Power system protection
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System protection is used to detect problems in power system components and isolate faulty equipment to maintain reliable power. The key elements of a protection system include differential relays to protect generators and transformers from internal faults, overcurrent and distance relays to protect transmission lines from external faults, and bus differential relays to protect distribution buses. Protective devices are needed to maintain acceptable operation, isolate damaged equipment, and minimize harm to personnel and property.
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Power system protection
- 2. OUTLINE System protection-Definition Need for the protection Elements of the protection system
- 3. What is System protection? System protection is the art and science of detecting problems with power system components and isolating these components.
- 4. Need for the protection The power system must maintain acceptable operation 24 hours a day Voltage and frequency must stay within certain limits Protect the public Improve system stability Minimize damage to equipment Protect against overloads
- 5. Damage to Main Equipment
- 7. COMPONENTS USED FOR PROTECTION
- 12. Components to be protected Generators Transformers Lines Buses Capacitors
- 14. Generator Protection What can go wrong? Stator Winding Problems 1. Winding-winding short
- 15. How Do We Protect the Stator? A. Differential Protection (what goes in must come out) 1. Detects phase-phase faults
- 17. TRANSFORMER PROTECTION
- 18. Transformer Protection What can go wrong? ● Winding-to-winding faults ● Winding-to-ground faults ● Bushing faults
- 19. Transformer Protection Protection Methods: Fuse Overcurrent Differential
- 20. FUSE
- 23. TRANSMISSION LINE PROTECTION
- 24. TRANSMISSION LINE PROTECTION What Can Go Wrong? FAULTS (Short Circuits) SOME CAUSES OF FAULTS: Trees Lightning Animals (birds, squirrels, snakes) Weather (wind, snow, ice) Natural Disasters (earthquakes, floods) Faulty equipment (switches, insulators, clamps, etc.)
- 26. TYPES OF FAULTS Single-Phase-Ground: 70–80% Phase-Phase-Ground: 17–10% Phase-Phase: 10–8% Three-Phase: 3–2%
- 28. How Do We Protect Transmission Lines? Overcurrent BiDirectional Overcurrent Distance (Impedance) Line Current Differential
- 30. DISTANCE PROTECTION A distance relay measures the impedance of a line using the voltage applied to the relay and the current applied to the relay. When a fault occurs on a line, the current rises significantly and the voltage collapses significantly. The distance relay (also known as impedance relay) determines the impedance by Z = V/I. If the impedance is within the reach setting of the relay, it will operate.
- 32. RELAY PROTECTION
- 33. BUS PROTECTION Bus Differential: Current into bus must equal current out of bus
- 35. Capacitor Protection Purpose of capacitors: Shunt capacitors raise the voltage on a bus or line to a higher level, thus helping keep the voltage at desired level Series capacitors cancel out the inductive reactance of a line, thus making the line appear shorter increasing load flow on the line.