A High-Voltage Hybrid DC Circuit Breaker Combining Mechanical Switches and an Advanced Multilevel Converter

Abstract

This paper presents a high-voltage hybrid dc circuit breaker that produces no conducting power loss during normal operating conditions and that has the capability to interrupt a large amount of short-circuit current within several milliseconds. It consists of a current-limiting inductor, a current-control inductor, the following two mechanical switches; a low-voltage quasi circuit breaker (LV-qCB) and a high-speed disconnecting switch (HS-DS), and an advanced multilevel converter based on the cascade connection of multiple single-phase bridge cells. This hybrid dc circuit breaker is characterized by achieving current commutation from the LV-qCB to the multilevel converter capable of fast current control. This circuit configuration makes it possible to eliminate power switching devices from the main current path. This elimination leads to producing no conducting power loss during normal operating conditions. This paper provides a theoretical and experimental discussion on the operation, control, and performance of the hybrid dc circuit breaker. It includes verification through a downscaled experimental system rated at 300 Vdc and 150Adc, as well as confirmation through circuit simulation using the “PSCAD” software package.