Research On Power Distribution Strategy And Stability Of Hybrid Energy Storage Based Virtual Synchronous Generator System

With the increase in the scale of new energy grid connection,the future power system will show the characteristics of a high proportion of renewable energy and a high proportion of power electronic devices.However,renewable energy sources have strong fluctuation,and traditional power electronic devices lack the necessary inertia,which makes the stability of the power system a huge challenge.Virtual Synchronous Generator(VSG)technology can effectively alleviate the problem of power system inertia drop caused by grid-connected renewable energy.However,the traditional VSG research mainly focuses on the control strategy,and seldom pays attention to the specific implementation of the power source.Based on this,this paper focuses on the research of hybrid energy storage based virtual synchronous generator system,including its power distribution strategy,parameter design,stability,etc.The specific content is as follows:First of all,this paper summarizes the origin of virtual synchronous generator technology,investigates and summarizes the research status of hybrid energy storage based virtual synchronous generation technology power distribution strategy and stability analysis.Secondly,this article briefly describes the classic structure of the traditional microgrid,and establishes the model of the hybrid energy storage based virtual synchronous generator in the microgrid based on the dynamic equation of the synchronous generator.The simulation model is built in PSCAD/EMTDC,and the results show that the virtual synchronous generator control strategy has a stronger frequency support effect than the traditional droop control strategy.Meanwhile,a virtual RC droop control strategy is proposed for the power source of the hybrid energy storage based virtual synchronous generator system.The power distribution strategy doesn’t require additional components such as filters to achieve power distribution.The simulation results verify the effectiveness of the proposed control strategy.Next,this article establishes the connection between the hybrid energy storage source and the virtual synchronous generator.By designing the virtual resistance-capacitance droop coefficient,the supercapacitor simulates the rotor in the synchronous machine,and the battery simulates the prime mover in the synchronous machine.On the basis of realizing power distribution,each energy storage source has a clearer physical meaning.The simulation verifies the correctness of the designed virtual resistance-capacitance droop coefficient.Furthermore,this article summarizes the capacity configuration method of the energy storage unit for the purpose of the hybrid energy storage based virtual synchronous generator system participating in the primary frequency modulation and inertial support of the microgrid.Finally,this paper establishes a complete state space model of the studied microgrid system,uses MATLAB to solve the eigenvalues of the system,and verifies the small signal stability of the studied system.At the same time,this paper analyzes the variation of the system eigenvalues with the key parameters of the system,draws the corresponding root locus and guides the design of some key parameters of the system.Finally,a simulation model is built to verify the correctness of the system’s small signal analysis.