Sliding mode approach to torque and pitch control for an wind energy system using FPGA

Wind energy, being a fluctuating resource, requires a tight control management to ensure stability when integrated with the grid system. This has triggered interest towards developing advanced controllers. Hence this paper presents the study of a variable speed wind energy conversion system that uses a Double Fed Induction Generator (DFIG). Above rated wind speed, pitch control has been applied and below the rated speed torque control has been adopted. Generator torque control is able to reduce the effects of the pitch actuator limitations. Sliding mode control is applied for torque and pitch control in WECS and it has been implemented in MATLAB SIMULINK and FPGA to achieve control of active and reactive power exchange between the stator of the DFIG and the grid. Performance parameters like pitch angle, active, reactive power, turbine speed, and DC voltage has been compared by using SMC, Hill Climbing (HC) Algorithm and Perturb and Observe (P&O) Algorithm and performance for these three methods has been simulated and implemented in FPGA. Total Harmonic Distortion for all the performance parameters has been reported. Hardware implementation of developed algorithm was accomplished with the help of Xilinx system generator and Xilinx Tool Kit