Optimization Of Optimal Output Control Strategy For Wind Energy Conversion System Based On Sliding Mode Extremum Seeking

As one of the most promising renewable energy sources,the proportion of wind energy in global renewable energy applications is increasing year by year.It is of great significance for improving the ecological environment of the earth and adjusting the global energy structure to improving the efficiency of wind power generation and popularize the application of wind powerThis paper mainly studies the optimization strategy of the control algorithm parameters of the small permanent magnet WECS under sliding mode extremum seeking control(SMESC).By analyzing the operating characteristics of the wind turbine in part of the load region,the relationship between the rotational speed of the permanent magnet motor,the DC side voltage of the rectifier circuit and the output power is derived.The sliding mode based on the optimized parameters of the Invasive Weed Optimization(IWO)algorithm is introduced to achieve the MPPT of WECS.The structure of SMESC is simple and reliable,which could track the MPP without power characteristic curve or mechanical sensor.In order to maintain the tracking speed and steady-state accuracy of the SMESC algorithm,this paper deduces the relationship between the control parameters and the tracking speed and steady-state accuracy of different SMESC stages.The IWO algorithm is introduced after constructing and selecting appropriate fitness function and steady-state criteria to optimizes the SMESC parameters.In initial stage,long steps are adopted for MPPT.After entering the steadystate stage,a small integral gain is set to reduce the steady-state power oscillation of the SMESC.Thus,the contradiction between the tracking speed and the steady-state precision of the traditional SMESC algorithm is avoided.Meanwhile,in order to ensure the real-time optimization of the SMESC parameters conducted by IWO algorithm,this paper introduces the Lévy flight space diffusion method and optimal individual ratio based seed number adjustment strategy.The convergence rate of the IWO algorithm is accelerated without affecting the performance of the algorithm.This paper builds a simulation model based on MATLAB/Simulink platform,analyzes and verifies the performance of the proposed optimal output control strategy.Compared with the traditional SMESC algorithm,extreme value search algorithm,hillclimbing algorithm and SMESC control schemes optimized by particle swarm optimization and firefly algorithm,the control performance under the condition of sudden wind speed and random wind speed is analyzed.The simulation results verify the effectiveness and feasibility of the proposed strategy.