USB PD based Microgrid for Accelerating the Power Grid Transition to a Low Carbon Future

Abstract

The USB-C PD is becoming the unified power interface standard for most DC appliances as in the recent EU move to legislatively mandating a USB-C port as a common charging port. The latest standard USB PD 3.1 can deliver up to 240W. It is natural to imagine a world that moves to USB-C direct current outlets in the buildings and even a separate DC backplane throughout the buildings. The USB PD provides more versatile functions enabling the control of “things” regarding power than just supplying power. In this paper, we discuss a configuration method of a USB-C PD based microgrid by networking the units called “Virtual Grid Hubs (VG-Hub),” where the USB-C ports on the wall do not only supply power but also receive power input. A VG-Hub is a device with a fixed number of USB-C ports to collect and distribute power. Distributed batteries absorb surplus power from the utility grid and decrease power demands by distributing the stored power to USB devices connected to the microgrid when a power shortage in the utility grid. We formalize the VG-Hub network topology design problem. The optimum regular graphs for the performance indices are enumerated and shown to be practical in terms of total power storage capacity and power flow by using the commercially available portable chargers.