Protection Systems for Power generators
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NOv 2014 presentation that conducted by me at Myanmar's Leading Generator Selling company.
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Protection Systems for Power generators
- 1. by Nicholas Naing Protection Systems for the Power Generators
- 2. Index Agenta : 1 Nov 2014 1 p.m ~ 3 p.m “AGGC” 1.00 p.m : Welcome Speech by AGCC CEO 1.10 p.m : Introduction to the Speaker 1.15 p.m : Fault Analysis Detail 1.50 p.m : Tea Break 2.00 p.m : Protection Systems for Power Generators 2.40 p.m : Question and Answer Section 3.00 p.m : End of Presentation
- 3. Index Generator Protection What a Generator looks like
- 5. Index Why Upgrade? Generator and Transformer Existing generator and transformer protection (more than 5 years or non-digital) may: – Cause protection security issues Tripping on through-faults, external faults, swings, load encroachment and energizing – May lack comprehensive monitoring and communications capabilities Not provide valuable forensic info that can lead to rapid restoration – Not be up to ANSI/IEEE Standards! Insurance, Asset Reliability and Personal Liability Issues C37-102: Guide for the Protection of Synchronous Generators C37.91: Guide for Transformer Protection
- 6. Index Theory
- 7. Index Show Generator Theory General Overview and Typical System from Training CD
- 8. Index Generator Protection Internal and External Short Circuits The "Wild" Power System G Exciter Stator Ground Stator Phase System Ground System Phase
- 9. Index Generator Protection Review – Abnormal Operating Conditions Loss of Synchronism Abnormal Frequency Overexcitation Field Loss Inadvertent Energizing Breaker Failure Loss of Prime Mover Power Blown VT Fuses Open Circuits
- 10. Index Generator Protection Abnormal Operating Conditions The "Wild" Power System G Exciter Loss of Field Loss of Field Overexcitation Overexcitation Overexcitation Open Circuits Loss of Synchronism Inadvertent Energizing, Pole Flashover Abnormal Frequency Abnormal Frequency Breaker Failure Reverse Power Over Power
- 11. Index Small Machine Protection IEEE Buff Book Small – up to 1 MW to 600V, 500 kVA if >600V 32 Reverse Power 40 Loss of Excitation 51V voltage restraint 51G Ground overcurrent 87 Differential
- 12. Index Small Machine Protection IEEE Buff Book Medium – up to 12.5 MW 32 Reverse Power 40 Loss of Excitation 46 Negative Sequence 51V voltage restraint 51G Ground overcurrent 87 Differential
- 13. Index Small Machine Protection IEEE Buff Book Large – up to 50 MW 32 Reverse Power 40 Loss of Excitation 46 Negative Sequence 49 Thermal Overload 51V voltage restraint 51G Ground overcurrent 64 Ground Relay 87 Differential
- 14. Index Unit Connected, High Z Grounded Large Machine Protection IEEE C37.102 32 Reverse Power 40 Loss of Excitation 46 Negative Sequence 49 Thermal Overload 51V voltage restraint 51G Ground overcurrent 64 Ground Relay 87 Differential
- 16. Index Protection Functions Protection Functions Include: • Generator Stator Differential • Backup Distance Protection • 100% Stator Ground • Generator Unbalance • Loss of Excitation • Accidental Energization • Breaker Fail • Phase Overcurrent – Voltage Restraint • Neutral Inst. / Timed Overcurrent • Neg. Sequence Overcurrent • Under / Over Voltage • Under / Over Frequency • Generator Thermal Model
- 18. Index Generator Protection with GSU Wrap PTs on Low Side
- 19. IndexGenerator Protection with GSU Wrap PTs on High Side
- 20. IndexGenerator Protection PTs on Low Side
- 21. Index Desirable Attributes - Generator – Reverse Power (32) Should be sensitive to 0.05 pu to properly detect motoring in large steam turbines Existing E/M and Static relays not sensitive enough May cause shutdown difficulties – Negative Sequence (46) Should be sensitive to low values to detect open poles/conductors on system after GSU Existing E/M and Static relays not sensitive enough Long time low level events may cause excessive rotor heating, thermal tripping and damage rotor – 100% Stator Ground (59N / 59D) Protects all of the stator winding Existing schemes typically only see 90% Stop low level fault near neutral from degrading into a high level fault and causing large
- 22. Index Desirable Attributes - Generator Inadvertent Energizing (50/27) – High speed tripping of unit after breaker accidentally closed on dead machine, also pole flashover prior to syncing Most existing schemes do not incorporate – Many schemes fail due to complexity (reliance on breaker auxiliary switches, yard distance relays, etc. – If breaker is not tripped rapidly, mechanical and electric damage can occur to machine in fractions of a second! – Pole flashovers must be cleared by high speed breaker failure, as the breaker is open!
- 23. Index Line – Ground faults – Delta Connected Generator
- 24. Index Line – Ground faults – Wye Connected Generator
- 25. Index Protection Functions Generator Stator Differential • Stator Phase Differential • Dual Slope Percent Restraint Operating Characteristic • Directional Supervision under saturation conditionsDistance Backup Protection • 2 or 3 Zone Mho Distance Protection • Backup for primary line protection • Configurable Reach and Angle Distance Characteristic 100% Stator Ground Protection • 95% Fundamental OverVoltage • 15% Third Harmonic UnderVoltage Dual Slope Phase Differential Two Zone Distance Backup
- 26. Index Protection Functions Voltage Restraint Overcurrent Undervoltage Trip Curves Voltage Protection • Phase Overvoltage • Phase Undervoltage • Neutral Overvoltage (fundamental) • Neutral Undervoltage (3rd Harmonic) • Voltage Phase ReversalCurrent Protection • Phase, Ground and Negative Sequence Overcurrent Tripping • IEC, ANSI , IAC and Customizable Overcurrent Curves • Voltage Restraint increasing sensitivity under low voltage conditionsFrequency Protection • Overfrequency • Underfrequency
- 27. Index Protection Functions Loss of Excitation Thermal Protection • Generator Thermal Model • RTD Alarming and Tripping • RTD Biased Thermal Model Inadvertent Energization • Prevents Accidentally Closing a Stopped Generator onto a Live Line • Armed when Generator is Offline and Voltage is below a pre-set level Loss of Excitation (show Training CD) • Uses Impedance Circle for loss of excitation detection • 2 Zones for fault detection and control Volt/Hertz (Overexcitation) • Detects changes in the Volts/Hertz ratio of the generator or associated transformer Thermal Model – Voltage Dependant Overload Curves
- 28. Index Wiring
- 29. Index
- 30. Index
- 31. Index
- 32. Index
- 33. Index Example
- 34. Index Agenda : 1 Nov 2014 1 p.m ~ 3 p.m “AGCC” THANK YOU.