Research On Risk Assessment And Preventive Control Of Cascading Failures In The Large Power Grid

Large-scale grid interconnection improves the reliability of the power system,but it brings a series of problems, such as angle stability, voltage control, cascadingfailures. In recent years, cascading failure blackouts occur frequently around theworld, resulting in huge losses. Cascading failure analysis and preventive control isof important practical significance and it has become a hot topic in the field ofpower systems. Research the develop mechanism of cascading failures, and proposethe cascading failure prevention and control measure to prevent cascading failureoccurring, which is the main purpose of this paper.In this paper, the mechanism of cascading failures is studied by cascadingfailure fault chain model. It selects the initial failure of cascading failure usingintegrated circuit breaking rate indicators. Considering the flow of the runningsystem, the flow of the transition state and hidden failures of relay protectionsystem, this paper predicts the subsequent failure of cascading failure effectively.This paper evaluates the risk of cascading failures by calculating the probability andconsequence of cascading failure and it tells the key transmission lines with asignificant rate of transmission line.This paper measures the risk of system status with node voltage offset risk andover limit risk of transmission lines, and controls the power system based on therisk of system status. This method can optimize the system flow and reduce the riskof system failures. In order to ensure economy of preventive control method, thispaper presents a cost-effective indicator to measure the effect and costs of thecontrol method. The primary means is to adjust the generator power and reduce loadpower. For the critical transmission lines in the power system, this paper presents arigid risk indicator to measure the impact of critical transmission line to the powersystem state, and control the critical transmission lines based on the rigid riskindicator of critical transmission lines to reduce the risk of cascading failureblackouts.For the various types of disturbances which the power systems suffered from,this paper presents a potential failure risk indicator, which measures the probabilityand consequence of the system failure, and based on the indicators that is the risk ofpotential failure, this paper proposed a cascading failure preventive control methodwhich considers the risk of multiple failures. The control method can effectivelycontrol the power system considering the power system status and developmenttrend of the power system. Compared with the traditional method of prevention andcontrol, the method which considers the risk of multiple failures results in a significant aspect of reducing the risk of cascading failures and this method is theeffective control of cascading failures.