Hybrid Automaton-Fuzzy Control of Three-Phase Four-Wire Shunt Active Power Filter with Split Capacitor

This study presents a harmonic and reactive power compensating system using a four-leg shunt active power filter (SAPF) in a three-phase, four-wire distribution network. The structure used by studied system employs a three-leg split capacitor voltage source inverter (VSI). We seek the achievement of the two control objectives: i) compensation of the current harmonics and the reactive power absorbed by the nonlinear load by forcing the grid currents to be in phase with the grid voltages in order to achieve power factor correction (PFC) and ii) regulation of the voltage of the DC link capacitor. To achieve the above control objectives, a two-loop cascaded nonlinear controller is developed using hybrid automaton approach based on the hybrid nonlinear model with a simple technique to estimate of harmonics reference signal in the inner-loop for ensuring the unit power factor. A fuzzy logic regulator is developed in the outer-loop to ensure a strict regulation by controlling the capacitors voltage to follow their references. This approach is examined using Matlab\Simulink, which show that the proposed controller meets its objective under different operating conditions.