Direct Power Control for three phase active power filter with observer for the source’s voltage

Abstract

In this work, we propose nonlinear control for three-phase active power filter (APF) to compensate reactive and harmonic power generated by the linear, nonlinear, and nonlinear unbalanced load. The proposed control strategy direct power control (DPC) uses the concept of direct control for active power (DCAP) to extract the harmonic power generated by the nonlinear load and the reference value of the active power. Based on the average model of the (APF) system, we have used the Back-stepping technic to elaborate the power’s regulator and integrative-proportional (PI) regulator to regulate the voltage DC-link capacitor. Moreover, in this study, we supposed that the grid source voltage is not accessible to the measurement and the reactance of the network, not nil, in order to render better the control performance. For that, we have developed a Luenberger observer to estimate the source voltage of the network. The control objective of this work is threefold. i) the APF must compensate the reactive and deformed power generated by the loads, ii) maintain the DC bus voltage stable. Moreover, iii) the observer must provide the estimate instantaneous value of the grid source voltage. The simulation result using the Matlab/Simulink environment shows that the control strategy succeeds to improve power quality with various load conditions.