Analyzing the Impact of Ground Resistance on Distance Relay Performance with Mho Characteristics

Ground resistance (Rg) plays an important role in designing, operating, and maintaining transmission lines (TLs). This paper investigates the impact of ground resistance along the TL route on the performance of a distance relay with Mho characteristics. The performance of the distance relay has been investigated for various types of faults and a wide range of Rg changes. The effect of soil resistivity on impedance trajectory in single-line-to-ground faults in boundary point faults is investigated. The results show that Rg can lead to alterations in the line’s electrical characteristics, affecting signal transmission, power losses, and overall system efficiency that is not considered in distance relay settings. A simple 2-bus network is used in PSCAD/EMTDC software to simulate and implement distance relay settings. Also, MATLAB software has been used to calculate phase sequence impedances due to Rg changes. The simulations performed in the 2-bus test system show a significant effect of Rg on the performance of the distance relay.