Investigation of overvoltage on square, rectangular and L-shaped ground grids of high voltage substations by ATP/EMTP

Ground grid system is important for preventing the hazardous effects of overvoltage in high voltage substations due to fault current perhaps fromlightning strike or device malfunction. Therefore, this study aimed toinvestigate the effects of overvoltage on square, rectangular and L-shapedground grids with ground rods being distributed in mesh-pattern by usingalternate transients program/electromagnetic transients program(ATP/EMTP) program. The models were simulated in the cases that 25 kAfault current being injected into the center or one of the corners of groundgrids. The results showed that the highest level of overvoltage (6.3349 kV)was detected at the corner of rectangular ground grid when the fault currentwas injected into its corner. However, the lowest level of overvoltage wasfound when the fault current was injected into the center of square groundgrid. The results from this study indicated that ATP/EMTP program wasuseful for preliminary investigation of overvoltage on ground grids of different shapes. The obtained knowledge could be beneficial for further designing of ground grid systems of high voltage substations to receive theminimal damages due to fault current.