Modeling and experimental verification of on-line PD detection in MV covered-conductor overhead networks

The falling trees on covered-conductor (CC) overhead distribution lines produce partial discharges (PDs). The measurements have been taken in the laboratory and PD signal characteristics under various circumstances have been described. In this paper, an on-line single-phase PD monitoring system using Rogowski coil is simulated in EMTP-ATP. The simulation results are compared with those obtained from the laboratory measurements. The proposed model can be used to estimate the length of the practical CC lines at which PDs due to falling trees can be detected and localized; thus, deciding the number and positioning of the sensors over a particular length of the CC lines. The different noise sources have been described that cause interference with low level PD signals, which is a major challenge for on-line/on-site condition monitoring. The design aspects of the wireless sensor for this specific application are also discussed. Automatic detection of falling trees will reduce visual inspection work after storms and it will improve reliability and safety of the CC distribution system.