Experimental evaluation of a simple robust control for active power filtering under unfavourable conditions

This paper deals with shunt active power filtering for power quality improvement under unfavourable non-linear load and source conditions. A simple hybrid control strategy is used, based on a numerical integrator proportional (IP) DC bus controller combined with a phase-locked loop (P.L.L.) output to generate reference currents. A second analogue current controller is developed to insure- three phase sinusoidal synchronised waveforms of the main currents. The experimental evaluation of the robustness control is verified using 20 KVA shunt active power filter (SAPF) not only for transient conditions (step load, switch-on of SAPF) but also for the worst case of unbalanced loads (break phase) and source voltages. Several experimental results are presented and discussed to prove the robustness and the excellent performance of the proposed technique.