Research On Rapid Risk Assessment Model Of Power System Cascading Failure

The Interconnection of regional power grids makes the contact between subnetsmore closely. If not effectively controlled, partial failure may develop into a globalfailure, causing blackouts. Therefore, strengthening the monitoring of the power systemoperation status and detecting the presence of cascading failure risk in time appears to beparticularly important. For the lack of the existing cascading failures models on accuracyand speed of assessment, this paper presents a rapid assessment model of cascadingfailures.The several larger blackouts worldwide are analyzed comparatively and the generalrules and forms of its development are summarized. According to the time length ofdevelopment, the critical events and boosting factor the cascading failures are dividedinto three types, the basic commonality of which is analyzed in detail.The power grid is converted into a directed graph which is storage with adjacencyby basic knowledge of graph theory. And on this basis the origins path chain is searched.For the problem of the change of the grid topology and power flow direction, the localmodification methods of origins path chain is proposed, which avoids the re-search of it.The transfer characteristics of power flower after branch breaking is analyzed. Thesearch method of effective origins path chains is proposed on the fact that the brancheswhich are affected relatively large by power flow transfer are often distributed thedirected paths between the nodes on both sides of breaking branch, whose electricaldistance are relatively short. Combined effective origins path chains with distributionfactor of breaking branch the key transmission section is identified.On the base of historical statistics of the component outage probability, the linesegmented fitting calculation method is proposed considering the impact of the real-timepower flow. The bus low-voltage, the relative transfer amount of the power flow and therelative amount of loss loads are selected as measure of the consequences severity fromthe perspective of system static security. When the mode of cascading failure is searched,the initial fault is selected by the factor of the key line and the middle fault link isselected by the key transmission section of breaking branch, which narrows the analysisscope of the system safety and accelerates risk assessment.