Three measuring points for partial discharge location in energized covered-conductor overhead distribution lines: Algorithm and experimental evaluation

The experimental evaluation of Rogowski coil performance for locating partial discharge (PD) in energized covered-conductor (CC) overhead lines is performed. A multi-end measuring point is introduced, where the Rogowski coils looped around the CC line at three different locations and connected to the oscilloscope for measurements. The tests are carried out concerning different measurement conditions such as off-line and on-line PD measuring systems. For off-line measurements, the calibrator pulse is used to inject PD source to the CC overhead lines. Meanwhile for on-line measurement, CC line is energized by a 110/20 kV power transformer and the concept of twisted-coil around the CC is introduced in order to produce a pulse similar to the PD source. The performance of Rogowski coil is tested in noisy environment. Chirp detector is used as a signal processing tool to extract the high frequency signals in order to determine the time of arrival (TOA) signals at each measuring sensors. The locator function algorithm for multi-end measurement is developed. The results obtained from this work confirm the capability of the Rogowski coil to measure and locate the high frequency PD source on the CC line in consistent with energizing AC source. Meanwhile, using the locator function algorithm developed, the localization of PD source point on CC overhead lines is found out without the need to know the propagation velocity of the signals.