# B-6 Testing Numerical Transformer Differential Relays - IEEE

of 40/40

date post

11-Nov-2014Category

## Documents

view

3.105download

18

Embed Size (px)

description

### Transcript of B-6 Testing Numerical Transformer Differential Relays - IEEE

- 1. IEEE Rural Electric 2009 Testing Numerical Transformer Differential Relays Steve Turner Beckwith Electric Co., Inc.
- 2. Testing Numerical Transformer Differential Relays
- Commissioning versus Maintenance Testing

- Types of Transformer Differential Protection:

- Restrained Phase Differential

- High Set Phase Differential

- Ground Differential

- 3. Testing Numerical Transformer Differential Relays
- Topics:

- Transformer Differential Boundary Test (Commissioning)

- Ground Differential Sensitivity Test (Commissioning/Maintenance)

- Harmonic Restraint for Transformer Inrush (Maintenance)

- 4. Testing Numerical Transformer Differential Relays
- Commissioning

- Common Practice :

- Test all numerical relay settings

- verify settings properly entered

- Easily facilitated using computer

- automate test set & store results

- Hundreds of tests are possible

- numerical relays have many settings

- 5. Testing Numerical Transformer Differential Relays
- Commissioning

- Final Goal

- Ensure the transformer is properly protected for the particular application

- 6. Testing Numerical Transformer Differential Relays R G 46 Typical Distribution Transformer 46 : Negative-Sequence Overcurrent Element ( sees ground faults through bank ) R G : Grounding Resistor (Industrial Load)
- 7. Testing Numerical Transformer Differential Relays R G 46 E + Z T Z T Z T 3R G 46 I 2 Sensitive setting for ground fault - overreach for phase-to-phase fault
- 8. Testing Numerical Transformer Differential Relays Transformer Differential Characteristic Boundary Test I 2 I 1 87 Y Y Y Y I 1 = Winding 1 per unit current (A, B or C-phase) I 2 = Winding 2 per unit current (A, B or C-phase) 3 elements per function (A, B & C-phase) * Simulate Through Current
- 9. Testing Numerical Transformer Differential Relays Differential Characteristic Operating Equations I d = |I 1 I 2 |, Differential Current I r = |I 1 | + |I 2 |, Restraint Current 2
- 10. Testing Numerical Transformer Differential Relays Differential Characteristic I d I r Minimum Pickup (per unit) Percent ( % ) Slope X Y % = Y X *100%
- 11. Testing Numerical Transformer Differential Relays Differential Characteristic I d I r Minimum Pickup Percent Slope Trip Region Block Region
- 12. Testing Numerical Transformer Differential Relays Matrix I
d I r [ ] =
- -1

- 13. Testing Numerical Transformer Differential Relays Inverted Matrix I 1 I 2 [ ] = 1 - 1 [ ] * I d I r [ ]
- 14. Testing Numerical Transformer Differential Relays Differential Characteristic Test Current Equations I 1 = 0.5*I d + I r , Winding 1 Test Current (per unit) I 2 = -0.5*I d + I r , Winding 2 Test Current (per unit)
- 15. Testing Numerical Transformer Differential Relays Differential Characteristic Test Points I d I r Minimum Pickup Percent Slope Minimum Pickup = 0.2 per unit Slope = 28.6% 1 2 3 4
- 16. Testing Numerical Transformer Differential Relays Differential Characteristic Test Points (Per Unit) I d I r I 1 I 2 1 0.2 0.3 0.4 0.2 0.2 0.7 0.8 0.6 0.4 1.4 1.6 1.2 0.6 2.0 2.3 1.7 2 3 4 TABLE 1
- 17. Testing Numerical Transformer Differential Relays Delta-Wye Differential Characteristic I 2 I 1 87 Y Y Y I 1 = Winding 1 per unit current (A, B or C-phase) I 2 = Winding 2 per unit current (A, B or C-phase) 3 elements per relay (A, B & C-phase) * Simulate Through Current DAB
- 18. Testing Numerical Transformer Differential Relays Delta-Wye Differential Characteristic ( Relay Internally Compensates Test Currents ) I A1 relay = I A1 /TAP1 DAB WINDING I B1 relay = I B1 /TAP1 I C1 relay = I B1 /TAP1 I A2 relay = (I A2 - I B2 )/(TAP2*SQRT(3)) WYE WINDING I B2 relay = (I B2 - I C2 )/(TAP2*SQRT(3)) I C2 relay = (I C2 - I A2 )/(TAP2*SQRT(3)) TAP# = MVA# kV# LL *CTR#*SQRT(3)
- 19. Testing Numerical Transformer Differential Relays Delta-Wye Differential Characteristic ( Single-Phase Test for A-Phase Element ) I d I r I 1 I 2 0.2 0.7 0.8 0.6 2 From TABLE 1 : I A1 = I 1 *TAP1 I A2 = I 2 *TAP2*SQRT(3) I A1 test = 0.8*TAP1 I A2 test = 0.6*TAP2*SQRT(3)
- 20. Testing Numerical Transformer Differential Relays Ground Differential Element Sensitivity Test Directionality (I 0 vs. I G ) Ground Fault Location along Windings
- 21. Testing Numerical Transformer Differential Relays Ground Differential Element Directional Element +90 o -90 o I G I 0 Disabled if |3I 0 | less than 140 mA (Improves Security for CT saturation during external faults) Internal External
- 22. Testing Numerical Transformer Differential Relays Ground Differential Element Pickup Operate When : |3I 0 I G | > Pickup
- 23. Testing Numerical Transformer Differential Relays Ground
Differential Element Sensitivity Test Power System Parameters :
- Source Impedance ( Varies )

- X T = 10%

- R F ( Varies )

- Ground Fault Location (5% from Transformer Neutral)

- 24. Testing Numerical Transformer Differential Relays Ground Differential Element R F Coverage vs. Source Strength
- 25. Testing Numerical Transformer Differential Relays Ground Differential Element Pickup Setting Cold Load Pickup Reclosing into Single-Phase Load Pickup > Unbalance Directional Element Disabled if 3I 0 Low I G R
- 26. Testing Numerical Transformer Differential Relays I G2 = 0.3 Amps @ 177 o 3I 0 (2) = 0.136 Amps @ 58 o ( Threshold = 0.14 Amps ) |CTCF*3I 0 (2) I G2 | = 0.75 Amps Original Pickup = 0.3 Amps
- 27. Testing Numerical Transformer Differential Relays I G2 CTCF*3I 0 (2) INTERNAL EXTERNAL I OP New Pickup = 1.0 Amps Directional Element
- 28. Testing Numerical Transformer Differential Relays Even
Harmonic Restraint during Inrush COMTRADE PLAYBACK
- Waveform Sources :

- Events from Numerical Relays

- Events from Digital Fault Recorders

- Simulate using Transient Software

- 29. Testing Numerical Transformer Differential Relays Even
Harmonic Restraint during Inrush Traditional Approach
- 2 nd Harmonic Restraint

- Cross Phase Blocking

- 30. Testing Numerical Transformer Differential Relays Even Harmonic Restraint during Inrush Auto-Transformer Model 600 MVA Auto-Transformer (Tertiary Winding DAC) wye wye delta 13.2 kV 345 kV 230 kV W 1 W 2 W 3
- 31. Testing Numerical Transformer Differential Relays Auto-transformer Characteristics Z HM = 0.01073 per unit Z HL = 0.04777 per unit Z ML = 0.03123 per unit = 0.0140 per unit = -0.0029 per unit CTR W1 = 1200:5 (wye connected) CTR W2 = 2000:5 (wye connected) Even Harmonic Restraint during Inrush Auto-Transformer Model Z H = Z M = Z L = = 0.0340 per unit
- 32. Testing Numerical Transformer Differential Relays Even Harmonic Restraint during Inrush Auto-Transformer Model TAP1 = 600 MVA 345 kV * 240 * SQRT(3) TAP2 = 600 MVA 230 kV * 400 * SQRT(3) = 4.18 = 3.77 Minimum Pickup* = 0.5 per unit Slope = 25% * Original Pickup = 0.45 per unit
- 33. Testing Numerical Transformer Differential Relays Even Harmonic Restraint during Inrush Energize Bank with Heavy A-Phase Residual Flux Total Phase Current
- 34. Testing Numerical Transformer Differential Relays Even Harmonic Restraint during Inrush Energize Bank with Heavy A-Phase Residual Flux 2 nd Harmonic Phase Current
- 35. Testing Numerical Transformer Differential Relays Even Harmonic Restraint I even = (I 2 2 + I 4 2 ) 1/2
- 36. Testing Numerical Transformer Differential Relays Even Harmonic Restraint during Inrush Energize Bank with Heavy A-Phase Residual Flux 4 th Harmonic Phase Current
- 37. Testing Numerical Transformer Differential Relays Even Harmonic Restraint during Inrush A-Phase Current (Winding 2)
- 38. Testing Numerical Transformer Differential Relays CONCLUSIONS
- 39. Testing Numerical Transformer Differential Relays
- Transformer Differential Boundary Test ( Commissioning )

- Ground Differential Sensitivity Test (Commissioning/Maintenance)

- Harmonic Restraint for Transformer Inrush (Maintenance)

- 40. Testing Numerical Transformer Differential Relays QUESTIONS