Rotor Loss and Thermal Analysis of Synchronous Condenser Under Single-Phase Short-Circuit Fault in the Transmission Line

Abstract

A synchronous condenser (SC) can provide the reactive power for the Ultra High Voltage Direct Current (UHVDC) converter station to keep voltage stability and prevent commutation failure. The single-phase short circuit at a transmission line is prevalent and it can result in not only the voltage drop but also the increase of the rotor loss and temperature of the SC. In order to study the ability of the SC to withstand a single-phase short-circuit fault, the rotor loss and temperature field of a 300-MVar SC are studied by coupling the electromagnetic and temperature field models of the SC with the models of the electric circuit and power grid. The loss distributions in the rotor core and slot wedges are calculated under a single-phase short-circuit fault at the different positions of the transmission line. The rotor temperature distributions of the SC under over- and under-excitations are calculated and verified by the experiments. The influence of short-circuit duration on the rotor temperature of the SC is calculated under the single-phase short circuit. The study can provide a theoretic basis for the improvement of the operating ability of the SC under the single-phase short-circuit faults.