Power Control Of Oscillating Float Wave Power Generation System

With the rapid development of the economy,human development is constrained by shortage of resources and serious environmental pollution.The exploitation of renewable energy has attracted people's attention.In renewable energy,the traditional solar energy and wind energy have been extensively researched and putted into commercial use.Among them,wave energy has the characteristics of high energy density,abundant reserves and good predictability,but its development is still in a relatively lagging state.Wave energy is a renewable energy with great potential.In order to improve the power generation of wave energy generation system,There are two main research directions: First,according to fluid mechanics,the mechanical structure of the energy harvesting device is matched with the wave characteristics to maximize the acquisition of wave energy;the second is to maximize the conversion of the collected wave energy into electrical energy through the control method.In this paper,based on the oscillating float direct drive wave power generation system,the passivity-based control and segmentation control methods are used to make the system stably output the maximum power.This paper first expounds the background and significance of the research,introduces the two major components of wave power generation: WEC(Wave Energy Converter)device and PTO(Power Take-off)device,and introduces the research status and development history of the oscillating float WEC device and PTO control strategy.Also,a brief introduction to the origin of passive control.Secondly,the model of the system is established.The establishment of the system model is divided into two parts.The establishment of the float model and the establishment of the permanent magnet synchronous linear generator model.The wave force received by the vertical cylindrical float is calculated by the Froude-Krylov theory method.Based on that,the floating force model of the single-degree-of-freedom float structure and the force model double-degreeof-freedom float structure are separately discussed,and the operating characteristics of the two float structures are compared.The model of a permanent magnet synchronous linear motor is established in different coordinate systems.Under the model,and establish the equivalent circuit model of the motor.The simulation model of the float and permanent magnet synchronous linear motor is built in Matlab/Simulink environment,and the waveforms of each variable when the motor has three-phase resistive load are discussed.Then,the basic theoretical of passive control and dissipative port-controlled Hamiltonian system(PCHD)is introduced.The PCHD model is built according to the force model of the float,the energy function of the system is constructed,and the energy function is shaped to ensure that the shaped energy function satisfies the Lyapunov stability theorem.We can deduce the control law of the system through it and improve the control law of the system by injecting damping and adding the interconnect matrix.Simulation verifies the stability of the passivitybased control under regular waves and irregular waves,respectively.Finally,the passivity-based control can ensure the system satisfy the asymptotic stability,based on that,the segmentation control strategy low-speed no-load energy storage-segment and high-speed load-carrying power generation is introduced to increase the power generation of the system.At the same time,the trajectory planning method is used to make the system variables smoothly transitioned when the load state is switched in the segmentation control.The segmentation control and trajectory planning are verified in simulation.