Research On Parallel Control Of Multi-dc Microgrid Based On Adaptive Droop Control

With the increase of people's awareness of environmental protection and the intensification of energy problems,the research and development of distributed power sources has gradually matured.In order to better disseminate distributed power sources,distributed power sources are usually combined into a microgrid and then integrated into the power grid.Micro-grid is a controllable system composed of distributed power(DG),energy storage system(ESS)and load,which can realize on-grid and off-grid switching.When the number of micro-grids gradually increases to reach the scale,different micro-grids in adjacent areas can be controlled through the concept of "multi-micro-grids" and used as an important part of future smart grids.A DC microgrid is a controllable power grid that uses a DC bus to connect distributed power sources and energy storage systems.Because DC power does not require voltage frequency and phase control,it has the advantages of simple control and high reliability.Therefore,for the multi-DC microgrid parallel system,the research contents of this paper are as follows:First of all,this paper classifies the operating conditions of a multi-DC microgrid parallel system,and divides the three operating conditions into 12 operating modes according to the different voltage building units,and then establishes a corresponding mathematical model for each operating mode.Next,the mixed potential function is constructed using Brayton-Moser's hybrid theory,and the stability criterion is obtained.The energy management strategy is formulated by the stability criterion.Then construct the Lyapunov function to verify the system stability theoretically,and prove that the system can run stably under large disturbance.In order to reduce system bus voltage fluctuations and enhance system stability,a state-space model of a multi-DC microgrid parallel system with droop control was subsequently established to analyze the influence of droop coefficient on system stability.Adapt to the value range of the droop coefficient and improve the voltage stability of the system.Then build a simulation model based on Matlab / Simulink and verify the simulation.Finally,an experimental platform is established,and the effectiveness of the control strategy of a multi-DC microgrid parallel system based on adaptive droop control is verified through experiments.