Reliability Study Of Power Network System Considering Cascading Failures

Power network system is complex network system which has the largest number of components and whose coverage are the most widely in the world,in addition,power network system is the most important infrastructure in a country,for the reason that the development of modern society is closely related to the supply of high quality and usable power.In modern power network system,the probability of cascading failures,although very small,but once will lead to the collapse of the entire grid,resulting in widespread power outages and causing heavy losses.With the speeding up of the process of social modernization,production and life increasingly depend on power so that the losses is also increasing.Power network system should have high reliability,thus,in this paper,further considering the cascading failure,we study on the reliability of power network system.Combining with my professional knowledge,research fields and direction during the period of master,with reference to the related research achievements of theory and methods in field of power network and complex network,research content of this paper were carried out as follows:(1)Cascading failure model of power network system.In order to close to the practical power system operation and to analyze the basic of electric power network system construction,the real life grid is simplified to topology model in this paper.Making grid generators,transformer substations and power supply stations be nodes and high voltage transmission line be edges,we revise the traditional betweenness method for calculating the initial loads on nodes in a power station,analyze its dynamics evolution mechanism in detail,and construct cascading failure model for power network system,starting from the global system.(2)Reliability of power network system under random attack.When the power station nodes are attacked,to ensure there is not a large area of cascading failures in the whole power network system and consume the minimum cost,we identify the key power station nodes using more comprehensive and reasonable methods.We take the IEEE30 electrical power grid as an example to verify the validity of the model,and then apply the model on the electrical power grid in five provinces of southern China.(3)Reliability of power network system under deliberate attack.Focusing on cascading failures when attack the node which has the highest load in power network system,pointing at the electrical power companies in five provinces of southern China,we find phenomenon of the ability paradox,which means,when we increase the capacity of power station nodes in a certain range,the reliability of the whole power network system turned out to be reduced.We explore the essence of this phenomenon comparing with the U.S.power grid.In this paper,cascading failure model in the power network system enriches the existing power network research field,while the proposed evaluation model for identifying key power station node and the phenomenon of the ability paradox we found when focus on cascading failure caused by attacking the node which has the highest load in power network system have practical significance for controlling and preventing the happening of the cascading failure,reducing the spread of power network system damage and improving the security and reliability of power network system.