Study On Microgrid Grid-connected System Based On Energy Storage System

More countries are becoming more and more concerned about the problem of environment and energy sources, and getting more safety and reliability requirements of power system. Distributed generation(DG) based on the renewable energy has become a trend, such as micro-turbines, fuel cell, photovoltaic power generation, wind power generation and so on, is located in the vicinity of power load. But due to the impact of the volatility, instability, and low utilization, it is difficult to connect to the grid directly. The microgrid can solve the problems of DG technology effectively, and become the frontier research field of power industry quickly, so it is attended and studied abroad by many countries. The microgrid consists of DG part, energy storage part, control and protection part, load part, and has two kinds of basic operation mode: grid-connected operation and islanded operation. But the microgrid is still in the study and experimental stage and not widely used, because the technique has yet to mature. So this paper studies on microgrid grid-connected system based on energy storage system.This paper first introduces the concept and composition of the microgrid, and its situation and trend. In photovoltaic power generation unit, wind power generation unit, and the battery unit case, the thesis also study on the three main control strategies: PQ control, V/F control and droop control. And then it describes the master-slave operation and the peer to peer operation, and other control strategies.The design of three-phase inverter closed-loop control system was discussed, and it laid the foundation for the control experiment. The simulation model is established based on the design principle and control system of PQ control and V/F control.Based on that, the micro power of battery energy storage system, and the microgrid model used the PQ control and V/F control were been simulated through Matlab/Simulink, and the simulation parameters are given. Through the analysis of the simulation results, we get the experimental waveform expected, and verify the correctness of the control method successfully.