Protection Schemes in Low-Voltage DC Shipboard Power Systems

Shipbuilding industry has increased interest into DC shipboard power systems (SPS) for their benefits, such as improved fuel efficiency and installation footprint. These new power systems come with technical challenges in system protection owing to lack of natural zero crossing in case of DC fault currents and low thermal capability of semiconductors. This paper presents feasible protection schemes against DC short circuit faults for three different types of, commercially available, low-voltage DC (LVDC) rectifier systems: a six-pulse diode rectifier, a six-pulse thyristor rectifier and a two-level active rectifier. In addition, a novel protection method, which provides a simply way for limiting fault currents, is proposed and discussed for the active rectifier