| The construction of large-scale centralized power sources and long distance transmission lines are both important means to satisfy the fast growing electricity demand.However,there are also many disadvantages such as great investment,long cycle,insufficient operation flexibility and high risk of blackouts.As a necessary complement to large power grid and an efficient application of distributed energy,micro-grids have been applied more and more all over the world.There are various types of micro-sources in a micro-grid and the characteristics are different from each other.Consequently,the synergetic optimized operation under different scenarios has become a hot topic at present.In this paper,a two-time scale optimized operation model and the corresponding solution algorithm are studied based on the multi-sources stand-alone AC micro-grid with consideration of four typical external scenarios.The main contents are as follows.Firstly,on the basis of researches about micro-grid's operation modes and typical structures,this paper exhibits the mathematical models of different micro-sources,including photovoltaic cell(PV),wind turbine(WT),micro turbine(MT)combined cooling-heating-power(CCHP)system,diesel engine(DE),fuel cell(FC)and energy storage(ES).Secondly,a two-time scale multi-objective optimization model which contains day-ahead scheduling and real-time scheduling is presented considering the cost of power generation,load control compensation and environmental benefits.Through the synergetic dispatch of ES and controllable loads in real-time scheduling,micro-grid could weaken the negative influence comes from the forecasting errors of load demand and renewable power generation and then improve the comprehensive performance of micro-grid's operation.Thirdly,for the model solution,this paper introduces search improvement process(SIP),chaotic optimization(CO)and elite retention strategy(ERS)into the basic particle swarm optimization(PSO)to improve the search ability and operation speed.Finally,four different scenarios are designed according to the day types(work day or weekend)and weather categories(sunny or rainy day): sunny-work day,sunny-weekend,rainy-work day and rainy-weekend.Through the analysis and comparison of simulation results with real data in different scenarios,the effectiveness of proposed optimization model and algorithm for micro-grid in this paper were verified.As a significant way to achieve the self-healing,user side interaction and demand response of smart distribution networks in the future,micro-grid's technical means will be improved continually with the development of electric power industry.Moreover,the policies,regulations and market mechanism need also to be innovated at the same time. |
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