West Texas Congestion Chad Thompson Congestion Management Working Group August

Background ERCOT has received several inquiries from market participants regarding congestion patterns in West Texas This congestion has been influenced by challenges associated with modeling, telemetry, and outage submissions ERCOT has been working diligently with stakeholders and the interconnecting transmission companies to develop plans to ensure grid reliability in the region

Outline Walkthrough the process of picking up Sharyland load Discuss Operational Challenges encountered in the last 10 months Discuss “on-going” stakeholder concerns with congestion management practices

Evolution of the Sharyland Area

October 2013

Evolution of the Sharyland Area November 2013

Evolution of the Sharyland Area December 2013

Evolution of the Sharyland Area December 2013

Evolution of the Sharyland Area December 2013

Evolution of the Sharyland Area May-June 2014

Evolution of the Sharyland Area August 2014

Evolution of the Sharyland Area

Operational Challenges Outage Scheduler/Telemetry –Coyote – Vealmoor (Jun 27-30, Aug 18-19) Submitted as outage, energized in RT –Gardendale POI – Pecan Grove (Aug 18-19) Tie point added on Aug 8 –Triangle (June 6) When location changed in the model, SCADA had the station de- energized, but flow was going through the station Modeling –Pecan Grove and Triangle –Gardendale POI – Telephone Rd temporary tie –Eiland – Polecat Creek Nomenclature –Substation names changing (e.g. Telephone Rd vs Telephone Pole Rd) –SPP cutover name changes

On-Going Stakeholder Concerns Inconsistent management of constraints –2 % shift factor cut-off June 18: Skywest – Spraberry overloads Midland East – Buffalo June 27-29: Skywest – Salt Flat Rd overloads Midland East - Buffalo –Operator discretion on when constraints are activated & deactivated Especially with this area, continued vigilance to verify telemetry and model data may result in delays in activating/deactivating constraints SCED Constraint Management Transparency Posting on the MIS

Summary In the last several months, the load in the area has increased ~300 MW (peak) Challenges with telemetry have influenced real- time congestion management decisions Challenges with scheduling equipment in the Outage Scheduler has influenced congestion in forward markets (e.g. DAM) Oncor/Sharyland built temporary tie to move Sharyland load to the Midland East – Moss 138 kV line Continue to use MIS postings for information regarding constraint activation