Research On Control Strategy Of DC Microgrid Based On Consensus Algorithm

Conventional DC microgrid control methods can be divided into centralized control methods and decentralized control methods.Although the centralized control method of the DC microgrid can obtain higher control accuracy,when the central controller fails,the entire DC microgrid will lose its stability.At the same time,the decentralized control method of DC microgrid can obtain higher reliability,but the control accuracy will be affected.The control strategy based on the consensus algorithm can effectively combine the advantages of the above and avoid the shortcomings of the above.While maintaining the control accuracy,it also ensures the stability of the bus of the DC microgrid.Therefore,this paper proposes an improved droop control strategy based on consensus algorithm,and analyzes the proposed control strategy and the influence to the DC microgrid.Due to the existence of the line impedance,in order to solve the contradiction between the current distribution accuracy and the bus voltage stability in the traditional multi-micro source system,this paper first regards the micro sources in the DC microgrid as an agent,and proposes a ring topology between the micro sources.The dynamic expressions of the current observers based on the consensus algorithm are given,and the ideal output current of each micro source is obtained,which can improve the reliability of the system.Aiming at the non-linear problem caused by the higher permeability in the power system,an improved droop control method is proposed to change the droop coefficient through the fuzzy control method.At the same time,a voltage compensation control method can realize the accurate distribution of current according to the capacity,and the system voltage can also be effectively controlled.However,with the scale of microgrids is increasing,it is necessary to consider the coordinated control of DC microgrid groups.In the consensus algorithm,the time for the values observed by each observer to reach convergence increases with the increase of the number of agents.Therefore,a group consensus algorithm suitable for multi-bus structure microgrid is proposed.Taking the dual-bus DC microgrid as an example,the power units on the high and low buses are grouped and interconnected,and the maximum communication delay under which the system can converge is achieved through derivation.At the same time,the anti-interference state observer is added to reduce the influence of the disturbance caused by the voltage and current observers,improving the convergence accuracy of the consensus algorithm and achieving the balance between power distribution and bus voltage.In summary,the application of the consensus algorithm in the DC microgrid control strategy is introduced firstly.Then,in order to solve the non-linear problem caused by the high permeability of the power system,the current distribution accuracy and voltage stability are realized through the consensus algorithm combined with the fuzzy droop control.Then,in order to solve the problem of too long convergence time caused by too many micro sources in the microgrid,a group consensus algorithm is proposed.And the maximum communication delay that the system can converge is obtained through mathematical derivation.The research of this control strategy can better meet the actual demand of the power system and ensure the stability of the DC microgrid connected to the large grid.