Performance Analysis Of Communication Networks And Cyber Security Assessment OfPower Systems

The information system in a modern power system is becoming more and more important. The modern power system is developing towards a cyber physical power system. In a cyber physical power system, intelligent terminal devices will be widely used to realize its real-time monitoring and control, and large amount of monitoring data will be generated and transmitted by using standard communication protocols. These characteristics are helpful to implement the functions and visions of smart grids, but also bring some negative influences. For example, the transmission of mass data put forward a test to the communication networks in power systems; the cyber security risks in information space can even influence the normal operation of a power system.Given these backgrounds, this dissertation explores the performance of a communication network, the propagation mechanism of cyber security risks and the vulnerability assessment issue in a cyber physical power system. The detailed contents of this dissertation are as follows:(1) Performance analysis of communication networks in large-scale charging and swapping stations of electric vehicles. First, the structure of the monitoring system in a charging and swapping station is analyzed. Then, all the data in the communication network is classified by its characteristic and the related mathematical models are proposed. Finally, a simulation model is built to simulate different communication mechanism by the aid of OPNET. Based on these simulation results, some useful advices for building communication networks in a charging and swapping stations of electric vehicles are put forwarded.(2) The propagation mechanism of security risk in cyber physical power systems. In cyber physical power systems, the cyber security risks can have influences on the normal operation of primary power systems. First, the source of cyber security risks and the way to transmit risks in different spaces are discussed. Then, a cellular-automata-based model is carried out and the transition rules are proposed. Finally, the propagation processes of cyber security risks are depicted and some important factors which have significant impacts on the propagation of cyber security risks are discussed according to the simulation.(3) A vulnerability assessment method of cyber security for distribution automation systems (DAS). Compared with generation and transmission systems, distribution systems face with more cyber security risks, therefore the DAS is more vulnerable to cyber attacks. The potential physical consequences of cyber-attacks are first analyzed from two levels:terminal device level and control center server level. Then, the attack process is modeled based on the well-established game theory and the relationships among different vulnerabilities are analyzed by introducing a vulnerability adjacency matrix. Vulnerability assessment of cyber security for DAS is helpful for identifying the bottleneck of cyber security.(4) A vulnerability assessment method of power information systems based on information value. First, the impacts of the security attributes on the information value are discussed and the concept of asset attractiveness is proposed. Then, the attack processes are divided into two stages from the attack’s point of views:selecting access points and then attacking other vulnerabilities from the access point. The attackers can choose the next-step attack node according to the attack difficulty or the payoff of attacking a specific vulnerability. At last, a case study is carried out to demonstrate the effectiveness of the proposed assessment method.