Multi-source Coordinated Control Strategy For DC Microgrid Based On Optimal Droop Control

Microgrid technology integrates distributed power,energy storage system and user load into a regional power system,which realizes the complementary advantages of multiple sources and has the characteristics of "clean","autonomous" and"friendly".In addition,with the increase of DC loads and distributed power supply for electric vehicles,air conditioners,computers,etc,the DC characteristic of DC microgrid are becoming more and more obvious.The use of DC microgrid technology can reduce the number of power conversion links and inverters,reduce power loss and cost,and improve power supply efficiency.In view of the advantages of the above-mentioned DC microgrid,and relying on new energy,energy storage,flexibility and other technologies,DC microgrid technology has gradually become a research trend,which can realize the production,transmission,storage and management of distributed energy.In the future,DC microgrids have bright prospects in industrial parks,commercial buildings,residential buildings and other fields.Therefore,how to realize multi-energy complementary,multi-source coordination and stable and reliable operation of DC microgrid system is the key to study the coordinated control of DC microgrid.Firstly,the paper summarizes the research status of DC microgrid system structure and control system at home and abroad.Then the mathematical model of each distributed power supply and grid-connected converter is established,and the control strategy adopted by each unit interface converter is further studied,grid-connected converter adopt droop and limit control modes,photovoltaic unit MPPTand droop control mode,and energy storage unit droop antrol mode.Secondly,the power relationship of DC microgrid under different conditions is analyzed,and then the system is divided into four working modes according to the fluctuation range of bus voltage,and the control strategies of each unit under each operating condition are given in detail.Finally,to solve the problem of bus voltage deviation and unreasonable current distribution caused by droop control in DC microgrid primary control,the discrete consensus algorithm is adopted to realize the information sharing and collaborative control of each unit of DC microgrid system in a fully distributed way.At the same time,the effect of noises on consensus convergence in sparse communication networks is effectively suppressed by introducing the consensus gain function,and the performance of anti-interference is better,which further improves the convergence accuracy and the reliability of control strategy,the consistency algorithm also has good anti-jamming performance,which further improves the convergence accuracy and the reliability of the control strategy.