Grid-Connecting Strategies And Coordinating Control Of Distributed Generation

Since the 21^st century, energy supply became very tight, environment continued to deteriorate, how to make use of clean energy more and better increasingly becomes a concern of people all over the world. Since the Europe and America proposed to develop the smart grid with flexible, clean, safe, economical, friendly as its performances, Distributed generations(DGs) attract widespread and highly attention of scholars home and abroad, because the DGs contain the most widely used clean energy——wind energy and solar energy. Large-scale use of them can improve the energy and environmental issues. However, once that occured, the transportation problem must be taken into consideration. Connecting them to the grid will be the most effective way. So, research on the grid-connecting strategy and the coordinated control with the traditional power or load should be done immediately, in order to ensure the grid run effectively, reliable and of high quality.This article summarizes the generating principles, characteristics and grid-connected impact of various distributed generations. Focus on photovoltaic system as its research core, build simulation model of PV system connected to the grid on MATLAB/SIMULINK, and research on the grid-connecting strategy and coordinate control measures. main content are as follows:1) Establish a photovoltaic system grid-connected simulation model, simulate the PV system power change as the external voltage turns on different illumination and temperatures. Use the perturb and observe(P&O) method and incremental conductance method to achieve the maximum power point tracking(MPPT). Grid-connected simulation uses the two-stage inverter system, integrate the MPPT to the DC/DC boost stage, the second stage of DC/AC make the grid-connected current track the grid voltage phase. And discuss the influence to the grid.2) Research and summarize PV grid-connecting strategies——the capacity determination of PV system, grid-connected position choosing, grid-connected efficiency optimization, grid-connected control program, islanding detection.3) Research and summarize PV system grid-connected applications——residential photovoltaic grid-connected systems, large-scale photovoltaic power plants, wind-photovoltaic integration generation system, micro-grid.4) Research photovoltaic system grid-connected coordinated control measures, propose the coordinated control principles of photovoltaic system and other power supply.5) Simulate the grid-connected characteristics of electric vehicle charging stations, and research the coordinated control measures of PV system plants and the electric vehicle charging stations.