| Wave energy conversion device can convert wave energy into available electrical energy.In order to make full use of wave energy,the effective control strategy must be used to improve the wave energy converter conversion efficiency for capturing wave energy maximum.The randomness of wave and the nonlinear of the system model make the application of traditional control methods in the control of the wave power generation system limited.For this reason,model predictive control is presented and applied to point absorber wave power system in this paper.Meanwhile the position and velocity of the float and the current of the motor are taken to consist of the state space model.Since the model predictive control method has less demanding on the accuracy of the model,and has the advantage of taking the system constrains into account and is also can make the prediction for external input,all the reasons make it has a great advantage in control of wave power system.So the study of model predictive control method has broad prospects and great realistic significance in wave power system.Model predictive control method of point absorber wave power system is studied in this paper mainly from the flowing aspects:(1)Conduct the analysis of the current development of wave power technology and the significance of research in detail.Meanwhile make a summary of the benefits of point absorber wave power generation system compared with other types which are used in the field of ocean wave energy.Make detail analysis of the advantages and disadvantages of existing wave energy generation devices and working principle,and detailed summary and study of wave power system control strategy.(2)Study the working state of float wave power generation system and the specific circumstances of each part of the movement;make a model of the incident wave for the point absorber wave energy generation system.The single float wave power system is regard as the research object,then analysis the forces working on the flout;make sure to take a linear motor as the power take-off device,deduct the mathematical model,and then get the mathematical model of the wave power generation system.(3)A state space model for model predictive control method is established.Taking the motor current and the float as the reference trajectory respectively,and the speed of flout and the current and the displacement of the motor consist of the state space variables,the wave force generated by the incident wave is used as an input variable,motor voltages as the control variable,then the model predictive control continuous model is obtained.Furthermore the system model is discrete,in the end the rolling optimization and feedback correction is conducted by using the prediction formula and objective function.Simulation and verification of the control method of two different objective functions by MATLAB/SIMULINK.Compare the effect of these two different reference trajectories,and also carry out the simulation of the system with PI control.By compare these control effects the feasibility and superiority of the model predictive control theory to the point absorber wave power generation system are verified by simulation.(4)This paper made model predictive control research of wave generation system which has two floats,then build the predictive control model.The objective function of this model is different from wave generating system which just has one float,and the objective function is power direct maximization.At last simulation analysis is carried out with regular wave as input.The result proved that model predictive control method in wave power system which has two floats also has good application performance. |
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