配网高阻接地故障伏安特性分析及检测

Analysis and Detection of Volt-ampere Characteristics for High Impedance Faults in Distribution Systems

中性点有效接地中压配电网常发生弧光高阻接地故障,短路电流小,零序保护无法动作切除,但存在的电弧易引发火灾、人身伤亡等恶性事故。传统故障检测算法一般基于电弧热平衡模型,采用基于傅里叶变换的频域信号分析方法,但在非线性电弧的强噪声环境下检测成功率较低。针对该问题,首先提出了基于固体介质电击穿原理的非线性电弧模型,分析了电路线性元件和高阻接地非线性电阻的伏安特性,从时域角度采用最小二乘线性拟合抽取故障特征,提出了基于故障电阻非线性识别的高阻接地故障检测算法。大量仿真数据和现场试验数据证明了该故障模型比传统模型更精确,且所提检测算法具有较高的灵敏性和可靠性。

High impedance faults （HIFs） often occur in effectively grounded medium voltage （MV） distribution systems, while their fault currents are too low to be tripped by zero-sequence over-current protection, but the existing arc flash is easy to produce fire hazard and personal injury. Existing HIF detection （HIFD） algorithms, which are mainly based on arc thermal equation and frequency domain analysis based on Fourier transform, however, have a relatively poorer performance because of strong noises accompanied by arc flash Aiming to solve this problem, an accurate nonlinear resistance model, based on the solid dielectric electrical break-down theory, was proposed to simulate the fault point. After analyzing the Voltage-Current characteristics of linear electrical components and nonlinear arc resistance, a nonlinear resistance identification based HIFD algorithm was proposed with fault characteristic extraction by least square fitting. Extensive field data and simulation results testified the higher accuracy of the proposed fault model over traditional models, as well as high sensitivity and reliability of the proposed algorithm.