Identification of the Faulted Distribution Line Using Thyristor-Controlled Grounding

For ungrounded systems, identifying the line experiencing a single-phase-to-ground fault is very difficult because an ungrounded system produces very low fault current. This paper presents a novel method that can help to overcome this difficulty. The idea is to temporarily convert an ungrounded grounded system into a grounded system through a controlled grounding of the system neutral. The result is a controllable ground fault current that is large enough for identifying the faulted line and yet small enough not to cause system problems. Theoretical analysis, computer simulation and lab experiments verified the effectiveness of the proposed method. The proposed method also applies to high-resistance grounded and resonant grounded systems.