Research On Layered Control Of Networked Microgrids Based On Ring Network Architecture

Since entering the 21st century,the utilization of solar energy and wind energy has become the main application form of new energy.The scale of photovoltaic power generation and wind power generation has increased rapidly in recent years: by the end of 2020,the installed capacity of wind power and photovoltaic power generation in China has reached 216 million k W and281 million k W respectively.The application of new energy represented by photovoltaic power generation and wind power generation has developed rapidly.However,due to the randomness and intermittency of new energy power generation,it is difficult to apply new energy power generation on a large scale at this stage.Moreover,there are many obstacles when new energy is connected to the large power grid,and there may even be factors affecting the safe and stable operation of the large power grid.In order to solve this problem,the concept of microgrids came into being.Microgrids can realize local consumption of electric energy and reduce transmission loss.However,the microgrids alone still has the disadvantages of insufficient power supply voltage,low reliability and poor anti disturbance ability.With the improvement of control strategy and the demand of rapid development of microgrids,the application of interconnected microgrids has attracted extensive attention from scholars from all walks of life.Based on this background,this paper focuses on the related problems of interconnected microgrids control:(1)Firstly,the stable operation of independent microgrid is studied.Starting from the basic units of microgrid: distributed micro source,energy storage system,load and interface circuit,the working principle of each basic unit and the working mode switching control of interface circuit are studied.On this basis,by analyzing the relevant research on Microgrid control in the original literature,this paper proposes an improved droop control strategy based on discrete consistency control.(2)On the basis of realizing the stable operation of independent microgrid,then the control strategy of interconnected microgrid based on ring connection architecture is studied.By analyzing the advantages and disadvantages of the existing connection architecture and control strategy of interconnected microgrid,this paper takes the ring connection architecture as the connection form of interconnected microgrid,and adopts droop control to realize the group network control of interconnected microgrid based on hierarchical control: on the basis of independent microgrid control strategy,secondary voltage control and power flow control are added,Improve the balance of distributed micro source power output and the mutual aid ability of power flow between units.In addition,a centralized energy storage system independent of each microgrid is added as an efficient and safe operation guarantee of the interconnected system to improve the stability and anti disturbance performance of the interconnected microgrid.(3)Finally,a model is built to verify the effectiveness of the control strategy.The theoretical model and simulation model of the basic unit of Microgrids and the corresponding interface circuit are built,and then the ring connection architecture is used in Simulink to connect the interconnected Microgrids.Through a variety of operating conditions,the voltage equalization and current distribution ability of the proposed control strategy,the stability of bus voltage in response to emergencies,and the SOC equalization accuracy and efficiency of the centralized energy storage system are verified.