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
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