Improvement of Reliability and Efficiency of Lightning Protection of Overhead Transmission Lines by Reducing Grounding Resistance

Abstract

The analysis of methods of artificial reduction of grounding resistance, applied in places with a high specific resistivity of the ground, has been carried out. As a result of the analysis, the most effective and long-term method of artificial underestimation of soil resistance was determined. The main requirements for a grounding device are determined in accordance with the current regulatory documentation

The analysis of the influence on the change of grounding resistance on the reliability and efficiency of lightning protection of overhead transmission lines (OTL) has been carried out. A series of mathematical simulations for OTL supports with different ground resistance values was performed, as a result of which the curves of dangerous parameters were constructed, and numerical characteristics of the lightning protection reliability were calculated.

The impulse factor for calculating the impulse resistance of grounding was determined, as a result of which a series of mathematical simulations were carried out and indicators of the reliability of lightning protection in absolute and relative units were calculated.

The probability of occurrence of dangerous atmospheric overvoltages was calculated from the value resistance of the grounding when the lightning strikes conductor or the cable of the OTL.

As a result of the conducted studies, the regularities between the values of the ground resistance and the probability of the appearance of a impulsed discharge on the insulation of the transmission line, as well as, the regularities between the magnitude of the impulse resistance of grounding and the values of the parameters of dangerous overvoltages were determined. It has also been found that the reduction of the grounding resistance of tower of OTL with a cable is one of the main ways to reduce the probability of impulse overlap of insulation when a lightning strikes a cable or a resistance.