1. HARRY ALLEN TRANSFORMER REMEDIAL ACTION SCHEME (RAS)
Presentation to: WECC REMEDIAL ACTION SCHEME RELIABILITY SUBCOMMITTEE (RASRS) November 15, 2017
Adeline Grubb – Transmission Planning
Alex Campos – System Protection

2. TRANSMISSION PLANNING INFORMATION FUNCTIONAL DESCRIPTION
Background: Path 35 connects NV Energy and Pacificorp
Two parallel 345/230 kV transformers
Two parallel phase shifters
345 kV line
Rated for 600 MW (North to South) and 580 MW (South to North)
FUNCTION: RAS monitors flow on Harry Allen – Red Butte 345 kV line (WECC Path 35).
If flow exceeds 410 MVA (686 A) value, the RAS is armed.
Once armed, if a trip of one Harry Allen 345/230 kV transformer occurs, the RAS will trip the other Harry Allen 345/230 kV transformer.
This effectively protects both transformers from overloading above emergency rating of 409 MVA (violation of NERC-TPL P1-3).
Planned In-Service Date: March 2018

3. ONE-LINE DIAGRAM

4. RAS CLASSIFICATION
Violations of TPL-001-WECC-CRT-3 System Performance Criteria?
No. The Criteria relates to parallel transmission circuits, while this RAS is designed to mitigate thermal overload of two parallel transformers.
Maximum load loss of ≥ 300 MW? No
Maximum generation loss ≥ 1000 MW?
No.
Conclusion
This RAS is a Local Area Protection Scheme (LAPS).

5. TRANSMISSION PLANNING STUDIES
CONDITION 1: PSLF Power Flow Studies under 407 MW north to south flows on Path 35 (Red Butte to Harry Allen)
Loss of one Harry Allen 345/230 kV transformer loads the other parallel transformer to 95% of the emergency rating.
CONDITION 2: PSLF Power Flow Studies under 421 MW south to north flows on Path 35 (Harry Allen to Red Butte)
Loss of one Harry Allen 345/230 kV transformer loads the other parallel transformer to 96 % of the emergency rating.
Maximum Flow
Power flow studies under maximum rated North to South flows (600 MW).
Power flow studies under maximum rated South to North flows (580 MW).
RAS is effective in mitigating overload in both cases.
RAS does not cause overloads or low voltage problems under maximum flow on Path 35.

6. CONDITION 1: PRE-CONTINGENCY (P0)

7. P1: HARRY ALLEN 230/345 kV TRANSFORMER #2 OUTAGE; HARRY ALLEN 230/345 kV TRNSFORMER #3 AT 95% LOADING

8. CONDITION 2: PRE-CONTINGENCY (P0)

9. P1: HARRY ALLEN 230/345 kV TRANSFORMER #2 OUTAGE; HARRY ALLEN 230/345 kV TRNSFORMER #3 AT 96% LOADING

10. SUMMARY

11. RAS DESIGN – PHILOSOPHY AND CRITERIA
Redundant systems (System #1 & System #2) with breaker failure protection
Primary Action
For an overload condition on transformer 2, trip breakers 4505 and 4506
For an overload condition on transformer 3, trip breakers 4504 and 4506
Breaker Failure Action
For an overload condition on transformer 2, initiate breaker failure for breakers 4505 and 4506
For an overload condition on transformer 3, initiate breaker failure for breakers 4504 and 4506
RAS failure is a non-credible event
Failure of a single component, element, or system will not effect successful operation of the RAS

12. RAS DESIGN – LOGIC 30 cyc pickup for inrush current
MVA ≤ 390 for RAS disarm
Breaker status from spare 52b contacts to 2440
Load detection supervision from 487E relays

13. RAS DESIGN – LOGIC HARDWARE
Detection - Redundant SEL-487E relays
Separate CT and PT inputs
Monitors loading on banks 2 and 3
Detects load on low-side and high-side breakers for additional supervision
Logic Processing and Tripping - Redundant SEL-3555 RTACs
Sequential Event Recorder (SER)
Indications to RTU and back to SCADA
Initiates tripping and breaker failure
Communication Logic Processing - Redundant SEL-3555 RTACs
Communication to SEL-2440’s via SEL Fast Messaging
Communication to SEL-3354 RTAC RTU via DNP

14. RAS DESIGN – ARCHITECTURE

15. SCADA Indications SCADA Point Response Code
345KV HA XFMR RAS SYS 1 & 2 DEFEATED NA
345KV HA XFMR RAS SYS #1 ACTIVE
345KV HA XFMR RAS SYS #1 TRIP INITIATED 1R
345KV HA XFMR RAS SEL RLY TRBL
345KV HA XFMR RAS SEL BAD COMM 2R
345KV HA XFMR RAS SYS #1 SUSPECT
345KV HA XFMR RAS SEL RLY TRBL
345KV HA XFMR RAS SEL BAD COMM
345KV HA XFMR RAS SYS #2 ACTIVE
345KV HA XFMR RAS SYS #2 TRIP INITIATED
345KV HA XFMR RAS SEL RLY TRBL
345KV HA XFMR RAS SEL BAD COMM
345KV HA XFMR RAS SYS #2 SUSPECT
345KV HA XFMR RAS SEL RLY TRBL
345KV HA XFMR RAS SEL BAD COMM
345KV HA XFMR RAS SEL-87T/AT2 BAD COMM
345KV HA XFMR RAS SEL-87BU/AT2 BAD COMM
345KV HA XFMR RAS SEL-87T/AT3 BAD COMM
345KV HA XFMR RAS SEL-87BU/AT3 BAD COMM

16. CONCLUSION Scheme is fully redundant
Designed to prevent overload on transformer 2 or 3 at Harry Allen for loss of the other
Classified as a Local Area Protection Scheme (LAPS)
Initiation of RAS results in:
Transformers 2 and 3 at Harry Allen out of service
Interruption of WECC Path 35 (loss of Harry Allen-Red Butte 345kV line)
RAS failure is a non-credible event
Failure of a single component, element, or system will not effect successful operation of the RAS
Scheme is fully redundant
Planned In-Service Date: March 1, 2018

17. QUESTIONS?