# Operational Resilience Metrics for Complex Inter-Dependent Electrical Networks
## 5 Results
### Assessing the Impact of Improved Distribution Automation Systems (DAS) on the EDN Resilience  
Moving forward from these previous efforts and works, ENEA and Areti SpA, the Roma EDN operator, started a collaboration with the objective to improve the proposed resilience framework by including: (1) a more realistic power grid topology and (2) the simulation of the actual restoration procedures, also considering the fault detection procedures adopted by the operator to individuate the faulted components of the grid. Moreover, the improved RecSIM allows for the assessment of the performances of the power grid considering _normal_ or _most-likely_ failure conditions, which are failures on sections of MV lines connecting two substations. These improvements make RecSIM a valuable framework for the operator to assess the impact of technological improvements and to optimize the company investments needed to implement them. This section describes the results that were obtained using the improved RecSIM to assess the impact on the power grid performances of different algorithms for the power grid distribution automation systems (DAS). In particular, simulations considered the \(N-1\) case analysis of the subset of MV lines (denoted with \(L^{hc}\) in the following) identified by the operator as _high concentration_ lines, i.e., MV lines supplying a large number of customers. For each line \(l\in L^{hc}\) the tool performed a \(N-1\) case analysis considering (i) the actual DAS procedures described in Appendix A and denoted \(FRG\) in the following, where the automatic failure detection ad isolation was operated through the timely coordination of automatic switches in the line and (ii) a possible improvement of these procedures through the _cooperation_, through 4G network communication, of automatic switches along the line. In the former case, DAS avoids the disconnection of the substations upstream of the last automatic station before the faulted MV line section (please refer to the Figure A3, which shows an example of how the current DAS procedure works). \begin{table}
\begin{tabular}{l c} \hline \hline \multicolumn{2}{c}{**Model Parameters S3 Simulations**} \\ \hline network topology & normal configuration \\ number of technical crews available on the field & 4 \\ time for tele-control operation (\(tlc_{t}\)) & \(5\pm 2\) min \\ time for technical intervention on-site (\(travel_{t}\)) & \(60\pm 10\) min \\ time for installing an electrical generator (\(pg_{t}\)) & \(220\pm 20\) min \\ fraction of tele-controllable SS being not tele-controllable & 0.4\% \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Parameters used for S3 (_high traffic_) simulation. Figure 13: Resilience vs. different traffic congestion. On the other hand, the cooperation of automatic switches in the improved DAS procedure would avoid the disconnection of substations upstream of the last automatic station before the faulted MV line section (as in the previous case) and the substation downstream the first automatic substation after the faulted MV line section. Figure 14 shows an example of how the improved DAS procedure is able to isolate the failure of the D-E line section through the cooperation of the automatic switches in substations C, F, H and X. Please note that the new DAS procedure requires that all switches in the frontier substations (e.g., substations F and H in Figure 14) are equipped so that they are able to perform the automatic procedures. Figure 15 compares the results of the \(N-1\) case analysis preformed considering the MV lines in the \(L^{hc}\) set. The plot represents the mean impact values (kmin) obtained adopting (i) the actual FRG procedure (blue area) and a (ii) the improved 4G procedure (red area). Results show that adopting the 4G procedure for all lines in \(L^{hc}\) the \(KMIN_{\text{TOT}}\) computed summing up all mean impacts of each line decrease of a percentage of 16%. It is reasonable to assume that the transformation process to the new improved DAS procedure is constrained by the available budget.