Study on transients and effect on capacitor voltage transformer caused by disconnector switching of UHV Series Capacitor Banks

During the system commissioning test of Ultra High Voltage (UHV) project with Series Capacitors Banks (SCB), the adjacent capacitor voltage transformer (CVT) was damaged during the switching operation of disconnectors of SCB. In this paper, the transients on adjacent CVT caused by disconnector switching of UHV SCB were studied by simulation. The causes of damage of CVT were analyzed. The effectiveness of suppressing the transients by use of damping resistor of disconnector, series reactor and series resistor were studied by simulation. In UHV AC test base, a test circuit was established. It includes true type UHV SCB platform, UHV CVT and disconnector. Tests were carried out when the circuit was with or without limitation measures. Test results were compared with the simulation results. The simulation and Test results were in agreement.