Research On Load Distribution Of DC Microgrid Under Coordinated Control Strategy

With the acceleration of the process of energy decarbonization,DC microgrid as an effective integrated distributed power supply scheme has been rapidly developed.As the two basic control tasks of DC microgrid,voltage balance and load distribution compete with each other,so it is difficult to meet the requirements at the same time.Therefore,it is necessary to propose a new control strategy which can improve the accuracy of load distribution and the ability of voltage regulation,and study the voltage balance and load distribution of DC microgrid under the unified framework.In this paper,the voltage balance and load distribution of DC microgrid are studied.The main research contents are as follows.For a kind of DC microgrid with n groups of distributed generation units and nonconstant current load,a novel strategy of indirectly regulating bus voltage through the converter reference voltage is proposed.The strategy uses the output proportion of distributed generation and the feedback signal of bus voltage to realize the load distribution and bus voltage balance of microgrid,which can improve the load distribution accuracy and voltage regulation ability of the system.Meanwhile,the Hurwitz stability criterion proves theoretically that the proposed control strategy can stabilize the system.Finally,the simulation and experimental analysis of the microgrid system under different conditions are carried out through MATLAB and the intelligent microgrid experimental platform to verify the effectiveness of the proposed control scheme.For a class of DC microgrid withn subsystems,a new load distribution method based on distributed strategy is proposed.This strategy can use local communication to obtain global information,and can realize load distribution and voltage balance in the microgrid under the unified framework.Firstly,load distribution and voltage balance problems of DC microgrid are transformed into multi-objective optimization problems.A centralized control strategy for load distribution and voltage balance is obtained by solving the problem,and the design method of droop controller is given.In order to reduce the communication burden of the system,a distributed control strategy which only exchanges information with neighbor nodes is proposed.The distributed control strategy can converge to the optimal solution of multi-objective optimization problem.Finally,the robustness and plug and play performance of the system are verified by simulation,and the effectiveness of the proposed strategy is proved.