Cascading failure analysis of interdependent water-power networks based on functional coupling

Due to the increasing interdependence and interconnection, the water supply network (WSN) and electric power network (EPN) face a higher risk of cascading failures. Existing studies mainly focus on the cascading failures of the single network but rarely on the interdependent water-power networks (IWPN) under earthquakes. Therefore, combined with the physical operation characteristics, this paper proposes a cascading failure analysis method for interdependent water-power networks based on functional coupling. First, we define the functional coupling relationships between the IWPN and establish a topology model of the IWPN. Subsequently, the joint probability and functional coupling strength are introduced to determine the failure probability of coupled components in the WSN and EPN. The initial failure components are determined by a random method. Then, the node load function and line capacity function are introduced as the judgment conditions of cascading failure of the WSN and EPN, respectively. The cascading failure transmission process of the WSN and EPN is further conducted based on the dynamical flow model. Further, a calculation method for the functional loss of the WSN and EPN is proposed. Finally, the proposed methodology is applied to the coupling WSN of a certain city and IEEE118 node network. The results show that cascading failures in the IWPN spread wider than a single network and cause more serious functional losses. The findings of this work would have important implications for formulating disaster prevention and mitigation measures and seismic performance improvement strategies for interdependent infrastructure networks.