Active fault-current foldback control in thyrister rectifier for DC shipboard electrical system

Turbine-generator set integrated with the thyristor-based rectifier system provides the dc power for the emerging medium voltage dc (MVDC) shipboard electrical distribution systems. Active foldback via firing-angle control can be implemented in the thyristor rectifier to protect the primary distribution bus, thereby possibly eliminating the bulky dc circuit breakers. This paper presents the detailed modeling and design of the active foldback control by considering multiple impact factors, like dc inductor, control bandwidth, generator frequency, and rectifier topologies. A new foldback control method is proposed to minimize the fault isolation time. The complete design of fault detection, fault current foldback, and post-fault recovery is proposed and simulated for the breakerless MVDC architectures.