Harmonics-resistant adaptive algorithm for line-frequency signal processing

Adaptive filters are often used in signal processing tasks related to line-frequency signals in power distribution systems. In this paper, we discuss a computationally efficient adaptive algorithm for transversal discrete-time filters. The algorithm, which is based on the so-called general parameter method, uses only two dynamically adjusted parameters, each to be added to a block of coefficients of a fixed basis finite-impulse response filter. The parameter updating formula involves running addition of the data samples, causing suppression of certain frequencies. Therefore, the algorithm can be designed to adapt mainly according to the primary input frequency while being tolerant against specific harmonic components. This is advantageous, for instance, when processing 50/60-Hz line-frequency signals. The properties and stability of the algorithm are analyzed.