Microprocessor Relay Protection Jasvinder Blah & Naveen Manikarnika

Agenda Transformer Protection Electromechanical Relays Microprocessor Relays Relay Characteristics & Testing

got relays?

Relay Protection What is Relay Protection? Typical transformer protection: 51N8751V N

Primary Protection - 87 Kirchhoff's Current Law i1i1 i2i2 i3i3 i4i4

Transformer Protection BKR (3) 3000/5A To 13kV Bus Transformer: 68kV/13.8kV

Electromechanical 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 I AB I BC I CA I a’ I b’ I c’ 30 º Secondary Currents Lags the Primary by 30 Degrees A B C a’ b’ c’ A B C I a’ I c’ I b’

Electromechanical CT Compensation

Microprocessor CT Compensation

CT Compensation

Internal Phase Compensation A B C -I b’ Ia’Ia’ Ic’Ic’ Ib’Ib’ 30 º I a ’-I b ’ Ia (Comp) = Ib (Comp) = Ic (Comp) = I a(comp)

Transformer Protection with Microprocessor Relays BKR 8751N51V N (3) 600/5A (3) 3000/5A (1) 1200/5A (3) CCVTs 72.5kV/67.08V (3) PTs 14,400V/120V Incoming 69kV Feeder To 13kV Bus Transformer: 68kV/13.8kV SEL-487E

87 Percent Differential Extended Security Mode

87 Testing

Microprocessor Relay Testing Dual RS-232 Output Contacts Current Inputs Voltage Inputs ABCABC

87 – Differential BKR 8751N51V N (3) 600/5A (3) 3000/5A (1) 1200/5A (3) CCVTs 72.5kV/67.08V (3) PTs 14,400V/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 8751N51V N (3) 600/5A (3) 3000/5A (1) 1200/5A (3) CCVTs 72.5kV/67.08V (3) PTs 14,400V/120V Incoming 69kV Feeder To 13kV Bus Transformer: 68kV/13.8kV SEL-487E Initiate DTT Initiate BKR Failure Timer

51N – Neutral Overcurrent BKR 8751N51V N (3) 600/5A (3) 3000/5A (1) 1200/5A (3) CCVTs 72.5kV/67.08V (3) PTs 14,400V/120V Incoming 69kV Feeder To 13kV Bus Transformer: 68kV/13.8kV SEL-487E Trip Bus-Tie Breaker

51V – Voltage Controlled Overcurrent BKR 8751N51V N (3) 600/5A (3) 3000/5A (1) 1200/5A (3) CCVTs 72.5kV/67.08V (3) PTs 14,400V/120V Incoming 69kV Feeder To 13kV Bus Transformer: 68kV/13.8kV SEL-487E Trip Bus-Tie Breaker

67 – Directional Overcurrent BKR 8751N51V N (3) 600/5A (3) 3000/5A (1) 1200/5A (3) CCVTs 72.5kV/67.08V (3) PTs 14,400V/120V Incoming 69kV Feeder To 13kV Bus Transformer: 68kV/13.8kV SEL-487E Initiate BKR Failure Timer

59 – Zero Sequence Overvoltage BKR 8751N51V N (3) 600/5A (3) 3000/5A (1) 1200/5A (3) CCVTs 72.5kV/67.08V (3) PTs 14,400V/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 2 nd Harmonic Block to disable 87

2 nd Harmonic Block

Fault Playback Play fault back to the relay Useful for investigations Fully functional test Oscillography/SER

Oscillography

Future (GOOSE) Merging Units Optical CTs Sample Values

Conclusion Evolution of relay protection Challenges – Training and learning curve – Cybersecurity

Questions?