基于小波的继电保护装置电磁干扰软件防护快速算法研究

Fast software anti-interference algorithm of digital relay based on wavelet

基于Mallat分解的小波变换方法能可靠地检测出电力波形中的奇异点,但不适合于实际工程应用。提出了基于S变换的改进的快速算法,即对AD采样点进行前向差分。对于正常的正弦采样信号,点与点之间的采样点值相差较小,所以差分值也较小;而对于奇异信号,在奇异点附近AD采样值有突变,所以差分值较大。因此,选择合适的差分门槛值就可以检测出信号中的奇异点。分析奇异点附近差分值的正负特性可以检测出该奇异点是正常的故障信号或是受干扰信号。最后,通过对典型波形的仿真计算和实际的电磁兼容性试验,验证了该软件抗干扰措施能显著提高数字式继电保护装置运行的稳定性。

Singular point detection of wavelet transform based on Mallat decomposition is not suitable for practical engineering application. A fast algorithm based on S-transform is proposed,which applies forward differential to AD sampling points. The difference between neighboring sampling values of normal sinusoidal signals is small,while that nearby singular points is large,according to which the singular points can be detected by setting suitable. Whether the singular point is fault signal or interference signal depends on its positive or negative characteristics. Simulative calculation and EMC experiment prove that,the software anti-interference measures can significantly improve the stability of digital relay.