The Research Of Droop Control In DC Microgrid

In order to solve the problem of distributed energy generation,microgrid has been proposed as one of the options.Compared with AC microgrid,DC microgrid is more suitable for many distributed power equipment.In order to ensure the stable operation of the DC microgrid,it is necessary to develop a set of effective energy management strategies.How to solve the problem of current sharing in the bottom control of the energy management has become the key to implementing the reliable operation of each component unit in DC microgrid system.The droop control is widely investigated and discussed as a typical method of implementing current sharing.This thesis mainly focuses on the droop control in DC microgrid.The working principle of the DAB converter under the Single-Phase-Shift control has been analyzed,and the small signal model has been built.Combining the working principle and the small signal modeling results,the voltage and current double closed-loop system of the DAB converter has been designed,and the correctness of the closed-loop system has been verified by simulation.The principle of the traditional droop control has been expounded and its limitation has been revealed.In order to improve this limitation,this thesis innovatively introduced and analysed the existing improved droop control according to the methods of changing curve.By comparing and summarizing the characteristics of these various methods,the key technology of the droop control research in DC microgrid has been obtained,namely the selection of compensation methods and communication methods.From the perspective of solving two major problems in droop control,a control strategy with the parallel moving of droop curve based on double compensation has been proposed in this thesis,and its principle has been explained in detail.The feasibility and superiority of the proposed control strategy have been verified by simulation.The experimental platform based on DSP TMS320F28335 has been built,and the hardware circuit design and software system design have been described.Finally,the experimental verification of a single DAB converter and the two-unit parallel connection system has been realized.