An Improved Method for Measuring Grounding Resistance of Transport Tower

Abstract

The grounding resistance of the transmission line tower is an important parameter to ensure the safe and stable operation of the power system. The accurate grasp of this parameter is the premise of formulating appropriate lightning protection measures for the power system. Since the periodic test task of the tower grounding resistance is heavy and half of the towers are located in the mountainous area, the conventional three-pole test method is difficult to carry out, so most of the tests are currently carried out by the clamp method. Generally, the high-voltage transmission line tower in operation senses the interference signal with amplitude variation on the grounding device. However, the caliper test instrument in the domestic market is weak in anti-interference, which results in large test error and cannot meet the requirements of on-site measurement. This paper presents an improved caliper type tower grounding resistance measurement method. The method is based on the principle of the clamp method, injects the adjustable frequency excitation voltage source, automatically switches the excitation source frequency through the self-check interference signal frequency band, avoids the interference signal frequency band, and obtains the response signal by loading the digital filtering module, and calculates the in-service Tower grounding resistance. The method has passed the test verification, which greatly saves human and financial resources, improves the accuracy value of the grounding resistance of the transport tower, and has a large application prospect.