Research Of System Modeling And Control Strategy For Microgrid

Energy is our essential material resources for human survival and development.Withthe development of human society, the per capita energy consumption is higher than theold days. The energy crisis has prompted people increaseing strength to study and use ofrenewable energy and to improve energy utilization.Electricity is the most convenientform for transport and utilization of energy. The new energy sources such as photovoltaic,wind power generation is widely used in the world and the way of use energy developmentis becoming more and more attention.Micro-grid integrated regional variety of renewableenergy electricity and two-way transmission to large power grid for greatly improve theutilization rate of renewable energy and the reliability of the power supply to theuser.Because the micro grid system itself contains a variety of power electronic deviceswhich is small inertia, photovoltaic and wind power and other natural features, so how toguarantee the stable operation of micro grid system, how to promote renewable energy useefficiency, is no only the research hot spot of micro power grid, but also the popularizationand application of the micro power grid development and key technologies.This paper mainly studies in coordinated control strategy in micro-grid and s serialsof model with different kinds of sources.The main contents and results are below:(1) The paper established mathematical model for all kinds of micro source of micro-grid system through analyzing their characteristics, and analyse the model simulation inPSCAD/EMTDC software. In this paper, we have analysed lots of micro power modelwhich almost covers common type of generating unit, such as photovoltaic cell, windpower generation unit, the micro-gas turbine generating unit, battery energy storagesystem and super capacitor. The mathematical modeling, model design and simulationanalysis in software are already set up one by one, which is good for the subsequentbuilding a micro grid system and studying its stability and coordinated control strategy. (2) In view of the micro grid master-slave control structure, this paper analyse thecurrent typical V-f control mode and P-Q control mode, and put forward an improved V-fcontrol mode and P-Q control mode structure. The simulation in the soft verify theeffective-ness of the control strategy;(3) In order to promote the utilization rates of renewable energy, to keep the micro gridsystem running on maximum power point of photo-voltaic cell array, considering theenergy storage battery SOC features, the paper designed the battery control scheme andthe coordinate strategy of the whole system structure. The simulation model are also builtup and the simulation figure verified the control method correctness and effectiveness. Thenew control strategy of micro-grid system not only improved the utilization rates ofrenewable energy sources such as photo-voltaic (PV), but also guaranteed the stability inmicro grid system on the islands mode;(4) Considering the micro gas turbine have inertia and relative slow responds,thesystem are added the super capacitor to compensate instantaneous power fluctuations inthe control mode switch point.It solved the smooth transition problem under the master-slave control structure in micro-grid system. Through the PSCAD/EMTDC simulationsoftware, the simulation of results validated the control strategy’s correctness andeffectiveness.