多分辨HHT在STATCOM并补线路故障位置识别中的应用

Application of multi-resolution HHT in fault locating for lines with shunt STATCOM compensation

引入多分辨分析方法对Hilbert-Huang变换(HHT)进行改进:根据信号的特征尺度对信号筛分后进行经验模态分解(EMD)处理,然后对固有模态函数(IMF)分量进行Hilbert变换,求取各分量的瞬时频率和幅值。通过对信号按不同时间尺度进行滤波,有效消除模态混叠;同时对信号进行分段样条拟合,减少计算量。用多分辨HHT方法对含静止同步补偿器(STATCOM)的并补线路保护在稳态和故障暂态时的测量信号以及在不同故障位置时的谐波进行仿真分析,结果表明:STATCOM会使故障时保护安装处的电压谐波含量明显增大;谐波分量的特征与故障回路中是否包含STATCOM有关,故障回路包含STATCOM时特征谐波的幅值很大,否则幅值很小。将该谐波特征用于STATCOM并补线路的故障位置识别,可以自适应地判断故障点的位置,与距离保护相结合,可以有效地解决距离保护用于并补线路时的超越误动和欠范围拒动问题。

The multi-resolution analysis is introduced to HHT（Hilbert-Huang Transform）：the screened signal is treated by EMD（Empirical Mode Decomposition） according to its characteristic scale and the IMF（Intrinsic Mode Function） is then processed by Hilbert transform to get the instantaneous frequency and amplitude of each component.The mode aliasing is effectively eliminated by signal filtering in different time scales.The piecewise spline fitting is carried out for the signal to reduce the computational load.The multi-resolution HHT is used to analyze the measurements of lines with shunt STATCOM compensation in both steady and transient states and the harmonics for different fault locations.Simulative results show that,STATCOM makes the voltage harmonics sampled by protection obviously increased during fault;the amplitude of characteristic harmonic is big when STATCOM is located in the fault circuit.The characteristic harmonic can thus be used to adaptively locate the fault,which,combined with the distance protection for the lines with shunt STATCOM compensation,avoids its improper protection operations.