Analysis on Operational Characteristics of DC Hybrid SFCLCB With Self-Pickup Function

Abstract

Most of electric power devices used by consumers receive power through power converters, and as the number of power converters increases, the loss that occurs during the power conversion process also increases. For this reason, in modern power systems, the number of AC/DC hybrid power distribution systems is increasing along with the increase of DC power distribution systems. In DC power distribution systems, fault characteristics are that the DC fault current increases faster than in the AC fault current and DC current has no zero-crossing point. DC fault current requires quick interruption dozens of times faster than AC. In the existing protection method, when a relay detects a fault through current or voltage, the relay generates a trip signal, and the breaker operates by receiving the trip signal. This method can cause communication delay between the relay and the circuit breaker, which can affect rapid operation. In this paper, a DC hybrid superconducting fault current limiter circuit breaker (SFCLCB) was proposed to solve communication delays between protection devices. By combining a circuit breaker inside the DC hybrid superconducting fault current limiter (SFCL), the only controller engages in both current limiting and blocking, reducing operating time delays. The DC hybrid SFCLCB was conducted through simulations using PSCAD/EMTDC.