compensator ground fault coverage through a delta-wye...
TRANSCRIPT
-
© 2019 Caterpillar and SEL
Compensator Ground Fault Coverage Through a Delta-Wye Transformer –
A Case Study
Dustin HohenberyCaterpillar
Ryan McDaniel, Harish Chaluvadi, and Michael J. ThompsonSchweitzer Engineering Laboratories, Inc.
-
• Case study• Initial analysis• Dynamic compensator characteristic• Transformer connection effects on distance elements• Case study using dynamic compensator characteristic• Summary
Overview
-
• Ground fault on Line L1
• Breaker 1 relay trips
• Breaker A relay does not trip
• BT trips
Case Study Overview
B
Main B Relay
Bus-Tie RelayA
Main A Relay
13
4
Utility Sub X Utility Sub Y
2
Line L1
Line L2
Line L2Line L1
Bus BBus A
51N51
21C51 51N21C51 51N
BT
-
Breaker 1 Event Report
-
Breaker A Event Report
-
Initial Compensator Distance Analysis
PPCOMP AB AB R
PPCOMP BC BC R*
TORQUE
S1 V I • Z1S2 V I • Z1
PPCOMP IM • (S1• S2 )
= −
= −
=
PPCOMPTORQUE
Reach
VA
PPCOMP Balance
0 10 20 30 40 50 60
8000600040002000
0–2000–4000–6000–8000
-
Initial Mho Distance Analysis
PPMHO(SELF) PP PP R
PPMHO(SELF) PP
*TORQUE
S1 V I • Z1
S2 V
PPMHO(SELF) RE • (S1• S2 )
= −
=
=
MHO(SELF) Torque
Reach
VA
MHO(BC) BalanceMHO(CA)MHO(AB)
15000100005000
0-5000
–10000–15000–20000–25000–30000
0 10 20 30 40 50 60
-
• Compensator includes two relays Three-phase relay (3PCOMP)
Phase-to-phase relay (PPCOMP)
• PPCOMP evaluates V1 / V2 at relay reach point
Compensator Review
R R R
R R R
V1 I1 • Z1 V1C= = 1< V2 I2 • Z1 V2C
−θ
−
-
Compensator PerformanceEvaluate Without and With Transformer (YD11)
Z1S Z1RZ1L
ES ER
S R
Z1R
Fault Point
Z1S Z1R
ES ER
S R
Z1R
Fault Point
Z1L
-
Dynamic Compensator CharacteristicBC Fault With No Transformer
PPCOMPMHO(BC)MEM
-
Dynamic Compensator CharacteristicBC Fault With Transformer
PPCOMPMHO(BC)MEM
-
Dynamic Compensator CharacteristicBCG Fault
PPCOMPMHO(BC)MEM
No transformer With transformer
-
Dynamic Compensator CharacteristicBCG Fault With Transformer
PPCOMPMHO(BC)MEM3PCOMP
-
Dynamic Compensator CharacteristicCG Fault With Transformer
PPCOMPMHO(BC)MEM3PCOMP
-
Dynamic Compensator CharacteristicFault With Transformer
BCG fault – no load CG fault – heavy load
PPCOMPMHO(BC)MEM3PCOMP
-
Revisit Case Study
PPCOMPMHO(BC)MEM3PCOMP
-
Revisit Case Study
MHO(PP)COMP
-
• PPCOMP offers unreliable performance for close-in ground faults, including PPG
• Excessively long reach settings hinder performance• Lines with tapped loads require special attention• Compensated mho elements offer more reliability for
close-in ground faults through a transformer
Summary
-
Dynamic Compensator CharacteristicBC Fault With No Transformer
PPCOMPMHO(BC)MEM
Compensator Ground Fault Coverage Through a Delta-Wye Transformer – �A Case StudyOverviewCase Study OverviewBreaker 1 Event ReportBreaker A Event ReportInitial Compensator Distance AnalysisInitial Mho Distance AnalysisCompensator ReviewCompensator Performance�Evaluate Without and With Transformer (YD11) Dynamic Compensator Characteristic�BC Fault With No TransformerDynamic Compensator Characteristic�BC Fault With TransformerDynamic Compensator Characteristic�BCG FaultDynamic Compensator Characteristic�BCG Fault With TransformerDynamic Compensator Characteristic�CG Fault With TransformerDynamic Compensator Characteristic�Fault With TransformerRevisit Case StudyRevisit Case StudySummaryDynamic Compensator Characteristic�BC Fault With No Transformer