Lightning current measurement by differential loop for 110kV transmission line

Abstract

The measurement of lightning current is essential to lightning protection in grid, because only if accurate amplitude and waveform of the lightning current is obtained can the correct lightning protection measures be taken. However, in a high voltage power system, it is almost impossible to measure directly the lightning currents accurately and safely. So aiming at solving the problem of accurate and safe measurement of the lightning current on the overhead transmission lines, the differential loop which has been widely used in the pulse power measurement technique is applied, and a new method of measurement which based on the principle of differential loop can measure the lightning current on overhead transmission lines contactless is used and improved considering the actual running conditions in the 110kV level of transmission line. In this essay, the principle of differential loop for measuring lightning current and the design of the detector are introduced. In laboratory by using the high impulse current generator to simulate the lightning currents, the experiment results show that: for the 1.4m measurement distance, through selecting appropriate size of differential loop and the number of turns, and choosing reasonable shielding, combined with self-integral, the measurement sensor can reflect the waveform and the amplitude of the currents which is produced by the high impulse current generator accurately, and has the advantage of safety, strong anti-interference, well linearity and accuracy.