Research On Control Of Distributed Photovoltaic Power Generation System Based On VSG

In order to realize the sustainable development of society,increasing the proportion of renewable energy represented by photovoltaics in the energy structure is an important task for my country’s current energy development.Distributed photovoltaic power generation is an important part of photovoltaic power generation.Photovoltaic power supplies generate direct current to input electrical energy into the grid through static grid-connected inverters.If a large amount of electric energy is connected to the grid through an inverter with an improper control strategy,it will inevitably lead to a relative decrease in the rotation capacity of the grid,which is not conducive to the relatively stable frequency and voltage of the grid,and will threaten the stable operation of the grid.Imitating the mathematical model of a synchronous generator,a virtual synchronous generator(VSG)control strategy is established,which can be used as an inverter control strategy to make the inverter output have the inertial output characteristics of a synchronous generator and help support the grid frequency and Voltage.This paper studies the VSG-based grid-connected inverter control technology in distributed photovoltaic power generation systems.The grid-connected inverter of the energy storage unit uses the VSG control strategy to establish an active frequency control loop and a reactive voltage control loop.The quasi-PR control is used in the internal current loop to achieve non-difference tracking of the grid signal.A simulation model of the grid-connected energy storage unit based on the VSG control strategy was built,and compared with the traditional PQ control strategy to verify the superiority of the VSG control strategy.Aiming at the problem that the control parameters of VSG have a great influence on the performance of dynamic regulation,a VSG control strategy with coordinated adaptive control of moment of inertia and damping coefficient is proposed.According to the mathematical model,the influence of the control parameters on the output active power and frequency is analyzed.After obtaining the corresponding conclusions,the coordinated control algorithm of the moment of inertia and the damping coefficient is given.Finally,a simulation model of a distributed photovoltaic power generation system is established,and a structure in which photovoltaic power generation units and energy storage units are independently connected to the grid through their respective gridconnected inverters is selected.The energy storage inverter adopts a VSG with coordinated adaptive control of parameters.Control Strategy.The effectiveness of the distributed photovoltaic power generation system based on VSG is verified through simulations of different working conditions and compared with traditional control methods,it can provide certain support for the grid frequency and voltage.