Optimal Control in Energy Conversion of Small Wind Power Systems with Permanent-magnet-synchronous-generators

This paper presents the results of experimental investigation of a low-power wind energy conversion system (WECS), based on a permanent-magnet synchronous generator (PMSG) connected directly to the turbine. A development system was built in order to carry out the experiments. Its detailed description is also provided. The development system can work as an autonomous system for remote sites or as a gridconnected system, illustrating the concept of distributed production of electrical energy. It includes a wind turbine simulator, which is speed or torque controlled and offers a "wind shaft", where the static and dynamic characteristics of a turbine are obtained. The wind shaft generator drives a permanent magnet synchronous generator (PMSG). The other components of the hybrid system are: a battery, a classical source and, possibly, a PV source. The hardware/software application is based on the dSPACE system. The experimental results show that the performance of a multi-polar-PMSG-based small wind power system is strongly determined by the generator’s behaviour. Two optimal regimes characteristics (ORC) are defined in this paper: the first one represents the mechanical power versus the rotational speed (ORC ) and the second one is the electrical power delivered to a load versus the rotational speed (ORC ). An optimal control loop aiming to maximize the delivered electrical power is designed, namely its reference is computed based on the ORC . In this way, the global efficiency of the energy conversion is maximized. The effectiveness of the proposed optimal control loop is illustrated by experimental results. m