Abstract When a DC bus ground fault occurs near the grounding point in a back-to-back DC transmission system, overvoltage may occur after the system is blocked. This paper analyzes the short-circuit circuit formed between the fault point and the grounding point, which causes the valve short-circuit protection to act before the pole grounding protection. In such a fault situation, the valve short-circuit protection action X block, causing overvoltage in the DC system during the blocking process. But the DC bus ground fault to act Y block, or the valve short-circuit fault to act X block, does not appear the overvoltage phenomenon after blocking. In this paper, the ground current is introduced as an auxiliary criterion, and two optimization methods are proposed. When the same DC bus ground fault occurs near the grounding side, the control system selectively performs different blocking mode. It can effectively avoid the DC system overvoltage after blocking, and is beneficial to the reliable isolation of power system faults and reduce the risk of the system’s primary equipment operation.
LIU Qiao,WANG Junsheng. Analysis and optimization of overvoltage after fault blocking in back-to-back DC transmission[J]. Electrical Engineering, 2024, 25(3): 79-84.
2024, Vol. 25 
