Output feedback control of a three-phase shunt active power filter

A three-phase shunt active power filter is generally used to compensate current harmonics demanded by non-linear loads, so that the source current remains quasi-sinusoidal and therefore the level of harmonic pollution in an electrical network is decreased. Most of the existing classical control methods for a three-phase shunt active filter usually lead to a non-linear control problem due to the non-linearity of the Park transformation. In a previous work, a compensated three-phase power distribution system has been successfully represented by a dasiasimplepsila linear state space model. Its state matrix contains a fundamental parameter used to extract the desired frequency component of any electrical signal. The linearity of the model enables one to use the control theory in a linear context in order to build a control system. In this paper, a three-phase shunt active filter is driven using output feedback control with H_infin performance in order to reduce the number of measured outputs. The control method is mainly based on Linear Matrix Inequalities which are considered as a powerful tool for numerically solving control problems. The ability of the synthesized controller to provide an acceptable harmonic compensation is investigated through both numerical simulations on a prototype built in Simulink and experimental results.