With the increasing application of Information and Communication Technologies (ICTs), cyberattacks have become more prevalent against Cyber-Physical Systems (CPSs) such as the modern power grids. Various methods have been proposed to model the cybersecurity threats, but so far limited studies have been focused on the defensive strategies subject to the limited security budget. In this paper, the power supply reliability is evaluated considering the strategic allocation of defense resources. Specifically, the optimal mixed strategies are formulated by the Stackelberg Security Game (SSG) to allocate the defense resources on multiple targets subject to cyberattacks. The cyberattacks against the intrusion-tolerant Supervisory Control and Data Acquisition (SCADA) system are mathematically modeled by Semi-Markov Process (SMP) kernel. The intrusion tolerance capability of the SCADA system provides buffered residence time before the substation failure to enhance the network robustness against cyberattacks. Case studies of the cyberattack scenarios are carried out to demonstrate the intrusion tolerance capability. Depending on the defense resource allocation scheme, the intrusion-tolerant SCADA system possesses varying degrees of self-healing capability to restore to the good state and prevent the substations from failure. If more defense resources are invested on the substations, the intrusion tolerant capability can be further enhanced for protecting the substations. Finally, the actuarial insurance principle is designed to estimate transmission companies’ individual premiums considering correlated cybersecurity risks. The proposed insurance premium principle is designed to provide incentive for investments on enhancing the intrusion tolerance capability, which is verified by the results of case studies.

中文翻译：

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考虑最优防御资源分配的电力系统可靠性网络安全保险模型

随着信息和通信技术（ICT）的日益普及，网络攻击已变得越来越普遍地对抗诸如现代电网之类的网络物理系统（CPS）。已经提出了各种方法来模拟网络安全威胁，但是到目前为止，在安全预算有限的情况下，有限的研究集中在防御策略上。在本文中，考虑了国防资源的战略分配来评估电源的可靠性。具体来说，最佳混合策略由Stackelberg安全博弈（SSG）制定，以将防御资源分配到遭受网络攻击的多个目标上。通过准马尔可夫过程（SMP）内核在数学上建模了针对入侵容忍的监控和数据采集（SCADA）系统的网络攻击。SCADA系统的入侵容忍功能可在变电站故障之前提供缓冲的停留时间，以增强网络抵御网络攻击的鲁棒性。通过对网络攻击场景的案例研究来证明入侵容忍能力。根据防御资源分配方案，容错SCADA系统具有不同程度的自愈能力，可以恢复到良好状态并防止变电站发生故障。如果在变电站上投入更多的防御资源，则可以进一步增强入侵容忍能力，以保护变电站。最后，考虑到相关的网络安全风险，精算保险原则旨在估算传输公司的个人保费。