Research On Smooth Switching Of Operation Mode Of Microgrid

There are two modes of microgrid:grid connection and island isolation.Its operation capability is an important indicator of economy and technology of microgrid.The switching process between the two is the key point to ensure stable operation of microgrid and continuous power supply of load.Therefore,this paper has carried out relevant analysis and research on the switching between grid-connected and island mode of microgrid,so as to ensure the smooth and stable operation mode switching process.For the switching of operation mode of microgrid,the following work is mainly done:Firstly,this paper summarizes the research of some scholars on the operation mode switching of microgrid in recent years,analyzes several control strategies of traditional microgrid,and summarizes their applicability,advantages and disadvantages.The principle and structure of photovoltaic power generation system and battery energy storage device are analyzed,and the simulation model is built in MATLAB/Simulink.As an indispensable connection between micro power supply and micro power grid,the inverter coordinates the parameters of the inverter to provide a basis for the design of the control strategy.Aiming at the limitation of traditional control method,the principle of virtual synchronous generator is introduced,and the control strategy is designed by constructing the connection between synchronous generator and inverter.Secondly,according to the characteristics of photovoltaic power generation system and battery energy storage device in micro power grid,a control strategy suitable for mode switching in this paper is designed,that is,PQ control and VSG control are combined.In the process of switching from isolated island to grid-connected microgrid,presynchronous control unit and phase-locked loop technology are adopted to realize smooth switching of grid-connected microgrid by real-time tracking and effective processing of grid voltage amplitude.In the VSG control module,the correctness of the application of VSG control in the switching process is verified by studying the waveform of p-f and q-u.In view of the switching process from grid-connection to island,the island detection is carried out to quickly judge the operation state of the micro-grid,so as to ensure the stable and continuous power supply of the load.Finally,through MATLAB/Simulink simulation platform,the simulation model of micro power grid is built.The simulation verifies that the two modes can complete smooth transformation under the control strategy adopted,and the micro power grid can run stably and the load can continue to supply power,thus illustrating the correctness and feasibility of the control strategy designed in this paper.