microprocessor relay protection jasvinder blah & naveen manikarnika
TRANSCRIPT
Microprocessor Relay ProtectionJasvinder Blah
&Naveen Manikarnika
Agenda
• Transformer Protection• Electromechanical Relays• Microprocessor Relays• Relay Characteristics & Testing
got relays?
Relay Protection
• What is Relay Protection?• Typical transformer protection:
51N87 51V
59 67 87N
Primary Protection - 87
Kirchhoff's Current Lawi1
i2 i3
i4
𝑖1+𝑖2+𝑖3=𝑖4
Transformer Protection
BKR(3) 3000/5A (3) 3000/5A
To 13kV Bus
Transformer: 68kV/13.8kV
Electromechanical Relays
Microprocessor Relays
Microprocessor Relays
ADVANTAGES• All elements and phases in
one box• Self-checking and alarm• Internal compensation• Oscillography and SER• Direct Tripping
DISADVANTAGES• Technology advancing in a
fast pace• Firmware defects/upgrades
11
Delta - Wye
IAB
IBC
ICA
Ia’
Ib’
Ic’
30º
Secondary Currents Lags the Primary by 30 DegreesA
B
Ca’
b’
c’
A
B
C
Ia’
Ic’
Ib’
Electromechanical CT Compensation
Microprocessor CT Compensation
CT Compensation
Internal Phase Compensation
A
B
C
-Ib’
Ia’
Ic’
Ib’
30º
Ia’-Ib’
Ia(Comp) =
Ib(Comp) =
Ic(Comp) =
3
)(
3
)(
3
)(
''
''
''
ac
cb
ba
II
II
II
Ia(comp)
Transformer Protection with Microprocessor Relays
BKR
87 51N 51V
59 67 87N
(3) 600/5A (3) 3000/5A
(1) 1200/5A
(3) CCVTs72.5kV/67.08V
(3) PTs14,400V/120V
Incoming 69kV Feeder To 13kV Bus
Transformer: 68kV/13.8kV
SEL-487E
0 0.6 1.3 2 2.4 2.8 3.2 3.6 5 6 7
0
0.5
1
1.5
2
2.5
3
3.5
I Restraining
I Ope
ratin
g
Restraint Region
Operating Region
Unrestrained Differential
87 Percent Differential
Exten
ded S
ecurit
y M
ode
87 Testing
0 0.6 1.3 2 2.4 2.8 3.2 3.6 5 6 7
0
0.5
1
1.5
2
2.5
3
3.5
I Restraining
I Ope
ratin
g
Restraint Region
Operating Region
Unrestrained Differential
Microprocessor Relay Testing
Dual RS-232
Output Contacts
Current Inputs
Voltage Inputs
A B C A B C
87 – Differential
BKR
87 51N 51V
59 67 87N
(3) 600/5A (3) 3000/5A
(1) 1200/5A
(3) CCVTs72.5kV/67.08V
(3) PTs14,400V/120V
Incoming 69kV Feeder To 13kV Bus
Transformer: 68kV/13.8kV
SEL-487E
Initiate DTT
Initiate BKR Failure Timer
Pop Quiz !!!
87N – Neutral Differential
BKR
87 51N 51V
59 67 87N
(3) 600/5A (3) 3000/5A
(1) 1200/5A
(3) CCVTs72.5kV/67.08V
(3) PTs14,400V/120V
Incoming 69kV Feeder To 13kV Bus
Transformer: 68kV/13.8kV
SEL-487E
Initiate DTT
Initiate BKR Failure Timer
51N – Neutral Overcurrent
BKR
87 51N 51V
59 67 87N
(3) 600/5A (3) 3000/5A
(1) 1200/5A
(3) CCVTs72.5kV/67.08V
(3) PTs14,400V/120V
Incoming 69kV Feeder To 13kV Bus
Transformer: 68kV/13.8kV
SEL-487E
Trip Bus-Tie Breaker
51V – Voltage Controlled Overcurrent
BKR
87 51N 51V
59 67 87N
(3) 600/5A (3) 3000/5A
(1) 1200/5A
(3) CCVTs72.5kV/67.08V
(3) PTs14,400V/120V
Incoming 69kV Feeder To 13kV Bus
Transformer: 68kV/13.8kV
SEL-487E
Trip Bus-Tie Breaker
67 – Directional Overcurrent
BKR
87 51N 51V
59 67 87N
(3) 600/5A (3) 3000/5A
(1) 1200/5A
(3) CCVTs72.5kV/67.08V
(3) PTs14,400V/120V
Incoming 69kV Feeder To 13kV Bus
Transformer: 68kV/13.8kV
SEL-487E
Initiate BKR Failure Timer
59 – Zero Sequence Overvoltage
BKR
87 51N 51V
59 67 87N
(3) 600/5A (3) 3000/5A
(1) 1200/5A
(3) CCVTs72.5kV/67.08V
(3) PTs14,400V/120V
Incoming 69kV Feeder To 13kV Bus
Transformer: 68kV/13.8kV
SEL-487E
Initiate BKR Failure Timer
Testing Challenges
• Breaker Failure– Time delay for all elements– Perform testing without disabling elements– Requires some creativity
• Utilize 2nd Harmonic Block to disable 87
2nd Harmonic Block
Fault Playback
• Play fault back to the relay• Useful for investigations• Fully functional test• Oscillography/SER
Oscillography
Future
• 61850 (GOOSE)• Merging Units• Optical CTs• Sample Values
Conclusion
• Evolution of relay protection• Challenges
– Training and learning curve – Cybersecurity
Questions?