Ice storm disaster has various negative impacts on power grid security and stability. To evaluate the power grid risk accurately

a risk assessment method for power grid icing based on short-time icing forecast is proposed. The ice and wind loads on lines can be forecasted by the icing forecast system. The time-varying failure rates of transmission lines can be calculated by the time-varying structure reliability theory. A restoration time model of transmission line with DC deicer is built as is a time interval model of deicer. Owing to the incapability of reflecting the time-varying failure rate of iced lines using the traditional Monte Carlo method

a sequential Monte Carlo method of solving this rate is proposed. The proposed model is tested on an IEEE RTS-79 system. The effects of the time interval of icing forecast and deicer on risk indices are analyzed and related suggestions made. This work is supported by National Natural Science Foundation of China(No. 51577075).