Selection and stability issues associated with a navy shipboard DC zonal electric distribution system

The U.S. Navy is currently investigating the implementation of a DC Zonal Electric Distribution System (DC ZEDS) for the next generation of surface combatant. In replacing the current ac radial distribution system, significant gains can be realized in terms of survivability, weight, manning and cost. DC ZEDS is predicated on having starboard and port dc busses feeding electrical zones delineated by watertight bulkhead compartments. The main bus dc voltage is stepped down within the zone and then converted to three-phase ac and lower voltage dc by additional power converters. Due to the large interconnection of tightly-regulated power converters in a stiffly-connected system, negative input impedance effects create the possibility of unwanted resonances. In this paper, the authors describe the rationale for the dc zonal system, characterize the stability issues, and discuss fault detection and load shedding problems.