RDFT算法在有源电力滤波器中的应用

摘要

提出了一种基于递归离散傅里叶变换(RDFT)的谐波检测算法,该算法采用滑窗迭代方法由离散傅里叶变换推导而来,具有运算量小、实时性好等特点,适合用数字信号处理器实现.并联型有源电力滤波器(APF)可以采用RDFT算法单独检测出非线性负载电流的基波成分与各次谐波成分,并根据需要生成补偿电流指令,实现对谐波电流的选择性补偿或全补偿.仿真结果表明,APF采用该谐波检测算法可以在一个基波周期内完成对负载电流变化的跟踪并实现谐波检测.利用实验室APF样机选择性地补偿非线性负载5次谐波电流分量,可使系统电流中5次谐波含量由22.51%降至1.1 %;当APF完全补偿负载谐波电流时,系统电流总谐波崎变率可由27.63%降至3.45 %.%A harmonic current detection algorithm based on the RDFT(Recursive Discrete Fourier Transform)is proposed,which is deduced from the discrete Fourier transform with the sliding-window iterative method,suitable for the implementation by digital signal processor because of its less computation. It can be applied in shunt APF(Active Power Filter) to detect the fundamental component and different harmonic components of nonlinear load current,and then generate the compensation current reference as need for selective or full harmonic current compensation. Simulative result shows that,the APF with RDFT algorithm detects the harmonic current and follows its variation in a fundamental period. A lab APF prototype is used to selectively compensate the 5th harmonic current of nonlinear load,which reduces the 5th harmonic current of system from.22.51％ to 1.1％. For full harmonic current compensation,the total harmonic distortion of system current is reduced from 27.63％ to 3.45％.