As part of the PNRR Green Ports programme, dedicated to decarbonising port areas through quay electrification and the introduction of new electric or hybrid handling equipment, the client launched interventions to supply electrical power to operational activities on the quays. The Green Ports programme supports interventions for the electrification of port infrastructure and the replacement or conversion of traditional equipment with lower-emission solutions.

For the related Green Ports contract, a dedicated analysis was developed for short-circuit current calculations and protection selectivity verification, with particular attention to the integration of amperometric and logic selectivity on the same communication infrastructure used by the SCADA system.

The electrical network under study is a radial distribution system directly connected to the E-Distribuzione grid, structured across two medium-voltage levels: 20 kV, for DSO supply, and 10 kV, for powering outlets located at the port quays destined for the new electric cranes. The planned protections include phase and residual overcurrent functions, as well as earth-fault directional protection on the 20 kV delivery and distribution lines.

The study made it possible to verify that selectivity was achieved in all envisaged operating scenarios, documenting the results also in graphical form on a single-line diagram. This mode of representation, supplementary to classic setting tables and coordination diagrams, makes the results clearer and more immediate for both the designer and the client.

The calculation was performed with DigSilent PowerFactory, using the same network model employed for the short-circuit current analysis and simulation models developed by Thytronic for the XMore line protection relays. This made it possible to evaluate protection behaviour for every fault type, at every network node and in every operating configuration, also taking into account any logic selectivity interlocks.

The analysis thus confirmed correct protection coordination and system selectivity under the various operating conditions. The documentation produced in turn provided an effective representation of tripping times and the opening of the involved circuit-breakers, contributing to a more robust, readable and reliable design of the electrical distribution system.