Research On Power Network Cascading Failure Model Based On Complex Network Theory

With the expansion of the scale of power system and power loads continue to grow,people's dependence on safe and reliable electricity is growing.However,due to the cause of the power system itself limits and the influence of external disturbance conditions,accidents occur frequently in the power system.A large part of the blackout accidents are developed by chain trip accidents,this kind of cascading failure is often caused by a single component failure or circuit overload,a lot of parts left running cause blackouts and even the collapse of the entire grid.This thesis expects study research on power grid cascading failure model using complex network theory,combined with optimal power flow based on the security constraints and based on the center of the network growing point of local evolution model in the world to improve the OPA model.In this thesis,we finally build a kind of power grid cascading failure model,which has two dynamic.In this thesis,the main work is as follow:(1)In the fast dynamic process of OPA model,using simplified optimal power flow model based on security constraints to calculating failure trend in the distribution of power grid after the failure.(2)In the fast dynamic process of OPA model,if the trend in the power grid is not convergence,the defense measures are acting.According to the priority,remove parts of load with larger generating betweenness to make the trend to convergence again.(3)In the slow process of dynamic of OPA model,considering the evolution of the growth of the network the choice of the access location of a new node is according to the local evolution model based on the network and the center of the growing point in the world.(4)In the slow process of dynamic of OPA model,when the spare capacity is not enough in the power grid,consider build new power plants,expand the power plants already have new energy resources connected to grid.(5)In the slow process of dynamic of OPA model,search important lines according to the betweenness of lines,search weak lines according to the loading rate of transmission lines.Expand the important lines and the weak lines in order to increase the security of the power grid.Compared with OPA model the power network cascading failure model based on complex network in this thesis,has advantages as follows:At the time of calculating failure distribution trend in a grid,calculation results are more accurate while meeting the requirements of computing speed;Take active defence measures when the trend is not convergence in the grid,remove the load which is not important prioritily;Increase the network evolution module,the network which is evolved by the evolution of the model was constructed by myself has inhibitory effect on the spread of cascading failure;Focus on the protection of the important routes in the grid,protect the important loads continous suppling power.In this thesis,when the failure occurs in the power grid.The purpose of building model is the generation of simulation grid fault and spread and the impact of the power grid through the model of fast dynamic process.Expected to fault seldom happened evolved into large-scale chain and has a strong network of sex,through the model of slow dynamic process.