Holly STATCOM - FACTS to Replace Critical Generation, Operational Experience

Austin Energy plans to decommission an old oil-and gas-fired plant near downtown Austin, Texas, USA. In addition to providing the generation capacity, an important reason the four-unit Holly plant has been kept in operation is to stabilize the voltage on the transmission system. Retirement of the power plant without a reliable dynamic reactive source would have a negative impact on the transmission system voltage stability. A special requirement in Austin Energy´s case is recovery from voltage sags where a fast response is necessary at low voltages, i.e. transient voltage recovery. Furthermore, physical limitations related to aesthetics, electromagnetic field emissions, and audible noise had impact on the solution to be implemented. Transmission planning studies determined that the voltage requirements could be met using a STATCOM. This paper provides details on the background, an overview of the STATCOM technology, and shows results from the first period of operation of the Holly STATCOM, delivered by ABB