Research On Frequency Control Of Grid-connected Optical Storage System Based On Virtual Synchronous Generator

With the rapid progress of society and technology,more and more countries are paying attention to the development of new energy sources.The rapid development and smooth grid connection of new energy generation is being achieved in China,led by the goal of "double carbon".The precondition for ensuring the penetration of new energy sources,such as photovoltaic power generation,is to improve the existing grid connection technology and to ensure that the microgrid remains stable and compatible while using clean energy efficiently.To address this challenge,this paper uses PV with energy storage systems to compensate for the balance between supply and demand of system power and to reduce the impact of PV power instability on the system.stability.The topologies of PV virtual synchronous generators are classified and compared,and a two-stage common DC bus PV virtual synchronous generator is identified for this paper.The mathematical model of PV power supply and energy storage battery is established,and the maximum power point tracking(MPPT)control method applied to the PV boost converter is improved.From the perspective of the control of the optical storage grid-connected inverter,the inverter uses VSG control to change its parameters in real time to improve its performance.Firstly,a block diagram of the VSG active loop control is drawn and the closed-loop transfer function of the active loop is established.Secondly,a parametric analysis is carried out to plot the step response curves of the system under different parameter values,and the influence of the parameters on the system performance is investigated in depth.Finally,a simulation model is built on the simulation platform to verify that the control strategy can show good dynamic performance when the system is disturbed.From the control of the light storage DC side system,the PV reserved power can participate in the frequency regulation of the grid,but when the system faces sudden changes in light intensity,the fixed load shedding rate cannot quickly make up for the power shortage,so the control method of changing the load shedding rate according to the light intensity is used.Due to the bi-directional power flow of the energy storage system,the coordinated control of the light storage system further provides primary frequency regulation and inertia support for the system.Simulations verify the superiority of the control strategy under both sudden changes in load and sudden changes in light intensity.