| As the basic condition for the development of all walks of life in society,power infrastructure is very important to ensure its safety and reliability.In recent years,the frequency and intensity of extremely random and destructive extreme weather events have gradually increased,causing major consequences and losses to the power infrastructure,resulting in frequent large-scale blackouts.Therefore,there is an urgent need to improve the resilience performance of the power system,thereby improving the resistance of the power grid to extreme disasters and enhancing the flexibility of the power grid.The resilience of the grid under the influence of disasters can be divided into three phases: pre-failure prevention phase,failure development phase,and post-failure recovery phase.Therefore,from the prevention of the pre-disaster grid,the enhancement of the flexibility of the grid during the disaster and how the grid is restored after the disaster,the resilience of the grid is studied.The main work of this paper is as follows:In the pre-failure prevention phase,taking the ice storm incident as an example,segmentation differentiated planning for transmission branches spanning different meteorological regions and different voltage levels,using the Pearson III-type random function to calculate the branch failure probability,and considering the risk assessment indicators,a line segmentation differentiated planning model with the goal of minimizing the sum of risk loss costs and differentiated cumulative costs is established.The correctness of the IEEE-18 node system simulation verification model.In the stage of failure development,in order to deal with the hurricane event with strong destructive and wide range,a grid elasticity enhancement strategy based on Markov decision is proposed.Firstly,the Markov fault state of the grid under the hurricane scenario is studied.Secondly,considering the constraints of important nodes to ensure power supply,the grid elasticity based on Markov decision is established with the minimum cost of the load and the economic cost caused by the generator set output.The IEEE-30,IEEE-118 grid node system is solved to verify the correctness of the optimal strategy.In the fault development stage,the hidden state of cascading failure caused by hurricane attack on the power grid is also considered,and the elastic enhancement strategy based on hidden Markov chain in cascading failure is established.The cascading failure process that leads to the next-level fault state by the hidden state burst is described by hidden Markov chain,and the fault probability of the observable sequence in the hidden Markov chain is substituted into the reward function of Chapter 3,with the generator output as the independent variable,the economic cost caused by the load loss is the objective function,and the IEEE-30 grid node system is elastically enhanced.The obtained results verify that the proposed strategy can reduce the system load loss during cascading failure and reduce the blackout.Finally,in the recovery phase after the system failure,the two factors of recovering the resources from the grid and the recovery order of the faulty components are comprehensively considered to restore the grid.Based on the OutageRank algorithm,the fault component order value restoration strategy based on OutageRank algorithm is proposed.The effectiveness of the proposed restoration strategy is verified by comparison with the random restoration strategy and the restoration strategy based on PageRank algorithm. |
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