Research On Micro-grid Model And Its Control Strategy With Energy Storage System

The challenge of global energy crisis promotes the development of new energygeneration technology, but its volatility and intermittent impact the main grid. Modern griddevelops toward the direction of large generator, high voltage and big grid, emphasizing theimportance of safety and reliability of the grid. Microgrid is a new power supply mode,which not only improves the power supply reliability but also decreases the impact of newenergy generation to the grid, with energy storage system. It’s a new problem how to runmicrogrid with the assist of energy storage system(ESS).Firstly, this paper expounds the structure and working princeple of microgasturbinegeneration system(MTGS) and introduces mathematical model of every parts of the system.Then build the whole model of the system on PSCAD/EMTDC. Its inverter applis PQcontrol strategy when microgrid is combined to the main grid and V/f control stragegywhen isolated. The way to run microgrid safely and steadily is to change the controlstrategy according to whether microgrid is combined to the main grid or isolated from themain grid. The validity of the model is verified by simulation.Secondly, photovoltaic(PV) power generation and wind power generation are newenergy generation technology, which are more fully developed relatively. As a kind of greenESS of large capacity, vanadium redox flow battery(VRB) has a broad developmentprospects. This paper introduces the technical feature, working principle and mathematicalmodel of PV, wind power generation and VRB and builds the model of microgrid includingMTGS, PV, wind power generation and VRB on PSCAD/EMTDC. The function andcontrol problems of microgrid without ESS are pionted out by simulation.Finally, on the basis of the constraints of the function and control of microgrid, thecontrol principle, such as taking full advantage of the renewable energy when the microgridis combined to the main grid, is established whether the microgrid is combined to the maingrid or not. According to the principle, the control strategy is established depending on thefunction state of microgrid, whose validity is verified by simulation.