Research On Control Technology Of Virtual Synchronous Generator With Storage

With the rapid development of distributed generation technology,the penetration rate of distributed energy in the power system is continuously increasing,which leads to a relative reduction in the inertial and damping characteristics of the power system,and it has a non-negligible adverse effect on the operation and control of the power system.The virtual synchronous generator technology enables the distributed generation unit to simulate the inertia and damping characteristics of the synchronous generator,and have the static and dynamic characteristics of the synchronous generator,which plays a certain role in supporting the power system.Thus it become a solution to the high penetration rate of distributed energy in the power system,and has received people’s extensive attention.This paper mainly focuses on the subject of energy-storage converters equivalent to virtual synchronous generators,studies the control strategies of energy storage units and grid-connected converters,and focuses on the study of the parameter design method of virtual synchronous generators under volume and power constraints of energy storage units,moreover,the coordinated control strategy of virtual synchronous generators and state of charge(SOC).Firstly,the paper summarizes the research status and development trend of virtual synchronous generator control technology based on the extensive research of domestic and foreign literature,and points out that the matching of energy storage unit characteristics and virtual synchronous generator control strategy is worthy of in-depth study.In order to realize the virtual synchronous generator control strategy,this paper establishes the DC side model composed of energy storage unit and bidirectional DC-DC converter,and gives its control strategy.Afterwards,according to the principle of synchronous generator,this paper gives the ontology model of the virtual synchronous generator control strategy,then combines the reference of the control structure of traditional grid-connected converter,so the overall control strategy of the virtual synchronous generator is given.As to the problem of the system stability and parameter design of energy storage virtual synchronous generator,a small-signal signal model of active-frequency loop of virtual synchronous generator is established first,then the influence of inertia factor and damping factor on the dynamic performance of the system is analyzed.In order to know the relationship between active power,energy and damping ratio of the virtual synchronous generator,the model in the time domain is derived.Then gives the selection procedure of control parameters under the constraint of energy storage characteristics.The output characteristics of the energy storage unit will change during the operation process.In order to obtain accurate matching parameters and improve the reasonable utilization rate of the energy storage unit,this paper considers the influence of the SOC of the energy storage unit on its output power and energy,and adopts a real-time adjustment parameter control strategy based on the SOC.Moreover,to improve the SOC maintenance ability of the energy storage unit and ensure the sustainability of the frequency regulation capability of the energy storage unit,this paper proposes the adaptive coordination control strategy of SOC control and damping control,and analyzes the SOC control factor together with the coordinate control functions.The simulation model of energy storage virtual synchronous generator was built on the Matlab/Simulink simulation platform.Simulation analysis was performed on the theoretical analysis and control strategy.The simulation results showed the correctness of the theoretical analysis and the effectiveness of the proposed control strategy.Finally,the basic function of the virtual synchronous generator is verified on the physical platform.The experimental results show that the design method of the virtual synchronous generator control parameters is effective.