基于改进增益型自适应LMS算法的谐波检测方法

摘要

基于自适应噪声对消原理的谐波电流检测方法相对其他检测方法来说，具有实现简单、鲁棒性强等特点。该方法利用信号处理中的自适应干扰对消原理，将电网电压信号作为参考输入，负载电流作为原始输入，从负载中实时消除与电压波形相同的基波有功电流分量(或基波电流)，从而得到负载电流中所有谐波与基波电流无功分量之和。再配合有源电力滤波器(APF)，由补偿装置注入一个与谐波和基波电流无功分量之和大小相等极性相反的补偿电流，达到抑制谐波与基波电流无功分量的目的。提出了一种基于改进增益型自适应谐波电流的检测方法，该方法采用的反馈量不同于以往方法中的误差信号，而是将误差信号经过数学转换，使其转换成一个能真正反映系统跟踪误差的信号，并将其作为自适应滤波器权系数迭代的反馈量。通过Matlab证明该方法能够在保持较小的稳态失调的情况下也具有较快的动态响应速度。%Compared with other detection method, harmonic detection method based on adaptive noise cancellation principle has the advantages like being easier to achieve, strong robustness and so on. This method uses the principle of adaptive interference cancellation in signal processing, takes the grid voltage signal as the reference input and the load current as the original input, eliminates the fundamental active current waveform that is similar to the voltage waveform in the real time from the load current, gets the sum of harmonic and fundamental reactive current, injects a compensation current that has the same value and the reverse polar with the sum of harmonic and fundamental reactive current to load current through compensation device of APF, and then achieve the purpose to suppress harmonic and fundamental reactive current. This paper proposes a new harmonic detection method based on LMS algorithm of improved adaptive gain. What this new method takes as feedback is different from previous researches. Previous studies use the error as feedback, but this new research's feedback is the change form of the error which is the true signal to reflect the system's tracking situation, and this feedback is used to the iterative process of the adaptive filter's weight coefficient. This new method is proved through the MATLAB simulation that it is able to keep small steady state error also has faster dynamic response speed.