Optimization Of Controller Parameters For Wind Turbine Based On Differential Evolution Algorithm

Wind turbines have faced overspeed faults or power instability problem,which may cause the operation of the power system to be unsafe and unstable.For the overspeed faults,they are prone to occur in the transition areas.When the real-time wind speed exceeds the rated speed,the wind turbine's output power cannot be stable around the rated power for the pitch control is not timely.The simulation model is established based on a 5 MW doubly-fed wind turbine.,wind turbine torque-speed transfer function model and pitch angle-speed transfer function model are derived at each wind speed point through the model linearization energy module of GH Bladed software.Given the mentioned function models,the third-order transfer function model is obtained through MATLAB System Identification.The third-order transfer function model and the PI controller form the closed-loop system.The overshoot of the closed-loop system,the time and control energy are adjusted to form the fitness function.The differential evolution algorithm is used to find the optimal solution of the fitness function.The PI controller parameter corresponding to the optimal solution is the expected value.Linear interpolation is performed between the optimal PI controller parameters at each wind speed point to form a variable gain torque PI controller and a variable gain pitch PI controller.Using the generated controller,an external controller program is coded with Visual Studio and input into the GH Bladed software for simulation calculations.The experimental results illustrate that,in the transition zone,the deviation of the generator speed from the rated value before the optimization is 2.85%,while the deviation reduces to 0.92%through the proposed optimization methods under the gust conditions;the standard deviation of the generator speed is reduced by 32.93%through the proposed optimization methods under the turbulent conditions with the average wind speed of lOm/s.In the operating range above the rated wind speed,the optimized output power is quickly restored to the rated value and the maximum deviation is rduced through the proposed optimization methods under the gust conditions;the output power standard deviation is reduced by 23.31%.22.78%and 18.32%,under the turbulent conditions with the average wind speed of 16m/s.18m/s and 20m/s.respectively.The optimized controller has good robustness to wind speed turbulence,stabilizes the generator speed in the transition zone,and makes the output power curve smoother in the operating range above the rated wind speed.