**6. Conclusions**

This paper has described how it is possible to improve electrical feeding substations, by changing transformer technology and by installing dedicated high-power oriented storage systems.

In particular, a considerable reduction in losses up to 58% has been performed by simply changing the transformer technology, which guarantee a cost of ownership significantly lower than the standard transformer solution. Additionally, further losses reduction is obtainable by introducing half-power transformers.

Then, installation of storage systems was analyzed also by considering the improvement in terms of system reliability, in addition to energy e fficiency. Results have shown also that installation of the storages is able to guarantee di fferent tramway services, also when reducing the sizing of the installed transformers. Moreover, this last aspect can also compensate the extra-costs for the storages.

The presented results are produced on a specific case study, which represents a typical configuration for very common tramway systems and trolleybuses. Since significant similarities can be identified regarding the technical characteristics of these systems, it is therefore to be expected that the highlighted benefits from the proposed changes are nearly the same by moving from one system to another.

**Author Contributions:** Conceptualization, G.L., R.G., and L.S.; methodology, G.L., R.G., and L.S.; software, G.L. and L.S.; validation, G.L., R.G., and L.S.; formal analysis, G.L., R.G., and L.S.; investigation, G.L., R.G., and L.S.; resources, G.L., R.G., and L.S.; data curation, X.X.; writing—original draft preparation, G.L. and L.S.; writing—review and editing, G.L., R.G., and L.S.; visualization, G.L., R.G., and L.S.; supervision, R.G.; project administration, L.S.; funding acquisition, L.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was co-financed under Tuscany POR CREO 2014-2020 Project "FAT" (CUP 7165.24052017.112000040).

**Conflicts of Interest:** The authors declare no conflict of interest.
