An anti-windup mechanism for state constrained linear control of wave energy conversion systems: Design, synthesis, and experimental assessment

Abstract

Motivated by the necessity of suitable state constraint mechanisms within linear time-invariant (LTI) energy-maximising control of wave energy converters (WECs), we present, in this paper, an anti-windup (AW) scheme for state constraint satisfaction, where the associated unconstrained controller is designed via impedance-matching theory for WEC systems. As in the standard (input) AW scenario, the adopted technique provides a mechanism for ‘informing’ the (unconstrained) controller when constraints are active, so that appropriate modifications to future control actions can be taken accordingly. The overall adopted AW technique is tested experimentally, on a prototype of the Wavestar WEC system, available at Aalborg University (Denmark). We explicitly demonstrate that the proposed AW scheme is able to consistently respect the defined state constraints, having a mild impact on overall energy absorption performance when compared to its unconstrained counterpart.