Research On Power Supply Restoration Method And Strategy Based On Active Distribution Network

With the development of economy and the progress of science and technology,the application of electric power in all walks of life is more and more widely,and the demand for electric power in all fields of production and life is increasing day by day.The distribution network is responsible for distributing electric energy to the users.Because of its wide coverage,it is easy to break down and cause power outages.The rapid and efficient restoration of power supply after failure has become a hot issue.In recent years,the country has vigorously advocated energy conservation and emission reduction,seeking clean energy that can replace fossil energy to reduce the damage to the environment.Distributed energy has gradually entered the public eye due to its advantages of energy conservation and environmental protection,and it has a broad prospect for development.The normalization of the grid connection of distributed energy also increases the difficulty of power supply restoration.The power supply restoration method previously applied to traditional distribution network is no longer applicable to today’s distribution network.Therefore,it is particularly important to formulate a power supply restoration strategy for distribution network including Distributed Generation(DG).Aiming at active distribution network,this paper discusses the problems related to power supply recovery after failure from two aspects:network reconstruction and island division.The main contents are as follows.Firstly,the relevant theories and concepts of power supply restoration in the distribution network are introduced,and the impact of the access of DG to the distribution network is analyzed.Different types of DG and different types of grid-connected nodes are introduced and compared.At the same time,based on the topology analysis and power flow calculation of the distribution network before power supply restoration and other related content,the improvement and optimization are carried out,specifically to simplify the network topology and adopt the backward forward method for power flow calculation to reduce the difficulty of subsequent solution and improve the efficiency of solution.Secondly,a power supply recovery method based on improved genetic algorithm is proposed,the core of which is to operate the switch and transfer the non-fault area to the safe line.In this method,the coding strategy of the traditional genetic algorithm has problems such as large solution space,many unfeasible solutions and poor convergence,and the reconstructed mathematical model is optimized,and the importance of load is taken into consideration.Taking the IEEE33 node model as an example,the improved genetic algorithm and the traditional genetic algorithm are respectively used for the post-fault recovery and reconstruction of multiple working conditions of DG without access,DG access,single fault and multiple fault.The results show that the power supply recovery strategy in this paper is effective.Finally,based on the feature that DG can form independent island to recover power loss load,a power supply recovery strategy based on power circle island division and network reconstruction based on improved genetic algorithm is proposed.On the premise of meeting the constraint conditions,the island range and power supply recovery path are determined according to the set division principle,so as to ensure the priority of power supply restoration for important loads.A concrete example is given to verify the correctness of the proposed island division strategy.At the same time,after the island division is completed,the external distribution network of the island is reconstructed to further play the active role of the main network.The island division and network reconstruction cooperate to further reduce the scope of power outage.Similarly,taking the IEEE33-node network with distributed power access as an example,the simulation verification is carried out,and various schemes are compared to prove the superiority of the proposed power supply recovery strategy of first island division and then network reconstruction in solving the power supply recovery problem of the distribution network.