TRANSIENT SIMULATION STUDY FOR THE 1500 KM NORTH-SOUTH 500 kV INTERCONNECTION IN VIETNAM

To assess the performance required for the 500 kV equipment, an exhaustive electromagnetic transient study was performed for the design of the existing NorthSouth seriescompensated 500 kV interconnection in Vietnam. This study covered several aspects such as : the transient recovery voltages (TRVs) across the 500 kV circuit breakers (CBs), the temporary and snitching overvoltages (TOVs and SOVs) in the 500 kV system, the energy stresses on the metal-oxide varistors (MOVs) protecting seriescapacitor banks as well as the analysis of secondary arc current extinction. All those aspects were thorough ly investigated. These study results have allowed the selection of the 500 kV circuit breakers to withstand severe TRV conditions on series compensated lines. A special protection scheme has also been devised to control temporary overvoltages in the 500 kV system in case of total load rejection. Moreover, the MOV design criteria have been established in light of study results. Finally, the efficiency of the installed reactor neutral circuits for secondary arc current extinction has also been verified.