Digital realization of a novel detection algorithm based on instantaneous reactive power theory

An active power filter(APF) is an effective method controlling harmonic perturbations. Obviously, fast and precise harmonic detecting is one of the keys to design APFs. The paper thoroughly researches instantaneous reactive power theory and proposes a new variable step size least mean square(LMS) adaptive filter as the low pass filter(LPF) on harmonic detection circuit, where the step size of the algorithm is adjusted according to the square of the time-averaged estimate of the autocorrelation of e(n) and e(n-l). As a result, the algorithm can effectively adjust the step size while maintaining the immunity against harmonic current disturbance. The proposed algorithm allows more flexible control of misadjustment and fast convergence rate without the need to compromise one for the other. Simulation and experiment results illustrate that the performance of the proposed approach is satisfactory.