Adaptive Nonlinear Control of Wind Energy Conversion System with PMS Generator

This paper addresses the problem of controlling wind energy conversion systems (WECS) which involve permanent magnet synchronous generator (PMSG) fed by IGBT-based buck-to-buck rectifier-inverter. The goal of the control is to maximize wind energy extraction and this necessitates letting the wind turbine rotor operate in variable-speed mode. The control strategy involves: (i) a nonlinear regulator designed by the backstepping technique; (ii) a sensorless online reference-speed optimizer designed to achieve the maximum power point tracking (MPPT) requirement. Considering the whole association ‘converter-motor’ makes it possible to consider, in addition to motor speed regulation, three other important control objectives such as power factor correction (PFC) with respect to the supply net and DC Link voltage regulation. To achieve these objectives, an adaptive control strategy is developed, based on a nonlinear model of the whole ‘converter-motor’ association. Adaptation is motivated by the uncertain nature of some motor characteristics, especially the mechanical parameters. It is formally shown that the proposed controller actually meets its control objectives. This theoretical result is confirmed by several simulations.