Identification of the faulted line using controlled short circuit of PT delta-connected winding

For ungrounded and resonant grounded systems, it is very difficult to identify the line experiencing a single-phase to ground fault. This is due to the fact that such grounding schemes produce very small fault current. This paper presents a novel method that can overcome the difficulties. The idea is to convert the ungrounded system into a grounded system temporarily through a controlled short circuit of the distribution bus potential transformer (PT) delta-connected winding. The result is a controllable ground fault current that is large enough for identifying the faulted line and yet small enough not to cause power quality problems. Results of theoretical analysis and computer simulation have confirmed the effectiveness of the proposed method.