Study On Two-stage Collaborative Planning For Energy Storage And Demand Response In An Active Distribution Network

Active distribution network,as an important part of the future smart grid,is being developed from conventional distribution network.With certain upgrated in the environment of smart grid,active distribution networks are served as energy hub for power generation,distribution and consumpsion.Due to the intermittent and uncertainty of the renewable energy,it is difficult to achieve dynamic balance between the generation and demand of the distribution network.As a result,when it comes to the planning or operation management of the active distribution network,the key technical issue is how to coordinate the balance between the ternary structures.The distributed energy storage or demand response with the feature of energy buffering can be easily transformed between power generation and absorving.This paper mainly focuses on the distributed energy storage system and demand response planning problem considering the uncertainties.The proposed methodology and framework provide an effective and scientific approach to the widespread implementation and application of active distribution network technology.Based on the theory of two-stage optimization method,this paper studies the optimal allocation of energy storage and demand response in an active distribution network under uncertainties.The outline of the thesis is presented as follows:(1)With the rapid development of renewable energy,the main issue during the upgrade of distribution network is introduced and summarized.Meanwhile the significance of this thesis is clarified,and then the key issues of active distribution network planning research are summarized.Based on the above key issues,from the active distribution network renewable energy consumption strategy and the planning method to deal with uncertainty,the domestic and international research is expounded.Combined with the existing research deficiencies and shortcomings,the important issues of the research is proposed and the organization,main contents of this paper are given.(2)Combined with the active distribution network planning methodology,the general mathematical model with uncertainties in the active distribution network planning is introduced,and then the robust optimization and stochastic optimization model are established.The two-stage optimization model under two mathematical methods is proposed.Finally,the basic principles of the two-stage optimization problem solving algorithm are summarized,and the general steps are given to provide theoretical support for the following research work.(3)Aiming at the fully accommodation of renewable energy in the active distribution network under the premise of ensuring safe operation,a feasibility-check based robust optimization method for energy storage planning is proposed.Based on the uncertain feature of distributed renewable energy,this method realizes the decoupling interaction between pre-planning and feasibility check in the worst-case scenario through the two-stage robust optimization model.A column-and-constraint generation algorithm(C&CG)and the big-M linearization method are employed to solve the associated optimization problem.Numerical experiments demonstrate the effectiveness of the proposed model.(4)Based on enabling and optimizing the demand response of active distribution network in electrical market environment,a two-stage robust optimization model of demand response investment of active distribution network is proposed.The stepwise approximation theory is conducted to linearize and reconstruct the nonlinear elasticity demand-price model,which makes the problem trackable.The model focuses on the two-stage demand response planning in the market environment with time-varing electricity price.Within,the investment decisions are optimized in the first stage,and the demand response participation with the coordination of distributed generators is adjusted in the second stage.The investment cost of demand respones,operation and maintenance cost of distributed generators and the main network power supply cost,the electricity bill are optimized to achieve the overall economic cost,system reliability,and security benefits.(5)Considering the complementary advantages of energy storage and demand response,a joint planning method for energy storage and demand response in an active distribution network is proposed.Considering the random correlation between uncertain variables,a set of uncertain scenarios are generated based on Copula theory.Typical scenarios are selected by scenario reduction technique.Then,a two-stage stochastic optimization based joint planning model for distributed energy stotage and demand response is established.Since the demand response and energy storage operation feature are considered,it can effectively cope with the uncertainty fluctuations of wind power,photovoltaic and load while reducing the overall cost.