Experience with Operating the Ancillary-Service Markets in ERCOT

Ancillary Services procurement and deployment are critical operations for maintaining the adequacy and security of power system. Electric Reliability Council of Texas (ERCOT) operates one of the largest independent power systems in the United States. This article presents the structure and experiences of the current ERCOT ancillary service market after five-year evolution. First, we summarize the fundamental framework of ancillary service procurement at ERCOT including types of services, submitting schedule, market clearing process, settlement. Secondly, we show the historical performance of the operation and the market at ERCOT. Thirdly, we compare the current ERCOT market, some market improvement proposal and a nodal structure possibly to be implemented in the future.