基于检测暂态高频电流的配电网故障处理方法研究

针对故障暂态电流产生自故障点并向线路末端传播的特点,设计了基于暂态电流边界保护原理的故障区段判断方法。在馈线各分段开关处即各供电区段边界处安装故障判断装置,其实质为并联在馈线上的谐振电路,使得在谐振频段附近的电流成分被衰减。通过比较边界两侧特定频段电流成分的差异,自主判断故障区段。对开关两侧电流互感器输出的三相电压信号进行模变换、抗混叠滤波、A/D转换、数字带通滤波处理后得到特征频段信号幅值,计算开关两侧信号能量,将两侧电流能量衰减比例同设定阈值相比较判断故障发生的范围。仿真分析了不同故障条件下故障点上、下游开关两侧电流和能量,以及相应的衰减比例。结果显示:该方法不受故障类型的影响,对不同的故障电阻及故障初始角也可保持良好稳定性。

Fault location method for distribution feeders based on transient high-frequency current detection

According to the traveling wave theory,fault on a power line produces wideband transient current at the fault point and spreads along the power line to both ends of the feeder.A new non-communication fault location method for overhead distribution feeders by utilizing fault generated high frequency current signals is presented.Designed fault locators are installed at sectional switches i.e.boundaries of sections,which in fact are resonant circuits connected to the feeder line in parallel to shunt the resonant frequency band component of the transient current.By detecting and comparing the difference between currents at both sides of the boundary in selected frequency band,the fault section can be determined by the locator.The three-phase voltage signals from current transformers at both sides of the switch are dealt with Clark transformation,anti-aliasing low-pass filtering,A / D conversion and band-pass digital filtering,then the signal amplitude in characteristic frequency band is achieved for signal energy calculations.By comparing both sides of current energy attenuate ratios with the set threshold,the fault can be located.Both sides of currents and energies of upper and lower switches as well as corresponding attenuate ratios are simulated under different conditions.Results show that the proposed method is free of fault types and keeps stable for different fault resistances and fault inception angles.