Cyber-physical risk assessment for smart grid System Protection Scheme

System Protection Schemes (SPS) being widely used in smart grid often involve multiple geographically distributed devices that cooperate in a timely manner which relies highly on the wide area communication. Due to this functional nature, SPSs are extremely vulnerable when cyber-attacks take place and significant impacts and losses might follow. Under such circumstances, risk assessment for SPS has become critical. A novel cyber-physical SPS risk assessment method is proposed in this paper which takes into account both the possible cyber-attacks and SPS physical responses. Cyber-physical SPS system is modeled based on Deterministic and Stochastic Petri-Net (DSPN), and the risk is measured as the expected value of social welfare decrease. IEEE 9-bus model equipped with generation rejection protection scheme is selected as a study case to demonstrate the risk assessment method. According to the assessment results, critical scheme components are pinpointed so that mitigation actions can be taken correspondingly.