降低地线感应电压方法及绝缘间隙电压分析

Analysis on Voltage of Insulation Gap and Methods to Reduce Induced Voltage for Ground Wires

为了降低地线损耗,地线通常采用绝缘的方式,但是这种方法会导致地线感应电压过高,威胁带电作业人员安全,所以降低地线感应电压是非常有必要的。以特高压为例,利用ATPEMTP计算3种常用的接地方式下的地线感应电压和电流,并在无损接地方式的基础上,计算对比了不同地线分段长度、换位距离、接地位置和导线相序排列下的感应电压。计算结果表明:中点接地的感应电压是线路末端接地的一半,合理换位间距和分段长度可以降低感应电压至安全限制内。另外,绝缘技术的关键是确定绝缘间隙的大小,最后计算了正常运行工况和故障下的绝缘间隙的电压,确定了绝缘间隙距离,为以后工程建设提供参考。

The ground wire insulation is widely applied to reduce energy loss of ground wires, but this method easily causes high induced voltage, endangering human＇ s safety. Therefore, it is very necessary to reduce induced voltage. An example of UHVAC transmission line is presented to calculate induced current and voltage of ground wires with three common operation modes by ATP-EMTP. Based on no-loss method for ground wires, induced voltage is calculated and compared in different transposition pitch, segment length, grounding position and phase sequence of conductors. The result shows： Induced voltage for ground wires grounded at midpoint is half of that grounded at end of the line; Induced voltage can be reduced to limited value by reasonable transposition pitch and segment length. What＇s more, the key technology of insulation is defining distance of insulation gap. Therefore, induced voltages under normal and fault conditions are calculated to determine size of insulation gap, which provides an example for engineering construction.