Studies On Modeling And Control Of Distributed Energy Storage System In Microgrid

A large number of distributed generations'access, the impact of which to the grids'security and stability can not be ignored. The microgrid is a good solution to the access. For the stable operation of microgrid, energy storage system has played a significant role. The key is the control of the energy storage system. So this paper has researched on modeling and control strategy of energy storage system in microgrid.This paper begins with a macro perspective, an analysis of the overall structure of the microgrid. At first, modeling of microgrid, a simulation platform is built in Matlab. Based on the Siemens benchmark 20kV middle voltage distribution network and 400V low voltage feeder, the simulation models of 10kV medium voltage distribution network and 400V microgrid are established, by modifying the voltage level and some parameters. Then further research is on modeling of distributed generation in microgrid. Taking into account the distributed generations in microgrid network generally small, this paper concentrates the three-phase photovoltaic and asynchronous wind turbine, studying the mathematical models and control strategies. Both simulated access to microgrid, improve the accuracy of modeling by analyzing characteristics of their ports.This article focuses on the modeling of energy storage system, first determining the basic structure of the energy storage system: Batteries through the buck-boost DC/DC circuit connected to a bi-directional DC/AC converter, and then step through the filter and the transformer to the grid. Each modeling and control strategies of DC/AC converter and DC/DC converter are studied in depth. The simulation model of energy storage system is simulated in microgrid. Energy storage system can exchange power with the microgrid, which verifies the feasibility of this structure.Innovation of this paper is the proposed short-term load forecasting based on active control strategy for energy storage system. For batteries'charge and discharge characteristics can not be frequent, the traditional control strategy has been improved. The charge and discharge intervals of energy storage system are determined by the load forecasting result, and do the relevant simulation for load shifting in the microgrid. Do research on the energy storage system improving the stability of distributed generations in microgrid. Proposed a battery and ultra-capacitor hybrid energy storage structure, consider the complementary of battery and ultra-capacitor's characteristics, and both take a different control strategy. The hybrid energy storage system is used to stabilize the fluctuations in microgrid in simulation. Analysis of simulation results shows that this structure is feasible.