提高谐波电流检测性能的LMS/LMF自适应滤波器

LMS/LMF adaptive filter for harmonic current detection performance improvement

为提高基于瞬时无功功率理论的谐波电流检测法在检测精度和收敛速度方面的性能,提出了一种新颖的最小均方(LMS)与最小四阶矩(LMF)相结合的LMS/LMF自适应滤波器算法,根据误差信号自适应地调整LMS和LMF算法在权值更新中的占比,以同时发挥LMF算法收敛速度快和LMS算法稳态精度高的优点。推导了该算法的收敛条件、时间常数和失调公式,分析得出适当减小步长可以更好地兼顾收敛速度和检测精度。仿真和试验结果表明,该算法使低通滤波器动态过程收敛更快,稳态误差更小,从而提高瞬时无功功率理论谐波检测法的性能。

In order to improve the detection accuracy and convergence speed of harmonic current detection method based on instantaneous reactive power theory,a novel algorithm of LMS/LMF adaptive filter is proposed,which combines LMS al- gorithm with LMF algorithm. The new algorithm can adjust self-adaptively the proportions of LMS and LMF in weight up- date,and integrate the merits of both fast convergence speed of LMF algorithm and high stability precision of LMS algo- rithm. The convergence condition, time constant and misadjustment formula of the proposed algorithm are derived, and a conclusion is reached that the proposed algorithm can achieve both fast convergence speed and high detection accuracy by properly decreasing step size. The simulation and experiment results show that the proposed method can make the dynamic response of the low pass filter faster and its stability accuracy better,thus improve dynamic and steady performances of the harmonic current detection method based on instantaneous reactive power theory.