College of Electrical Engineering, Zhejiang University, Hangzhou310027, China

With the evolution of the informatization and intelligence level of microgrids, malicious cyber attacks are becoming more serious threats to the safe and stable operation of microgrids. Compared with the distribution network, the microgrid has smaller scale, higher renewable energy penetration, and weaker adjustment capacity, and is more vulnerable to cyber attacks. In order to analyze the vulnerability of microgrid cyber physical system against cyber attacks, first, a physical-side model of microgrid considering control strategy and renewable energy output uncertainty, and a data flow based cyber-side model considering cyber attacks are formulated. Secondly, in order to analyze cyber attacks, the correlation matrix of attack method and attack target and a bi-level programming model considering the behavior of the attacker and the dispatching center are established. Then, based on the characteristics of load redistribution and Shapley value method, a vulnerability index calculation method based on attack consequences and vulnerability assessment process are proposed. Finally, the simulation is carried out on a 38-bus system to assess the vulnerability of the microgrid cyber physical system against cyber attacks, and the effectiveness of the proposed method and its guiding significance for formulating defense strategy are analyzed and verified.