一种提取基波分量的高精度快速滤波算法

Accurate and Fast Filtering Algorithm for Fundamental Component

为满足微机继电保护速动性的要求,短数据窗傅里叶算法得到了广泛应用。在系统发生故障期间,电压电流信号中包含大量的非周期分量与谐波分量,这将极大地延迟传统半波傅里叶算法的收敛速度。为此提出了基于狭窄带通滤波与半波傅里叶算法相结合的快速滤波算法,该算法充分利用了狭窄带通滤波算法对低频和高次谐波良好的抑制作用,同时结合了半波傅里叶算法计算实部受衰减直流分量影响小的特点,计算速度快,且滤波效果明显优于传统算法。

In order to have fast responding time of microprocessor-based protection, the half-cycle discrete Fourier transform （HCDFT） has been most widely used for fast computing the fundamental frequency component. However, when a fault occurs, both the voltage and current signals contain large harmonics and the decaying DC component during the fault duration. These abnormal components involved in measurements will significantly postpone the convergent speed of conventional HCDFT algorithm. In order to solve the problem, this paper presents a novel algorithm, which combines the constrictive band-pass filter and HCDFT. Combining the characteristics of decaying DC component has less influence on the real part of HCDFT and the advantage of low frequency and high harmonics can be restrained effectively by constrictive band-pass. Hence the proposed algorithm can calculate the fundamental frequency component more quickly. Simulation tests show that the filtering results of the proposed algorithm are better than that of the conventional algorithms.