Research On Identification Method Of Critical Lines And Cascading Failures In Power Grid

With the growing increase in electricity load, this reality has brought more challenges to the electrical network security. There are some key lines in the large-scale structure of the electricity network, the key lines plays a vital role in the spread of cascading failures lead to the collapse of the whole network. Therefore we need a critical path identification method which is fit for being practical and consistent with the physical reality of the electrical network, as well as a screening method to determine the follow-up cascading failures element. The existing system research methods are classified, namely to consider the network structure of the key line assessment, taking into account the running state key line assessment and comprehensive assessment of key lines. According to domestic and foreign scholars of history grid chain collapse accident statistic analysis, to explain the evolution of cascading failure process, expounded the key link of fault is a wide range of cascade the cause of the accident, and boost the role in the process of fault propagation.In key line identification section, this paper adopts advanced power transmission distribution factor function calculation for different load node power loss every line the sensitive degree of change, from the perspective of network structure quantitative transmission network in each branch of the key. At the same time, using the modified branch transient stability function, can solve the temporary situation of the slip road stability, from the Angle of running condition assessment of fragile degrees of each branch. Finally, through effective integrated two evaluation function, scientific quantitative each key role in power transmission lines in the entire network transmission.In chain fault line identification section, after the initial fault line open circuit lead to wide tidal current transfer system, the rest of the line trend variation of different level, at this time should be both fault line of the safety margin and the influence degree of the branch by the trend of the transfer. So this article innovation is the combination of branch open circuit distribution factor function and branch load rate as subsequent fault line selection, exclude transmission power near maximum load capacity but branch line open circuit distribution factor is not high, so as to select the most likely crash cascading failure subsequent lines.PowerWorld was used to construct IEEE30 node system, from the MatPower function package IEEE30 electrical data, through every branch of the carrying capacity of the pie chart to evaluate the percentile every branch of vulnerability. Through a comprehensive method for evaluating the key line fault, headed by calculation of the branch, in turn, to show a fault chain, so as to verify the feasibility and effectiveness of screening subsequent methods.