Averaged Modelling, Simulation and Linear Control Design of a PWM Fixed Frequency Three-Phase Four-Wire Shunt Active Power Filter for a Typical Industrial Load

Current harmonics, which are injected in the utility by nonlinear loads, cause major problems that tend to deteriorate the power quality at the mains. To reduce such harmonics, Active Power Filters (APF) are commonly employed. In this paper, a new constant-frequency control scheme for a shunt three-phase four-wire APF is proposed. The APF is used to compensate the current distortion and the reactive power created by a typical industrial load. The elaboration of the control law is based on a small-signal averaged model of the converter, computed in the (d,q,O) synchronous frame. The control scheme consists of multiple-loops PI controllers that ensure voltage regulation at the DC side of the filter, and current wave shaping at the AC side. The control system is implemented numerically using Matlab/Simulink tool. The performance of the proposed control approach is finally discussed through the obtained simulation results.