Research On Optimization Design And Control Of Magnetic Bearings Support System For Flywheel Energy Storage

According to the requirements of the "14th Five-Year Plan" and the "2035 Vision Target Outline",the new energy storage is not only an important technology and basic equipment for the construction of the new power system,but also an important support for the realization of carbon peak and carbon neutrality goals.The flywheel energy storage system has the advantages of high energy storage density,high instantaneous power,fast charge and discharge speed,long service life and high energy conversion efficiency,which is applied in new energy generation,distributed power supply system,uninterruptible power supply,new power vehicles and other fields.The problems of friction,wear and lubrication of mechanical bearing are solved by magnetic bearing,which is suitable for the flywheel energy storage system.Therefore,the study of magnetic bearing system for improving the performance of flywheel energy storage system has become a very frontier topic in the world.The eight-pole magnetic bearing is driven by two DC switching power amplifiers,and the three-pole magnetic bearing is only driven by a three-phase inverter,so the three-pole magnetic bearing control system has the advantages of small size and low cost,but the asymmetric structure of the three-pole magnetic bearing may cause the problems of poor linearity between suspension force and control current and the large coupling between two radial degrees of freedom,the coupling between two radial degrees of freedom can be reduced and the linearity between suspension force and control current can be improved by the six-pole bearing with structural symmetry,which is beneficial to realize the accurate control of the flywheel energy storage system supported by magnetic bearings.The research of this dissertation is of great significance for improving the key technology level of flywheel energy storage,breaking through the bottleneck of flywheel energy storage technology,and improving the application ability and international competitiveness of flywheel energy storage engineering in China.The theoretical and experimental research on parameter optimization design,mathematical model,sensorless control and decoupling control for magnetic bearing support system for flywheel energy storage are carried out.The main works and innovative achievements of the dissertation are as follows:1.The overall scheme of magnetic bearing support system for flywheel energy storage is designed.The principle of the three degrees of freedom six-pole outer rotor radial-axial hybrid magnetic bearing is analyzed.The mathematical model of the three degrees of freedom six-pole outer rotor radial-axial hybrid magnetic bearing is developed using equivalent magnetic path method.The specific parameter values are obtained through the parameter design method.The principle of the two degrees of freedom six-pole outer rotor radial hybrid magnetic bearing is analyzed,the mathematical model of the two degrees of freedom six-pole outer rotor radial hybrid magnetic bearing is developed by using maxwell tensor method.The specific parameter values are obtained through the parameter design method.2.The parameters of the magnetic bearing support system for the flywheel energy storage are optimized and designed.The design process of the magnetic bearing is introduced in detail,the maximum radial suspension force and volume are used as the optimization target of the six-pole outer rotor radial hybrid magnetic bearing.Eight parameters are selected as the optimization variables,and four significance parameters are obtained by performing the sensitivity analysis.The response surface model is built,and multi-objective optimization is performed by using a multi-objective genetic algorithm,the optimal parameters of the six-pole outer rotor radial hybrid magnetic bearing are obtained.The finite element simulation model is built,the performance of the six-pole outer rotor radial hybrid magnetic bearing before and after optimization are analyzed,the results show that the comprehensive performance of the six-pole outer rotor radial hybrid magnetic bearing is improved by the designed multi-objective optimization method.The optimized parameters for the six-pole outer rotor radial-axial hybrid magnetic bearing are obtained using the same method.3.For the large size and high cost of displacement sensor of the magnetic bearing support system for the flywheel energy storage and the fault tolerant control when sensor failure,a sensorless control method based on the least squares support vector machine(LS-SVM)is proposed.The modified particle swarm optimization(MPSO)is used to optimize the parameters of the LS-SVM,the optimal parameters are applied to LS-SVM and the displacement prediction model is built via LS-SVM.The simulation on the sensorless control system based on MPSO LSSVM is performed.The simulation comparison results show that the proposed algorithm has an accurate prediction capability.4.In view of the problem of coupling between different degrees of freedom of the magnetic bearing support system for the flywheel energy storage,the active disturbance rejection control method based on modified particle swarm optimization is proposed.The dynamic compensation is made by the expansion state observer of the active disturbance rejection control,three parameters of the expansion state observer are adjusted by using the modified particle swarm optimization,which makes the active disturbance rejection control achieve the better control effect.The simulation of the active disturbance rejection control with the modified particle swarm optimization is performed,the simulation results show that the decoupling control effect and antiinterference capability of the active disturbance rejection control based on the modified particle swarm optimization are better than the conventional active disturbance rejection control.5.The flywheel energy storage system prototype supported by the magnetic bearing is designed and manufactured,the hardware and software of the flywheel energy storage digital control system are designed,and the flywheel energy storage system experiment platform is built.Based on the experimental platform,the rotor lifting experiment,the rotor stable suspension experiment,the anti-interference experiment and load experiment are completed,and the operation performance of the digital control system is analyzed.The static and dynamic suspension experiment using the sensorless control method proved good performance on the experimental platform,and an anti-interference experiment is also performed.The results show that the displacement prediction model of the least squares support vector machine based on the modified particle swarm optimization is strong.The anti-interference experiment using the active disturbance rejection control based on the modified particle swarm optimization is performed,the results show that the anti-interference ability of the active disturbance rejection control based on the modified particle swarm optimization is better than that of the conventional active disturbance rejection control,experimental results confirm the correctness and effectiveness of the theory and the simulations.