Near zero energy load systems: The special case of port cranes

Significant developments in the electrical systems are strongly evolving towards the energy saving solutions and the installation of local renewable power sources. Port facilities have to organize their electric power systems as a unique loads area constituting a microgrid. A common renewable energy power system, organized for all the customers of a port, can be sized and operated more efficiently aiming to guarantee the self-consumption of the whole production and to allow pursuing the goal of a nearly net-zero energy power system. The paper contributes to propose an advanced solution to organize the port cranes even as nearly net-zero energy load systems, adopting a regenerative storage, by means of bidirectional converters and ultracapacitors. They can regenerate power during container dropping cycle and draw power when containers are lifted. Ultracapacitors assist for a momentary energy storage seamlessly as flywheels.