Management of ground faults in an ungrounded multi-terminal zonal DC distribution system with auctioneered loads

Abstract

A ground fault detection and location (GFDL) method has been developed suitable for shipboard multi-terminal zonal DC distribution systems having auctioneered loads. This method is suitable for locating ground faults to any connection point within an ungrounded, switching power converter-fed electrical distribution system. Common mode (CM) current feedbacks are processed and transmitted over a local area network to GFDL controls located in a Phase-Controlled Rectifier (PCR) that feeds one of two redundant main DC distribution buses. GFDL works by monitoring the voltage with respect to chassis ground for AC or DC voltage offsets at the PCR DC output and, when an offset is detected, initiating a sequence of steps to inject current into the ground fault and then pole CM current sensing stations within the system in order to determine the location of the ground fault. The system can operate uninterrupted with one ground fault. This paper presents the results characterization and testing of GFDL and results and analysis of tests performed when a second ground fault is applied to various locations.