| Due to the increasingly prominent environmental problems and the gradual depletion of fossil energy,energy saving and environmental protection?high reliability?power generation flexible distributed Generators(DG)has been more and more research and utilization.Connecting the distributed generation to distribution network,on the one hand can bring huge economic and environmental benefits and in the technical level to reduce load peak valley difference,eliminate transmission lines were jammed;and on the other hand access location and capacity of improper,not only difficult to take advantage of the potential,but also has a serious impact on the power quality?the system loss?the protection device and so on.reduce the safety and reliability of power grid operation.Therefore,it is very necessary to make a reasonable layout to the access mode of the distributed generators.In allusion to the randomness of various types of distributed power and load power intermittent problems,this paper carried out a detailed analysis on the characteristics of time series and give on the temporal power model of several typical distributed power supply and load in all seasons,considering on timing curve in each period of DG output power and load power,in order to improve the authenticity of the optimization results.On the basis of the time sequence power model,a multi-objective decision model for distributed generators,in which includes four aspects: the total power generation cost,the system loss,the static voltage stability index and environmental benefit,is established.Finally,the improved multi-objective free search optimization algorithm is used to solve the multi-objective model.Firstly,this algorithm establish a new fitness mechanism basing on the multi-objective function,each individual in the population according to their fitness values dynamically adjust the next search radius and the search step;at the same time,in order to improve the search efficiency of the algorithm in multi-object space,the got optimal position after each big stridden search is obtained as the starting point of the next search;and as for poor individuals,it will be with the quality of individuals to cross to enhance gene exchange channels,improve their own genes.In this paper,we introduce a crossover operator based on the similarity structure,which can adjust the crossover threshold adaptively according to the number of iterations to avoid invalid operation;Finally,in order to ensure the optimal solution of uniform and broad distribution in the Pareto front,this algorithm adopts adaptive grid method to remove the high concentration of the individual files.Several typical test functions are selected to carry on thesimulation computation,and the simulation results of IMOFS algorithm with SPEA2 and NSGA-II algorithm are compared and analyzed according to the three kinds of performance indexes?convergence?width and uniformity;The results showed that the algorithm IMOFS in dealing with the multi-objective problem overall performance of ten is superior.Taking power distribution network of IEEE-33 nodes as example,by comparing and discussing the planning results of IMOFS algorithm and NSGA-II algorithm,and combination of both the convergence curve of Pareto sets showed the advantages of IMOFS algorithm. |
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