Research On Optimal Design And Economic Dispatch Of Islanded Microgrid

Islanded microgrid has important practical significance for the development and utilization of renewable clean energy,the reform of power system and the improvement of power quality and reliability,it can effectively solve the problem of electricity consumption in remote areas and non-electric islands of China.The economy of the planning and construction stage and operation stage for islanded microgrid is the solid foundation for the popularization and development of islanded microgrid technology,it is also an important research content in the key technology of microgrid.The thesis focuses on the optimal design and economic dispatch of islanded microgrid,the main research contents are as follows:Research on quasi-steady state models of wind power generation,solar photovoltaic power generation,battery energy storage system and diesel generator,and a life model of battery based on improved throughput method is established.Because battery life is generally short,it is necessary to consider the impact of battery life factors on the economics of the microgrid.An improved NSGA-II(Non-dominated Sorting Genetic Algorithm II)is proposed in this thesis,the standard NSGA-II algorithm is improved from crossover and mutation operator,crowded distance operator and elite strategy.Optimize the ZDT test set using improved NSGA-II algorithm and Standard NSGA-II algorithm,the simulation results show that the improved NSGA-II algorithm has improved in terms of convergence speed,global search ability and individual population distribution performance.A multi-objective optimal design model of islanded microgrid solved with improved NSGA-II are presented as to minimize the loss of power supply probabitity,the cost of environment protection and the equivalent annual cost taking into account battery life factors.In order to improve the life of battery,an improved cycle charging operation strategy is proposed.The effect of different optimization objective combinations on the optimal design results of islanded microgrid is discussed,and the optimal design results of cyclic charging strategy and improved cyclic charging strategy are compared.The results verify the superiority of the improved cyclic charging strategy in improving the economy of battery operation and the economy of optimal design of islanded microgrid.This thesis establishes an economic dispatch model of islanded microgrid with two objective functions containing the cost of environment protection and the comprehensive operating cost including the cost of battery life loss.The model is solved by using static scheduling strategy and dynamic scheduling strategy combined with improved NSGA-II algorithm.A dimension reduction method is adopted for the decision variables,and a method for multi-constraints preprocessing is proposed to modify the evolutionary individuals to improve the efficiency of the algorithm.The static scheduling example and dynamic scheduling example are analyzed respectively,the effects of different compensation price for interruptible load cutting and different decision objectives on multi-objective optimization economic scheduling results are discussed.The effectiveness of the proposed optimization model in improving the service life of batteries is verified,and it is further verified that the dynamic scheduling strategy is better than the static scheduling strategy in maintaining the long-term operation of the battery and improving the economy and reliability of the islanded microgrid.