Simulation And Measurement Of The Switching Overvoltage Of Compensating Capacitor In Substations

The failure of compensating capacitor in the substation is a difficult problem which needs tosolve for power utilities. This thesis tries to discuss and find out the possible reasons for the failureof the compensating capacitor based on the overvlotage due to the switches of compensatingcapacitor. One thing is to analysis the overvoltage due to the switches of compensating capacitorusing ATP-EMTP program, the other thing is to develop an ovevoltage monitoring system to monitorthe overvoltage at the substation. Based on a real 10kV substation model, the simulation resultsunder various operating modes indicate that the overvoltage of the capacitor is much greater whenthe 10KV bus is light-loaded or the switch is multi-reburning. Moreover, the lowest overvoltageoccurs when the capacitor is switched while 3-phase bus-voltage is zero-cross separately. In addition,there is a higher overvoltage when the capacitor is switching according to the field test resultsusing the developed overvoltage monitoring system at Wangchun 10kV substation. The simulationresults and the field test show that the overvoltage due to the switching of capacitor might beone of possible reasons of the failure of compensating capacitor.