Transcript Microprocessor Relay Protection Area Station Transformers

Microprocessor Relay Protection
Jasvinder Blah
&
Naveen Manikarnika
Agenda
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Transformer Protection
Electromechanical Relays
Microprocessor Relays
Relay Characteristics & Testing
got relays?
Relay Protection
• What is Relay Protection?
• Typical transformer protection:
87
51N
51V
59
67
87N
Primary Protection - 87
Kirchhoff's Current Law
i1
i4
i2
i3
𝑖1 + 𝑖2 + 𝑖3 = 𝑖4
Transformer Protection
Transformer: 68kV/13.8kV
(3) 3000/5A
(3) 3000/5A
BKR
To 13kV Bus
Electromechanical Relays
Microprocessor Relays
Microprocessor Relays
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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
Delta - Wye
IAB
Ia’
IBC
Ib’
B
Ia’
Ib’
30º
A
ICA
Ic’
11
Ic’
b’
B
A
C
C
a’
c’
Secondary Currents Lags
the Primary by 30 Degrees
Electromechanical CT Compensation
Microprocessor CT Compensation
CT Compensation
Internal Phase Compensation
Ia(Comp) =
B
( I a'  I b' )
3
Ib’
Ia’
Ib(Comp) =
Ic(Comp) =
( Ib'  I c' )
3
(I c'  I a' )
3
30º
A
Ia(comp)
Ia’-Ib’
C
-Ib’
Ic’
Transformer Protection with
Microprocessor Relays
Transformer: 68kV/13.8kV
Incoming 69kV
Feeder
(3) 600/5A
(3) 3000/5A
To 13kV Bus
BKR
(3) CCVTs
72.5kV/67.08V
(1) 1200/5A
(3) PTs
14,400V/120V
SEL-487E
87
51N
51V
59
67
87N
87 Percent Differential
3.5
Unrestrained Differential
3
I Operating
2.5
Operating Region
2
1.5
Restraint Region
1
0.5
0
0
0.6
1.3
2
2.4
2.8
I Restraining
3.2
3.6
5
6
7
87 Testing
3.5
Unrestrained Differential
3
I Operating
2.5
Operating Region
2
1.5
Restraint Region
1
0.5
0
0
0.6
1.3
2
2.4
2.8
I Restraining
3.2
3.6
5
6
7
Microprocessor Relay Testing
Dual
RS-232
Output
Contacts
Current
Inputs
A
B
C
Voltage Inputs
A B C
87Pop
– Differential
Quiz !!!
Initiate DTT
Incoming 69kV
Feeder
Transformer: 68kV/13.8kV
(3) 600/5A
(3) 3000/5A
To 13kV Bus
BKR
(3) CCVTs
72.5kV/67.08V
(1) 1200/5A
Initiate BKR
Failure
Timer
(3) PTs
14,400V/120V
SEL-487E
87
51N
51V
59
67
87N
87N – Neutral Differential
Initiate DTT
Incoming 69kV
Feeder
Transformer: 68kV/13.8kV
(3) 600/5A
(3) 3000/5A
To 13kV Bus
BKR
(3) CCVTs
72.5kV/67.08V
(1) 1200/5A
Initiate BKR
Failure
Timer
(3) PTs
14,400V/120V
SEL-487E
87
51N
51V
59
67
87N
51N – Neutral Overcurrent
Transformer: 68kV/13.8kV
Incoming 69kV
Feeder
Trip Bus-Tie Breaker
(3) 600/5A
(3) 3000/5A
To 13kV Bus
BKR
(3) CCVTs
72.5kV/67.08V
(1) 1200/5A
(3) PTs
14,400V/120V
SEL-487E
87
51N
51V
59
67
87N
51V – Voltage Controlled Overcurrent
Transformer: 68kV/13.8kV
Incoming 69kV
Feeder
Trip Bus-Tie Breaker
(3) 600/5A
(3) 3000/5A
To 13kV Bus
BKR
(3) CCVTs
72.5kV/67.08V
(1) 1200/5A
(3) PTs
14,400V/120V
SEL-487E
87
51N
51V
59
67
87N
67 – Directional Overcurrent
Transformer: 68kV/13.8kV
Incoming 69kV
Feeder
(3) 600/5A
(3) 3000/5A
To 13kV Bus
BKR
(3) CCVTs
72.5kV/67.08V
(1) 1200/5A
Initiate BKR
Failure
Timer
(3) PTs
14,400V/120V
SEL-487E
87
51N
51V
59
67
87N
59 – Zero Sequence Overvoltage
Transformer: 68kV/13.8kV
Incoming 69kV
Feeder
(3) 600/5A
(3) 3000/5A
To 13kV Bus
BKR
(3) CCVTs
72.5kV/67.08V
(1) 1200/5A
Initiate BKR
Failure
Timer
(3) PTs
14,400V/120V
SEL-487E
87
51N
51V
59
67
87N
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
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Play fault back to the relay
Useful for investigations
Fully functional test
Oscillography/SER
Oscillography
Future
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61850 (GOOSE)
Merging Units
Optical CTs
Sample Values
Conclusion
• Evolution of relay protection
• Challenges
– Training and learning curve
– Cybersecurity
Questions?