Research On Optimization Strategy Of Regional Autonomous Power Grid Facing Reliable Power Supply

As an important part of the energy transfer of the power grid,the distribution network directly faces the society.Its power supply reliability has attracted widespread attention.The negative impact of the occurrence of power outages on economic production and social stability has penetrated into all sectors of all walks of life.In the current period of rapid development of new energy and distributed power generation,the distribution network has shown "multisource" characteristics,which enables the distribution network to have a certain degree of autonomy.Therefore,this article puts forward the concept of regional autonomous power grid as a special form of supplement to the distribution network,which is also a way to deal with various problems that threaten the reliability of power supply,and to improve the reliability of power supply of the distribution network.This article focuses on regional autonomous power grids to study and formulate optimization strategies,from the perspectives of functional positioning,element analysis,regional division,energy deployment,and operation management.The specific content is as follows:(1)Analyze the overall structure of the regional autonomous power grid.From the following aspects: 1)Research on the concept and form of regional autonomous power grid;2)Functional positioning of regional autonomous power grid;3)Propose regional autonomous power grid optimization strategies;4)Analyze and model the elements contained in the regional autonomous power grid.(2)Study the energy storage planning of regional autonomous power grids,and propose energy storage planning strategies based on the morphological characteristics and functional positioning of regional autonomous power grid,in order to improve the ability of regional autonomous power.Firstly,a method for dividing virtual autonomous regions of the distribution network based on the theory of community structure division is proposed.On this basis,considering the boundary constraints of the virtual region and the partition control method,a two-tier energy storage planning model that takes into account both economic and autonomous aspects is constructed.In the model,the outer layer model uses the minimum annual comprehensive planning cost as the objective function to plan the rated capacity,rated power,and location of the energy storage connected to each area;the inner layer model optimizes daily operation strategy with the objective of smallest network loss and power interaction cost between regions.The improved two-layer hybrid particle swarm algorithm is used to solve the two-layer model of energy storage planning.Finally,simulation examples verifies that the proposed strategy not only realizes the economical efficiency of energy storage planning,but also makes the virtual area present the characteristics of "single external controllability and tight internal autonomy" and improve regional autonomy.(3)Researches on the strategy for the division of isolated islands in regional autonomous power grid.In the case of a major power outage caused by a failure of the transmission system or the distribution system,the distribution network makes use of the support capacity of DGs to form island autonomous operation areas,which realizes the restoration of power supply to the loads in the island area by forming the island area autonomous operation,and guarantees the power supply of important loads.Based on the functional positioning of regional autonomous power grid and load recovery goals,a two-stage "search + adjustment" strategy for islanding regions is proposed.In the first stage,firstly formulate search rules based on load classification and DG classification.Secondly,use Dijkstra algorithm to search for the shortest recovery path of important loads and unreliable DG start path,forming a reliable DG and unreliable DG joint power supply area,and further based on the DG area’s remaining capacity and adjacency relationship,search for other load nodes into the DG island by priority search,forming the initial island area with the largest recovery range.In the second stage,considering multiple factors influencing autonomous operation,construct an optimization model of isolated island regions that takes into account economy and safety.Dynamically optimize and adjust the boundaries and load recovery amounts of island areas to ensure safe and reliable autonomous operation of the area,and finally form a real-time dynamic autonomous region.Through simulation and analysis of calculation examples,it is verified that the proposed strategy not only achieves the purpose of giving priority to the power supply of important loads in the event of a failure,but also makes full use of the power supply capacity of DG to achieve a higher load recovery rate.The autonomous operation area formed by this strategy also shows flexibility,safety and reliability.