Low cost control solution to optimize autonomous wind energy conversion

Based on a wind system equipped with a permanent magnet synchronous generator (PMSG), a rectifier, a chopper and a continuous load, three power optimization methods are investigated. The main objective of this paper aims a control solution for wind energy conversion optimization by using estimated wind speed in relation with optimal electromagnetic torque, when the power coefficient and the optimal tip speed ratio values are known. The investigated control methods are: a classical method based on three cascade control loops (a major power loop, an intermediate rotational speed loop and a inner current loop); a control method with two control loops (for rotational speed and load current), part of the previous control strategy but improved with a rotational speed reference provided as a dependence of estimated wind speed based on the electromagnetic torque given by the system frequency converter; and a third control strategy similar with the second one, the difference being given in this case by the estimated wind speed in relation with the electromagnetic torque generated as a dependence of load current and chopper duty ratio. Comparable results obtained with these methods and also their advantages are presented.