一种基于自适应理论的谐波检测算法

A new harmonic detection algorithm based on adaptive theory

为进一步改善有源滤波器(active power filter,APF)的滤波效果,基于最小均方误差理论,提出了一种变步长LMS/LMF谐波电流检测新算法,采用寻求目标函数最优和归一化的方法,通过权向量对步长的偏导估计并结合误差回馈信号的相干时间均值估计共同完成对步长参数的动态调节,并根据输入信号的特点自适应地调节阈值来实现LMS/LMF算法的自动切换,使得算法在便于控制动态参数的同时,不仅有效避免了高次谐波电流对步长更新迭代造成的干扰,而且更好地权衡了算法快速收敛和低稳态失调的矛盾。最后,该算法在仿真及实验中得到了有效验证。

In order to further improve the filtering effect of active power filter, a new variable step size LMS/LMF algorithm for harmonic current detection is proposed based on the theory of minimum mean square error, The method of finding the optimal and normalized target function is adopted. The dynamic adjustment of step length parameters is realized by weight vector partial derivative estimation and coherent time mean estimation of error feedback signal. The automatic switching of LMS/ LMF algorithm is realized by adjusting the threshold value adaptively according to the characteristics of the input signal. The algorithm can not only avoid the interference of high harmonic current on step length update iteration, but also control dynamic parameters. Meanwhile it has a better balance between the fast convergence and low steady-state maladjustment. Finally, the new algorithm gets validated effectively by the simulation and experiment.