1.School of Electric Power Engineering, Nanjing Institute of Technology, Nanjing 211167, China;2.Jiangsu Collaborative Innovation Center for Smart Distribution Network, Nanjing 211167, China;3.School of Electrical Engineering and Automation, Wuhan University, Wuhan 430072, China

Load redistribution (LR) attack is a special form of cyber-attack. It is of great practical significance to model the LR attack and study its influence on the power system operation. Firstly, the process of LR attack is analyzed, and the random process model of LR attack is established based on the semi-Markov chain. Secondly, the interaction process between the attacker and dispatcher under the LR attack is analyzed, and the load shedding model of the power generation and transmission system considering the LR attack is established. Then, a defense strategy for the vulnerable line based on the transmission line utilization rate is proposed from the perspective of protecting the critical measurement data, and a reliability evaluation algorithm of the power generation and transmission system considering the LR attack and defense of the vulnerable line is further proposed. Finally, the modified IEEE 14-bus system is taken as an example to verify correctness of the proposed reliability evaluation algorithm of the power generation and transmission system considering the LR attack and effectiveness of the defense strategy for the vulnerable line.