VSC直流侧故障限流方案及其特性分析OA

In DC power grid,when serious metallic short circuit fault occurs in the DC side line of voltage source converter(VSC),the fault current has the characteristics of a fast rising speed and a large peak.The DC circuit breaker is used to isolate the fault,which greatly increases the requirements for the quick action and breaking capacity of the DC circuit breaker.Based on the VSC bipolar short circuit fault characteristics,a fault current limiting scheme with residual current operated protective device(RCD)current peak suppression circuit in series with the DC line was proposed.The current limiting circuit,which controlled the opening and closing of the thyristor,not only interrupted the discharge loop of the DC side capacitor to the fault point,but also effectively reduced the peak fault current and limited the fault steady state current to a given reference value.The PSCAD/EMTDC simulation platform was used to test the VSC bipolar short circuit fault and the proposed current limiting scheme,and the effectiveness of the proposed scheme was compared with that of the other two fault current limiting schemes,which verified the superiority of the proposed scheme based on energy transfer circuit.