Research On Control Technology Of Direct-drive Wave Generation With Energy Storage

With the continuous development of China's "marine power" strategy,the aggravation of global energy crisis and the enhancement of environmental awareness,marine energy power generation technology has been widely concerned.The direct-drive wave power generation system uses permanent magnet synchronous linear motor as generator,and the mover is directly connected with the buoy.Under the action of the float wave machine,it does reciprocating motion,eliminating the transmission link.It has the characteristics of simple structure,high efficiency and strong stability.For realizing the stable operation and maximum wave energy extraction of the power generation system at the same time,It is necessary to select the appropriate power converter and control strategy for the system.In view of the fluctuation of the instantaneous power captured,the energy storage device is selected to stabilize the power fluctuation to meet the requirements of load power supply.Based on permanent magnet linear synchronous motor,this paper studies the structure and control strategy of the direct-drive wave power generation system,and is committed to solving the problems of stable operation and power smoothing of the direct-drive wave power generation system,The structure of direct-drive wave power generation system is as follows:1.The dynamic mathematical model and simulation model of permanent magnet synchronous linear generator are established.On the basis of coordinate transformation theory,the motor models in different coordinate systems are derived,and the simulation model of permanent magnet synchronous linear generator is established for subsequent simulation research.2.A generator side control strategy based on controlled rectifier is proposed.The three-phase voltage source rectifier is used as the generator side power converter,and its mathematical model is established.The zero d-axis current control strategy based on rotor flux orientation is proposed,and the current loop controller is designed.In order to achieve maximum energy capture,a maximum power tracking control strategy is proposed based on the hydrodynamic model of waves.3.Super-capacitor is used as energy storage system.The rationality and feasibility of super capacitor in direct-drive wave power generation system are analyzed.Using Bidirectional DC-DC as the power processing interface,the voltage and current double loop control strategy is proposed based on the complementary PWM control mode,and the correction network is designed.4.The simulation model of wave power generation system is built and analyzed.The simulation analysis of rectifier control strategy,maximum power capture control strategy and power smoothing control strategy with energy storage is carried out to verify the correctness of the theoretical analysis.5.The simulation experiment platform of wave power generation system is built for experimental research.The hardware design of generator control system is completed based on DSP28335,and the software of each part is written based on the hardware design.After debugging the hardware and software,the no-load experiment is carried out,and then the power capture experiment is carried out.The experimental results are analyzed to verify the correctness of theoretical analysis and simulation.The proposed generator side control strategy is used to capture wave energy,and the control strategy of energy storage system is used to stabilize DC link voltage and suppress power fluctuation.Through the simulation and experimental verification,the system runs stably,the power fluctuation problem is solved,and the power captured by the power generation system meets the power supply requirements and can be directly used for load power supply.