Research On Multi-fault Dynamic Recovery Strategy Of Active Distribution Network After Disaster

In recent years,extreme natural disasters and malicious cyber attacks have occurred frequently,leading to a significant increase in the probability of distribution grid failure,which seriously affects the normal operation of social production and people’s life.With the large-scale access of distributed generation,energy storage system,mobile emergency generation and other restoration resources,the network structure and energy flow of the distribution network have changed fundamentally.Therefore,how to fully utilize the active participation and operational flexibility of multiple recovery resources after a disaster,and how to develop a safe and effective cooperative optimization plan for fault repair and power restoration in the distribution network are crucial to enhance system resilience.To address the above issues,the main work done in this paper is as follows:Firstly,the basic principles of graph theory are explained to provide theoretical support for the subsequent network topology analysis.The shortest path problem used to describe the rapid dispatching process of repair crews in the traffic network is analyzed,and the Dijkstra solution algorithm is introduced in detail.And the tidal analysis method,linearization method of the model and the solution method of the model are discussed for the construction and solution of mixed integer linear programming.Secondly,a mixed integer linear programming model is established to solve the problem of collaborative optimization of multi-fault repair and power restoration in distribution networks containing distributed generation.The first stage allocates repair tasks based on geographical distance and resource constraints.In the second stage,a two-layer decision model with a recursive structure is established: the lower model takes the shortest road travel time as the goal to optimize the travel path of repair crews in the traffic network;the upper model takes the maximum comprehensive economic benefits of the distribution network as the goal to optimize the power supply restoration scheme.At the same time,considering the time-varying operation status of the distribution system and the cascading coupling of fault repair and power supply restoration,the modeling and solution time dimensions are taken into account,and the power supply restoration plan for subsequent periods is revised on a rolling basis according to the repair progress.The effectiveness,superiority and economy of the proposed method are verified by an example.Finally,we consider the fault propagation and isolation process,and further carry out the research on the dynamic restoration strategy of distribution network with multiple faults based on the active islanding effect of distributed generation.The mechanism of fault propagation and isolation is analyzed,and relevant mathematical models are established based on topological constraints and operational constraints.In order to give full play to the active restoration of distributed generation,a post-disaster active islanding model is established and a bubble sorting algorithm is used for island division.At the same time,the mobile emergency generation is introduced for supplementary recovery based on the existing recovery resources,and a two-layer decision model for dynamic multi-fault restoration of distribution networks with multi-source participation is established to collaboratively optimize the repair sequence,network reconfiguration scheme and mobile emergency generation scheduling scheme,and the effectiveness,superiority and economy of the proposed restoration strategy is verified by an example.