A Proportional-Resonant Current Controller for Selective Harmonic Compensation in a Hybrid Active Power Filter

This paper deals with reactive power compensation and harmonics elimination in medium-voltage industrial networks using a hybrid active power filter. It proposes a hybrid filter as a combination of a three-phase, two-level, voltage-source converter connected in parallel with the inductor of a shunt, single-tuned, passive filter. This topological structure greatly decreases the voltage and current stress over the elements of the active filter. Since the topology is composed of a single-tuned branch, the control algorithm also has to ensure sufficient filtering at other harmonic frequencies. We propose using a proportional-resonant, multiloop controller. Since the controller is implemented in a synchronous-reference frame, it allows us to use half the number of resonators, compared with the solution using proportional-integral controllers in the harmonic-reference frame. Theoretical analyses and simulation results obtained from an actual industrial network model in PSCAD verify the viability and effectiveness of the proposed hybrid filter. In addition, the simulation results are validated by a comparison with the results obtained from a real-time digital simulator.