Simulation Of Distributed Hybrid Storage System In Microgrid And Control Strategy Research

In recent years, facing the problems of environmental pollution,the exhaustion of fossil energy sources, and the development of the power electronic technology, more and more new energy access in medium-low voltage power networks. The micro-grid, which is a new power supply mode, contains various intermittent energy, loads and relative monitoring andprotection devices. It has two running status, which are grid connected and isolated, andtwo control mode, which are master-slave control and peer-to-peer control. The micro-gridcreates a new way for the new energy to connect with grid. While on the other hand, itbrings many problems as well. For example, it can cause power disturbance of the grid.Also, it’s hard to keep the voltage and frequency stable. As a result, the storage device isnecessary. There are many kinds of storage elements with different advantages. Theall-vanadium redox flow battery (VRB) has huge storage while the super capacitor (EDLC)can charge–discharge rapidly. The author does several research about the control methodsof DC/DC and DC/AC convertors, and studies the impact of distributed hybrid energystorage system in micro-grid by simulationThis paper first introduces the basic structure of the micro-grid and two control mode,which are master-slave control and peer-to-peer control. After that, it makes the design andmodel of the hybrid energy storage system. On the basis of comparing the energy storagesystem in parallel and cascade, the author proposes a structure with two DC/DC convertorsand builds the equivalent models of flow battery and super capacitor respectively. Then thecontrol loop of DC/DC convertor is designed to combine the advanteges of VRB andEDLC. What’s more, in order to adapt to different running status, there are several controlmethods for DC/AC convertor. Finally, simulations reveal three impacts of distributedhybrid energy storage system in micro-grid, which are improving the quality of power,promoting the reliability of grid and optimizing the intermittent energy output. Besides, theauthor does the research on stability of the micro-grid with multi-distributed hybrid energystorage system and puts forward the method of optimizing parameters.The paper focuses on the topological structure of hybrid energy storage system, aimingof improving the DC/DC’s control method and optimizing the parameters of Droop. Thenew topological structure is necessary for integrating the advantage of the energy storageelements. In the control loop of DC/DC, BP neural network is combined with traditionalPID, so that it’s easy to allocate power reasonably. Furthermore, the paper reveals a newway to optimize parameters in case of the unreasonable control parameters of Droop, whichis based on the small signal model. With a equivalently simplified micro-grid structure, itcalculates the parameters by Chaos Particle Swarm Optimization (CPSO) which has considered the asymptotic stability of the system, the bandwidth control and the robustness.Finally with simulation, it confirms that the parameters can maintain the voltage and thefrequency of the system stability and achieve to rational allocation of power.