Design of a Robust Model Reference Adaptive Control for a shunt Active Power Filter

This paper presents a design procedure for a discrete-time robust model reference adaptive control (DRMRAC) applied to a three-phase four-wire shunt active power filter (APF). The first step when designing the controller is to obtain a representative model for the plant. The theoretical basis for the DRMRAC, considers a parametric model which comprises a modeled part of reduced order, whose parameters are allowed to lie in a predefined range, and a multiplicative and/or additive terms describing the unmodeled dynamics. These dynamics pose a level of uncertainty for the plant, and reflect the difficult in describing the plant behavior, usually at high frequencies. The adaptive law is used to compensate the parametric variation of the plant and the control strategy is robust with respect to such unmodeled dynamics. The plant model, design procedures, main constraints and experimental results are presented.