Abstract：The fault characteristic analysis is the basis of designing protection schemes. Some positive and negative voltages/currents present long-term unbalance after single-pole breakage faults in the ring flexible DC distribution network, which endangers the safe and stable operation of the system, whereas little research on it has been implemented. Therefore, characteristics of single-pole breakage fault in ring flexible DC distribution network are studied. First, a typical complex ring flexible DC distribution network model was established, and the coordinated control strategy of key equipment and each port was defined. Second, by establishing the equivalent model of the system before and after the fault, the voltage and current characteristics of the single-pole breakage fault on the DC line, the link line between the sending-end converter and the DC bus, and the link line between the receiving-end converter and the DC bus were analyzed. Then, the influence of system grounding mode on the characteristics of the single-pole breakage fault was discussed. It shows that, the flow path of the fault current is related to the location of the single-pole breakage faults; the voltage characteristics of single-pole breakage fault on DC line are related to the power flow direction of converter station; the voltage characteristics of single-pole breakage fault on the link line between the sending-end converter and the DC bus are related to the control mode of converter; the system grounding mode has little effect on the fault characteristics. In addition, sudden load change will affect the current characteristics of the positive and negative lines between the converter station where the sudden load occurs and the sending-end converter station for which the power is transmitted when the fault occurs on the DC line and the link line between the sending-end converter and the DC bus. Finally, the model of the ring flexible DC distribution system was built in PSCAD/EMTDC, and the result confirmed the validity of the theoretical analysis.
戴志辉, 陈思琦, 李毅然, 焦彦军. 复杂环状柔直配电网单极断线故障特性分析[J]. 电工技术学报, 2022, 37(5): 1229-1241.
Dai Zhihui, Chen Siqi, Li Yiran, Jiao Yanjun. Characteristic Analysis of Single-Pole Breakage Fault in Complex Ring Flexible DC Distribution Systems. Transactions of China Electrotechnical Society, 2022, 37(5): 1229-1241.
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2022, Vol. 37 
