Observational Technique of Lightning Current Striking to UHVAC Overhead Transmission Line

For the sake of differentiating shielding failure trip from back stroke trip and observing the amplitude and polarity of the lightning stoke current,so as to realize the further optimization on lightning protection calculation method and design of China UHVAC overhead transmission line,we put forward a lightning observation method suitable for UHVAC overhead transmission line by widely arranging magnetic steel sticks.We installed two lightning rods at the top of each transmission tower,and placed magnetic steel sticks on each rod and on ground wires of both sides of each tower,namely,six points in total per tower,to measure lightning current.Furthermore,the location efficiency was improved by combining lightning strip towers with lightning location system.Test results indicate that the new type of magnetic steel sticks have less eddy current loss,higher sensitivity,better stability,and larger linearity scope.According to the amplitude and flow direction of the lightning curent measured by the new type of magnetic steel sticks,and combining with simulation calculation,we can not only differentiate shielding failure trip from back stroke trip and observe the amplitude and polarity of the lightning stoke current,but also define the location of lightning stroke on the line and the distributary coefficient of the tower.