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

• The study operates in two modes: actual observation and simulation. Several 115 kV transmission systems of EGAT were observed, while simulations were conducted using the ATPDraw program. • The performance of the proposed method was validated by comparing actual and simulation observations. • This study considers the effects of complex variables such as impedance resistance, which were not considered in previous studies. 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.