Study On Grid-friendly Operation And Control Strategy Of Microgrid

At present, Micro grid is the focus of research on power system. It is an important part of Smart Grid. The aim of Microgrid is to solve the problems caused by the integration of a large amount of renewable generation and strengthen the flexibility and reliability of large interconnected power system. There are many demonstration Microgrids in USA, Europe, Japan and China. Microgrid is a small power system which contains power resources and loads simultaneously. It is connected to main power system through Point of Common Coupling (PCC). The single direction of power flow will be changed by the access of Microgrids. It can strengthen the support of voltage, impact the sytem loss and many aspects of operation of power system. So Microgrids should be grid-friendly and reduce the harmful impacts on the power system. In the paper, it is proposed that the definition of strategy of grid-friendly control. Through the verification of demonstration Microgird, Demand Respons can reduce the operation cost of Microgrid. It makes use of the economic benefits to urge Microgrids to choose the grid-friendly operation strategies spontaneously. There are many advantages belonging to Microgrids other than other loads because of the controllability and sustainable power supply. As a result, the implementaion mechanism of Demand Response must be changed to adapt to the access of Microgrids. PQ control strategy, Vf control strategy and Droop control strategy are three control strategies of Distributed Generation in common use. For a Microgrid, when different distributed generation adopts different control strategy, it can realize different target. In this paper, it uses Digsilent simulation tool to set the model of demonstration Microgrid. The operation of Microgrid is simulated in the process that the sudden surge of load in connected state and the transformation of Microgrid between the connected state and isolated state. In connected state, the proposed control strategies can make sure that the increase of load can be assumed by distribution network or battery, respectively. When the Microgrid transfers from the connected state to isolated state, it splits into two parts. The strategy has the ability to make each part to be steady. The results of simulation can prove the control strategy proposed in the paper is effective.