计及过渡电阻影响的配电网断线接地复合故障保护方法

Protection Method of Compound Break Fault With Grounding for Distribution Network Considering Influence of Fault Resistance

为保障配电网安全运行,近年来断线故障保护受到重视,但对于断线接地复合故障的研究尚处于起步阶段。由于断线接地复合故障特征与断线不接地或单相短路故障存在显著区别,现有断线和短路故障保护方法对于断线接地复合故障存在局限性。特别是高阻下故障特征的进一步弱化,加大了故障识别难度。为此,提出了一种计及过渡电阻影响的配电网断线接地复合故障保护方法。首先,推导了断线电源侧接地故障和断线负荷侧接地故障的序电流,解析了负序、零序电流的变化特征和关联关系,进而构建了融合负序电流和零序电流的保护判据,提出了一种配电网断线接地复合故障的灵敏保护方法。理论分析和仿真结果表明,该方法兼顾了故障类型、负荷大小与分布、故障位置等多重因素的影响,适用于各种中性点接地方式,能够实现过渡电阻全范围内的断线接地复合故障可靠识别。

To ensure the safety of distribution network, the break fault protection has been paid more attention, but the research on compound break fault with grounding is still in its infancy. Since the characteristics of compound break fault with grounding are significantly different from the break fault and short-circuit fault, the existing protection methods have limitations. In particular, the further weakening of fault characteristics under high fault resistance makes accurate identification more difficult. For this reason, this paper proposes a Protection method of compound break fault with grounding for distribution network considering influence of fault resistance. First, the sequence currents of break fault with power side or load side grounding are deduced, and the change characteristics and correlation of the negative sequence and zero sequence current are analyzed. As a result, a protection criterion combining negative sequence current and zero sequence current is constructed, and a sensitive protection method of compound break fault with grounding is proposed.Theoretical analysis and simulation results show that the method takes into account the effects of multiple factors such as fault resistance, size and distribution of load, and is suitable for various neutral grounding modes, which can realize the identification reliably in the full range of fault resistance.