基于正序电压差的含分布式电源配电网断线接地复合故障定位方法

分布式电源(distributed generation, DG)大量应用给电网故障识别与定位提出了更高要求。配电网断线故障时绝缘虽未遭到破坏，但可能导致DG故障穿越，甚至诱发并网逆变器闭锁，造成电气量越限，威胁电网稳定运行。为此，提出了一种利用正序电压差实现含DG配电网的断线接地复合故障定位方法。通过解析不同故障情况下配电网馈线序电流和DG并网点电压，发现了非故障点两端正序电压差等于线路压降，而断口两端正序电压差恒为正数且多大于非故障区段压差的特征，构造了基于正序电压差的故障定位判据。针对定位判据可能出现的死区问题，引入DG输出电流作为辅助判据提高定位可靠性，进而提出了含DG配电网的断线接地复合故障定位方法。理论分析和仿真结果表明，所提方法能够实现不同DG容量、故障位置下的断线接地复合故障区段准确定位，且具有较强的耐过渡电阻能力。

Fault location method of a compound break fault with grounding for distribution networkcontained distributed generation based on positive sequence voltage difference

The massive application of distributed generation (DG) has brought forward higher requirements for grid fault identification and location. Although the insulation is not damaged during a break fault in the distribution network, it may lead to DG fault ride-through and even induce grid-connected inverter blocking, causing an electrical quantity exceeding the limit, and thereby threatening the stable operation of the power grid. Thus a method is proposed to locate the compound break fault with grounding in a distribution network with DG using the positive sequence voltage difference. By analyzing the sequence currents and voltages point of common coupling voltages of the distribution network under different fault conditions, it is found that the positive sequence voltage difference at both ends of the non-fault section is equal to the line voltage drop, while the positive sequence voltage difference at both ends of the break is constant positive and more than the difference of the non-fault section. Thus a fault location criterion based on the positive sequence voltage difference is constructed. For the possible dead zone problem of the location criterion, the DG output current is introduced as an auxiliary criterion to improve reliability. Finally, the method of fault location of a compound break fault with grounding is proposed. The theoretical analysis and simulation results show that the proposed method can accurately locate the compound break fault with grounding section with different DG capacity and fault location, and has strong resistance to transition resistance.This work is supported by the National Natural Science Foundation of China (No. 51877018).