DC Marine Power System: Transient Behavior and Fault Management Aspects

DC marine vessels with medium-voltage compact dc power systems are dominated by a significant amount of active loads and a finite number of generation sources. In such scenarios, the network configuration of the dc power system is expected to get dynamically altered to fulfill the required generation and load demands for the desired marine mission. Such varying network configurations make the transient responses significantly different from the conventional ac grids and the prospective dc grids. In this regard, this paper performs systematic transient studies to devise fault management strategies for the dc marine vessels. A platform supply vessel (PSV) is taken as an example of the marine vessel, due to its complex operating scenarios and wider applicability in the marine industry. Pole-to-pole short-circuit faults are considered owing to its severity. A novel current-only directional protection for the dc PSV is proposed based on the directional zonal interlocking and short-time Fourier transform. The efficacy of the proposed method is substantiated by confirming against a range of fault impedances initiated at the generator terminals, load terminals, lines, and buses of the dc PSV. All the analyses are conducted in the real-time simulation model of the dc PSV.