Research On DC Microgrid Distributed Energy Storage Balancing Control Strategy

As an important basis for the development of modern society,the development and reform of energy are directly related to the progress of human society.The development and utilization of renewable energy has become the trend of today’s energy crisis.Microgrid technology provides a feasible technical scheme for distributed generation.The traditional power grid is mainly based on AC microgrid.In recent years,with the increase of DC source and load,the advantages of DC microgrid gradually emerge.Firstly,the DC microgrid with distributed energy storage is taken as the research object to study the balanced control strategy of distributed energy storage.This paper summarizes the background,significance and development of microgrid technology,the role of distributed energy storage in microgrid and the existing problems.Then,the research status of DC microgrid and distributed energy storage equilibrium control is analyzed,and the research ideas of the existing equilibrium control strategy,the selection of equilibrium variables and the improved method based on the traditional droop control are analyzed.Meanwhile,it is pointed out that this method has the defects of voltage drop and requires multiple parameter restrictions.Secondly,in order to solve the problems of the current equalization control strategy,an equalization control strategy without bus voltage deviation is proposed.By introducing SOC and using logarithmic form to design the voltage scheduling function,the reference voltage is equivalent to the rated busbar voltage with approximately symmetrical change,and then the balanced control without busbar voltage deviation is realized.At the same time,the parameter selection process is simplified by using the proportional relationship between the reference voltage and the output power.Considering the characteristics of the battery,the bidirectional Buck/Boost converter with Boost topological forward discharge was selected.Based on the state space model of Boost topology,the state space equation of the system is constructed and the stability of the system is analyzed.Moreover,in order to improve power quality,in view of the equivalent impedance converter and line impedance voltage drop,at the same time to better apply this paper proposed a balanced control strategy,design from the Angle of voltage compensation amount,was proposed based on the average reference voltage compensation control strategy,implementation of compensation control at the same time guarantee the system stability is not affected.Finally,the distributed energy storage equilibrium control of DC microgrid is experimentally studied,and the topological structure and hardware and software design of the experimental platform are introduced.The proposed equilibrium control strategy is experimentally verified,and the correctness and effectiveness of the proposed control method are verified.