Risk Assessment for Cyberattack in Active Distribution Systems Considering the Role of Feeder Automation

The extensive application of information and communication technology (ICT) can effectively improve the operational performance of active distribution systems (ADSs). On the other hand, the use of ICT may expose the systems to cyberattacks. Since feeder automation (FA) in advanced ADS provides fast-responding self-healing capability to restore service during an outage, the potential effect of cyberattacks on ADS becomes more devastating. In this paper, two simple yet powerful cyberattack methods targeting remote terminal units (RTUs) are proposed. The physical response of ADS to malicious cyberattacks on FA is elaborately investigated considering the output fluctuation of distributed generators. The impact of this specific cyberattack on ADS is quantified by a risk assessment index measured in scale and in duration to full restoration. The probability of RTU potentially being attacked is modeled based on search theory. Furthermore, a Bayesian attack graph model is applied and designed to quantify the probability of successfully exploiting the currently known and zero-day vulnerabilities. The proposed methodology is tested and validated via using a modified three-feeder ADS and the IEEE 123 Node Test Feeder.