PCSMC design of permanent magnetic synchronous generator for maximum power point tracking

Abstract

This study develops a perturbation compensation based sliding-mode control (PCSMC) strategy of a permanent magnetic synchronous generator (PMSG) for optimal extraction of wind energy. Firstly, PMSG non-linearities, uncertain parameters, unmodelled dynamics, and stochastic wind speed variations are aggregated into a perturbation. Then, it is estimated by a sliding-mode state and perturbation observer in the real time. Further, the perturbation estimate is fully cancelled by sliding-mode controller (SMC) for global control consistency, together with considerable robustness thanks to the sliding-mode mechanism. In addition, the upper bound of perturbation is replaced by its real-time estimate; thus more proper control costs could be achieved without over-conservativeness. Moreover, PCSMC does not require an accurate PMSG model while only the measurement of d-axis current and mechanical rotation speed is required. Four case studies are carried out, e.g. step change of wind speed, low-turbulence stochastic wind speed, high-turbulence stochastic wind speed, and PMSG parameter uncertainties. Simulation results demonstrate that PCSMC can rapidly extract higher power under different wind speed profiles against vector control and SMC. Lastly, a dSpace-based hardware-in-the-loop experiment is undertaken which validates its implementation feasibility.