Supercapacitors for Enabling Mechanical Circuit Breakers in Shipboard Zonal Secondary DC-Grids

This article proposes a variant design philosophy for shipboard zonal secondary dc distribution systems. The main features of such a power system are the insertion of supercapacitor devices together with chopper power converters that enable the implementation of mechanical circuit breakers for feeder and bustie protection. Hence, an overview of low-voltage dc protection technologies and navy pulse power load applications are discussed. The proposed secondary single-line diagram establishes the feasibility of fault levels and, consequently, the implementation of mechanical circuit breakers. Then, a transient event is carried out to highlight the zonal electrical distribution system performance in terms of continuous power supply into the dc-grid secondary zones. Results show that supercapacitors located in dc-bus enhance the circuit's voltage time constant, allowing extended periods for opening and closing protection devices (controlled by a power management system) and increasing the grid survivability for critical impulsive loads.