基于调整滤波器初相位的新型半波傅氏算法

Half-wave Fourier algorithm based on adjusting initial phase of filter

提出了一种新型的半波傅氏算法。通过适当调整正弦、余弦滤波器的初相位,使衰减直流分量对基波的泄漏在较宽的时间常数变化范围内约是衰减直流分量初始值的常数倍,利用这一特性,根据半波傅氏算法的幅频泄漏规律并移动数据窗快速提取出基波分量、偶次谐波分量及衰减直流分量初始值。当4次以上的偶次谐波含量很小时,算法的数据窗长度为每周期采样点数的一半加3个采样点,计算量约为全周傅氏算法的3/4。大量仿真实验表明,配置合适的前置低通滤波器,可以达到较高的精度,是一种简单实用的新型微机继电保护算法。

A half-wave Fourier algorithm is presented.By proper adjusting the initial phase of the sinusoidal or cosinoidal filter,the leakage of the decaying DC component into the fundamentals can be nearly equivalent to a constant multiple of the initial value of the decaying DC component in a wide variation range of time constant.This property can be employed to extract quickly the initial values of the decaying DC components,fundamentals and even harmonics by shifting the data window according to the amplitude-frequency leakage law of half-wave Fourier algorithm.When the4th and above harmonic components are neglectable,the data window length of the algorithm will be half the samples of each cycle plus three samples and the computation amount is about three quarters of that for full-cycle Fourier algorithm.The substantial simulative tests show that,if proper preceding low-pass filters are provided,higher accuracy could be obtained and this algorithm is simple and practical for microprocessor-based protective relays.