Operation Algorithm of Protection Coordination for Isolating Fault Section in Radial MVDC Distribution System

• Published in: Journal of electrical engineering & technology Vol. 17; no. 3; pp. 1651 - 1658
• Main Authors: Lee, Hu-Dong, Han, Byeong-Gill, Choi, Sung-Moon, Kang, Seong-Hyun, Rho, Dae-Seok
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 01.05.2022; 대한전기학회
• Subjects: Electrical Engineering; Electrical Machines and Networks; Electronics and Microelectronics; Engineering; Instrumentation; Invited Paper; Power Electronics; 전기공학; CLR; Slope index of fault current; Protection coordination; MVDC distribution system
• ISSN: 1975-0102; 2093-7423
• DOI: 10.1007/s42835-022-01047-w

Generally, the existing AC distribution system adopts a protection coordination method using the T-C characteristic curve. However, unlike the method which has coordination time interval with tens ~ hundreds of milliseconds, the protection devices in DC distribution system rapidly operate within several milliseconds, so that it is difficult to ensure a protection coordination time interval between protection devices. In order to overcome this issue, this paper proposes operation algorithm of protection coordination in radial MVDC distribution system to rapidly isolate fault sections by using slope characteristics of fault currents and presents prevention method for shutdown of the main power source based on the CLR (current limit resistor). And also, this paper performs modeling of 20 kV-scaled MVDC distribution system, which is composed of substation, main and section converter, based on the PSCAD/EMTDC S/W. From the simulation results of fault characteristics at primary and secondary side in MVDC, it is confirmed that the main converter in primary feeder cannot be shut down due to keeping fault currents within allowable limits of main converter, if the proper capacity of the CLR is installed at secondary side of section converter. In addition, it is found that the proposed method can isolate outage sections in primary feeder and minimize them, if slope ranges of fault current are properly determined at each protection section.