Research On Control Technology Of Direct-Drive Wave Power Generation System Based On Fuzzy Sliding Mode

Wave energy in the ocean is not only high in energy density but also rich in reserves.The rational development and utilization of these energy sources is of great significance to solving the power supply problem in remote coastal areas,especially offshore islands.This paper takes the direct-drive wave power system as the research object.By establishing the mathematical model of the system,the resonance conditions for achieving the maximum wave energy capture are deduced.And on this basis,a vector control strategy for permanent magnet synchronous linear motors is proposed.Based on the input conditions of ocean wave frequency and amplitude,the optimal reference current value of Permanent magnet linear generator is calculated online,and the sliding mode variable structure algorithm is used to control its q The shaft current tracks the reference current value in real time,so that the wave energy conversion device resonates with ocean waves,thereby achieving the maximum wave energy capture and optimal power output of the system.However,the discontinuous switching characteristics of sliding mode control cause high-frequency chattering of the system,which leads to large fluctuations in the output power of the system,which affects the control effect and output power quality of the system.Therefore,this paper introduces fuzzy control on the basis of sliding mode control,and adjusts the approach rate parameters in the sliding mode controller in real time according to the system operating status,which can weaken the system while retaining the strong robustness and good control performance of sliding mode control.The purpose of chattering,improving system dynamic performance and smoothing system output power.First,the structure of the direct-drive wave power generation system is analyzed,and the mathematical model of the wave energy conversion device and the Permanent magnet linear generator is established.By analyzing its operating characteristics,the ideal working conditions of the wave energy conversion device are derived,and on this basis,the vector control strategy of the Permanent magnet linear generator is proposed.Secondly,the principle and structure of sliding mode control are introduced,a sliding mode controller is designed,and a simulation model is built on the Matlab/Simulink platform to compare and analyze the direct drive wave power generation system when using uncontrollable rectification and sliding mode control.The running situation.The simulation results show that the direct-drive wave power generation system can track the optimal reference current value when the sliding mode control is adopted,and meet the conditions for the system to achieve the maximum wave energy capture,which verifies the effectiveness of the sliding mode control strategy.However,the inherent chattering phenomenon of sliding mode control also affects the control effect of the system,resulting in large fluctuations in the output power of the system.Finally,in view of the chattering problem in sliding mode control,fuzzy control is introduced,and a fuzzy sliding mode controller is designed to replace the original sliding mode controller.Simulation experiments prove that when fuzzy sliding mode control is adopted,the wave power generation system can not only follow the ideal working conditions and achieve the maximum wave energy capture,but also weaken the buffeting of the system,and reduce the output power of the system fluctuation.