Optimal Control Of Passive Sliding Mode Power For Direct Drive Wave Power Generation System

Wave energy is widely distributed and abundant,and is a kind of renewable energy with excellent value.However,there are problems such as uneven distribution,changes in time and region,and strong volatility,which lead to many problems in the commercial application of wave energy power generation.At this stage,wave energy power generation cannot be marketed like photovoltaic and wind power generation.This thesis takes the direct-drive wave power generation system as the research object,and proposes an improved wave energy capture strategy and a control strategy for the wave power generation system based on passive-sliding mode control.First,the float hydrodynamic equation is introduced to build a direct-drive wave power generation system.The mathematical model of the permanent magnet synchronous linear motor is constructed,the equation of motion of the float under the action of regular waves is analyzed,and the circuit equivalent principle is used to obtain the desired electromagnetic force control curve to realize the maximum wave energy capture strategy under the regular excitation.Secondly,considering that the effect of the optimal wave energy capture strategy is related to the accuracy of the float hydrodynamic model,and the hydrodynamic parameters are related to the excitation frequency,an improved bilinear amplitude method is introduced to extract the wave frequency.Compared with traditional fast Fourier transform and bilinear amplitude method,it has higher accuracy.At the same time,considering the harsh environment where the power generation equipment is located,it will cause the controller input with complex noise and interference.Using the expansion state observer to replace the traditional speed sensor equipment can not only effectively reduce the maintenance cost of the equipment,but also avoid noise interference,and has strong anti-interference ability.Then,according to the fact that the actual wave is composed of many regular waves,the float hydrodynamic equation is expanded by Fourier series,and the designed objective function is converted into the maximum value of the quadratic form under the constraint condition by linearizing the hydrodynamic equation.question.Then,by solving the maximum value of the objective function considering the copper loss of the linear motor,the wave energy capture strategy of the actual sea state is obtained.Finally,aiming at the optimal electromagnetic force tracking problem of wave system under complex sea conditions,a passive-sliding mode control strategy is proposed,and a Hamilton model of port controlled dissipation is established according to the motor terminal voltage equation.By adjusting the energy distribution of the system,the transformed energy The function satisfies the Lyapunov stability discriminant theorem,and the system control law is obtained.Under the condition that the system is passive,a sliding mode variable joint structure control link is added to the control law to satisfy the system robustness.