Simulation Research On Charge And Discharge Control Of Flywheel Energy Storage Digital Twin

As the country pays more and more attention to the development of new energy,especially with the proposal of the goal of "double carbon",renewable energy and new power system have become an important part of green and low carbon,which has been highly valued by major countries.Energy storage system has been paid more and more attention as an important regulation link in power grid because of its advantages such as high energy storage density,high power density,fast response,high number of cycles,long service life,non-pollution recovery and so on.This paper takes the flywheel energy storage system as the main research object,because of considering the production cost,the equipment operation data need to be tested and obtained after the product production.In order to reduce the production waste and simulate the dynamic characteristics of flywheel rotor more accurately,the digital twin technology is used to establish the digital twin model of flywheel unit.The control problems in the charge and discharge operation of the flywheel energy storage unit are deeply studied,which lays a foundation for the research of the flywheel energy storage array.The main contents are as follows:(1)according to the basic structure of the flywheel energy storage system,the overall structure formed by the demand analysis of digital twins and the main research objectives of this paper,the primary task is to build a three-dimensional model of flywheel energy storage unit parts according to the composition structure and geometric size of flywheel energy storage unit,and then assemble into an integral flywheel energy storage unit.In order to facilitate the following simulation calculation,the three-dimensional model is lightweight in this paper.Secondly,the finite element model of the flywheel rotor is built,and the internal stress distribution characteristics of the flywheel with the highest speed are analyzed.Taking the radius as the independent variable and the internal stress of the flywheel as the dependent variable,the stress field of the flywheel rotor is calculated by using the analytical formula,and the finite element results are analyzed and discussed.Through the modal analysis of the rotor,the natural frequency and critical speed are obtained,and compared with the actual test data to verify the accuracy of the twin model.(2)according to the basic structure of flywheel energy storage system and the main research object of this paper,the primary task is to construct the threedimensional model of flywheel energy storage monocular parts according to the information of flywheel energy storage unit entity structure and geometric size,and then assemble the flywheel energy storage unit into an integral flywheel energy storage unit.at the same time,in order to facilitate the following simulation calculation,the three-dimensional model is lightweight.Secondly,the finite element model of the flywheel rotor is built,and the internal stress distribution characteristics of the flywheel with the highest speed are analyzed.Taking the radius as the independent variable and the internal stress of the flywheel as the dependent variable,the stress field of the flywheel rotor is calculated by using the analytical formula,and the finite element results are analyzed and discussed.Through the modal analysis of the rotor,the natural frequency and critical speed are obtained,and the accuracy of the twin model is verified by the relative ratio of the actual test.(3)Motor control is also the core of charge and discharge control of the twin of flywheel energy storage unit,and it is the core of energy conversion of flywheel energy storage unit.Establishing the model of machine-side converter and analyzing the control strategy of using stable motor are not only the necessary task of digital twinning at flywheel energy storage unit level,but also the basic requirement of developing flywheel energy storage array.In this paper,250kW/50kWh flywheel energy storage unit as the research object,the establishment of flywheel energy storage unit motor control model and machine-side converter model to achieve flywheel energy storage start and stop,charge and discharge,and power follow charge-discharge switching and other functions.(4)aiming at realizing the digital twin human-computer interaction and visualization function of flywheel energy storage unit,using the powerful calculation and simulation ability of MATLAB/Simulink,the flywheel energy storage unit humancomputer interaction,virtual entity condition monitoring and three-dimensional twin model real-time running visual interface are developed to form the final flywheel energy storage unit digital twin system.