Research On Typical Power Supply Mode Of Micro-grid And Optimal Allocation Of Micro-power

Distributed generation power supply system can save resources and operation costs for grid as well as improve the efficiency of using renewable energy. It is an important supplementary for large power grid in the future. However, distributed generation is always subject to the environment and grid, and its advantages can not be fully shown. Therefore quite a few scholars put forward the concept of Micro-grid to solve the problem. Micro-grid is seen as a controllable unit for large power grid and it can help make use of the renewable resource. Meanwhile it can improve the reliability for certain users and build CCHP system.The research on Micro-grid is at its infancy and the specific way for Micro-grid planning system has not formed yet. The traditional theory and planning method of distribution network is cited in this thesis, and some applied engineering projects of Micro-grid, both home and abroad, are studied. The development trend of Micro-grid is predicted, based on which the general steps for the planning of power supply mode is designed and put forward.Firstly, the typical structure pattern of Micro-grid is raised, including the design of topological structure of electrical connection and the AC/DC power supply mode, as well as the site selection of distributed generation. Three typical aspects are considered including voltage class and access capacity of Micro-grid. The advantages and disadvantages of all kinds of structure pattern are compared, and the power supply mode of distributed network containing Micro-grid is analyzed as well.Secondly, the renewable resource distribution in China is summarized, including wind energy, solar energy, hydropower, geothermal energy, ocean energy and other resources. Based on the result of investigation, some planning methods for different distributed generation system are raised. These Micro-grids consist of independent power supply Micro-grid, hybrid Micro-grid containing wind, solar and diesel, gas turbine Micro-grid, small hydroelectric Micro-grid and others. These models are chosen according to different renewable resource distribution and different load characters to suit the development of local area.Finally, the issue of capacity optimal combination for all the distributed generation in a specific Micro-grid is studied. The way to find the best configuration for the elements involved is explored, and the physical model as well as economic model is raised to analyze an established Micro-grid thoroughly. An appointed wind-solar-diesel-battery hybrid island Micro-grid is used as the example. The renewable resource and load characteristic on the island is collected. The simulation software HOMER is used to help calculate the best allocation within the generations. The final result is presented for the decision maker to choose a relatively best one among a few initially selected plans.