Prediction of voltage sag in the transmission system of Vietnam, A case study

In this paper, a novel effort for prediction of voltage sag in the entire transmission system of Vietnam is presented. As the Vietnamese electricity industry moves toward the electricity market, prediction will help utilities have early assessment of power quality in transmission system. The proposed prediction approach uses a fault position method in which the fault distribution in the transmission system is created based on an actual fault occurrence in the entire 220kV and 500kV transmission system throughout Vietnam that took place in 2008. The research also makes use of the SARFI_CURVE with ITIC and SEMI curve, which takes into account of the actual fault clearing time of protective devices used in transmission system in Vietnam. By using SARFI_CURVE, a better assessment of voltage sag performance is obtained in the transmission system with regard to load´s voltage tolerance.