Basic Research on Protection of Distribution Lines through the Waveform Analysis of Surges caused by Lightning Discharges

本项目取得的成果总结为以下五项：通过测量点放电电流对地面电场强度进行了观测，并在冬季在石川工业大学和大学周围的几个地点进行了观测。冬季闪电放电中正闪和负闪的发生频率基本一致。根据观测记录，提出了一种图解方法来推测冬季雷雨云下电场的区域分布。精确的冲程位置由双四分之一VTR观察确定。这些击中的位置距离地面上电场的正负区域之间的边界约1公里。并将上述平地雷电特征与北陆地区的奥久国山和后津山雷电特征进行了比较。在Unoke变电站用4通道存储器记录仪测量了3条配电馈线上的雷击浪涌。在云对地闪点附近的线路上感应到的零相序电流波形与在其他线路上感应到的波形不同。实验研制了一种采用光纤系统的电容式电压检测器。在设计上的改进将在未来实现精确的波形记录。

Obtained results in this project are summarized as the following five items ;1. Observations of the electric field intensity on the ground by measuring the point discharge current have been performed at Ishikawa National College of Technology, and several sites around the College in winter. The frequency of occurrence of positive flash nearly the same as that of negative one in winter lightning discharges.2. A graphical method was developed to presume regional destribution of the electric field under the winter thundercloud on the basis of observed records. The accurated stroke locations were determined by the double-quarter VTR observations. These have struck positions within distance of about 1 km from the boundary between the positive and negative areas of the electric field on the ground.3. Lightning characteristics in the flat ground mentioned above were compared with one at Mt. Okushishiku and Mt. Houtatsu in Hokuriku district.4. Lightning surges induced on the three distribution feeders were measured by a memory recorder with 4 channel at the Unoke substation. A waveform of zero-phase-sequence currents induced on the line near the cloud-to ground flash point is different from one on the other lines.5. The capacitive voltage detector using an optical fiber system was produced as an experiment. The improvement in design will be achieved for recording a precise waveform in future.