Risk Assessment Of Transmission System Cascading Failure

Cascading failure in transmission system, although with low probability to happen, is an extremely serious accident which may result in outages in a large area. Several outages have happened in the world in resent dozens of years, and they were all caused by cascading failures. With the expansion of the scale of transmission system, the structure of the system has become more and more intricate and the state more and more mutative, and thus the security of the system has become a very thing of vital significance. The risk assessment of cascading failure in advance makes great sense to prevent the outage in large area and to improve the security of the system.This paper focuses on the establishment of the analysis model of cascading failure outage simulation and risk assessment indices of cascading failure and their calculation. First of all, complex network based topology model and power system analysis based simulation model of cascading failure are proposed considering the factors such as influence of the equipment operational state on the failure probability, hidden fault of relay protection devices and so on based on the analysis of the mechanism, procedure and characteristics of the cascading failures. Then, the paper establishes the risk assessment indices system of cascading failure and the calculation method from the aspects of network structure, outage loss and value at risk (VaR) combining with the theory of risk assessment of power system and VaR theory in finance. Finally, the risk assessment of cascading failure of IEEE118 system and a practical transmission system in China is used to prove the effectiveness of this researching work.