To solve engineering application defects such as lack of assessment details and risk information in the risk index system

this paper presents a power grid operation risk assessment and rating system. Firstly

redefine the risk structure as a set of risk grade

risk kind

risk probability

risk severity

reason set and consequence set

while classifying risk categories as loss of load

overload

voltage deviation

grid splitting

blackout of plant/station

and blackout of important users. Secondly

design the rating method of risk probability grade

risk severity grade and risk grade. Finally

divide the system flow into five parts as information collection

risk identification

risk assessment

risk rating and risk warning

and illustrate the system application effects in Dispatch and Control Center of State Grid Anhui Electric Power Company. This work is supported by National Natural Science Foundation of China (No. 51177143)

Zhejiang Provincial Natural Science Foundation of China (No. LZ12E07002) and National High Technology Research and Development Program of China (863 Program) (No. 2011AA05A120).