An approach to improve grounding resistance characteristic in existing 115 KV transmission towers

Abstract

Effective grounding can attenuate fault currents and reduce damage to power system equipment, making the grounding system a crucial protection scheme. Generally, the ground resistance is set to a value less than 10 Ω. However, in practice, it is difficult to achieve this in certain areas, such as mountains, plains, and swamps. To address this problem, this study analyses the (1) actual footing resistance, (2) ground resistivity, and (3) ground length of transmission towers located in specific areas. Non-linear factors, impedance, and coupling effect are considered instead of traditional variables. A grounding design algorithm is proposed based on the ATPDraw program. Simulation results are applied to the 115 kV real-world system of the Electricity Generating Authority of Thailand. The grounding system exhibits a satisfactory performance improvement, as evidenced by comparisons between simulation and actual measurements. The findings are useful for implementing future improvements in grounding protection schemes.

Keywords

• Grounding system
• Transmission towers
• Lightning strikes
• Electrical grid
• Ground resistance
• Ground impedance