Novel method for real time overhead power line segments high frequency impedance measurement based on signal injection

Abstract

The overhead power line plays a vital role in transmission and distribution networks. Continuous operation of the overhead power line is a necessity for a reliable power grid. The condition of the power line such as failure and aging can be monitored through its high frequency impedance characteristics. Continuous measurement of power line impedance at high frequencies is quite challenging. The high frequency impedance model of the overhead power line requires variety of network behaviors and parameters. Existing high frequency impedance measurement techniques cannot measure the impedance of specific segment of the energized overhead power line. In this paper, a novel real time impedance measurement technique to measure a desired segment of overhead power line impedance at high frequencies is presented. The new method is based on the high frequency signal injection into the middle section of the desired segment with one unit and blocking the injected signal with two other units at opposing ends of the segment. The proposed blocking topology is based on the non-intrusive active clamp filter (NIACF), which is capable of blocking a specific frequency in the power line using control techniques. The proposed blocking and impedance measurement methods are tested and validated through experimental studies.