Research On Control Of Optical Storage And Generation System Based On Virtual Synchronous Motor

In recent years,with the rapid development of society and science and technology,governments pay more and more attention to the development of Distributed Generation(DG),in which new energy gradually occupies a dominant position in distributed energy.Due to the instability of new energy sources,while using clean energy efficiently,microgrid also needs good grid-connected technology to improve distributed energy penetration.Virtual synchronous generator(VSG)technology can make distributed inverters display a control technology with similar characteristics of synchronous generators when facing the challenge of new energy,thus improving the stability and compatibility of microgrid.In order to adjust the control parameters flexibly in the virtual synchronization control strategy,the small signal model is analyzed and a reasonable adaptive control method is proposed.Then considering the coordinated control of optical storage power generation system and the bidirectional energy flow of grid-connected inverters in microgrid,the virtual synchronous generation technology is further discussed.Finally,the system model is built in Matlab/Simulink,and the related control strategies are verified under different scenarios.The main contents of this paper are as follows:1)The working principle,mathematical model and equivalent circuit of photovoltaic and energy storage modules on DC side of optical storage system are studied.In photovoltaic module,the maximum power point tracking(MPPT)is analyzed according to the slope of voltage-power curve.A hybrid step-size control strategy is proposed,which combines variable step-size and fixed step-size according to the threshold of voltage change.In the energy storage module,the relationship between charge state and charge-discharge characteristics is analyzed,and an adaptive control strategy is introduced.Finally,the simulation results verify the correctness of the proposed strategy..2)Virtual synchronous generators can control motor parameters in real time to achieve system stability.In this paper,the influence of inertia parameters and damping coefficients on the system stability is analyzed by combining the power angle characteristic curve and frequency oscillation curve of traditional active power control loop of synchronous generator.Based on the existing control methods,a joint adaptive control strategy based on the optimal damping ratio of inertia parameters and damping coefficients is proposed.Finally,the advantages of the system in the face of challenges are verified by simulation.3)The research object is based on the optical storage system consisting of photovoltaic system,energy storage device,grid-connected inverters and AC/DC load.The control strategies of off-grid and grid-connected operation modes are studied respectively.Considering the randomness of the photovoltaic side,the charging and discharging properties of the energy storage device and the variable load,the DC side voltage layered operation is proposed.Based on the DC voltage amplitude,the operation mode of each module is reasonably designed,and the virtual synchronous generation technology is further studied for the grid side bidirectional converter,so as to reduce the power conflict within the system and ensure the stability of power exchange.