基于同步零序电流谐波群体比相的谐振接地系统高阻故障选线及区段定位方法

Feeder Selection and Section Location of High Impedance Fault at Resonant Networks Based on the Phase Differences Between the Synchronous Harmonics of the Zero Sequence Currents

高阻接地故障选线和区段定位是配电网故障处理的难点,谐振接地系统因其故障特征的特殊性又给高阻接地故障诊断带来挑战。针对传统小电流接地故障定位方法在面对高阻接地故障问题时因量测精度不足、故障特征提取不准确造成的定位困难问题,从高阻接地故障非线性特征入手,推导谐振接地系统健全线路(区段)和故障线路(区段)特征的差异;分析消弧线圈补偿度和系统阻尼率对故障特征的影响;利用区段合成零序电流的同步波形,提出不依赖于故障特征产生时间且适用性更广泛的同步三次谐波群体比相定位方法。实测案例验证了所提理论的正确性和方法的有效性。

Location of high impedance fault(HIF),including the faulty feeder selection and section location, is a challenge of distribution system protection. HIFs mostly happen as the single-line-to-earth faults, which are more difficult to be located for the resonant grounding system. In order to deal with the problems that the required features of HIFs are too weak to be reliably extracted and utilized by traditional methods, this paper theoretically deduced the differences between fault and healthy sections from the aspect of nonlinearity characteristic. Effects of the detuning index and damping ratio were both considered. By using the synthetic zero-sequence currents in each section, a more general algorithm was proposed based on the phase differences of the synchronous 3 rd harmonics, which existed all the time as long as the electrical connection between the line and earth was maintained. The correctness of the theory and the effectiveness of the algorithm were verified with real-world HIFs.