| China’s energy consumption is mainly made up of coal and oil, facing resources shortage and serious pollution problems. Development and application of renewable energy is a vital approach to solve energy and environmental crisis. Micro grid is an effective approach to take in distributed renewable energy such as wind, sun and biomass energy. Existing studies have shown that distributed generation connected to the power grid in the form of micro grid will be the best way to realize the use of renewable energy. Micro grid can operate in grid or island mode and support power grid for each other. Together with traditional power grid, micro grid is a significant auxiliary way to the power system development. It can effectively solve the energy demand, realize the environmental protection and save the investment. It is also an important manner to develop rural power and can improve the flexibility and reliability of power supply. At present, micro grid research is particularly popular. The diversity of distributed generation especially the uncontrollability and intermittent of renewable energy and the complexity of the operation mode make the operation optimization and control is difficult and becomes the key problem of micro grid energy management. In this paper, micro grid based on renewable energy is researched and operation optimization problem is mainly studied. From the perspective of when and how to optimize, this paper’s main work is summarized as follows:Firstly, the equipment model is researched. Because the characteristic of equipment directly influences power dispatching, it has to analyze the equipment feature and build the equipment model. The output and cost model is researched and constructed in detail. Among them, the output model determines the distributed power and battery’s output characteristics, constraint condition and so on. The Cost model influences the relationship between equipment unit and the optimization goal such as economic and environmental benefits.Secondly, the excitation mechanism of micro grid optimization is studied. It is used to solve the problem when to optimize. Equal time step optimization and event inspired optimization is put forward and three-level optimization time scale framework including day-ahead, short-term and real-time is set up. The equal time step optimization mainly contains day-ahead and short-term optimization. In event inspired optimization aspect, micro grid real-time power quality synthetic evaluation result is proposed as the real-time excitation mechanism. The real-time optimization will launch if the real-time power quality is unqualified.Thirdly, based on the second research, the micro grid power quality facing renewable energy is analyzed and power quality comprehensive evaluation problem is researched. After introducing a basic structure of micro grid, the research situation and trait of micro grid power quality is summarized and analyzed. Based on fuzzy comprehensive evaluation, a new micro grid power quality evaluation method based on optimal membership is put forward. And its validness is verified by simulation experiments.Fourthly, multi-objective operation problem of micro grid is studied. The micro grid operation efficiency, load satisfaction and quality of power supply are selected as optimization goals. NSGA-Ⅱ intelligent algorithm is adopted to complete the micro grid multi-objective optimization of different time scales and Pareto optimal solutions are obtained. The effectiveness of the algorithm is verified by simulation experiments including two different situations. One thing to be mentioned is that this paper puts forward the interruptible load as a shiftable load from the user’s perspective. It can guide users to select the electricity time of the interruptible load according to the optimization results. It not only reduces the users’ cost, but also dispatches resources more efficiently and improves system’s efficiency and quality. It also guides the optimal using of battery.The research in this paper was supported by the project of National Natural Science Foundation of China(No.60904078 and No.51177050). |
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