A simple active power filter with 5-level NPC inverter

In utility distribution systems, the abundance of nonlinear electronic loads has resulted in the deterioration of power quality. Active Power Filters (APF) can provide reliable reactive and harmonic power compensation. Active power filters are employed in the developed countries in many industrial sectors such as distributions and plants. In this work, the MATLAB-Simulink program was used as tool for design and development of the APF. The chosen APF topology is the Shunt APF. The Direct Testing and Calculating Method (DTCM) have been chosen as the specific current reference generation technique. This is due to its simplicity and low related cost. As for the main controller block, the current control technique chosen, is the Sliding Mode control. Its advantages are the robustness to system parameters variation. The inherent advantages of multilevel inverter topology have added to the performance of the active power filter. Results obtained from simulation have shown significant THD improvement whereby a nonlinear load of 82% THD has been decreased to 24% THD using the proposed active power filter.