One-sample-period-ahead predictive current control for high-performance active shunt power filters

Abstract

An improved predictive current controller for active shunt power filters is proposed in this work. The algorithm is based on the conventional deadbeat control and introduces a modified approach to compensate for delays incurred through digital implementation of the control, by predicting a system behaviour one and two sample instants in advance with respect to the measurement instant. Compared with the conventional deadbeat control the proposed solution is more suitable for practical implementations where measurement noise is very likely to appear. An analytical study of the sampled-quantities’ noise propagation through the controller is provided. A polynomial-type extrapolation predictor is considered to predict the active shunt filter reference currents and some issues related to its use are addressed. As an alternative, a more robust predictor based on the fact that in practice most distorted loads exhibit a periodic behaviour is also proposed. The system stability under model uncertainties is analysed. The theoretical expectations are verified through experimental tests.