Development of a pumped-storage power station model for power system stability study

Since a pumped-storage power station generally is located far from the load center, it frequently encounters problems of power system stability, especially at the pumping operation mode. Capacity of units constructed in recent years is as large as a few hundred megawatts, and water head is as high as 500 m. The period of water pressure oscillation of such a high head station becomes longer and closer to power system swing. Under such condition the output is affected by the conduit system dynamics and becomes different from analytical results using the classical model which assumes constant torque or output during power system disturbance at the pumping operation mode. This paper describes the newly developed simplified pumped-storage plant model based on the elastic theory of the conduit system and the complete characteristics of the turbine, which has necessary accuracy to be analyzed because it is connected to bulk power system. Comparison with the real plant test result verifies the validity of the developed model. The interaction with power system is examined by linearized analysis and simulation study.