基于小波分析理论的特高压输电线路故障选相研究

Research of fault phase selection on UHV transmission lines based on wavelet analysis

为了满足特高压输电线路的超高速保护要求,基于小波分析能检测故障信号中奇异信号突变时刻及其大小的特点,提出了一种故障选相方法。首先为了消除各相间的耦合影响,该方法将暂态故障电流经相模变换,然后用离散小波变换(DWT)提取出各模故障电流中的奇异成分并求出其模极大值,模极大值经归一化处理后作为选相方法的判据因子。最后根据模故障电流特征总结出不同故障类型下判据因子之间的关系,构造一种新型的特高压故障选相方法。通过PSCAD建模与Matlab计算,验证了所提选相方法受暂态故障信号幅值的干扰较小,自适应能力好,耐过渡电阻能力强,选相速度快且准确,能简单、有效地实现特高压输电线路的超高速保护。

To meet the requirements of ultra-high speed protection on UHV transmission lines, this paper proposes a fault phase selection method based on the characteristic of wavelet analysis which can detect the mutations＇ time and size of singular signal in fault signal. Firstly, this method transforms the transient fault current into model fault current to eliminate the impact of the various phases＇ coupling, then extracts its singular ingredients and modulus maximum by discrete wavelet transform （DWT）, treats the normalized modulus maximum as the criterion factors. Finally, it summarizes the relationship among criterion factors according to the characteristics of mode fault current, and constructs a new UHV fault phase selection method. Through PSCAD simulation and Matlab calculation, this method is proved that it is disturbed less by amplitude of the transient fault signal, and it has a good adaptive capacity and a strong ability for fault resistance, and its speed is also fast and accurate, the proposed approach can be implemented simply and effectively.