一种用于谐波检测的改进型自适应变步长最小均方算法

An Improved Adaptive Variable Step Size LMS Algorithm for Harmonic Detection

在低信噪比的环境下,噪声的存在容易造成有源电力滤波器谐波电流检测的不准确,从而导致补偿结果不精确。为了提高自适应检测算法对谐波电流检测的精度和跟踪速度,基于最小均方自适应算法提出了一种改进的变步长LMS算法。该算法根据稳态谐波均值为零的特点,采用历史误差的遗忘加权和来代替单一时刻的系统误差以动态控制步长的更新,通过步长因子与系统误差均值估计的类Sigmoid函数关系,实现动态控制其参数的变化,以保证算法具有较快的收敛速度、较高的精度和动态跟踪效果。仿真实验结果验证了该方法的有效性。

It is difficult to detect harmonic current accurately when APF in low SNR condition. In order to improve the accuracy and tracking speed of harmonic current detection, an improved variable step-size LMS （least mean square ） algorithm was proposed based on LMS algorithm. Based on the characteristic that mean value of steady state harmonics is zero, the system error at a certain moment is replaced by the forgetting weight sum of historical error to control the step size dynamically. Dynamic control of parameter change is realized by the generic Sigrnoid function between step size factor and system error. The dynamic of Sigmoid parameters ensures that the improved adaptive algorithm has the faster convergence speed, higher precision and dynamic tracking effect. Simulation results show the effectiveness of the proposed method.