Abstract
A converter-fed variable-speed generator-motor for a pumped storage power plant has been developed in order to contribute to the automatic frequency control on an electric power system during pumping operations, as well as to improve the efficiency of turbines during generating operation together with electric power stability. This system consists of a reversible pump-turbine, generator-motor, cycloconverter and control units. The rotor of the generator-motor, wich is coupled directly with the turbine runner, is normally operated at a rotating speed equal to the difference between the frequency of the electric power system and that of the rotor current. In the state that a fault has occurred in the secondary circuit of the generator-motor, the variable-speed generator-motor fault current differs from that of a conventional synchronous generator-motor.
This paper describes the fault current analysis results for the condition that a sudden short-circuit is made on the secondary side of the generator-motor, and collates the results with the EMTP simulation results.
