Reliability evaluation of power grids considering worm spreading pattern in SCADA

Active worms are capable of compromising the cyber security of the supervisory control and data acquisition (SCADA) network in power systems within quite a short time. This may bring high vulnerability to the cyber-physical power system, which is becoming more dependent on the communication technologies deployed in the SCADA system. The reliability of the power system may be compromised by the worms spreading through the SCADA networks. In this paper, the impact of worm spreading attacks on power system reliability is analyzed. A forced outage rate (FOR) model is proposed considering the impacts of spreading worms on the reliability characteristics. The spreading and detection models of active worms through the network in the SCADA system lead to non-negligible effects on the FOR values. With different FOR values derived by the models of both worm spreading and detection, the loss of load probabilities (LOLP) in two reliability test systems are estimated. The simulation results demonstrated that the reliability of the power system is simultaneously influenced by both the spreading and detection intervals of active worms.