A "two ahead" predictive controller for active shunt power filters

In this paper an improved predictive control is proposed for the control of the current in a three-phase voltage source converter. The application for this work is an active shunt power filter (ASF). The proposed control system takes into account unavoidable digital controller delays, which make it difficult to predict the ASF behaviour in the next sampling period. A "Two Ahead" current reference prediction is proposed which predicts the filter current two samples in advance. The predictor is based on a polynomial-type extrapolation method, and can also account for step changes in the reference waveform. In addition to good tracking performance, the controller has good stability with respect to the system parameters and model mismatch, and good resistance to the measurement noise. The design and implementation of the digital controller are developed in detail in this paper and the effectiveness of the proposed method is verified through experiment.