Use of a static frequency converter for rapid load response in pumped-storage plants

Most pumped-storage power plants have the capability to operate as synchronous condensers. As such, they can be brought online very quickly to support power system load requirements. However, one of the effects of making a rapid transition from synchronous condenser operation to turbine/governor operation is an initial reverse power flow into the machine. This reverse power flow can be very undesirable at a time when the power system is calling for load support. On weak or isolated power systems, this reverse power flow can lead to objectionable voltage and frequency dips in the power system. With the proper utilization of a static frequency converter (SFC) and its associated controls and auxiliary switchgear systems, the reverse power flow resulting from a transition from synchronous condenser operation can be eliminated. This paper describe a method by which an SFC system can be used to make this rapid load response in pumped-storage power plants without incurring a reverse power flow and to provide additional instantaneous short term power to support the grid.