Research On 10/350μs Standard Lightning Current On-line Detection System

Lightning protection measurement has been taken on different grade voltage transmission lines, which was used to reduce damage in China. However, our country’s lightning current data is not accurate enough, which impedes lightning protection of the national grid. In order to further analyses the cause of lightning stroke, it is very necessary to collect the lighting waveform accurately.Based on previous research achievements, this paper has developed a 10/350μs standard lightning current online detection system. It was used to detect the waveform, amplitude, polarity, lightning tower number and lightning time etc.According to IEC62305 and GB500057-2010, this paper studied the mathematical model of 10/350μs standard lightning current and researched the waveform’s Fourier transform, and then analyzed the amplitude and energy distribution of standard lightning current from the angle of Fourier spectrum. Rogowski coil was designed to meet the spectrum range of standard lightning current, whose measurement error is less than 3%, when using shunt to adjust accuracy.According to the amplitude, slope and half peak time of the standard lightning current, this paper proposes the lightning current identification method and cyclic trigger to improve the reliability of trigger and the integrity of the waveform detection.Signal detection board was designed to detect lightning current output form the sensor, and then the signal was quantized, stored, identified and sent etc. Solar power board was designed to provide power and the charge rate of battery was control by using charging controller.Finally, terminal PC was programmed in C++ language to receive data, redraw waveform and calculate amplitude of the lightning current. The reliability of lightning current identification method and cyclic trigger was verified by detecting lightning waveform form NSG3060 group pulse generator. The practicability of detection system was verified by using high frequency large current detection experiment, and the accuracy of detection system was adjusted.