多端柔性直流电网故障恢复过/欠电压机理及抑制方法OA北大核心CSTPCD

After removing the faulted line in a multi-terminal flexible DC grid,the power flow transfer under the change of each converter station's restoration operation mode is prone to cause DC over/under voltage,which endangers the safe operation of the system.To address this problem,a corresponding suppression control method is proposed based on the DC over/under voltage mechanism during grid recovery.Under the restoration of grid open-loop mode,a line voltage analysis model that considers the direction of the power flow is established.The additional voltage drop caused by the power flow transfer is identified as the essential factor leading to the over/under voltage,and the over/under voltage suppression and control method combining the adjustment of the voltage reference value and the power reduction is proposed to solve the DC over/under voltage problem effectively.The test results show that the proposed method has good over/under voltage suppression performance,which can reduce the peak overvoltage value by 39.92%and lift the under-voltage valley value by 30.46%compared with the traditional method.