1. Daniel J Marquis PNM Transmission Engineering
PNM ICLSS Modification Path Out Sensing San Juan (to Cabezon) to Rio Puerco – Overview –
Daniel J Marquis
PNM Transmission Engineering
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[PNM CONFIDENTIAL]

2. Import Contingency Load Shedding Scheme (ICLSS) History
Original Scheme
Purpose – Arrest voltage collapse and relieve overload of the Four Corners-Ambrosia-West Mesa 230 kV line following an extreme event
Approved by WECC and Operational since 2006
Modified in 2015 for Rio Puerco Expansion
Reviewed by RASRS in January of 2015
Added ability to remove overloads of Norton-Hernandez 115 kV line to scheme objectives following and extreme event.
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3. Northern New Mexico Transmission
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4. Purpose of ICLSS Modifications
Need to Modify Line Loss Detection:
Addition of Cabezon results in splitting existing 345 kV line into two 345 kV lines.
Requires modifying ICLSS input to recognized outage of either segment of the original line.
Scheme was originally set to use low current to determine line loss; however, this is no longer an accurate method.
With high wind generation in eastern New Mexico, low current and reversed flow on the 345 kV lines is now a normal condition.
Breaker and MOD status for sensing line loss is now more appropriate.
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5. PNM ICLSS Logic Overview (modification in red)
Insert Cabezon
Line Loss Modified to key on breaker or mod status instead of current.
Two Items
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6. Proposed Change to Path Out Sensing: Sub-paths “San Juan to Rio Puerco”
Adding Cabezon Station in middle of the “San Juan to Rio Puerco” path. Cabezon will feed a third party utility radially.
Need to update sensing to account for new “San Juan to Rio Puerco” sub-path outages.
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7. Proposed Change to Path Out Sensing: Sensing Method
Current Sensing is no longer effective due to Increased Wind, and has been replaced by Breaker Status.
PNM will be adding MOD open conditions.
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8. Existing – Path Out Sensing: San Juan (SJ) to Rio Puerco (RP)
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9. Existing – Path Out Sensing: San Juan (SJ) to Rio Puerco (RP)
Line relays at San Juan (SJ) sense local SJ breaker status, declare “path out” if both SJ breakers are open, transmit “path out” to line relays at Rio Puerco (RP) end. Line relays at RP end send “path out” high signal to physical, hard wired OR gates (ICLSS system 1 & system 2).
Sensing relays at Rio Puerco (RP) declare “path out” if both local RP breakers are open AND there is no significant line current at RP terminal. Sensing relays send “path out” high signal to physical hard wired OR gates (ICLSS system 1 & system 2).
Final “path out” signals to ICLSS system 1 and 2 are transported from Rio Puerco to Person station controllers 1 and 2, respectively, using the redundant and independent Rio Puerco to Person communications paths.
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10. Proposed – Cabezon Layout
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11. Proposed – Path Out Sensing: San Juan (to Cabezon) to Rio Puerco
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12. Proposed – Path Out Sensing: San Juan (to Cabezon) to Rio Puerco
Redundant San Juan to Cabezon (SJ-Cab) line relays 1,2,3 at San Juan (SJ) sense local breaker and line MOD status. If a relay senses both breakers open OR line MOD open then it sends “path out” to its Cabezon (Cab) remote end line relay over the two redundant and independent SJ-Cab communications channels.
Redundant SJ-Cab line relays 1,2,3 at Cabezon (Cab) sense local breaker and line MOD status and receive “path out” status from San Juan (SJ) remote end. If a relay senses both breakers open OR line MOD open OR remote end “path out” signal, then relay sends “path out” to an associated Cabezon to Rio Puerco (Cab-RP) line relay (1,2,or 3) at Cabezon (Cab) using hard wired +125VDC.
Redundant Cab-RP line relays 1,2,3 at Cabezon (Cab) sense local breaker and line MOD status and receive “path out” status from SJ-Cab line relay. If a relay senses both breakers open OR line MOD open OR SJ-Cab “path out” signal, then it sends “path out” to its Rio Puerco (RP) remote end line relay over the two redundant and independent Cab-RP communications channels.
Redundant Cab-RP line relays 1,2,3 at Rio-Puerco (RP) sense local breaker and line MOD status and receive “path out” status from Cabezon (Cab) remote end. If a relay senses both breakers open OR line MOD open OR remote end “path out” signal, then relay sends “path out” to both the ICLSS 1 input “OR gate” and the ICLSS 2 input “OR gate” at Rio Puerco using hard wired +125VDC.
As before, final “path out” signals to ICLSS system 1 and 2 are transported from Rio Puerco to Person station controllers 1 and 2, respectively, using the redundant and independent Rio Puerco to Person communications paths.
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13. Side by Side– Path Out Sensing Change: San Juan (to Cabezon) to Rio Puerco
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14. Proposed Changes – COMM Paths
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15. Proposed Changes – COMM Paths
Original Communication paths from San Juan to Rio Puerco were Microwave/Fiber and Fiber.
Proposed changes for Cabezon include insertion of Cabezon into Fiber Path.
Redundant and Independent Communications Paths are maintained.
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16. What PNM Is Requesting This is a general overview.
Detailed, final submittal paperwork with additional transmission planning study work is in process and will be submitted in Q
Desired in-service date for Cabezon for serving neighboring utility is April 2016.
PNM is asking for WECC RAS Subcommittee to consider a special call-in meeting to review and approve changes to ICLSS. If not, PNM would request detailed ICLSS review at next regular meeting.
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17. Questions? Suggestions for Design Improvement?
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18. Thank You
End of Slides
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