# Operational Resilience Metrics for Complex Inter-Dependent Electrical Networks
## 1 Introduction
Currently, RecSIM is a component of the CICCast Decision Support System, referred hereafter as CICCast-DSS [22], developed as part of the CIPRNet project and one of the main platforms used within the European Infrastructure Simulation and Analysis Centre (EISAC) that aims to establish a collaborative, European-wide network of national centers, empowered by advanced technologies, to inform, support and empower the different players involved in the urban resilience enhancement and assessment [23; 24]. Regarding the influence of energy systems and, in particular, of EDNs to contribute to implementing resilient cities, RecSIM is used to assess the speed of action and recovery of EDNs following a perturbation. RecSIM is part of the CICCast-DSS, a large platform containing models and tools for decision makers in order to optimize the management of a crisis and/or to proactively improve the systems resilience relying on the platform situational awareness data and risk assessments results [13; 25]. Similarly to what is proposed in [26], where the authors developed a modeling and analysis tool allowing us to detect the critical chains of dependency in a inter-dependent scenario, the RecSIM tool performs a topology-based simulation of an EDN crisis by providing a prediction of its extension, of its impact in terms of KPI, the best strategy to recover the system functionality, thus being a valuable support to decision makers and infrastructure operators to estimate the effect of different security controls and thus to select the best actions that may contribute to an increase in the overall resilience. The CICCast DSS operates in two different modes: _situational awareness online mode_ and _simulation offline mode_. In the former case, the platform uses different sources of data (e.g., weather forecast and now-casting data), basic territorial data (e.g., primary services, hospitals, roads) to anticipate, as much as possible, infrastructure networks contingencies (e.g., contingencies due to extreme weather conditions). In particular, in the situational awareness online mode the DSS needs to exchange data with the operator data center. For instance, the CICCast DSS instance designed and deployed for the Metropolitan City of Rome established a secure communication channel with the ARETI SpA data center to constantly exchange data with it. More in particular, CICCast DSS needs to update the EDN topology configuration on a regular basis, which may change due to issues such as maintenance interventions or for failure events. On the other hand, the ARETI SpA receives alerts in case the platform foresees possible outage scenarios involving the EDN. The CICCast DSS platform can also be used to assess significant physical damage to infrastructure due to extreme events such as earthquakes (Section 4). In the latter case (i.e., in the simulation offline mode), the platform can be used to assess the performances of the technological networks in synthetic scenarios such as synthetic earthquakes events. In both cases RecSIM receives input of a damage scenario (i.e., a set of electrical stations in the not-working state), the functioning state of other infrastructures (telecommunication networks and roads infrastructure) and, considering the actual EDN topology and the operator operation procedures, it computes the impact of the damage scenario on the EDN in term of the chosen KPI. The present paper is organized as follows. Section 2 introduces the operational resilience metric that has been used in RecSIM for the quantitative assessing of the resilience of EDNs. The same metric can be used to estimate the resilience of EDN during large crises due extreme natural events [27; 28] and during daily, normal operations (that represents the main contribution of this paper). It is worth noting that the proposed resilience assessment approach, similar to [17], considers the dependencies of EDNs with other urban infrastructure networks such as roads and telecommunications networks.