Design of variable structure control for wind energy system-based permanent magnet synchronous generator and operating under different grid conditions

Abstract

This paper proposes a nonlinear control approach for an electrical network connected variable speed wind energy system VS-WES based on a permanent magnet synchronous generator PMSG. The proposed configuration consists of a wind turbine WT, a direct driven PMSG, a rectifier and an inverter which is connected to the power grid through a filter. Under the variation of wind velocity, the generator side rectifier is used to control the speed of the PMSG with maximum power point tracking MPPT. The grid-side converter is employed to inject the extracted power into the electrical network, to regulate dc-link voltage and to attain unity power factor UPF. This work explores a variable structure sliding mode control VSSMC considering the variation of wind speed. Lyapunov stability theory is used to find the conditions for the existence of the sliding mode. So, the performance of the VS-WES has been demonstrated under varying wind conditions and under a grid fault. The simulation results through MATLAB/Simulink show the effectiveness of the proposed VSSMC approach.