ERCOT experience in using online stability analysis in real-time operations

This paper discusses experiences in the use of online stability analysis tools in Electric Reliability Council of Texas (ERCOT) interconnection, USA. In order to prevent certain unstable system conditions, the online stability analysis tool - DSATools - has been implemented in the ERCOT control room. Using real-time information from the Energy Management System (EMS), DSATools calculates the system stability limits based on both voltage and angle stability. The system architecture and hardware setup are presented. The defining of study scenarios is also presented, using the voltage and transient study cases. As the online tool runs and updates the stability limits every 15 minutes, system operators use the Megawatt (MW) difference between actual power flow and stability limit to evaluate the system stability conditions. Using various real-time tools, system operators can re-dispatch generation to manage the system security margins, and therefore ensure system reliability.