Four Quadrant Bus-Tie Switch for Protection of Shipboard Power Systems

The desire to increase the voltage of DC shipboard power distribution networks to the medium voltage level derives from the pressure to reduce the operating costs of such systems by increasing their efficiency. Solid state bus-tie switches are accepted to be an essential component of such installations at the low voltage level, as they allow system reconfiguration and prevent fault propagation through ultrafast fault current identification and interruption. Nevertheless, the lack of standardisation in medium voltage DC shipboard power systems hinders the development of such technologies as custom, ad hoc solutions must be found according to the selected voltage level. This paper presents a solid state bus-tie switch topology that is scalable in both power and voltage rating and relies exclusively on existing, commercially available technologies. This provides a simple, readily employable solution with the flexibility needed to bridge the technological gap in the time required for medium voltage system operating voltages to become standardised. This paper presents the prototype of the bus-tie switch and validates its scalability through extensive experimental tests.