Flatness-SVPWM Control for Three-Phase Shunt Active Power Filter Based on Five-Level NPC Inverter

Abstract

The increasing use in the industry of nonlinear loads based on power electronic elements has introduced serious perturbation problems in the electric power distribution grids. These nonlinear loads generate non-sinusoidal currents to the mains which degrade the system's performance. Active power filters have been developed over the years to solve these problems and improve power quality. This study focuses on the use of a shunt active power filter to compensate nonlinear load's current harmonics and reactive power. To this end, a regulator based on the flatness control technique combined with an SVPWM strategy for a three-phase shunt active power filter based on a five-level neutral-point-clamped (NPC) inverter is used. The control objectives of this work are twofold: i. compensating the current harmonics and the reactive power produced by the nonlinear loads, and ii. regulating the inverter's DC capacitor voltage. To achieve these objectives, two cascaded loops are designed; an inner loop for the reactive and harmonic currents compensation based on a flatness controller and an outer loop for the DC voltage regulation based on a PI regulator. The simulation results are developed under MATLAB/Simulink environment to prove the satisfactory performance of the proposed controlled system.