Sliding mode approach to torque and pitch control for a wind energy system

Wind energy, is a variable source which requires a robust controller to achieve good pitch and torque control performance. A sliding mode control(SMC) strategy is proposed to ensure stability by using Torque and Pitch control despite of model uncertainties in Double fed induction generator (DFIG) for wind energy conversion system. This technique was implemented in MATLAB SIMULINK and Field Programmable Gate Arrays (FPGA). The generator-side converter (rectifier) is used to control the speed or torque of the generator with maximum power point tracking (MPPT) scheme. The grid-side converter (inverter) is employed for the control of DC link voltage and grid-side reactor power. Performance of the SMC has been compared with Hill Climbing (HC) algorithm and Perturb and Observe (P&O) algorithm. Finally the results obtained in MATLAB SIMULINK are implemented in FPGA. Both simulation and validation results show that the proposed control strategy is effective in terms of power regulation. Moreover, the sliding mode approach is arranged so as to produce no chattering in the generated torque that could lead to increased mechanical stress because of strong torque variations.