Conservative Power Theory Used in NPC-Based Shunt Active Power Filter to Eliminate Electric Metro System Harmonics

In this work, a Shunt Active Power Filter (SAPF) using a multilevel inverter operating in low switching frequency is used to improve the power quality in electric metro power supply systems. The proposed topology is a three level/phase voltage source Neutral Point Clamped (NPC) and the Conservative Power Theory (CPT) is used to extract the harmonic currents. A current control schema sensing only the grid side voltages and currents is used and a capacitor voltage controller that balances the natural point voltage is implemented. Simulation results validate the ability of this set to mitigate harmonic currents.