Harmonic detection using an affine projection algorithm for active power filter

With the development of adaptive filter theory, many adaptive filtering techniques are used for harmonic current detection, and achieved some good results. However, conventional algorithms still have some poor properties, such as low accuracy and slow convergence rate. Based on adaptive noise cancellation theory, this paper proposed a variable step size affine projection algorithm (VSS-APA) for harmonic current detection. The step size of the proposed method is updated by the coherence average estimation of the proportion denoted by the error signal in the total signal. The VSS-APA has fast convergence rate and good tracking performance of fundamental and harmonic components from distorted signals, and simulation results prove the algorithm having a good feature.