Study On Coordinated Control Of Microgrid Multi-power Supply Based On The Hybrid Energy Storage

With the increasing capacity of micro grid, distributed power supply is increasinglybeing added to the micro grid. In the micro grid which contains various distributed poweraccording to the different characteristics of different micro power. We can take advantageof one’s strengths to make up the weaknesses of others. So that, the lasting, stable andefficient operation of the whole micro grid will come true. In order to improve the stabilityof the micro grid and its energy utilization efficiency, the paper, based on the micro gridsystem with hybrid energy storage system, develops its research into the coordinatedcontrol between them.At first, this paper introduces the basic principles and mathematical models of thephotovoltaic power generation system, the lead-acid battery and the super capacitor. And itsets up an ideal mathematical model of photovoltaic grid connected inverter, thethree order dynamic model of lead-acid battery, the super capacitor RC model. Thesimulation analysis is carried out on the Grid connected photovoltaic battery, the chargeand discharge characteristics of battery and super capacitor.Next, the structure and coordinated control strategy of the hybrid storage system areintroduced in this paper, where it studies the structure and principle of Bi-directionalDC/DC converter, the calculation principle of hysteretic current, current controller. Also,based on such coordinated control strategy, the paper optimizes the charge and dischargeprocess of energy storage system, and carries out a simulation comparison and analysis onthe charge-discharge process of the battery energy storage and hybrid energy storage.Then, introduces the coordinated control strategy of the micro grid in detail of thispaper, designs a Bi-directional DC/AC converter, introduced V/f control and constantpower control strategy, carries out the energy transfer and power output principle of theenergy storage system, and photovoltaic generation system and diesel generation system,and then introduced the load detection and the grid control strategy, it puts forwardmultiple power energy coordination strategy appropriate for this paper’s micro gridcombined with energy management principle of each power supply.Finally, based on the simulation model builded in the MATLAB/Simulink of themicro grid with multi-power supply, the paper make a comparison on the coordinated control strategy between the normal state and over discharge state of the energy storagesystem under the island operation situation. In addition, a simulation analysis is alsocarried out on the feedback power from micro grid to large power grid in paralleloperation and the parallel operation under the condition of energy storage system’sovercharge.