study about the basics of Power quality in
electrical engineering.
A Review on Basic Concepts and Important Standards of Power Quality in Power ...
This paper deals with the basic of Power quality in power system. In addition basic definition and important concepts was discussed in simple way. This paper also covers the important power quality standards. In addition IEEE, IEC, SEMI and UIE Power quality standards are listed. This paper would be helpful for the UG and PG students to study about the basics of Power quality in electrical engineering.
Regulatory Guidelines to set up Voltage Quality Monitoring
This session is part of the Clean Energy Regulators Initiative Webinar Programme.
Theme 2 - Pressure Points
Module 2: Voltage Quality Regulation
Voltage quality, sometimes called power quality or technical quality, covers a variety of disturbances in an electrical power system. It is mainly determined by the quality of the voltage waveform and it is an important aspect of the electricity service.
Customers are becoming increasingly sensitive to disturbances in voltage quality. This issue is particularly important taking into account the new regulatory frameworks which put strong emphasis on cost reduction, thereby potentially jeopardizing quality. When setting up a quality regulation framework, there are a number of basic issues that need to be considered first. This understanding is crucial in order to make the right choices in order to arrive at an effective voltage quality regulatory system. It is important to clearly define voltage quality and develop suitable indicators.
This presentation assesses the issue of what regulators need to consider whenever establishing a voltage quality regulatory framework for distribution networks (i.e. up to 35 kV). It presents a general set of guidelines that regulators could consider in introducing and developing voltage quality regulation. Regulation of five important voltage quality dimensions is considered: short-interruptions, voltage dips, flicker, supply voltage variation and harmonic distortion.
A power quality monitoring system gathers and analyzes electricity measurement data to provide useful information. It allows plants to perform energy management, preventive maintenance, quality control, and save money. Power quality monitoring equipment includes digital fault recorders, smart relays, voltage recorders, in-plant power monitors, and special-purpose power quality equipment. These devices monitor voltage, current, and other measurements to detect issues like harmonics, sags, disturbances and optimize power quality and performance.
This document discusses digital voltmeters (DVMs). It explains that DVMs display voltage measurements as numerical readings rather than using an analog needle gauge. The document covers various types of DVMs including ramp type, dual slope integrating type, successive approximation type, and microprocessor-based versions. It provides block diagrams and explanations of the operating principles for different DVM designs. Advantages of DVMs like accuracy, ease of reading, and versatility are also summarized.
basic electrical and electronics engg. components of LT switch gear, switch fuse unit, MCB, MCCB, ELCB, TYPES OF WIRES AND CABLES, ELECTRICAL EARTHING, TYPES OF BATTERIES,
Electric heating works by converting electrical energy to heat energy using the principle of Joule heating. When an electric current passes through a resistor, it produces heat due to I2R losses. There are various domestic and industrial applications of electric heating, including water heaters, ovens, welding, and heat treatment processes. Electric heating has advantages over other heating methods like being clean, allowing for accurate temperature control, and providing uniform heating. Resistance heating and dielectric heating are two common methods for electric heating. Resistance heating directly or indirectly heats an object by passing a current through it or a nearby resistive element. Dielectric heating generates heat in non-conductive materials using electromagnetic fields.
Performance Analysis of Three-phase Four-wire Shunt Active Power Filter
This document discusses the performance analysis of a three-phase four-wire shunt active power filter (SAPF). It first introduces power quality issues caused by nonlinear loads and defines active power filters as emerging devices that can effectively diminish harmonic pollution. It then presents the mathematical model of a SAPF using instantaneous reactive power theory. The performance of a three-phase four-wire SAPF is analyzed using proportional-integral (PI) and proportional-integral-derivative (PID) controllers. Simulation results in MATLAB verify the SAPF can compensate for harmonics and reactive power when controlled by PI and PID controllers.
This document describes the modeling and simulation of a brushless DC motor drive system in MATLAB/Simulink. It includes models of the BLDC motor, three-phase inverter, current controller, speed controller and reference current generator. The motor is modeled using a three-phase variable model. A PI controller is used to control the current and an outer speed loop controls the rotor speed. Simulation results can be used to predict system behavior and determine controller parameters.
study of a DC-DC converter for solar LED street lighting
The document discusses a proposed DC-DC converter for integrating the charging and discharging circuits of a solar LED street lighting system into a single converter. In charging mode during the day, the converter uses pulse-width modulation to step down the voltage from the solar panel to charge the battery. In discharging mode at night, it steps up the battery voltage to power the LED street lights. Simulation results show the converter can successfully charge the battery during the day and power the lights at night with only one integrated converter rather than two separate converters.
DESIGN OF MATRIX CONVERTER BASED DYNAMIC VOLTAGE RESTORER FOR POWER QUALITY ...
The document proposes a matrix converter-based dynamic voltage restorer (DVR) system for power quality enhancement. The DVR uses a single matrix converter instead of a conventional AC/DC/AC converter. It is connected between the distribution feeder and load to mitigate voltage sags. The control system is based on dqo modeling of the matrix converter. It injects power from an energy storage device like a flywheel to restore the load voltage during sags. Simulation results show the DVR is able to effectively reduce sags and regulate the supply voltage, improving power quality.
simulation of maximum power point tracking for photovoltaic systems
This document discusses simulation of maximum power point tracking (MPPT) algorithms for photovoltaic (PV) solar systems. It notes that PV panels have non-linear output characteristics and produce maximum power at a single operating point, but this point varies with temperature and light intensity. Various MPPT algorithms have been developed to track this maximum power point (MPP) under changing conditions. The document outlines the components of a typical PV system and describes the role of the MPPT in matching the PV panel impedance to the load impedance to extract maximum available power. It also provides details on the perturb and observe (P&O) MPPT algorithm and concludes that accurate simulation models are important for evaluating PV system performance under different operating environments
grid power quality improvement and battery energy storage in wind energy systems
This document proposes using a static compensator (STATCOM) connected to a battery energy storage system (BESS) to mitigate power quality issues from wind energy generation. Wind power fluctuates due to changing wind speed, which affects power quality. The STATCOM and BESS work together to absorb or inject reactive power and regulate real power flow to the load. Excess power generated during low demand hours can be stored in the batteries. This combination of battery storage and wind generation helps stabilize the output waveform and improve power quality at the point of common coupling.
This document proposes using a static compensator (STATCOM) connected to a battery energy storage system (BESS) to mitigate power quality issues from wind energy generation. Wind power fluctuates due to changing wind speed, which affects power quality. The STATCOM and BESS work together to absorb or inject reactive power and regulate real power flow to the load. Excess power generated during low demand hours can be stored in the batteries. This combination of battery storage and wind generation helps stabilize the output waveform and improve power quality at the point of common coupling.
This document proposes using a static compensator (STATCOM) connected to a battery energy storage system (BESS) to mitigate power quality issues from wind energy generation. Wind power fluctuates due to changing wind speed, which affects power quality. The STATCOM injects reactive power from the BESS to absorb harmonic current and regulate voltage. This improves power quality by making the source current harmonic-free and stabilizing the system voltage. The combination of BESS and STATCOM helps compensate for wind power fluctuations and produces higher quality power from the wind generation system.
The project "Social Media Platform in Object-Oriented Modeling" aims to design
and model a robust and scalable social media platform using object-oriented
modeling principles. In the age of digital communication, social media platforms
have become indispensable for connecting people, sharing content, and fostering
online communities. However, their complex nature requires meticulous planning
and organization.This project addresses the challenge of creating a feature-rich and
user-friendly social media platform by applying key object-oriented modeling
concepts. It entails the identification and definition of essential objects such as
"User," "Post," "Comment," and "Notification," each encapsulating specific
attributes and behaviors. Relationships between these objects, such as friendships,
content interactions, and notifications, are meticulously established.The project
emphasizes encapsulation to maintain data integrity, inheritance for shared behaviors
among objects, and polymorphism for flexible content handling. Use case diagrams
depict user interactions, while sequence diagrams showcase the flow of interactions
during critical scenarios. Class diagrams provide an overarching view of the system's
architecture, including classes, attributes, and methods .By undertaking this project,
we aim to create a modular, maintainable, and user-centric social media platform that
adheres to best practices in object-oriented modeling. Such a platform will offer users
a seamless and secure online social experience while facilitating future enhancements
and adaptability to changing user needs.
A brand new catalog for the 2024 edition of IWISS. We have enriched our product range and have more innovations in electrician tools, plumbing tools, wire rope tools and banding tools. Let's explore together!
A brief introduction to quadcopter (drone) working. It provides an overview of flight stability, dynamics, general control system block diagram, and the electronic hardware.
OCS Training - Rig Equipment Inspection - Advanced 5 Days_IADC.pdf
OCS Training Institute is pleased to co-operate with
a Global provider of Rig Inspection/Audits,
Commission-ing, Compliance & Acceptance as well as
& Engineering for Offshore Drilling Rigs, to deliver
Drilling Rig Inspec-tion Workshops (RIW) which
teaches the inspection & maintenance procedures
required to ensure equipment integrity. Candidates
learn to implement the relevant standards &
understand industry requirements so that they can
verify the condition of a rig’s equipment & improve
safety, thus reducing the number of accidents and
protecting the asset.
Encontro anual da comunidade Splunk, onde discutimos todas as novidades apresentadas na conferência anual da Spunk, a .conf24 realizada em junho deste ano em Las Vegas.
Neste vídeo, trago os pontos chave do encontro, como:
- AI Assistant para uso junto com a SPL
- SPL2 para uso em Data Pipelines
- Ingest Processor
- Enterprise Security 8.0 (Maior atualização deste seu release)
- Federated Analytics
- Integração com Cisco XDR e Cisto Talos
- E muito mais.
Deixo ainda, alguns links com relatórios e conteúdo interessantes que podem ajudar no esclarecimento dos produtos e funções.
https://www.splunk.com/en_us/campaigns/the-hidden-costs-of-downtime.html
https://www.splunk.com/en_us/pdfs/gated/ebooks/building-a-leading-observability-practice.pdf
https://www.splunk.com/en_us/pdfs/gated/ebooks/building-a-modern-security-program.pdf
Nosso grupo oficial da Splunk:
https://usergroups.splunk.com/sao-paulo-splunk-user-group/
Vernier Caliper and How to use Vernier Caliper.ppsx
A vernier caliper is a precision instrument used to measure dimensions with high accuracy. It can measure internal and external dimensions, as well as depths.
Here is a detailed description of its parts and how to use it.
Response & Safe AI at Summer School of AI at IIITH
Talk covering Guardrails , Jailbreak, What is an alignment problem? RLHF, EU AI Act, Machine & Graph unlearning, Bias, Inconsistency, Probing, Interpretability, Bias
Understanding Cybersecurity Breaches: Causes, Consequences, and Prevention
Cybersecurity breaches are a growing threat in today’s interconnected digital landscape, affecting individuals, businesses, and governments alike. These breaches compromise sensitive information and erode trust in online services and systems. Understanding the causes, consequences, and prevention strategies of cybersecurity breaches is crucial to protect against these pervasive risks.
Cybersecurity breaches refer to unauthorized access, manipulation, or destruction of digital information or systems. They can occur through various means such as malware, phishing attacks, insider threats, and vulnerabilities in software or hardware. Once a breach happens, cybercriminals can exploit the compromised data for financial gain, espionage, or sabotage. Causes of breaches include software and hardware vulnerabilities, phishing attacks, insider threats, weak passwords, and a lack of security awareness.
The consequences of cybersecurity breaches are severe. Financial loss is a significant impact, as organizations face theft of funds, legal fees, and repair costs. Breaches also damage reputations, leading to a loss of trust among customers, partners, and stakeholders. Regulatory penalties are another consequence, with hefty fines imposed for non-compliance with data protection regulations. Intellectual property theft undermines innovation and competitiveness, while disruptions of critical services like healthcare and utilities impact public safety and well-being.
Best Practices of Clothing Businesses in Talavera, Nueva Ecija, A Foundation ...
This study primarily aimed to determine the best practices of clothing businesses to use it as a foundation of strategic business advancements. Moreover, the frequency with which the business's best practices are tracked, which best practices are the most targeted of the apparel firms to be retained, and how does best practices can be used as strategic business advancement. The respondents of the study is the owners of clothing businesses in Talavera, Nueva Ecija. Data were collected and analyzed using a quantitative approach and utilizing a descriptive research design. Unveiling best practices of clothing businesses as a foundation for strategic business advancement through statistical analysis: frequency and percentage, and weighted means analyzing the data in terms of identifying the most to the least important performance indicators of the businesses among all of the variables. Based on the survey conducted on clothing businesses in Talavera, Nueva Ecija, several best practices emerge across different areas of business operations. These practices are categorized into three main sections, section one being the Business Profile and Legal Requirements, followed by the tracking of indicators in terms of Product, Place, Promotion, and Price, and Key Performance Indicators (KPIs) covering finance, marketing, production, technical, and distribution aspects. The research study delved into identifying the core best practices of clothing businesses, serving as a strategic guide for their advancement. Through meticulous analysis, several key findings emerged. Firstly, prioritizing product factors, such as maintaining optimal stock levels and maximizing customer satisfaction, was deemed essential for driving sales and fostering loyalty. Additionally, selecting the right store location was crucial for visibility and accessibility, directly impacting footfall and sales. Vigilance towards competitors and demographic shifts was highlighted as essential for maintaining relevance. Understanding the relationship between marketing spend and customer acquisition proved pivotal for optimizing budgets and achieving a higher ROI. Strategic analysis of profit margins across clothing items emerged as crucial for maximizing profitability and revenue. Creating a positive customer experience, investing in employee training, and implementing effective inventory management practices were also identified as critical success factors. In essence, these findings underscored the holistic approach needed for sustainable growth in the clothing business, emphasizing the importance of product management, marketing strategies, customer experience, and operational efficiency.
Conservation of Taksar through Economic Regeneration
This was our 9th Sem Design Studio Project, introduced as Conservation of Taksar Bazar, Bhojpur, an ancient city famous for Taksar- Making Coins. Taksar Bazaar has a civilization of Newars shifted from Patan, with huge socio-economic and cultural significance having a settlement of about 300 years. But in the present scenario, Taksar Bazar has lost its charm and importance, due to various reasons like, migration, unemployment, shift of economic activities to Bhojpur and many more. The scenario was so pityful that when we went to make inventories, take survey and study the site, the people and the context, we barely found any youth of our age! Many houses were vacant, the earthquake devasted and ruined heritages.
Conservation of those heritages, ancient marvels,a nd history was in dire need, so we proposed the Conservation of Taksar through economic regeneration because the lack of economy was the main reason for the people to leave the settlement and the reason for the overall declination.
Loading Capability Limits of Transmission LinesRaja Adapa
This document discusses the four main loading capability limits of transmission lines: thermal, voltage, dielectric, and stability limits. The thermal limit depends on ambient temperature, wind conditions, conductor size and is usually the main limiting factor. Voltage limits require the transmission voltage to be maintained within a specified range, like plus/minus 5% of nominal. The dielectric limit concerns insulation and allows for some increase in normal operating voltage. Stability limits involve ensuring the power system remains stable after the loss of a single element to prevent cascading outages. FACTS technology can help utilize more of the thermal limits and improve stability.
This document discusses different types of firing angle control schemes for HVDC converters, including individual phase control (IPC) and equidistant phase control (EPC). IPC allows independent control of each phase's firing angle based on commutation voltages. EPC generates firing angles at equal intervals through a ring counter. Higher-level controllers are also discussed that can control DC power modulation for frequency regulation, emergency control, reactive power control, and damping of sub-synchronous oscillations. Voltage source converter control is mentioned, where the modulation index and phase angle are used to regulate active and reactive power flow.
Gcsc gto thyristor controlled series capacitorLEOPAUL23
The document discusses the GTO Thyristor Controlled Series Capacitor (GCSC), which consists of a fixed capacitor in parallel with an anti-parallel GTO pair. The GCSC can continuously vary the voltage across the capacitor between zero and its maximum value by controlling the turn-off delay angle of the thyristor valve. It works by closing and opening the thyristor valve in synchronism with the supply frequency. The GCSC can operate in either voltage compensating mode, to maintain a rated compensating voltage over a range of line currents, or in reactance compensating mode, to maintain a maximum rated compensating reactance at any line current.
This document is a final year project presentation on Static VAR Compensator (SVC). It discusses Flexible AC Transmission Systems (FACTS) which use power electronics to control power flow and increase transmission capacity. SVCs in particular provide fast reactive power support to control voltage and improve stability. Different types of SVC are described including series and shunt compensators using thyristor controlled capacitors and reactors. Mechanically Switched Capacitors are also discussed as a type of shunt compensator. The project layout and applications of SVC systems for transmission systems are outlined.
Different method of frequency and voltage control8141245710
This document discusses different methods of load frequency control and voltage control in power systems. It provides introductions and explanations of various load frequency control concepts including reasons for constant frequency, methods of load frequency control for single and two area power systems, and automatic generation control. For voltage control, it describes the importance of maintaining constant voltage and several methods used including shunt compensation, series capacitors, synchronous condensers, tap changing transformers, and auto transformers.
This document provides an introduction to Flexible AC Transmission Systems (FACTS). It discusses why transmission interconnections are needed, including to minimize generation and fuel costs and supply electricity at minimum cost. It also explores if the full potential of interconnections can be used and describes opportunities for FACTS technology to control power flow and enhance transmission line usage. Some key limitations on transmission line loading capability like thermal, dielectric, and stability limits are also summarized.
Series & shunt compensation and FACTs Deviceskhemraj298
Series compensation is used to improve the performance of extra high voltage transmission lines by connecting capacitors in series with the line. It allows for increased transmission capacity and improved system stability by reducing the phase angle between sending and receiving end voltages for the same power transfer. Shunt compensation controls the receiving end voltage by connecting shunt capacitors or reactors to meet reactive power demand and prevent voltage drops or rises. Flexible AC transmission systems use high-speed thyristors to switch transmission line components like capacitors and reactors to control parameters like voltages and reactances to optimize power transfer.
This document discusses active and reactive power flow control using a Static Synchronous Series Compensator (SSSC). The SSSC injects a controllable voltage in series with a transmission line to regulate power flow. It can control both real and reactive power flow to improve transmission efficiency. The SSSC consists of a voltage source converter connected to the line via a transformer. It provides advantages like power factor correction, load balancing, and reducing harmonic distortion.
1. HVDC transmission systems use direct current for electricity transmission over long distances or through underwater cables. This became practical with the development of thyristors and solid state valves.
2. DC transmission has advantages over AC transmission for long distance transmission, as power transfer in DC lines is unaffected by distance. It also allows asynchronous interconnection between grids and monopolar operation.
3. While DC transmission has higher upfront equipment costs, it has better technical performance than AC transmission for long distance or underwater cables, making it economical beyond the break-even distance.
FACTS DEVICES AND POWER SYSTEM STABILITY pptMamta Bagoria
This presentation provides an overview of Flexible AC Transmission Systems (FACTS) and power system stability. It defines FACTS as using power electronics to control power flow and enhance transmission system capacity and stability. The document outlines different types of FACTS controllers including series compensation and shunt compensation. It also classifies power system stability into rotor angle stability, voltage stability, and frequency stability and discusses factors that can lead to losses of each type of stability.
concept of resilience and self healing in smart gridKundan Kumar
The document discusses concepts related to resilience and self-healing in smart grids. It defines a smart grid as an electrical grid using communications technologies to improve efficiency. Key functions include enabling customer participation and accommodating different generation options. Self-healing is the ability of a system to automatically restore itself without human intervention. For the electrical grid, this means timely detection of issues and minimizing loss of service through reconfiguring resources. The transmission and distribution components can be modeled using graph theory to analyze resilience. Automatic meter reading is one approach for distribution grids.
The document discusses Thyristor Controlled Series Compensation (TCSC), a FACTS device that uses thyristors to control the capacitive reactance of transmission lines. TCSC can enhance power flow, limit fault current, improve stability and transients. It introduces benefits like mitigating subsynchronous resonance risks, damping power oscillations, and improving post-contingency stability. TCSC operates in modes like blocking, bypass, capacitive boost and inductive boost to accurately regulate power flow and damp oscillations while increasing transmission capacity and stability.
POWER QUALITY ISSUES (POWER SYSTEM AND POWER ELECTRONICS)Rohit vijay
This document discusses power quality issues, specifically voltage sags. It defines voltage sags as decreases in voltage between 10-90% of nominal voltage lasting from half a cycle to one minute. Common causes of voltage sags include motor starting, faults in the power system, and sudden increases in load. The document discusses various methods for mitigating voltage sags, including power conditioning equipment like static VAR compensators, UPS systems, and custom devices like dynamic voltage regulators and D-STATCOMs. It also describes using an auto-transformer controlled by an IGBT switch as a method for mitigating voltage sags.
Distributed generation & power quality unit 5hariyenireddy1
The document discusses distributed generation (DG) technologies. It describes several technologies used in DG, including reciprocating engine gen-sets, combustion turbines, fuel cells of various types (phosphoric acid, proton exchange membrane, molten carbonate, solid oxide, alkaline), and direct methanol fuel cells. For each technology, it provides details on operating principles, typical power ranges, advantages and disadvantages. The goal is to explain the different options for distributed power generation on low voltage distribution networks.
The document discusses the design and components of electrical power grids. It begins with an introduction to power grids, noting their three main components: power stations, transmission lines, and transformers. It then covers various topics related to designing a power grid substation including selecting the site, layout designs, busbar schemes, safety clearances, earth mat design, and control rooms. Key equipment for grids are also discussed such as lighting arrestors, current and potential transformers, circuit breakers, and isolators. The presentation concludes that grids are important for supplying reliable and economic power from sources to loads and maintaining efficiency, though their design and components make them costly.
Protection against overvoltage
overvoltage
causes of overvoltage
lightning
types of lightning strokes
harmful effect of lightning
protection against lightning
This document discusses power quality monitoring. It defines power quality as the properties of the power supply delivered to users. Power quality can be affected by various steady state variations and events that cause deviations from the ideal voltage waveform. The document describes different types of power quality disturbances and how automatic classifiers are used to classify disturbances. It discusses power quality monitoring objectives and the types of commercially available power quality monitors used to identify and analyze power quality problems.
This document discusses the digital control of DC drives using microcomputers. It describes how microcomputers can be used to control the speed and current of DC motors through programs that implement constant torque and constant horsepower operations. The microcomputer provides reliable control, flexibility to change control strategies, and can incorporate additional features like diagnostics and protections. Microcomputers reduce costs and size compared to analog controls while improving control performance and reliability. Speed is detected and current sensed to provide feedback for the inner current and speed control loops implemented through the microcomputer.
Power quality conditioners are devices used in smart grids to improve the quality of power delivered to loads. They ensure efficient power transfer, isolate grids from disturbances, convert DC to AC, and integrate with energy storage. Common types include distribution static compensators (DSTATCOMs), active power filters, and unified power quality conditioners (UPQCs). DSTATCOMs regulate voltage and compensate for reactive power. Active power filters compensate for harmonics and reactive power. UPQCs combine series and shunt filters to compensate for both voltage and current issues. Power quality conditioners are important for integrating renewable energy and ensuring loads function properly in smart grids.
Emergency Power Supplies: Electrical Distribution Design, Installation and Co...Living Online
This manual will enable you to understand the level of failure-proofing that specific equipment may require, evaluate available options objectively, specify the best and most economical solution, and manage the installation, commissioning and maintenance of the distribution system.
FOR MORE INFORMATION: http://www.idc-online.com/content/emergency-power-supplies-electrical-distribution-design-installation-and-commissioning-24?id=39
Adaptability of Distribution Automation System to Electric Power Quality Moni...IOSR Journals
This document discusses adapting distribution automation systems for electric power quality monitoring in Nigeria's power distribution network. It reviews power quality problems like voltage sags, swells, interruptions and harmonics. It proposes using sensors at substations to measure voltages and currents, with an embedded system to coordinate sensors and communicate data to a central server. Initial results found some substations did not comply with power quality regulations. The study aims to help operators improve power delivery through monitoring and planning based on power quality data.
This document discusses power quality and defines it as any deviation from the normal sinusoidal voltage or current waveform. It covers various power quality issues like voltage sags, swells, fluctuations, harmonics, interruptions and more. It explains the causes and impacts of different power quality problems. The document also discusses classification of issues, measurement and evaluation of power quality as well as relevant standards from organizations like IEEE.
Voltage sags and interruptions are short-duration reductions or losses of voltage caused by faults in the power system. They can negatively impact sensitive equipment like computers and motor drives. Solutions exist at multiple levels, from protecting individual small loads to implementing power conditioning technologies or backup power sources for entire facilities. The best approach depends on the critical equipment and process requirements.
Application Note – Resilience, Reliability and RedundancyLeonardo ENERGY
This Application Note introduces the concepts of Resilience, Reliability and Redundancy, all of which are required to achieve high availability. It focuses on important system design issues, such as identifying and eliminating single points of failure and establishing good maintenance procedures to maintain high availability.
1) Voltage sags and interruptions are usually caused by faults on the power system and switching events to isolate faults. They are characterized by reductions in RMS voltage outside normal operating ranges.
2) A voltage sag is a short-term reduction in voltage lasting 0.5 to 30 cycles. A momentary interruption causes a complete loss of voltage for 2 to 5 seconds. Sustained interruptions last over 1 minute.
3) Utilities face more complaints about power quality due to sensitive electronic loads in customers' facilities. Sags and interruptions can cause processes and equipment to malfunction or restart, costing industries productivity.
Modeling Analysis& Solution of Power Quality Problems Using DVR & DSTATCOMijsrd.com
A Power quality problem is an occurrence manifested as a nonstandard voltage, current or frequency that results in a failure or a disoperation of end use equipment. Utility distribution networks, sensitive industrial loads, and critical commercial operations all suffer from various types of outages and service interruptions which can cost significant financial loss per incident based on process down-time, lost production, idle work forces, and other factors. With the restructuring of Power Systems and with shifting trend towards Distributed and Dispersed Generation, the issue of Power Quality is going to take newer dimensions. The aim therefore, in this work, is to identify the prominent concerns in the area and thereby to recommend measures that can enhance the quality of the power, keeping in mind their economic viability and technical repercussions. In this paper electromagnetic transient studies are presented for the following two custom power controllers: the distribution static compensator (DSTATCOM), and the dynamic voltage restorer (DVR). Comprehensive results are presented to assess the performance of each device as a potential custom power solution.
This document discusses power system faults and protection. It defines faults as defects in electrical circuits that divert current from its intended path. The most common faults are short circuits caused by insulation or conducting path failures. Switchgear such as circuit breakers, fuses and relays are used to isolate faulty elements and ensure continuity of power supply. Protective relays detect faults using changes in current, voltage, phase angle or frequency and must clear faults within fractions of a second to prevent equipment damage. Common faults include short circuits, over/under voltage/frequency, and overheating.
The document discusses voltage sags and interruptions. It covers sources of sags and interruptions such as faults in the distribution system. Methods to estimate voltage sag performance and mitigate sags are described, including reducing faults, improving fault clearing time, modifying the supply system, and using voltage stabilizers. Active series compensators and static transfer switches are discussed as technologies to improve power quality during sags. Ferroresonant transformers can handle most sag conditions by maintaining nearly constant output voltage.
This document provides an overview of power system reliability. It discusses key topics such as:
1. Definitions of power system reliability including adequacy, security, and reliability measures.
2. Factors that influence reliability such as transmission planning, reliability perspectives from different stakeholders, and measuring reliability through various indices.
3. Optimizing reliability by balancing higher reliability through improved equipment and redundancy against increased capital and operating costs.
4. Causes of outages and the "bathtub curve" model of failure rates over the life of equipment.
5. The importance of conducting power supply quality surveys to understand reliability issues before new connections.
Surge protection can improve reliability, availability, and return on assets (ROA) for process plants. Surges are a leading cause of up to 30% of premature electronics failures. While techniques like lightning protection, bonding, and UPS systems help mitigate surges, they do not eliminate the risk. Strategically applying surge protection, especially for critical assets or those at high risk, can directly reduce failures and increase availability. This improves ROA by minimizing downtime and maintenance costs. Prioritizing protection based on asset impact and risk exposure maximizes the financial benefits of surge protection.
Mantenimiento en los sistemas Eléctricos de distribución JOe Torres Palomino
1. The document discusses the importance of continuous electrical maintenance for companies to ensure facilities and equipment are operating safely and efficiently. It describes how maintenance activities help companies adapt to changes in electricity markets by meeting customer needs through globalization, competition, cost reduction, and quality service.
2. It provides details on CNEL EP, an Ecuadorian electricity corporation, and its annual preventative and predictive maintenance programs for its distribution networks and substations. This is done to identify and address issues before they impact the physical or electrical characteristics needed to provide continuous service.
3. Key parameters for evaluating service quality include reliability standards, safety, timely response to requests, accurate billing, restoration timelines, emergency response, customer information and service
The document summarizes power quality issues including defects like under voltage, over voltage, dips, surges, blackouts, harmonics, and transients. It discusses who is responsible for ensuring power quality and some typical problems caused by defects. Solutions mentioned include surge protection, UPS systems, generators, filters, proper wiring, and load zoning. Assuring high quality power is challenging as electricity must flow continuously from generators to consumers via a shared infrastructure.
Power quality is important for reliable operations and avoiding downtime. It refers to maintaining steady voltage and frequency levels. Poor power quality can cause equipment damage and failure through issues like harmonics, sags, swells, transients, unbalance, and flicker. Power quality monitoring involves continuous measurement and analysis to diagnose problems, improve reliability, and optimize maintenance. Janitza offers complete solutions for power quality monitoring and energy management that help facilities meet standards, protect assets, and reduce costs.
This document summarizes a research paper that models the performance of different types of Dynamic Voltage Restorers (DVRs) in mitigating balanced and unbalanced voltage sags on distribution systems. The paper presents modeling aspects of several DVR configurations and analyzes their effectiveness in compensating for various voltage sag scenarios through detailed simulation results. It also discusses the capability of DVRs to regulate voltage quality at load terminals during power quality issues like sags, swells and harmonics.
IRJET-Review on Power Quality Enhancement in weak Power Grids by Integration ...IRJET Journal
Prathmesh Mayekar, Mahesh Wagh, Nilkanth Shinde "Review on Power Quality Enhancement in weak Power Grids by Integration of Renewable Energy Technologies", International Research Journal of Engineering and Technology (IRJET), Volume2,issue-01 April 2015.e-ISSN:2395-0056, p-ISSN:2395-0072. www.irjet.net
Abstract
During Last decade power quality problems has become more complex at all level of power system. With the increased use of sophisticated electronics, high efficiency variable speed drive, power electronic controllers and also more & more non-linear loads, Power Quality has become an increasing concern to utilities and customers. The modern sensitive, Non-linear and sophisticated load affects the power quality. This paper deals with the issues of low power quality in weak power grids. Initially the various power quality issues are discussed with their definition or occurrence and then finally the solution to mitigate this power quality issues are discussed. The innovative solutions like integration of renewable energy systems along with energy storage to enhance power quality by interfacing with custom power devices are explained in detail. Nearly all sorts of solution for mitigating power quality issue require some sort of DC source for providing active power, which can be supplied by renewable energy source. Also the various energy storage systems are studied.
A Review on Basic Concepts and Important Standards of Power Quality in Power ...Editor IJCATR
This paper deals with the basic of Power quality in power system. In addition basic definition and important concepts was
discussed in simple way. This paper also covers the important power quality standards. In addition IEEE, IEC, SEMI and UIE Power
quality standards are listed. This paper would be helpful for the UG and PG students to study about the basics of Power quality in
electrical engineering.
A Review on Basic Concepts and Important Standards of Power Quality in Power ...Editor IJCATR
This paper deals with the basic of Power quality in power system. In addition basic definition and important concepts was discussed in simple way. This paper also covers the important power quality standards. In addition IEEE, IEC, SEMI and UIE Power quality standards are listed. This paper would be helpful for the UG and PG students to study about the basics of Power quality in electrical engineering.
Regulatory Guidelines to set up Voltage Quality MonitoringLeonardo ENERGY
This session is part of the Clean Energy Regulators Initiative Webinar Programme.
Theme 2 - Pressure Points
Module 2: Voltage Quality Regulation
Voltage quality, sometimes called power quality or technical quality, covers a variety of disturbances in an electrical power system. It is mainly determined by the quality of the voltage waveform and it is an important aspect of the electricity service.
Customers are becoming increasingly sensitive to disturbances in voltage quality. This issue is particularly important taking into account the new regulatory frameworks which put strong emphasis on cost reduction, thereby potentially jeopardizing quality. When setting up a quality regulation framework, there are a number of basic issues that need to be considered first. This understanding is crucial in order to make the right choices in order to arrive at an effective voltage quality regulatory system. It is important to clearly define voltage quality and develop suitable indicators.
This presentation assesses the issue of what regulators need to consider whenever establishing a voltage quality regulatory framework for distribution networks (i.e. up to 35 kV). It presents a general set of guidelines that regulators could consider in introducing and developing voltage quality regulation. Regulation of five important voltage quality dimensions is considered: short-interruptions, voltage dips, flicker, supply voltage variation and harmonic distortion.
Similar to Short and long interruptions- UNIT-II-POWER QUALITY (20)
A power quality monitoring system gathers and analyzes electricity measurement data to provide useful information. It allows plants to perform energy management, preventive maintenance, quality control, and save money. Power quality monitoring equipment includes digital fault recorders, smart relays, voltage recorders, in-plant power monitors, and special-purpose power quality equipment. These devices monitor voltage, current, and other measurements to detect issues like harmonics, sags, disturbances and optimize power quality and performance.
This document discusses digital voltmeters (DVMs). It explains that DVMs display voltage measurements as numerical readings rather than using an analog needle gauge. The document covers various types of DVMs including ramp type, dual slope integrating type, successive approximation type, and microprocessor-based versions. It provides block diagrams and explanations of the operating principles for different DVM designs. Advantages of DVMs like accuracy, ease of reading, and versatility are also summarized.
basic electrical and electronics engg. components of LT switch gear, switch fuse unit, MCB, MCCB, ELCB, TYPES OF WIRES AND CABLES, ELECTRICAL EARTHING, TYPES OF BATTERIES,
Electric heating works by converting electrical energy to heat energy using the principle of Joule heating. When an electric current passes through a resistor, it produces heat due to I2R losses. There are various domestic and industrial applications of electric heating, including water heaters, ovens, welding, and heat treatment processes. Electric heating has advantages over other heating methods like being clean, allowing for accurate temperature control, and providing uniform heating. Resistance heating and dielectric heating are two common methods for electric heating. Resistance heating directly or indirectly heats an object by passing a current through it or a nearby resistive element. Dielectric heating generates heat in non-conductive materials using electromagnetic fields.
This document discusses the performance analysis of a three-phase four-wire shunt active power filter (SAPF). It first introduces power quality issues caused by nonlinear loads and defines active power filters as emerging devices that can effectively diminish harmonic pollution. It then presents the mathematical model of a SAPF using instantaneous reactive power theory. The performance of a three-phase four-wire SAPF is analyzed using proportional-integral (PI) and proportional-integral-derivative (PID) controllers. Simulation results in MATLAB verify the SAPF can compensate for harmonics and reactive power when controlled by PI and PID controllers.
This document describes the modeling and simulation of a brushless DC motor drive system in MATLAB/Simulink. It includes models of the BLDC motor, three-phase inverter, current controller, speed controller and reference current generator. The motor is modeled using a three-phase variable model. A PI controller is used to control the current and an outer speed loop controls the rotor speed. Simulation results can be used to predict system behavior and determine controller parameters.
The document discusses a proposed DC-DC converter for integrating the charging and discharging circuits of a solar LED street lighting system into a single converter. In charging mode during the day, the converter uses pulse-width modulation to step down the voltage from the solar panel to charge the battery. In discharging mode at night, it steps up the battery voltage to power the LED street lights. Simulation results show the converter can successfully charge the battery during the day and power the lights at night with only one integrated converter rather than two separate converters.
The document proposes a matrix converter-based dynamic voltage restorer (DVR) system for power quality enhancement. The DVR uses a single matrix converter instead of a conventional AC/DC/AC converter. It is connected between the distribution feeder and load to mitigate voltage sags. The control system is based on dqo modeling of the matrix converter. It injects power from an energy storage device like a flywheel to restore the load voltage during sags. Simulation results show the DVR is able to effectively reduce sags and regulate the supply voltage, improving power quality.
This document discusses simulation of maximum power point tracking (MPPT) algorithms for photovoltaic (PV) solar systems. It notes that PV panels have non-linear output characteristics and produce maximum power at a single operating point, but this point varies with temperature and light intensity. Various MPPT algorithms have been developed to track this maximum power point (MPP) under changing conditions. The document outlines the components of a typical PV system and describes the role of the MPPT in matching the PV panel impedance to the load impedance to extract maximum available power. It also provides details on the perturb and observe (P&O) MPPT algorithm and concludes that accurate simulation models are important for evaluating PV system performance under different operating environments
This document proposes using a static compensator (STATCOM) connected to a battery energy storage system (BESS) to mitigate power quality issues from wind energy generation. Wind power fluctuates due to changing wind speed, which affects power quality. The STATCOM and BESS work together to absorb or inject reactive power and regulate real power flow to the load. Excess power generated during low demand hours can be stored in the batteries. This combination of battery storage and wind generation helps stabilize the output waveform and improve power quality at the point of common coupling.
This document proposes using a static compensator (STATCOM) connected to a battery energy storage system (BESS) to mitigate power quality issues from wind energy generation. Wind power fluctuates due to changing wind speed, which affects power quality. The STATCOM and BESS work together to absorb or inject reactive power and regulate real power flow to the load. Excess power generated during low demand hours can be stored in the batteries. This combination of battery storage and wind generation helps stabilize the output waveform and improve power quality at the point of common coupling.
This document proposes using a static compensator (STATCOM) connected to a battery energy storage system (BESS) to mitigate power quality issues from wind energy generation. Wind power fluctuates due to changing wind speed, which affects power quality. The STATCOM injects reactive power from the BESS to absorb harmonic current and regulate voltage. This improves power quality by making the source current harmonic-free and stabilizing the system voltage. The combination of BESS and STATCOM helps compensate for wind power fluctuations and produces higher quality power from the wind generation system.
Social media management system project report.pdfKamal Acharya
The project "Social Media Platform in Object-Oriented Modeling" aims to design
and model a robust and scalable social media platform using object-oriented
modeling principles. In the age of digital communication, social media platforms
have become indispensable for connecting people, sharing content, and fostering
online communities. However, their complex nature requires meticulous planning
and organization.This project addresses the challenge of creating a feature-rich and
user-friendly social media platform by applying key object-oriented modeling
concepts. It entails the identification and definition of essential objects such as
"User," "Post," "Comment," and "Notification," each encapsulating specific
attributes and behaviors. Relationships between these objects, such as friendships,
content interactions, and notifications, are meticulously established.The project
emphasizes encapsulation to maintain data integrity, inheritance for shared behaviors
among objects, and polymorphism for flexible content handling. Use case diagrams
depict user interactions, while sequence diagrams showcase the flow of interactions
during critical scenarios. Class diagrams provide an overarching view of the system's
architecture, including classes, attributes, and methods .By undertaking this project,
we aim to create a modular, maintainable, and user-centric social media platform that
adheres to best practices in object-oriented modeling. Such a platform will offer users
a seamless and secure online social experience while facilitating future enhancements
and adaptability to changing user needs.
A brand new catalog for the 2024 edition of IWISS. We have enriched our product range and have more innovations in electrician tools, plumbing tools, wire rope tools and banding tools. Let's explore together!
A brief introduction to quadcopter (drone) working. It provides an overview of flight stability, dynamics, general control system block diagram, and the electronic hardware.
OCS Training Institute is pleased to co-operate with
a Global provider of Rig Inspection/Audits,
Commission-ing, Compliance & Acceptance as well as
& Engineering for Offshore Drilling Rigs, to deliver
Drilling Rig Inspec-tion Workshops (RIW) which
teaches the inspection & maintenance procedures
required to ensure equipment integrity. Candidates
learn to implement the relevant standards &
understand industry requirements so that they can
verify the condition of a rig’s equipment & improve
safety, thus reducing the number of accidents and
protecting the asset.
Encontro anual da comunidade Splunk, onde discutimos todas as novidades apresentadas na conferência anual da Spunk, a .conf24 realizada em junho deste ano em Las Vegas.
Neste vídeo, trago os pontos chave do encontro, como:
- AI Assistant para uso junto com a SPL
- SPL2 para uso em Data Pipelines
- Ingest Processor
- Enterprise Security 8.0 (Maior atualização deste seu release)
- Federated Analytics
- Integração com Cisco XDR e Cisto Talos
- E muito mais.
Deixo ainda, alguns links com relatórios e conteúdo interessantes que podem ajudar no esclarecimento dos produtos e funções.
https://www.splunk.com/en_us/campaigns/the-hidden-costs-of-downtime.html
https://www.splunk.com/en_us/pdfs/gated/ebooks/building-a-leading-observability-practice.pdf
https://www.splunk.com/en_us/pdfs/gated/ebooks/building-a-modern-security-program.pdf
Nosso grupo oficial da Splunk:
https://usergroups.splunk.com/sao-paulo-splunk-user-group/
A vernier caliper is a precision instrument used to measure dimensions with high accuracy. It can measure internal and external dimensions, as well as depths.
Here is a detailed description of its parts and how to use it.
Response & Safe AI at Summer School of AI at IIITHIIIT Hyderabad
Talk covering Guardrails , Jailbreak, What is an alignment problem? RLHF, EU AI Act, Machine & Graph unlearning, Bias, Inconsistency, Probing, Interpretability, Bias
Understanding Cybersecurity Breaches: Causes, Consequences, and PreventionBert Blevins
Cybersecurity breaches are a growing threat in today’s interconnected digital landscape, affecting individuals, businesses, and governments alike. These breaches compromise sensitive information and erode trust in online services and systems. Understanding the causes, consequences, and prevention strategies of cybersecurity breaches is crucial to protect against these pervasive risks.
Cybersecurity breaches refer to unauthorized access, manipulation, or destruction of digital information or systems. They can occur through various means such as malware, phishing attacks, insider threats, and vulnerabilities in software or hardware. Once a breach happens, cybercriminals can exploit the compromised data for financial gain, espionage, or sabotage. Causes of breaches include software and hardware vulnerabilities, phishing attacks, insider threats, weak passwords, and a lack of security awareness.
The consequences of cybersecurity breaches are severe. Financial loss is a significant impact, as organizations face theft of funds, legal fees, and repair costs. Breaches also damage reputations, leading to a loss of trust among customers, partners, and stakeholders. Regulatory penalties are another consequence, with hefty fines imposed for non-compliance with data protection regulations. Intellectual property theft undermines innovation and competitiveness, while disruptions of critical services like healthcare and utilities impact public safety and well-being.
Best Practices of Clothing Businesses in Talavera, Nueva Ecija, A Foundation ...IJAEMSJORNAL
This study primarily aimed to determine the best practices of clothing businesses to use it as a foundation of strategic business advancements. Moreover, the frequency with which the business's best practices are tracked, which best practices are the most targeted of the apparel firms to be retained, and how does best practices can be used as strategic business advancement. The respondents of the study is the owners of clothing businesses in Talavera, Nueva Ecija. Data were collected and analyzed using a quantitative approach and utilizing a descriptive research design. Unveiling best practices of clothing businesses as a foundation for strategic business advancement through statistical analysis: frequency and percentage, and weighted means analyzing the data in terms of identifying the most to the least important performance indicators of the businesses among all of the variables. Based on the survey conducted on clothing businesses in Talavera, Nueva Ecija, several best practices emerge across different areas of business operations. These practices are categorized into three main sections, section one being the Business Profile and Legal Requirements, followed by the tracking of indicators in terms of Product, Place, Promotion, and Price, and Key Performance Indicators (KPIs) covering finance, marketing, production, technical, and distribution aspects. The research study delved into identifying the core best practices of clothing businesses, serving as a strategic guide for their advancement. Through meticulous analysis, several key findings emerged. Firstly, prioritizing product factors, such as maintaining optimal stock levels and maximizing customer satisfaction, was deemed essential for driving sales and fostering loyalty. Additionally, selecting the right store location was crucial for visibility and accessibility, directly impacting footfall and sales. Vigilance towards competitors and demographic shifts was highlighted as essential for maintaining relevance. Understanding the relationship between marketing spend and customer acquisition proved pivotal for optimizing budgets and achieving a higher ROI. Strategic analysis of profit margins across clothing items emerged as crucial for maximizing profitability and revenue. Creating a positive customer experience, investing in employee training, and implementing effective inventory management practices were also identified as critical success factors. In essence, these findings underscored the holistic approach needed for sustainable growth in the clothing business, emphasizing the importance of product management, marketing strategies, customer experience, and operational efficiency.
Conservation of Taksar through Economic RegenerationPriyankaKarn3
This was our 9th Sem Design Studio Project, introduced as Conservation of Taksar Bazar, Bhojpur, an ancient city famous for Taksar- Making Coins. Taksar Bazaar has a civilization of Newars shifted from Patan, with huge socio-economic and cultural significance having a settlement of about 300 years. But in the present scenario, Taksar Bazar has lost its charm and importance, due to various reasons like, migration, unemployment, shift of economic activities to Bhojpur and many more. The scenario was so pityful that when we went to make inventories, take survey and study the site, the people and the context, we barely found any youth of our age! Many houses were vacant, the earthquake devasted and ruined heritages.
Conservation of those heritages, ancient marvels,a nd history was in dire need, so we proposed the Conservation of Taksar through economic regeneration because the lack of economy was the main reason for the people to leave the settlement and the reason for the overall declination.
2. Interruptions are classified by IEEE 1159 into
either a short-duration or long-duration
variation. However, the term “interruption”
is often used to refer to short-duration
interruption, while the latter is preceded by
the word “sustained” to indicate a long-
duration. They are measured and described
by their duration since the voltage
magnitude is always less than 10% of
nominal.
3. Interruption is defined as the decrease in
the voltage supply level to less than 10%
of nominal for up to one (1) minute
duration.
They are further subdivided into:
Instantaneous (1/2 to 30 cycles),
Momentary (30 cycles to 3 seconds) and
Temporary (3 seconds to 1 minute).
4. Interruptions mostly result from reclosing
circuit breakers or reclosers attempting to
clear non-permanent faults, first opening and
then reclosing after a short time delay.
The devices are usually on the distribution
system, but at some locations, momentary
interruptions also occur for faults on the sub
transmission system.
The extent of interruption will depend on
the reclosing capability of the protective
device.
5. For example, instantaneous reclosing will
limit the interruption caused by a temporary
fault to less than 30 cycles. On the other
hand, time delayed reclosing of the
protective device may cause a momentary or
temporary interruption.
Aside from system faults, interruptions can
also be due to control malfunctions and
equipment failures.
6. Consequences of short interruptions are
similar to the effects of voltage sags.
Interruptions may cause the following (but
not limited to):
Stoppage of sensitive equipment (i.e.
computers, PLC, ASD)
Unnecessary tripping of protective devices
Loss of data
Malfunction of data processing equipment.
7. Sustained Interruption is defined by IEEE
1159 as the decrease in the voltage supply
level to zero for more than one (1) minute. It
is classified as a long duration voltage
variation phenomena.
Sustained interruptions are often permanent
in nature and require manual intervention
for restoration.
8. In addition, they are specific power system
phenomena and have no relation to the
usage of the term outage. Outage does not
refer to a specific phenomenon, but rather
to the state of a system component that has
failed to function. Furthermore, in the
context of power quality monitoring,
interruption has no relation to reliability or
other continuity of service statistics.
9. Sustained interruptions are usually caused by
permanent faults due to storms, trees
striking lines or poles, utility or customer
equipment failure in the power system or mis
coordination of protection devices.
Consequently, such disturbances would result
to a complete shutdown of the customer
facility.
10. Some interruptions may be preceded by a
voltage sag, particularly when these PQ
problems are due to faults on the source
system. The voltage sag occurs between the
time a fault initiates and the protective
device operates. On the faulted feeder, loads
will experience a voltage sag followed
immediately by an interruption.
11. The figure below illustrates a
momentary interruption during
which voltage on one phase sags
to about 20 percent for about 3
cycles, which subsequently
drops to zero for about 1.8 s
until the recloser closes back in.
13. To prevent interruptions, the utility may do the
following:
1. Reduce incidents of system faults
Includes arrester installation, feeder inspections, tree
trimming and animal guards
2. Limit the number of affected customers
interrupted
Improve selectivity through single-phase reclosers
and/or extra downstream reclosers
3. Fast reclosing
14. To protect equipment from interruptions,
end-users may use Uninterruptible Power
Supply (UPS) and other energy storage
systems. Back-up generator or Self-
generation is necessary for sustained
interruptions.
Other solutions include the use of static
transfer switch and dynamic voltage
restorer with energy storage.
15. Interruptions can be the result of
scheduled, the customers are announced before
doing any programmed actions into the
distribution network
accidentals, caused by the permanents or
temporary faults, generally produced by external
events, equipments faults etc.
power system faults
equipment failures
control system malfunctions
Delayed reclosing of the protective device may
cause
a momentary or temporary interruption
16. A power outage (also called
a power cut, a power out,
a power blackout, power
failure or a blackout) is the loss
of the electrical power network
supply to an end user.
17. There are many causes of power failures in
an electricity network. Examples of these
causes include faults at power stations,
damage to electric transmission
lines, substations or other parts of
the distribution system, a short
circuit, cascading failure, fuse or circuit
breaker operation
18. A customer is no longer
supplied with electricity
due to one or more
outages in the supply.
19. Long interruptions are by far the most severe
power quality event; thus any document
defining or guaranteeing the quality of
supply should contain limits on frequency
and duration of interruptions.
The international standards on power quality
do not yet give any limitations for
interruption frequency or duration.
20. The European voltage quality standard EN
50160 comes closest by stating that "under
normal operating conditions the annual
frequency of voltage interruptions longer
than three minutes may be less than 10 or up
to 50 depending on the area."
The document also states that it is not
possible to indicate typical values for the
annual frequency and durations of long
interruptions.
21. Many customers want more accurate limits
for the interruption frequency Therefore,
some utilities offer their customers special
guarantees, sometimes "power quality
contracts The utility guarantees the
customer that there will more than a certain
number of interruptions per year.
If this maximum number of interruptions is
exceeded in a given year, the utility will pay
a certain amount of money per interruption
to the customer.
22. This can be a fixed amount per
interruption, defined n the contract,
or the actual costs and losses of the
customer due to the interrupt Some
utilities offer various levels of
quality, with different costs.
23. The number of options is almost unlimited:
customer willingness to pay extra for higher
reliability and utility creativity are the main
influencing factors at the moment.
Technical considerations hot super to play
any role in setting levels for the maximum
number of interruptions or the cost of the
various pins For a customer to make a
decision about the be option, data should be
available, not only about the average
interruption frequency but also on the
probability distribution of the number of
interruptions per year
24. Contractual agreements about the voltage
quality are mainly aimed at industrial customers.
But also for domestic customers, utilities offer
compensation.
Utilities in the UK be to offer a fixed amount to
cash customer interrupted for longer than hours
In The Netherlands a court has ruled that
utilities have to compensate the customers for
all interruption costs, unless the utility can
prove that they are not blame for the
interruption. Also in Sweden some utilities offer
customers compensation for the interruption
25. The inconvenience of an interruption
increases very fast when its duration en few
hours This holds especially for domestic
customers.
Therefore it makes a not reduce in number
of interruptions (which might be very
expensive) but the duration Limiting the
duration of interruptions is a basic
philosophy in power system and operation in
almost any country. In the U.K., as an
example, the duration of the interruption is
limited in three ways:
26. The Office of Electricity Regulation (OFFER) sets
targets for the percentage of interruptions
lasting longer than 3 hours and for the
percentage of interruptions lasting longer than
24 hours. These are so-called "overall standings
of service.
The distribution company pays all customers
whose supply is interrupted for longer than 24
hours. This is a so called guaranteed standard of
service.
The design of the system is such that a supply
interruption is likely to be restored within a
certain time.
27. To consider interruptions of the
supply in the design and operation
of power system, the inconvenience
due to interruptions needs to be
quantified one way or the other.
The term inconvenience is rather
vogue and broad.
28. Additional investment does not
always give a more reliable system:
an increase in the number of
components could even decrease the
reliability.
Reliability is not a single-
dimensional quantity. Both
interruption frequency and duration
of interruption influence the
interruption costs.
29. Direct costs
Indirect costs
Non material inconvenience
Costs per interruption
Costs per interrupted KW
Costs per Kwh not delivered
Costs of interruption rated to the peak load
Costs per interruption rated to the annual
consumption
31. There is no shading scale of reliability and costs.
The system designer can choose between a
limited number of design options; sometimes
there are just two options available. The choice
becomes simply a comparison of advantage and
disadvantages of the two options,
The two cost terms cannot simply be added. One
term (building and opera notional costs) has a
small uncertainty, the other term (interruption
costs) has large uncertainty due to the
uncertainty in the actual number and duration
interruptions. A more detailed risk analysis is
needed than just adding the expected costs.
32. These are the costs which are directly
attributable to the interruption. The standard
example for domestic customers is the loss of
food in the refrigerator, For industrial customers
the direct costs consist, among others, of lost
raw material. lost production, and salary costs
during the non-productive period.
For commercial customers the direct costs are
the loss of profit and the salary costs during the
non-productive period.
When assessing the direct costs one has to be
watchful of double-counting. One should at first
subtract the savings made during the
interruption.
33. Indirect costs. The indirect costs are much
harder evaluate and in many cases not simply
to express in amount of money.
A company can lose future orders when an
interruption leads to delay in delivering a
product. A domestic customer can decide to
take an insurance against loss of freezer
contents:
A commercial customer might install a
battery backup. A large industrial customer
could even decide to move a plant to an area
with less supply interruptions.
34. The main problem with this cost term is that
it cannot be attributed to a single
interruption, but to the real or perceived)
quality of supply as a whole Non-material
inconvenience.
Some inconvenience cannot be expressed in
money. Not being able to listen to the radio
for 2 hours can be a serious inconvenience,
but the actual costs are zero.
35. In industrial and commercial environments,
the non-material inconvenience can also be
big without contributing to the direct or
indirect costs.
A way of quantifying these costs is to look at
the amount of money a customer is willing to
pay for not having this Interruption
36. Costs per interruption. For an individual
customer the costs of an interrupt of
duration d can be expressed in dollars.
There is no confusion possible about this. For
simplicity, we neglect the fact that the costs
not only depend on the duration but on many
other factors as well.
The costs per interruption can be determined
through an inventory of all direct and
indirect costs. .
37. Costs per interrupted kW, Let C(d) be the costs
of an interruption of d for customer i, and L, the
load of this customer when duration there would
not bae been an interruption. The costs per
interrupted kW are defined as
𝑪 𝒊 (𝒅)
𝑳𝒊
and are expressed in $/kW. For a group of
customers experiencing the same interruption,
the costs per interrupted kW are defined as the
ratio of the total costs of the interruption and
the total load in case there would not have been
an interruption:
⅀𝒊 𝑪 𝒊 (𝒅)
⅀𝒊 𝑳𝒊
38. Costs per kWh not delivered. In many studies
the assumption is made that the cost of an
interruption is proportional to the duration
of the interruption. The cost per kWh not
delivered is defined as
𝑪 𝒊 (𝒅)
𝒅𝑳 𝒊
and is constant under the assumption. The
cost per kWh is expressed in S/kWh. For a
group of customers the cost per kWh not
delivered is defined as
⅀𝒊 𝑪 𝒊
𝒅⅀𝒊 𝑳𝒊
39. Some utilities obtain an average cost per
kWh not delivered for all their customers.
This value is assumed constant and used as a
reference value in system operation and
design.
The term "value of lost load" is sometimes
used for the cost per kWh not delivered
averaged over all customers.
40. Cost of interruption related to the peak load.
A problem in surveys is that the actual load
of individual customers in case there would
not have been a interruption is often not
known.
One should realize that surveys cons
hypothetical interruptions, rarely actual
ones. For industrial and commercial
customers the peak load is much easier to
obtain, as it is typically part of the supply
contract.
41. The cost of an interruption can be divided by
the peak load, to get a value in $/kW. Some
care is needed when interpreting this value,
as it is not the same as the cost per kW
interrupted (also in $/kW).
For planning purposes the cost of
interruption related to the peak load can still
be a useful value. The design of a system is
based for a large part on peak load, so that
rating the cost to the peak load gives a
direct link with the design.
42. Cost per interruption related to the annual
consumption. For domestic customers it is
easier to obtain the annual consumption than
the peak load. Rating cost of an interruption
to the annual consumption gives a value in
$/kWh.
Note that this has no relation to the costs
per kWh not delivered.
43. The power system is often divided
into three functional parts, each
with its own specific design and
operation problems and solutions:
Generation
Transmission
Distribution
44. In the reliability analysis a similar
distinction is made between three
so-called hierarchical levels of
reliability
Level I: generation
Level II: generation and transmission
Level III: generation, transmission
and distribution
46. Level II reliability concerns the availability of
power at so-called bulk supply points:
typically transmission substations where
power is transformed down to distribution
voltage.
The power not only has to be generated but
also transported to the customers. The
availability of sufficient lines or cables has to
be taken into account.
Level II reliability studies are much more
difficult than level 1 studies, and are still
under considerable development.
47. Overloading of lines
Reliability of the protection
Dynamic system behavior
Common mode outages
Weather related outages
Normal weather
Adverse weather
Major storm disaster
48. Radial systems
Duration of an interruption
The availability of the
alternative supply
Adverse weather
Embedded generation
49. There is some serious confusion about
terminology on interruptions of different
duration.
Terms like short interruptions, momentary
interruptions, temporary interruption,
instantaneous interruption, and transient
outages are all used with more or less the
same meaning.
The definition of short interruptions used for
this chapter is not based on duration but on
the method of restoring the supply. This
chapter (short
50. interruptions) discusses automatic
restoration, where Chapter 2 (long
interruptions) discusses manual restoration.
Below, an overview is given of the various
terms and definitions used in t European
standard EN 50160 and in three IEEE
standards. The definition EN 50160 are
identical to the IEC definitions.
EN 50160
Long interruption longer than three minutes.
Short interruption up to three minutes.
51. IEEE Std.1159-1995
This standard is considered by many as providing
the basic power definitions It distinguishes
between momentary, sustained, and temporary
interruptions. Note the overlap between
sustained and temporary interruptions-
Momentary interruption between 0.5 cycles and
3 seconds.
Sustained interruption: longer than 3 seconds.
Temporary Interruption between 3 seconds and 1
minute.
52. IEEE Std. 1250-1995
This standard was published at about the same
time as IEEE Std. 1139-19 but it uses somewhat
different definitions. The difference is especially
striking for interruptions.
Instantaneous interruption between 0.5 and 30
cycles (half a second).
Momentary Interruption between 30 cycles and 2
seconds.
Temporary interruption between 2 seconds to 2
minutes.
Sustained interruption: longer than 2 minutes.
53. IEEE Std. 859-1987
This somewhat older standard document gives
definitions for terms related to power system
reliability. A distinction is made between different
types of outages based on the duration of the outage.
This standard does not me specific time range but
uses the restoration method to distinguish the
different types. Although outages and interruptions
are different phenomenal Section 2.1.3) they related
closely enough to compare the terminology.
Transient outages are restored automatically.
Temporary outage is restored by manual switching –
Permanent outages is restored through repair or
replacement.
54. Figure 3.1 shows an example of an overhead
distribution network.
Each feeder consists of a main feeder and a
number of lateral conductors.
Most faults on lines are transient: they
require operation of the protection, but do
not cause permanent damage to the system.
A typical cause of a transient fault is a
lightning stroke to overhead line.
56. The lightning stroke injects a very high
current into the line causing very fast rising
voltage.
The lightning current varies between 2 and
200 kA in peak value.
The typical lightning current has a peak
value of Ipeak= 20 kA which is reached within
1 µs after its initiation.
57. If the wave impedance Zwave of
the line is 200ohms, the voltage
can theoretically reach a value
of
𝑉𝑝𝑒𝑎𝑘 =
𝑍𝑤𝑎𝑣𝑒
2
𝐼 𝑝𝑒𝑎𝑘=100Ώ×20KA=2MV
58. The voltage will never reach such a value in
reality (with the possible exception of
transmission systems with operating voltages of
400 kV or higher), because a flashover to ground
or between two phases will result long before
the voltage reaches such a high value.
The result is an arcing fault between one phase
and ground or between two or more phases with
or without ground.
Soon after the protection removes the faulted
line from the system, the arc disappears.
Automatic reclosing will restore the supply
without any permanent damage to the system.
59. Also, smaller objects causing a temporary
path to ground will only cause a transient
short circuit.
The object (e.g. a small branch fallen from a
tree) will either drop to the ground or
evaporate due to the high current during the
fault, leaving only an arc which disappears
again soon after the protection intervenes.
The duration of an interruption due to a
transient fault can thus be enormously
reduced by automatically restoring the
supply after an interruption.
60. In case of a fault somewhere on the feeder, the
circuit breaker opens instantaneously and closes
again after a "reclosing interval" or "dead time"
ranging from less than one second up to several
minutes.
There is of course a risk that the fault was not a
transient one but permanent. In that case the
protection will again notice a large overcurrent
after reclosurer leading to a second trip signal.
Often the recloser gives the fault a second
chance at extinguishing, by means of a longer
tripping time and/or a longer reclosing interval.
61. The fuse saving scheme typically
uses a low set instantaneous
overcurrent element which will trip
the feeder breaker before
the fuse branch can blow, and the
breaker is then immediately
reclosed.
62. A practice associated with reclosing and short
interruptions is "fuse saving. In Fig 3.1 the
laterals away from the main feeder are
protected by means of expulsion fuses.
These are slow fuses which will not trigger when
a transient fault is cleared by the main
breaker/recloser.
Thus, a transient fault will be cleared by the
recloser and the supply will be automatically
restored.
A permanent fault can also be cleared by the
main breaker, but that would lead to a long
interruption for all customers fed from this
feeder. Instead, a permanent fault is
64. An expulsion fuse is a vented fuse in which
the expulsion effect of the gases produced
by internal arcing, either alone or aided by
other mechanisms, results in current
interruption. An expulsion fuse is not
current limiting and, as a result, limits the
duration of a fault on the electrical system,
not the magnitude
65. cleared by an expulsion fuse. To achieve this,
the recloser has two settings an instantaneous
trip and a delayed trip.
The protection coordination should be such that
the instantaneous trip is faster than the
expulsion fuse and the delayed trip slower, for
all possible fault currents.
From the above description we can conclude
that the following trade-off has been made a
short interruption for all customers (fed from
this feeder) instead of a long interruption for
some customers.
The alternative would be more long
interruptions, however, not every short
interruption would become a long interruption.
66. The combination of reclosing and fuse
saving, as described above, leads different
voltage magnitude events for different
customers.
Figure 3.2 shows the events due to one
reclosing action as experienced by a
customer on the faulty feeder (indicated by
"1" in Fig 3.1) and by a customer on another
feeder fed from substation bus (indicated by
"2").
In Fig. 3.2, A is the fault-clearing time and B
the reclosing interval.
69. The customer on the faulted feeder (solid
line) will experience a decrease in voltage
during the fault, similar in cause and
magnitude to a voltage sag.
The difference between the two customers is
in the effect of the fault clearing.
For customer on the non faulted feeder, the
voltage recovers to its pre-event value
customer will only experience a voltage sag.
For the customer on the faulted e the
voltage drops to zero
70. The customer on a neighboring feeder (dashed
line) will see a voltage sag with 2 duration equal
to the fault-clearing time.
The moment the recloser opens, the voltage
recovers. If the fault is still present at the first
recloser, the customer on the non faulted feeder
will experience a second voltage sag.
Customers on the faulted feeder will experience
a second short interruption or a long
interruption.
Figure 3.3 [11] shows an actual recording of a
short interruption.
72. The top figure corresponds to the dashed line
in Fig. 3.2 (customer on a non fault feeder).
The bottom figure is for a customer on the
faulted feeder (solid line in Fig. 3,2).
The fault-clearing time is about two cycles,
the dead time about two seconds.
The first recloser is not successful, the
second one is. The top figure shows a voltage
sag to about 75% of two-cycle duration, the
bottom figure a voltage reduction to 50% for
two cycles followed by zero voltage for
about two seconds.
73. When comparing Fig. 3.2 and Fig. 3.3, note that
the horizontal axis of Fig. 3.2 is not to scale, B is
much larger than A.
This is the typical situation. The fault-clearing
time (A) is only a few cycles, whereas the
reclosing time (B) can be up to several minutes.
Another example of the initiation of a short
interruption is shown in Fig. 3.4 (3) We see that
the voltage magnitude initially drops to about
25% of nominal and to almost zero after three
cycles.
The spikes in the voltage are due to the are
becoming instable around the current zero-
crossing. Apparently the arc gets more stable
after two cycles.
74. The moment the circuit breaker in Fig. 3.1
opens, the feeder and the load fed from it
are no longer supplied.
The effect of this is normally that the
voltage drops to zero very fast.
There are, however, situation.is in which the
voltage drops to zero relatively slow, or even
remains at a nonzero value. The latter would
strictly speaking not be an interruption, but
the origin is similar to that of an
interruption so that a short description of the
phenomenon is applied here.
77. All this assumes that the short-circuit fault is
no longer present on the feeder.
As long as the fault is present, all above-
mentioned machines feed into the fault so
that the feeder voltage remains low.
The fault-current contribution makes that
the arc is less likely to extinguish, but after
extinguishing of the arc there will be a
chance of a remaining voltage on the feeder.
78. For interruptions due to
incorrect protection
intervention there is no short
circuit fault present on the
feeder and the machines
connected to the feeder may
cause a temporary or permanent
nonzero voltage.
79. As short interruptions are due to automatic
switching actions, their recording requires
automatic monitoring equipment.
Unlike long interruptions, a short
interruption can occur without anybody
noticing it. That is one of the reasons why
utilities do not yet collect and publish data
on short interruptions on a routine basis.
One of the problems in collecting this data
on a routine basis is that some kind of
monitoring equipment needs to be installed
on all feeders.
80. A number of surveys have been performed to
obtain statistical information about voltage
magnitude variation and events. With those
surveys, monitors were installed a number of
nodes spread through the system.
The surveys will be discussed in more detail in
Chapter 6. As with long interruptions,
interruption frequency and duration of
interruption are normally presented as the
outcome of the survey.
Again like with long interruptions much more
data analysis is possible, e.g., interruption
frequency versus time of day or time of year,
distributions for the time between events,
variation among customers.
81. The number of short interruptions has been
obtained by various power quality surveys.
Comparison of the numbers obtained by each
survey gives information about the average
voltage quality in the various areas.
A comparison between the number of short
interruptions counted at various places in the
system can teach us how the interruptions
"propagate" in the system.
Such a comparison is made in Table 3.1 for two
large North American surveys: the EPRI survey
and the NPL survey (54) The EPRI survey
monitored both distribution substations and
distribution feeders.
82. From Table 3.1 we see that the overall trend is
for the number of short interruptions to increase
when moving from the source to the load. This is
understandable as there are more possible
tripping points the further one moves towards
the load.
Especially interruptions lasting several seconds
and longer mainly originate in the low-voltage
system.
For interruptions less than one second in
duration, the frequency remains about the same,
which makes us conclude that they probably
originate in the distribution substation or even
higher up in the system.
85. The large number of very short interruptions
(less than six cycles) on distribution feeders is
hard to explain, especially as they do not show
up in the low-voltage data.
Similar conclusions can be drawn from the CEA
survey (69) and from the EFI survey 167), some
results of which are shown in Tables 3.2 and 3.3.
We again see a larger number of interruptions,
mainly of 1 second and longer, for low-voltage
than for medium-voltage systems.
Both the Canadian (CEA) and the Norwegian (EFI)
data show a considerable number of very short
interruptions, for which no explanation has been
found yet.
86. A direct consequence of reclosing actions is that a
customer may experience two A or more events
within a short interval. When the short-circuit fault is
still present upon the first recloser, the customers
fed from the faulted feeder will experience a second
events.
This is another short interruption if a second attempt
at reclosing is made Otherwise the second event will
be a long interruption. A customer fed from a non
faulted feeder experiences two voltage sags in a
short period of time.
For a few years a discussion has been going on about
whether to count this as one event of a multiple
events (20J. The most recent publications of North
American survey consider a 1-minute or 5-minute
window.
87. If two or more events take place within such
a window, they are counted as one event.
The severity of the multiple event (e,
magnitude and duration) is the severity of
the most severe single event within the
window. Some examples of the working of a
"five-minute filter" are shown in Fig.
Using such filter is suitable for assessment of
the number of equipment trips as the
equipment will trip on the most severe event
or not at all.
88. The cumulative effect of the events is
neglected, but the general impression is that this
effect is small.
This has however not be confirmed by
measurements yet. In some cases it could still be
needed to know the total event frequency, thus
counting all events even if they come very close.
Two possible applications are components which
show accelerated aging due to short under
voltage events, and (2) equipment which only
trips during a certain fraction of its load cycle
91. In the latter case the equipment has a
probability to trip during each of the three
events, and the total probability is of course
larger than the probability to trip during the
most severe event only.
The NPL low-voltage data for short interruptions
have been presented with and without the
above-mentioned filter in Table 3.4 (54].
The three rows give, from top to bottom: the
number of short interruptions when each event
is counted as one event no matter how close it is
to another event; the number of events when
multiple events within a 5-minute interval are
counted as one event; the reduction in number
of events due to the application of this filter
92. The opening of the faulted phase during a single-
phase to ground fault.
Single-phase auto-reclosing (SPAR) is used for
restoring power supply to clear temporary
single-phase to ground fault in medium-voltage
distribution systems.
A relay protection scheme that provides for
single pole tripping and reclosing is one that,
after it detects a fault and establishes that
tripping should take place, will trip only the
faulted phase on single-line-to-ground faults and
all three phases on all multi-phase faults.
93. Single-phase tripping is used in
transmission systems to maintain
synchronicity between both sides of a
line.
Single-phase tripping is rarely used in
distribution or low-voltage systems.
Not only will it require more expensive
equipment, but it will also reduce the
chance of a successful reclosure.
94. The fault current continues to flow via the
nonfaulted phases.
This reduces the chance that the fault will
extinguish and thus increases the number of
reclosure attempts and the number of long
interruptions.
But if the reclosure is successful, single-
phase tripping has clear advantages over
three-phase tripping and therefore justifies
being discussed here.
95. We will have a look at the voltages experienced
by the customer during single-phase tripping.
A distinction is made between two distinctly
different situations, both assuming a single-
phase-to-ground fault followed by tripping of the
faulted phase.
The low-impedance path between the faulted phase
and ground (the fault) is still present so that the
voltage in the faulted phase remains zero or close to
zero. We will call this the "during-fault period.
The fault has extinguished, the short circuit has now
become an open circuit because the breaker in that
phase is still open. This we will call the post-fault
period."
96. Voltage during Fault period
Voltage during post Fault
period
Current during fault period
97. The phase-to-neutral voltages in the during-
fault period are, with a the faulted phase
𝑉𝑎 = 0
𝑉𝑏 = (−
1
2
−
1
2
𝑗 3 )𝐸
𝑉𝑐 = (−
1
2
+
1
2
𝑗 3 )𝐸 (3.5)
98. with E the magnitude of the pre-event
voltage.
It has been assumed here that the pre event
voltages form a balanced three-phase set,
and that the voltage in the faulted phase is
exactly equal to zero.
We will in most of the remainder of this book
use per unit voltages, with the pre-event
voltage magnitude as base.
In that case we get E = 1 and (3.5) becomes
100. Figure 3.9 shows the phase-to-neutral voltages
as a phasor diagram.
In this and sub sequent phasor diagrams the
during-event voltage is indicated via solid lines,
the pre- event voltage (i.e,, the balanced three-
phase voltage) via dotted lines, if different from
the during-event voltage.
If single-phase tripping would take place in a
low-voltage network, the voltages in Fig. 3.9
would be the voltages experienced by the
customers Only one out of three customers
would experience an interruption.
The others would not notice anything. Single-
phase tripping would thus reduce the number of
interruption events by a factor of three.
102. For tripping taking place on medium-voltage
feeders, the phase-to-phase voltages are of
more importance.
Large equipment fed at medium-voltage
level is in most cases connected in delta;
small single-phase equipment tends to be
connected between a phase and neutral but
at a lower voltage level fed via a delta-star
connected transformer.
In both cases the equipment experiences the
pu value of the phase-to-phase voltage at the
medium-voltage level.
103. The factor 3 is needed because 1 pu of the line
(phase-to-phase) voltage is 3 times as big as I pu
of the phase (phase-to-neutral) voltage. The
multiplication with j results in a rotation over
90° such that the axis of symmetry of the
disturbance remains along phase a and along the
real axis. The transformation in (3.7) will be the
basis of a detailed analysis of unbalanced
voltage sags in the forthcoming chapters, When
we leave away the prime ', we obtain the
following expressions for the voltages due to
single-phase tripping at the terminals of delta-
connected equipment:
104. Generally, a single line-to-ground fault on a
transmission line occurs when one conductor
drops to the ground or comes in contact with
the neutral conductor.
Such types of failures may occur in power
system due to many reasons like high-speed
wind, falling off a tree, lightning, etc.
106. When the fault extinguishes, the situation in the
faulted phase changes from a short circuit to an
open circuit.
In many cases a change in voltage occurs, thus
the resulting voltage is no longer equal to zero.
The voltage in the faulted phase depends on the
type of load connected To calculate this voltage
we need to consider the coupling between the
phases or use the theory of symmetrical
components.
To analyze an open circuit, the system has to be
modeled as seen from the open circuit point.
This results in three equivalent circuits: for the
positive sequence, for the
108. negative sequence, and for the zero sequence. These three
networks are shown in Fig 3.11. Zs1. Zs2, and Zso are
positive, negative, and zero-sequence impedance of the
source, ZL1. ZL2, and ZL0 are positive, negative, and zero-
sequence impedance of the load, ΔV1 ΔV2, and ΔV0. are
positive, negative, and zero-sequence voltage drop at the
open-circuit point, and E, is the positive-sequence source
voltage.
Negative and zero sequence source voltages are assumed
zero, and the load is assumed not to contain any sources.
Below we again assume E = 1 Sequence voltages and
currents at the open-circuit point can be calculated for
different types of open-circuit faults, by connecting the
three sequence networks in different ways.
For a single-phase open circuit, the voltage difference in
the two non faulted phases is zero and the current in the
faulted phase is zero:
109. ∆𝑉𝑏= 0
∆𝑉𝑐= 0
𝐼 𝑎 = 0
Where a is the faulted (open
circuited) phase.
110. Transforming these equations to symmetrical
component gives the following set of
equations
𝐼1 + 𝐼2 + 𝐼3 = 0
∆𝑉1=∆𝑉2
∆𝑉1=∆𝑉0