Research On Urban Power Network Vulnerability Assessment To Natural Hazards

Critical infrastructure,a crucial part of infrastructures,is the significant foundation of national development.Power network is one kind of critical infrastructure,greatly influencing people's life and national development.Social stability and economic development would be destroyed if the power network runs out.With the development of science and technology,the scale of power net work rapidly increased,which induces the problem of power network and power network accidents around the world.The accidents come from natural hazards,terrorist attack and faulty operation of workers.Power network is a classic complex network,one node or edge of the power network runs out may affect other nodes and edges in the network because of the cascaded effect of complex network,and then the equipment in the nodes would run out too.Risk management of power network draws increasing attention,researchers considered that the risk of power network comes from three parts,natural abnormal change,factitious abnormal change and technological abnormal change,and most of the research are about natural abnormal change.Research on power network vulnerability is an in-depth study of power network issues.This paper studies the protection of power network from the perspective of vulnerability on the basis of the multi-attribute comprehensive theory,complex network theory and science of disaster theory.Qualitative analysis method and quantitative analysis method were used to study the constitution and influence factors of power network vulnerability in order to propose a vulnerability assessment model.Firstly,literature and theory review enhanced logical relationship between power network vulnerability and reliability,risk and importance to get a theoretical basis for the whole paper;based on the sources of vulnerability and the target of assessment to analyze the constitution of power network vulnerab ility,the content of assessment,the theory basic and logical basic;and showed the theory and method which would be used in vulnerability assessment.The constitution of power network vulnerability: In the research,we divided it into five parts--equipment components vulnerability,environmentally induced vulnerability,network structure efficiency vulnerability,network structure function vulnerability and abnormal change induced vulnerability.Secondly,the research studied three key points of the asses sment process.The first point was power network cascaded iterative issue.Because nature hazards were the main reason of cascaded iterative failure,this research studied cascaded iterative based on the risk theory,and assesses the risk and vulnerability result of cascaded iterative effect.The second point was about the weight of network structure vulnerability,the vulnerability of the point and ledge in the network sometimes may be the same which yield from topology index calculation,but there exists much difference among them,Thus,if only evaluating the vulnerability which comes from topology index calculation but ignoring the truth,we may make some mistakes that could not reflect the truth.Getting weight from reliability can solve this issue.The third point is how to assess the network structure function vulnerability.The more important one point was,the more significant influence the function of the network would have if deleting one point,the more vulnerable the network structure was.Therefore,the function vulnerability of one point is crucial,because he power network provided power for the society,including company,government,family,school,hospital and so on.Thirdly,we built a frame of vulnerability assessment after solving the abo ve three issues,which included equipment components vulnerability,environmentally induced vulnerability,network structure efficiency vulnerability,network structure function vulnerability and abnormal change induced vulnerability,then,we built the component assessment model and comprehensive assessment model based on the vulnerabilities contents.In the process of building model,considering the three issues,the comprehensive vulnerability maintained risk,reliability and importance assessment,which was a better index for assessing safety of power network.Finally,based on the above analysis and comprehensive vulnerability assessment model,we studied the power network of S city and analyzed the normal vulnerability and disaster scenarios vulnerability,got the vulnerability of 46 nodes in the power network of S city.In the end,we gave some comments and suggestions for protecting the power network of S city according to the result of vulnerability assessment result and gave some assistance to take precautions against natural calamities and reduce natural disaster influence.Through comparing the research result with the power network disaster happened two years ago,we found that they were similar,and the assessment model could be used to efficient ly solve the actual problem.