Advanced commercial power system protection practices applied to naval medium voltage power systems

In the U.S. navy's transition to an all-electric ship, system designers must take great care to ensure that critical design choices provide highly reliable and safe power system operation and protection during all mission scenarios. Transitioning from low voltage (450 V/sub AC/) radial configurations to medium voltage (13.8 kV/sub AC/) multi-source systems requires new naval protection schemes. This paper specifically analyzes methods for quickly determining ground faults in ungrounded and high-impedance grounded naval power systems.

I. Introduction

Traditional naval power systems generally consist of 450 V_AC generators, bus-ties, switchboards with circuit breakers, and loads arranged in a radial, ungrounded configuration. Naval power systems are transforming into multisource or looped power systems that consist of multiple power sources and multiple paths to serve electrical loads. These configurations provide system designers greater flexibility managing generation versus load requirements, but at the cost of more complicated protection schemes.