Development of monitoring system for lightning current waveforms of transmission lines based on flexible Rogowski coil

Measurement of lightning current waveforms has important significance for researching characteristics of lightning and lightning protection of transmission lines. In order to perform long-term observation of lightning strikes, a novel monitoring system for lightning current waveforms of transmission lines is developed. The system consists of a measurement unit, a high-speed data acquisition and processing unit, a communication system and a backstage expert analysis query system. A kind of Rogowski coil with a flexible belt-like nonmagnetic core which can measure pulse current up to 100 kA is designed as the measurement unit. For this kind of Rogowski coil, large inductance is obtained by increasing the turns of the coil, which makes the coil have self-integrating capability and reduces the difficulty of additional integration. At the mean time, the coil would not work in nonlinear and saturation ranges as the core is nonmagnetic. High-speed data acquisition and processing unit is adopted to collect coupled voltage signal for ensuring the integrity and accuracy of the signal. The time and address of the lightning signal are determined through GPS synchronization positioning. The measured lightning current waveform signal is received and analyzed by backstage expert analysis query system through GPRS wireless data transmitting. Currently, the whole system has been installed at the 87 # tower of 330kV Jin-Huang line of Shaanxi provincial power company. The actual operating results show the entire system has good dynamic performance and could accurately measure the lightning current waveforms.