Determining Node Importance in Graph-Based Modelling of Cyber-Physical Power Systems

Electrical power systems have evolved into cyber-physical power systems (CPPS). The increasing interdependence between electrical power systems and cyber systems has introduced new sources of failure as well as causing additional security concerns. Therefore, it is vital to study the increasing level of interdependency using a whole system approach. Whilst power systems and cyber systems have well-matured models and simulation tools in their own regard, adequate whole system analysis tools are yet to be established. After evaluating the whole system challenges of CPPS modelling, this paper introduces a novel index for determining cyber node importance in a graph-based CPPS model. The proposed cyber node importance index (CNII) considers cascading failure, betweenness centrality and the time delay of the shortest paths, which provides a more accurate representation of power systems. To demonstrate the applicability of this approach, the UK’s British Telecom 21
^st
Century Network (BT 21CN) was linked with the GB Transmission System Reduced Model (GB TSRM). Experimental results show the improved accuracy and utility of this method as well as the applicability of analysing cyber contingencies in graph-based CPPS models.