Study On Power Controllability Of Multi Inverters In Microgrid

With the contradiction intensification between economic development and energy utilization,the distributed generation unit,represented by solar and wind energy,is becoming more and more popular.But distributed generation is not easy to control and can not be directly access to the traditional grid.The emergence of the microgrid integrates the different distributed generation units together,which can not only give full play to the advantages of distributed generation,but also have strong autonomy.The microgrid can operate in parallel or in island.It can get along with the large power grid.And how to coordinate the output of each distributed unit has become particularly important.This paper will discuss in the following aspects.First analyze the working principle of inverters controlled by FFC and UPC in detail,and second introduce the mathematical model of photovoltaic cells,the realization of the maximum power tracking(MPPT)algorithm and the control strategy of photovoltaic power generation in photovoltaic grid-connected systems.And in the last,verify the three-phase photovoltaic grid-connected power generation system by simulation.And also introduced the bi-directional DC-DC working principle in the energy storage system.Optical storage microgrid model is established by analyzing the characteristics of distributed generation.Active power coordination control strategy is proposed by combined with the energy storage device.It can egulate power by using characteristics of energy storage devices to cut peak and fill the valley in grid and island operation,which ensures its cnstant of tthe feeder value and the system frequency during the grid operatation.In order to maintain the voltage stability of microgrid system and a constant value of the reactive feeder during the grid operating,this paper analyzes the relationship between reactive power and voltage controlled by FFC,and then proposes a reactive power coordinated control strategy which can improve reactive power output of DG by switching its given value to ensure reactive power balance of the entire system.Based on the above theoretical analysis,a simulation platform is built in Matlab/Simulink to verify the feasibility of the proposed control strategy.Finally,a microgrid platform has been built.The hardware circuit and software design of the whole platform are briefly introduced in this paper,and the feasibility of the proposed power control strategy is verified by the experiment.