Understanding High Impact Transmission Elements and Congestion Outages

High Impact Transmission Elements (HITEs) Alex Lee OCITF ERCOT Public December 1, 2015

Proposed Development of HITE List Leverage existing analyses of outage impacts to minimize budget impact of NPRR Include outages that have been attributed as causing significant congestion in the past Based on analyses produced for the ROS report Add outages that might have caused significant congestion under different conditions Based on previous outage coordination studies Vet resulting list with stakeholders to identify any outages that should be excluded due to upgrades or other changes Approval by appropriate subcommittee of TAC 2

Historic Congestion due to Outages By Occurrences Identifies transmission constraints that are active or binding three or more times within a calendar month. Attributes these constraints to outages if appropriate From Nov 2014 to Oct 2015: 245 constraints are attributed to 107 outages (some are duplicate). For constraints with over $1 million congestion rent, outages on 43 distinct transmission elements are identified. Type BUS CB LN XF Total 69 kV 138 kV 345 kV Total 2 2 2 1 8 1 4 3 2 23 33 3 43 2 2 29 12 3 ERCOT OCITF

Historic Congestion due to Outages By Area Links Real-Time Congestion to related outage(s). Analyzes top three or four congestion per Load Zone. Criteria: Over $1 million Congestion Rent. From Nov 2014 to Oct 2015: 76 constraints are linked to 59 outages (some are duplicate). For constraints with over $1 million congestion rent, outages on 46 distinct transmission elements are identified. Type BUS CB LN XF Total 69 kV 138 kV 345 kV Total 4 1 2 1 5 1 9 6 2 2 28 35 3 46 2 2 35 4 ERCOT OCITF

Outages Potentially Causing Congestion from Historic OC Studies When ERCOT outage coordination studies indicate that a significant amount of resources must be re-dispatched to accommodate a requested outage, ERCOT sends the requestor a Market Impact Questionnaire. These Questionnaires provide an indication of outages that might cause significant congestion Although these outages may not ultimately result in congestion if they are moved in time or if conditions are different than studied From Jan 2014 Dec 2014: Market Impact Questionnaire was sent out for 57 distinct transmission elements. Type BUS LN XF Total 69 kV 138 kV 345 kV Total 14 35 8 57 1 1 10 19 3 15 8 26 2 29 5 ERCOT OCITF

HITEs Summary TDSP # HITEs Type BUS CB LN XF Total 69 kV 138 kV 345 kV Total 5 1 22 9 37 AEN AEN/LCRA AEP AEP/Sharyland AEP/STEC Brazos CNP CNP/TNMP CPS LCRA ONCOR ONCOR/Brazos STEC TMPA TNMP WETT Total 8 1 20 3 78 11 112 1 14 2 53 2 71 22 1 1 1 9 1 3 7 45 1 4 1 6 1 3 4 No related Transmission outage OR Congestion Rent < $1 mil By Occurrences 12 27 3 16 1 51 From OC Studies By Area 2 112 No related Transmission outage 6 ERCOT OCITF

Sources: R = By Occurrences C = By Area M = Historic OC Studies HITEs (Page 1) HITE Type kV CB 138 AEN LN 138 AEN LN 138 AEN LN 138 AEN LN 138 AEN LN 138 AEN LN 138 AEN LN 138 AEN LN 138 AEN/LCRA BUS 345 AEP BUS 138 AEP BUS 138 AEP BUS 138 AEP BUS 69 LN 345 AEP LN 345 AEP LN 345 AEP LN 345 AEP LN 138 AEP LN 138 AEP LN 138 AEP LN 138 AEP LN 138 AEP LN 138 AEP TDSP Source R,C C C,M R,M C R,C M R,C R C M C M M M R,C,M M M R,C M C R R,C R,C HITE Type kV BUS 138 Brazos LN 345 CNP LN 345 CNP LN 345 CNP LN 345 CNP LN 138 CNP LN 138 CNP LN 138 CNP XF 345 CNP XF 345 CNP TDSP Source M M M M M M M R M M M R,C R R,C M R,C M M M C,M R,C R M M Hamilton AEN HM_950 AEN Dunlap - Decker AEN Dunlap - Techridge Austrop - Daffin DCKT Dessau - Sprinkle Decker - McNeil AEN Decker - Sprinkle Kingsbery - Ed Bluestein McNeil AEN - McNeil LCRA Rio Hondo Bus Lane City Bus North Edinburg Bus Rio Hondo Bus San Diego Bus Ajo - Rio Hondo La Palma - Rio Hondo Lon Hill - North Edinburg Lon Hill - Pawnne Sw Azteca - SE Edinburg Bates - - Garza La Palma - Laureles Laureles - Port Isabel Polk Ave - North Pharr Rio Bravo - - Wormser Rd San Angelo Power - - San Angelo Concho Spur - Aspermont Lon Hill - Smith Sinton - - Beeville North Edinburg Auto #1 North Edinburg Auto #2 San Angelo Concho Auto Taylor Sharyland - Sharyland Victoria - Loop 463 Sub Whitney Bus Chambers - King Kings - Kuykendahl Kuykendahl - Roans Prairie Kuykendahl - Tomball Exxon - Lynch Fort Bend - - Orchard Fort Bend - Reading Ph Robinson Auto #1 Ph Robinson Auto #2 West Columbia - West Columbia Main Tnp LN 138 CNP/TNMP Ballpark - - Olmos Cibolocr - ... - Green_Mt Laredo 1 - Five Pts Schulenburg Bus Fayette Plant 1 - Fayetteville Hays Energy - Kendall Benedum - Upton Boerne - Welfare Gilleland - McNeil LCRA Bevo Auto #1 Carrollton NW - Lewisville Sw Choate - Four Corners Choate - Pawnee Sw LN 138 CPS LN 138 CPS LN 138 CPS BUS 138 LCRA LN 345 LCRA LN 345 LCRA LN 138 LCRA LN 138 LCRA LN 138 LCRA XF 138 LCRA LN 345 ONCOR/Brazos LN 138 STEC LN 138 STEC AEP LN 138 AEP R,C East Rio Hondo - ... - Central Ave LN 138 STEC R,C LN 138 AEP LN 69 LN 69 XF 345 AEP XF 345 AEP XF 138 AEP LN 138 AEP/Sharyland LN 138 AEP/STEC C R,C R,C M M R,C C M George West - George West Sw North Denton - Denton Arco Brazoria Bus West Columbia Main Tnp Bus Brazoria Tnp - Clemons Tap Tnp Commanche Switch Tnp - Tejas Tnp Dickinson - Freeway Park West Tnp - Ti Tnp Wett Faraday Bus LN 138 STEC LN 138 TMPA BUS 138 TNMP BUS 138 TNMP LN 138 TNMP LN 138 TNMP LN 138 TNMP LN 138 TNMP BUS 345 WETT M R,C M M M R,C R,C R C AEP AEP 7 ERCOT OCITF

Sources: R = By Occurrences C = By Area M = Historic OC Studies HITEs (Page 2) HITE Type BUS BUS BUS BUS BUS BUS BUS BUS BUS BUS CB CB LN LN LN LN LN LN LN LN LN LN LN kV 345 345 345 138 138 138 138 138 138 138 345 138 345 345 345 345 345 345 345 345 345 345 345 TDSP ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR Source R,M R,M M M C M R,C R,C M M R,C R M R,C M M M M M M R R,C R,C HITE Type LN LN LN LN LN LN LN LN LN LN LN LN LN LN LN LN LN XF XF XF XF XF kV 138 138 138 138 138 138 138 138 138 138 138 138 138 138 138 138 69 345 345 345 345 345 TDSP ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR ONCOR Source C R,C C R R,C C M M R,C C M M R C C R M M M C M R Carrollton Northwest Bus Forney Sw Bus Martin Lake Bus Allen Sw Bus Andrew North Bus Kirkland Park Bus Lake Creek Bus Moss Sw Bus Odess Ehv Sw Bus Stryker Creek Bus Norwood Sw CB 325 Andrew North CB 12365 Allen Sw - Monticello Lufkin Sw - Stryker Creek Midland East - Moss Sw Midland East - Odessa Ehv Sw Monticello - Paris Sw Morgan Creek Auto #4 Moss Sw - Odessa Ehv Sw Stryker Creek - Watermill Sw Temple Sw - Bell County East Sw Watermill Sw - Sargent Road Watermill Sw - West Levee Sw Calmont Sw - Western Hills Cedar Hill Sw - Mountain Creek Colony - Austin Ranch Eagle Mountain - - Calmont Sw East Levee Sw - West Netowrk Jim Payne - Lamesa Key Sub - Lamesa Lufkin - Nacogdoches South Tap Morgan Creek - Cosden Morgan Creek - Sun Sw Moss Sw - Odessa Southwest Odessa - Odessa North Permian Basin - Wink Sub Sansom - Eagle Mountain Snyder - Sacroc Wink Sub - Wink Gulf Tap Odessa Basin Sw - Odessa North Carrollton Northwest Auto #1 Everman Sw Auto #3 Lufkin Sw Auto #1 Odessa Ehv Sw Auto #3 Royse Sw Auto #1 8 ERCOT OCITF

Discussion Points Outages for Bus or open-ended-line. Congestion related to multiple outages. HITEs verification/expiration. 9 ERCOT OCITF