A Wavelet Controller for Shunt Active Power Filter

A wavelet-based controller for shunt active power filter (APF) has been proposed in this paper. The constructed controller based on multi resolution analysis has the advantage of better frequency bandwidth selection. The tuning parameters of the controllers are the gains to be applied to the time-frequency signals at different resolutions. This has the advantage of aiding the process of a proper choice of coefficients of tuning parameters. The developed simulation model of the APF with wavelet-based control shows satisfactory steady state and dynamic performance. A comparison with standard PI controller shows that the dynamic response of the proposed wavelet controller is much faster. This is of advantage in specific applications where the fast dynamic response of the controller is of importance to achieve a desired reference within a short duration of time. The novel technique of the generation of control signal ensures that even when the steady state error is zero, the controller can generate a steady control signal. The wavelet data window width is chosen optimally such that frequencies above 600 Hz are eliminated. This avoids the generation of high frequency spikes in the reference control current signal and ensures stability.