Abstract
The growing transition toward more-electric and all-electric vessels has intensified the demand for resilient, fast-acting protection solutions within marine direct current (DC) power distribution networks. Unlike in alternating current (AC) systems, DC fault currents rise extremely rapidly and lack natural current zero crossings, making conventional protection methods inadequate, particularly in multi-converter marine architectures. This paper presents a comprehensive fault analysis and protection methodology tailored for primary marine DC distribution systems. A detailed system-level model is developed, comprising the primary DC generation bus, secondary distribution buses fed through high-power DC-DC converters, and a hierarchy of protection components including solid-state bus tiebreakers (SSBT), solid state circuit breakers (SSCB), fast acting fuses (FAF), and galvanically isolating mechanical contactors. The influence of key system elements such as system inductance (bus bars, cables, and filters), converter DC-link capacitors, and protection device current settings, on fault current magnitudes and rise rates is analytically examined. Extensive time-domain simulations are performed in PSCAD to characterise fault behaviour such as primary bus faults and feeder faults. Based on fault profile insights, a coordinated protection strategy is proposed for both bus-level and feederlevel protection, combining the speed of various protection devices. The paper concludes by outlining the practical challenges associated with implementing high-voltage DC protection in marine environments.