The fault in a power distribution system disturbs the power dispatch under normal conditions therefore decreases the quality of the electric power. The single line to ground fault is an asymmetric fault that may have a high percentage chance to happen. The kind of fault changes power and voltage dramatically. The size of the phase voltage decreases which affect the economic damage of the system. This paper presents an analysis of grounding systems to reduce voltage drop in a power distribution system by using the technical analysis system in case of one phase to ground fault. The objective is to minimize voltage drop for users using the simulation with single line to ground fault in distribution system voltage level at 22 kV PEA’s test system. The simulation utilizes the EMTDC-PSCAD program. The results show that the grounding method can reduce the voltage drop and reduce the damage of the economic system

The analysis of the grounding system overvoltage in High voltage substation will be held at Bumnetnarong substation Electricity Generating Authority of Thailand ( EGAT ) by using ATP draw for grounding system’s model of substation also to model overvoltage from lightning and to read the result of overvoltage from differences positions. The advantages of the experiment are to be educated and to who design Grounding system in high voltage substation EGAT. The Study’s result of the over voltage level on Ground Potential Rise: GPR model shows that the pie will show close result to the result from the calculation by standard IEEE Std 80-2000 and the result of the Fault Current at the middle position of the grounding system will result in higher overvoltage than at the result at the corner position of Grounding system. The result of Ground Resistance: Rg shows that the increasing of overvoltage the increasing of Ground Resistance: Rg