Analysis on Operational Characteristics of DC Hybrid Fault Current Limiting Circuit Breaker with a Single Control System

DC distribution systems offer significant advantages over traditional AC systems, such as higher transmission capacity and lower power loss. As a result, active research is in progress to apply DC distribution systems in various fields, including data centers and microgrids. Despite these efforts, DC distribution systems currently lack sufficient regulations and equipment for fault protection. In AC systems, a fault detected by relay, which sends a trip signal to a circuit breaker (CB). Fault current limiters (FCLs) are used as protective devices to reduce stress on the CB. However, if both a CB and a FCL are used in same distribution line, each with its own micro control unit (MCU), computational and communication delays can occur as each device independently detects the fault. In this paper, a DC hybrid fault current limiting circuit breaker (FCLCB) which integrates CB, relay, and FCL for use in DC distribution system was proposed and analyzed. A hybrid CB combines a power semiconductor switch and a mechanical switch. The power semiconductor switch performs the current limiting function, while the mechanical switch handles the CB operation. The FCLCB performs its breaking operation after first limiting the fault current, which reduces the breaking capacity stress on the CB. By controlling both the current limting and breaking operations with a single MCU, the FCLCB enables a faster operation.