| Title |
Development of a Protection System for Loop-Type Low-Voltage DC Distribution Systems |
| DOI |
https://doi.org/10.5370/KIEE.2025.74.12.2053 |
| Keywords |
DC Distribution System; EMTP; FCL; Over-Current Relay; Protective Coordination |
| Abstract |
The increasing penetration of distributed generation such as photovoltaic and wind turbines, along with the growing demand from electric vehicle charging stations, data centers, and DC-based digital loads, has accelerated interest in DC distribution systems. These systems reduce unnecessary power conversion stages, thereby improving energy efficiency and reducing operational costs. However, reliable protection remains a major challenge, particularly in VSC (Voltage Source Converter)-based DC distribution system. A fault in distribution line can trigger rapid capacitor discharge currents and sustained contributions through antiparallel diodes, raising the risk of device damage and demanding fast fault isolation. Conventional protection approaches di/dt detection, undervoltage relays, ? and overcurrent relays each face limitations regarding selectivity, speed, and coordination, especially under current-limiting ? conditions. This paper analyses the fault current characteristics of VSC-based low-voltage DC distribution and the limitations of existing protection schemes. A coordinated protection strategy is proposed for loop-type low voltage DC distribution system, combining fault current limiters with inverse-time overcurrent relays to ensure reliable operation while reducing breaker stress.
Additionally, the use of Tie-Switch enables the restoration of healthy sections, minimizing outage areas. Simulation studies validate the effectiveness of the proposed method, confirming its potential for practical deployment in future DC distribution systems. |