Research On Power Control Strategy Of Direct Drive Wave Power Generation Systems

In order to improve the energy structure and develop a low-carbon economy,China is vigorously developing renewable energy.As a renewable energy source,wave energy has the advantages of large energy density,rich reserves,and good predictability,and has good development potential.This paper considers a direct-drive wave power generation system.The oscillatory float is used as the research object.A permanent magnet synchronous linear machine(PMSLG)is used as the power take-off(PTO)to study the system power.Optimize control issues.The main research contents of this article are divided into the following points:1)Introduce the research background and significance of wave energy power generation.For typical wave energy converter(WEC),including wave energy capture devices and power take-off(PTO),their respective advantages and disadvantages and the working principle is analyzed,and the development history and research status of domestic and foreign wave power generation technology are sum marized in detail.2)Mathematical modeling of wave power generation system.The first is the mathematical modeling of the wave energy capture device.Although the frequency domain model is simple,non-linear factors are not taken into consideration.Although the time domain model is considered with non-linear factors,it needs to calculate the Green function of the floating surface wet meshing in real time.This paper establishes a frequency domain model,calculates the Green's function in the frequency domain using Ansys/workbench software,and obtains the frequency domain response curve of the hydrodynamic parameters.Then use WEC-Sim to transform into time domain response curve.The Prony's method was used to fit the time-domain response curve,and finally a sixth-order state-space time-domain model of the device was obtained.Next is the mathematical modeling of PMALG.A mathematical model of PMSLG in the abc three-phase coordinate system is established,and the mathematical model of PMSLG in the dq two-phase coordinate system is finally obtained through the Park-Clark coordinate transformation.3)Based on the mathematical model of the system obtained above,classify and discuss the typical power control technology principles in recent decades.Aiming a t the problems of typical power control algorithms that only consider improving device power capture and ignore device physical constraints,the article proposes to apply Model Predictive Control(MPC)to wave power generation,while maximizing system power generation,To meet the system operation indicators and physical constraints,improve its economic utilization.First consider the traditional MPC to track the optimal speed trajectory.Aiming at the disadvantages that the traditional MPC may have unreachable reference points and a large amount of calculation,an improved MPC,namely economic MPC,is proposed.4)The vector control strategy with i_d=0 is used to decouple the dq axis current and design the parameters of the PI controller.SVPWM pulse widt h modulation is performed on the decoupled voltage signal to obtain the control signal of the three-phase full-control rectifier circuit,and the control signal is input to the rectifier bridge to realize the on and off of the IGBT and complete the energy tracking control of the wave power generation system.Finally,energy storage control is performed on the wave power generation system to achieve the purpose of stabilizing the bus voltage and smoothing the power.5)Build a model on Matlab/Simulink for simulation verification and analysis.