Study On Optimal Economic Dispatch Of Active Distribution Network With Distributed Energy Storage

To ease energy crisis and improve the environment,efficient use of renewable energy has become a trend.In order to integrate various distributed generations(DGs),achieve large-scale renewable energy consumption,improve the efficiency of distribution network resource utilization,and enhance the reliability and quality of power supply,active distribution network technology comes into being and gets more and more attention of researchers.As an important part of the active distribution network,distributed energy storage has the advantages of achieving independent control,“plug and play”,widely geographical distribution,flexible and convenient use,and other advantages that centralized energy storage doesn't have.With the dual characteristics of power supply and load of energy storage,applying it into the distribution network optimal dispatch can effectively reduce the operating costs of the distribution network,and to a certain extent realize power grid peak shaving and valley filling,as well as improve the power quality of the distribution network.Therefore,it is of great practical significance to study the economic optimal dispatch of active distribution network with distributed energy storage.At present,in the research of energy storage for the optimal economic dispatch of active distribution networks,most of the energy storage is configured and dispatched following in the centralized energy storage model.Research on the optimal dispatch of distributed energy storage is rare.With full consideration of the characteristics of distributed energy storage,formulating reasonable dispatch and multi-energy storage coordination optimal strategies for it are two key points as well as two difficulties in the process of research on distributed energy storage optimal dispatch.Therefore,this paper aims at carrying out the research on the economic and optimal dispatch of distributed energy storage by taking the active distribution network with various controllable,uncontrollable DGs and distributed energy storage as the research object,and by developing a reasonable coordination dispatch strategy of distributed energy storage.Firstly,the DG dispatch,distributed energy storage dispatch,and charge or discharge loss cost models were established,which laid the theoretical foundation for the establishment of the optimal economic dispatch model.Then,in order to solve the complicated optimal economic dispatch model of active distribution network,a modified wolf pack algorithm based on differential evolution was proposed.This algorithm could effectively solve the problems of high dimensionality and intractability of the model.Finally,by formulating dispatch strategies for various types of DG and distributed energy storage,a day ahead optimal economic dispatch model of active distribution network was established,and a modified IEEE33 nodes system was used for simulation test to verify the effectiveness of the proposed optimal economic dispatch strategy.The main research contents of this paper include:(1)Established DG dispatch and distributed energy storage dispatch and loss cost models.As the basis for the establishment of the active distribution network optimal economic dispatch model,the working principle of a controllable and uncontrollable distributed power generation system such as wind power generation,photovoltaic power generation,micro-turbine power generation,and its dispatch method in the active distribution network are briefly analyzed.Focusing on the advantages and disadvantages of the centralized and distributed mode of energy storage access distribution network,selected the access scheme of distributed energy storage access to the AC side of distributed power supply as the basis of this study,and analyzes the characteristics of distributed energy storage in the optimal economic dispatch of active distribution network and establishes its charge or discharge loss cost model.(2)A modified wolf pack algorithm based on differential evolution for solving the optimal economic dispatch model with high dimensionality,multivariable nonlinearity and non-convex of active distribution network was proposed.Based on the basic wolf pack algorithm,the search factor of search wolves,maximum number of raid wolves,adaptive siege step size were proposed to improve its intelligence behaviors.The crossover,mutation,and selection strategies in differential evolution were introduced into the wolf pack algorithm which reduces the computational cost of the algorithm while improving global search capability of the algorithm.Finally,the convergence of the proposed algorithm was proved by the Markov chain theory.By using multiple test functions,the proposed algorithm and other 3 algorithms were tested and compared.At the same time,the influence of the algorithm parameters was analyzed to verify the superiority of the proposed algorithm.(3)A optimal economic dispatch model of active distribution network with distributed energy storage was established and solved by the proposed differential evolutionary modified wolf pack algorithm.Under the premise of clearing the ownership of resources in the active distribution network and balancing the interest rules of all parties,in order to realize the adoption of large-scale renewable energy by the active distribution network and reduce the operating cost of the distribution network,the dispatch strategies of DG and distributed energy storage were formulated and a day ahead optimal economic dispatch model with the minimum operating cost of the active distribution network as the objective function and the safety operation of network as constraints was established.Then,using the modified IEEE33 nodes system combined with the proposed differential evolutionary modified wolf pack algorithm,the proposed dispatch strategy was verified by simulation.At the same time,the other three algorithms such as basic wolf pack algorithm were also used to solve the dispatch model and compared.The superiority of the proposed differential evolutionary modified wolf pack algorithm was verified again.