Power Distribution Feature of Coil-based Power-Tapping from Ground Wire of Typical HV Overhead Transmission Line

Power-tapping from ground wire is an ideal method to power on-line monitoring devices of HV overhead transmission line. And the way with bus-like power-tapping coil plays an important role for its simple engineering and excellent lightning protection performance. The key to the PTC way is whether enough power is available from ground wire. Study has revealed that for PTC of certain size and material the available power from ground wire is variable. Hence, to study the distribution performance of power from ground wire bears great reference value for the power-tapping design and installation of on-line monitoring device. In view of the power is in proportion to square of ground wire current, the power distribution performance is obtained through analyzing ground wire current of power-tapping circuit. Besides, effects of concerned factors on it are analyzed using EMTP-ATP program. Results show that the available power increases from the vicinity of terminal tower to middle zone of line, and tends to be stable when it is about 10 spans away. Besides, conductors transposition could reduce the current evidently while others show little impacts. Finally, on-cite measurements verified the above-said analysis.