H Control Design Methodology for a Three-Phase Active Power Filter

In this paper, an H_infin control design methodology is presented in order to synthesize a full-order dynamic output feedback controller for an active power filter connected in parallel to a three-phase voltage distribution system. A shunt active filter is usually used to improve power quality by eliminating harmonic distortion generated by non-linear and switching loads. In order to be able to extract desired harmonics, the multivariable system is described by a linear coupled state space representation in a rotating two-phase framework. The originality of this paper is that axes decoupling is achieved by representing the system in a new complex framework in which the model is mathematically decoupled and therefore physical decoupling can be avoided. Moreover, the validity and efficiency of the proposed methodology are proved through numerical simulations.