Research On The VSG Control Strategy Of Inverter With Energy Storage In Microgrid

Clean and efficient power supply has played a significant role in society,however,the use of coal and other non-renewable resources is bringing serious environmental and social problem.Instead,distributed power generation,such as wind power,photovoltaic power generation is becoming an important part of power supply system.More and more distributed power generation is changing the grid from a rotating machine based system to a complex system consisting of electronic grid-connected inverter,the compatibility of the old and new system is a key issue needed to be solved.Distributed power generation is generally connected to grid through three-phase inverter based on various kinds of strategies,And the output power of the distributed power generation is uncertain and fluctuating.These situations make it difficult to achieve plug and play and autonomy coordinate operation.Therefore,it is necessary to propose a new kind of control strategy.Virtual synchronous generator(VSG)is an ideal solution to this problem.This paper will analysis the math model of synchronous generator and add it to the power loop of the grid-connected inverter.The three-phase inverter can operate both island and interconnection with the algorithm of VSG.Firstly,I got the model of the VSG through the analysis of the synchronous generator,including the stator electrical equation and rotator motion equation.With the design of the controller including the governor and exciter,a complete algorithm of VSG is accomplished.Then I use the software of MATALB to confirm the correctness of the algorithm and to compare it with the algorithm of droop which is often used in grid-connected inverter.Then,I analysis the effect of some key parameters to the inverter.It is necessary for the VSG inverter to provide a certain capacity power storage in order to simulate the inertia of the synchronous generator,this paper will study the quantitative relationship between the energy storage unit capacity selection and the controller parameters.Finally,an experimental platform for grid-connected inverter is proposed,which is used to verify the effectiveness of the virtual synchronous generator control strategy proposed in this paper.