PSO tuned fuzzy based pitch blade controller of grid-tied variable speed wind turbine

The increasing penetration of installed the wind turbines is leading the power system towards instability and requires robust controllers to overcome the instability issues. The conventional synchronous generator based wind turbines comprise of an uncontrolled rectifier, a dc/dc boost converter, a controlled inverter and a pitch blade controller in grid-tied mode. The dc/dc boost converter controls the dc-link current according to the generator's rating and optimizes the rotor speeds to a preset value by extracting maximum energy using the MPPT algorithm, during lulls and gusts of wind. The inverter controls the AC power fed into the grid, regulates the dc link voltage and maintains the unity power factor by using d-q transformation. The pitch blade controller reduces the sudden mechanical stresses on the wind turbine during high speed periods. However, the PI or fuzzy controllers for the above-mentioned system are mostly manually tuned by trial and error methods for specific set-points. This approach lacks the dynamic behavior. Therefore in this paper, the authors have developed an optimal pitch blade controller to regulate the output wind power under variable wind conditions. A novel practical swarm (PSO) based search algorithm is employed to tune the fuzzy membership functions (MFs) dynamically according to the wind speed variations. The complete system is simulated in the Matlab2014b/Simulink environment. The results show that the proposed controller performs excellently.