Research On Control Strategy Of Hybrid AC/DC Microgrid With Multi Micro Sources

Under the strategic goals of " carbon peak" and " carbon neutralization",our country will promote energy revolution and build a number of clean,low-carbon,safe and efficient energy bases.Among them,hybrid AC/DC microgrid is an important part of the new energy grid,which can effectively reduce the power conversion structure and reduce the economic cost.However,at the same time,the randomness of the distributed power supply output,the access of a large number of flexible power electronic equipment and unbalanced load and other factors seriously threaten the safe and reliable operation of the system.Therefore,the research on the control strategy of microgrid has important theoretical and practical significance.This research focuses on control strategy of hybrid AC/DC microgrid with multi micro sources.Firstly,the topology structure and control strategy of hybrid AC/DC microgrid are analyzed and studied,and the control structures of distributed energy sources,intertying converters and related power electronic interface converters are introduced in detail.Through simulation analysis,the feasibility of hybrid AC/DC microgrid control strategy is verified,which lays a foundation for the subsequent research of multi micro sources microgrid.Secondly,aiming at the problems of current sharing and bus voltage offset in multi micro sources DC microgrid,the small signal modeling analysis of droop control is carried out,and the time-varying parameter model is deduced.Taking the first-order system as the research object,combined with robust adaptive control,the robust adaptive controller parameter of DC microgrid is designed,and its stability is proved.The simulation results show that the robust adaptive current sharing control of DC microgrid can make each DC micro source distribute the load according to the desired proportion and accurately control the DC bus voltage,and it is robust under the load mutation condition.The correctness of the simulation results and the effectiveness of the robust adaptive current sharing control are verified by experiments.Finally,according to the three-phase unbalance condition of multi micro sources AC microgrid,the power distribution mechanism of AC micro source is analyzed,the virtual impedance and negative sequence current compensation control loop are derived,and the positive and negative sequence current components are extracted by using double second order generalized integral.With the use of linear active disturbance rejection control(LADRC),according to the negative sequence current control model,the second-order linear active disturbance rejection unbalanced controller is designed,and the parameters of the linear extended state observer and the linear state error feedback are adjusted.Small capacity AC micro source negative sequence current compensation control.The feasibility and effectiveness of LADRC unbalanced control are verified by simulation analysis and experimental test.Compared with PI controller,linear active disturbance rejection control can track unbalanced negative sequence components more quickly and accurately,and improve the robustness and rapidity of the system.