Design and Analysis of an L-Shape Grid Grounding System for 150 kV Substation

A Substation is a part of electric power systems that have the potential to experience disturbances such as short circuit currents and lightning impulse voltages. A grounding system aims to improve substation protection and reduce the effect of these disturbances. This study aims to design and compare the performances of L shape grid grounding system with and without rod, therefore will give the optimal and effective grounding system. The method used is to change the number of x and y axis of grid conductors to obtain the configuration which fulfills the grounding criteria based on the IEEE Std.80-2000 standard. For L Shape grid grounding system, effective data was obtained, where the number of x and y axes are 9 and 22, respectively where this configuration needs 1700 m total conductor length. It shows that the design provides grounding resistance is 0.676 ohms, the mesh voltage is 727.1 V and the actual step voltage is 364.7 V. Furthermore, for L Shape Gird with rod grounding system, the effective design was obtained with number of conductors on the x and y axes are 7 and 20 respectively, while it needs 1425 m conductor length and 6 m rod length. This L shape with rod provides the grounding resistance at 0.687 ohms. The mesh voltage is 726.9 V and the step voltage is 361.4 V. Based on the use of materials and its mesh voltage, it can be conclude that the grounding system using L Shape grid with rod is more effective and has better performance.