兼具抗同步误差和耐高阻能力的直流配电网单极接地故障测距方法

Single pole-to-ground fault locating method with ability against synchronization error and high fault resistance for DC distribution network

针对已有双端故障测距方法的缺陷,基于RL线路时域微分方程建立双端故障测距模型,利用移动数据窗和最小距离方差计算实现双端数据自同步,降低对时误差带来的不利影响;同时构建不稳定点剔除判据,规避小量相除的运算场景。在此基础上,针对高阻接地故障,利用电压源换流器短时的零模式运行向系统注入小幅扰动,配合均值滤波算法和扩大的数据窗长提高所提方法的耐过渡电阻能力。三端环形直流配电网仿真结果表明,所提方法在考虑同步误差和过渡电阻为300Ω的接地故障的场景下仍具有理想的故障测距效果,性能较现有RL双端故障测距方法有了明显提升。所提方法对采样频率需求较低,在配电网中具有良好的应用前景。

Aiming at the defects of the existing two-terminal fault locating methods,the two-terminal fault locating model is established based on the RL power line time-domain differential equations,and the moving data window and the minimum distance variance calculation are utilized to achieve self-synchronization of the two-terminal data to reduce the adverse impacts of synchronization error. Meanwhile,the criterion for removing unstable points is constructed to avoid division operations of small numbers. On this basis,aiming at the grounding fault with high resistance,the short-time zero mode operation of the VSC(Voltage Source Converter) is adopted to inject a small disturbance into the system,cooperating with the mean filtering algorithm and enlarged data window,the ability against transient resistance of the proposed method is enhanced.Simulative results of a three-terminal circular DC distribution network show that the proposed method still has ideal fault locating effect under the situation of synchronization error and grounding fault with 300 Ωtransient resistance,and the performance of the proposed method is obviously better than that of the existing RL two-terminal fault locating methods. The proposed method has a low requirement for sampling frequency and a good application prospect in distribution network.