改进变步长LMS算法在软起动谐波检测中的应用

针对现有自适应变步长最小均方(LMS)谐波电流检测算法在低信噪比环境中易受干扰影响,提出一种改进自适应变步长LMS算法。该算法将误差信号与前一工频周期误差信号的差值作为反馈量,结合箕舌线函数构造出随动的动态因子,将此动态因子也作为调节权值的动量因子,利用自相干估计误差控制步长。该算法折中考虑收敛速度和稳态精度,并有效降低噪声信号的干扰。通过对电机软起动器工作过程中产生的周期重复性谐波进行检测和分析,证明了该谐波电流检测算法的可行性。

Improved Variable Step-Size LMS Algorithm in the Application of Soft-Starter Harmonic Detection

In view of the existing adaptive variable step size least mean square (LMS) harmonic current detection algorithm in low signal-to-noise environment effected easily, an improved adaptive variable step size LMS algorithm was introduced. The difference of the error signal and the signal from the previous cycle is used as the feedback,which combined with Versiera function constructed servo dynamic factors. The dynamic factor as the momentum factor, which adjusting weight. The coherence estimation error was used to control step length. The algorithm compromised convergence rate and stability ,in addition,it reduced effectively the noise interference. Through detection and analysis of motor soft-starter producing periodically repeatedly harmonic in the process of working,which proved the new detection algorithm is feasible.