| New energy resources generation with photovoltaic systems and wind powers as representatives,is penetrating into distribution network more highly and stochastic volatility and intermittent shock of its output also exert great influence on security,stability and optimal economic operation of the distribution network.Virtual power plant,the means of which can efficiently aggregate and coordinate Distributed Energy Resources(DERs),gradually gets more and more attention both at home and abroad.In studying optimal scheduling strategy of DERs in virtual power plant,this paper aims to coordinate DERs to provide auxiliary service to the distribution network and improve economy of the distribution network and DERs.This is of great practical significance to effective use of new energy resources generation as well as friendly interaction and coordinated development of source-grid-load.This paper,which is based on virtual power plant model,thoroughly researches optimal economic operation strategy,voltage control service to the distribution power system and reactive power optimization problems of virtual power plant.Firstly,the author researched the optimal economic scheduling strategy of commercial virtual power plant in this paper.A mixed integer programming mathematical model of optimization for CVPP's economic optimization scheduling is established with maximum profits of CVPP as objective function in the restrict conditions of distributed power's own restraints and network operation,in consideration of possible start-stop condition of small thermal power.Then,on the basis of Lingo optimization-simulation software,the mixed integer programming problem is solved.The CVPP simulation algorithm is provided,which contains wind power,photovoltaic systems,energy storage unit and small thermal power unit.And eventually simulation results proved validity and feasibility of the optimal economic scheduling strategy.Secondly,this paper proposes the idea of combining technicality of VPP with economy of VPP,namely TVPP pursues the maximization of its own economy in the condition of providing voltage control service to power grid.The TVPP's economic optimization scheduling model is firstly established and the model's objective function is the maximum economic profit in consideration of distributed power's own restraints,power balance restraints as well as network node-voltage constraints.Then the model is simulated and solved with the modified genetic algorithm,in which tournament selection strategy based on elite selection,double points crossover strategy,single point mutation strategy and real number code method are adopted and setting methods for penalty function and individual fitness function are presented.The algorithm,which is based on IEEE-3 3 nodes distribution network,verified correctness and feasibility of the VPP optimal economic operation strategy in consideration of providing node voltage control service to the distribution network.Lastly,this paper deeply researches voltage and reactive power optimization scheduling strategy for the virtual power plant connecting to the power distribution network.The VPP voltage and reactive power optimization mathematical model is established and the model's objective function is TVPP minimum network loss and minimum voltage deviation in the restrict conditions of distributed power' s own restraints and power balance restraints.The design of punishing function helps to convert the VPP multi-objective optimization problem into the single objective optimization problem which minimizes network loss.Also,the minimum problem of objective function is transformed into the maximum problem through the design method of individual fitness function.Then,the optimization model is simulated and solved with the help of the above improved genetic algorithm.Finally,the proposed voltage and reactive power optimization scheduling strategy is testified to be correct and feasible through the algorithm based on IEEE-33 nodes distribution network. |
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