Research On Structural Vulnerability Of Power Information Physical System For Preventing Cascading Failures

How to improve the safety of power grid,it is big topic for major national strategic needs."Double carbon" goal,the transformation of energy,high proportion of renewable energy and high power electronic equipment "combination" of the depth of the power system and information system coupling,for power grid operation efficiency,but also increases the vulnerability of network topology.Cascading failure has become a huge threat to power grid.Grid security problem is the basis of correct grasp of modern power grid cascading failure mechanism,but existing power system analysis and calculation of the theoretical and experimental methods in system failure chain ignores the overall characteristics of grid,leading people to just focus on some specific factors,basically can’t reveal the occurrence of cascading failure reasons and transmission mechanism.In order to avoid the defect of traditional method,people in urgent need of chain from the perspective of the overall understanding and explore the cause of the failure and the global dynamics of the rendered.To this end,this thesis from the perspective of system as a whole,the occurrence of cascading failure reasons and transmission mechanism,the inhibition method were studied.This article research results are as follows:First,to trigger a cascading failure of short-circuit current levels and the problem of electromagnetic loop network,this paper puts forward a kind of can be used in large power grid partition algorithm based on improved Biogeography(Biogeography--based optimization,BBO)community identification method.Algorithm to partition algorithm result of the global community we and convergence speed problem,population of BBO(habitat)topology structure was improved and used to limit the migration of BBO algorithm,with a small world model defined populations(habitat),the connection between the original habitat of BBO global topology into local topology;The habitat topological structure of complex networks of small world model compared with the global topology overcomes the premature phenomenon is easy to get the global optimal solution,compared with the ring topology to speed up the convergence rate.Secondly,the algorithm using simulated annealing operator as BBO new replacement strategy,can the probabilistic jump out of local optimum.Then,considering the actual power grid,the direction is the trend of change on the transmission line,so,ignore the direction of the trend.Using trend as the edge of network weights,the modularity Q function weighted improvement,evaluation scheme for dividing the grid community.Test results show that compared with the existing algorithm,the algorithm reduces the time complexity of the algorithm,improves the global we,suitable for large-scale power grid topology analysis.Finally,from the Angle of the lower failure after short circuit current to verify the effectiveness of the partitioning scheme in this paper.Second,the physical system for electric power information chain failure propagation problems,puts forward a comprehensive consideration of overlapping communities of overlapping nodes,node and edge betweenness center of index of topological relations and coupling characteristics of the power grid node importance evaluation method.First of all,the paper puts forward a kind of overlapping grid community recognition method based on link,edge in the grid algorithm is the main innovation as the research object,to have the right to spot diagram transformation chart the adjacency matrix of weighted correction,make the conversion chart after more rationality,is conducive to large networks shall have the right to network fast and exact recognition of overlapping nodes;Then,on the basis of the proposed in this paper,based on the node and its neighbor nodes topology importance algorithm,to calculate the importance of single-layer network nodes;Finally,this paper proposes a new consider monolayer network topology importance,overlapping grid structure and the coupling characteristics of twin wire grid node important degree evaluation method,comprehensive experiments and EEE node in the standard system.Compared with the experimental results show that the node shrinkage method and the Max-Cas algorithm,this algorithm can simultaneously identify important node of the traditional and easy to cause cascading failure of the node.Can be more detailed region may cause cascading failure potential nodes and the importance of nodes.Third,after the failure of the system state of accurate control,is a key factor whether eventually trigger a cascading failure.Therefore,cascading failure model,studies the failure propagation mechanism,from the Angle of information physics network structure vulnerability analysis,conducting follow-up assessment of the prediction and fault node network,at last,according to the type of key nodes with specific protection is very necessary.First of all,this paper proposes a new characterization of load variation index-electric grid node neighborhood betweenness,and compared to verify the effectiveness of the indicators.The index can overcome node betweenness index assuming that the shortage of the current flowing only in the shortest path between bus,more in line with the actual background grid,and needs only local information,low computing complexity and can be used in large power grid analysis.Then,based on the capacity load model and put forward a new index power grid cascading failure propagation model is established.Based on this model,each attack mode is studied,tolerance parameters,and the initial node removal ratio influence on grid structure vulnerability.Then,based on this,advances the power and the coupling of the double electric power communication network fault propagation model,analyzed the influence of different coupling model of network structure vulnerability.Study shows that the important degree of large power grid nodes connected to the importance of node in electric power communication network,at the same time to protect the key nodes,node appropriately increased autonomy decoupling,is a feasible strategy to reduce the vulnerability of the smart grid.Next,from the perspective of network attack after the impact on the node,this paper proposes a auxiliary method for prediction of subsequent fault node can be performed and to evaluate the structure of the network vulnerability.Finally,according to the type of key nodes,put forward corresponding protection strategies.Research results can be for the electric power information system of physical planning and safety promotion provide valuable theoretical reference.