Experimental and Numerical Study of Division Factors of Fault Current and Measuring Current Due to Ground Wires of Transmission Lines

Due to the shunting action of the overhead ground wires of transmission lines or the neutral conductors connected to substation grounding, evaluating the ground wire division factors is a key step while designing the substation ground system or measuring the grounding resistance. In this paper, the principle and calculation models of the fault current division factor and the measuring current division factor are analyzed. The distinctions and relations of the two division factors are discussed. A method to evaluate the fault current division factor based on the measuring current division factor is put forward. Both the fault current division factor and the measuring current division factor are measured in a 220-/110-kV substation. The simulation results are in good agreement with the measured ones.

I. Introduction

The grounding system is an important component for safety in a substation [1]. Evaluating the performance of a grounding system is not only necessary during the design process but also very important for the substation in operation [1]– [9]. During the design process, grounding resistance, touch voltage, and step voltage should be calculated to make sure that the grounding system is safe enough when a fault occurs [1]– [4]. During operation, the aforementioned parameters should be measured regularly to evaluate if the grounding system needs maintenance [5]– [9].