Overvoltage Occurrence Due to Ferroresonance Phenomena During The EHV Cable Feeder Charging

EHV cables have higher capacitance and a larger current, which increases the possibility of overvoltage occurrences during the charging. A 400kV EHV cable experienced a long-duration overvoltage incident that damaged the Lightning Arrestor. The incident was analyzed using EMTP®, and mitigation methods for cable charging were proposed. The EMTP simulation and site relay measurements matched closely. The presentation will share the analysis results and mitigation methods.