Research On Key Technology And Engineering Application Of Hybrid DC/AC Microgrid

Microgrid is considered to be an effective way to use distributed renewable energy generation and to solve the shortage problem of conventional power generation resources.Microgrid structures include AC microgrid,DC microgrid and hybrid AC/DC microgrid.This paper presents a hybrid DC/AC microgrid which is based on a DC microgrid.This microgrid not only has the advantages of simple structure,high efficiency,low cost,convenient control,high reliability which is like a DC microgrid,it can also meet the demand of AC load uninterrupted power consumption.So it has strong application value.In this paper,a special architecture of photovoltaic hybrid DC/AC microgrid system is studied.First,this paper introduces the background and significance of the research work,analyzes the current development situation of AC microgrid,DC microgrid and hybrid AC/DC microgrid and compares their merits and drawbacks.Secondly,according to the limitation of the current microgrids,the architecture of hybrid DC/AC microgrid system is presented,and its advantages in engineering application are discussed.The topological structure and composing elements are analyzed in detail.Then the micro sources of the system include photovoltaic power unit,storage unit,and grid interface converter unit is studied further.Their simulation models according to their working principles,their control strategy are further researched,and they are verified in the simulation platform of MATLAB/Simulink.Then based on the the hybrid DC/AC microgrid,two level control strategy is studied further.Through the superior control,the microgrid can receive orders from the grid and the bottom control uses bus voltage as the scheduling signal,which can connect each other without communication.Based on the two level control strategy of microgrid,in accordance with the power supply priority of using photovoltaic,AC power and energy storage,the working mode of the system is divided into three types.The three models are simulated by Simulink simulation respectively,the switching running state of the system are analyzed,the effectiveness of control strategy and stability of the system are verified.Finally,based on the request of green building and energy efficiency of Xiamen Municipal Construction Bureau,a lOkW hybrid DC/AC microgrid demonstration project was constructed,and the experimental verification was carried out.