Investigation of voltage sags due to faults in MEA´s distribution system

This paper reports an investigation to determine the magnitude and duration of voltage sags by faults simulation method in a simplified distribution system of the Metropolitan Electricity Authority (MEA). The three-phase faults and single line-to-ground faults on transmission and distribution radial systems are simulated in order to obtain voltage sag magnitudes at both source and load points. The operation of power system protection is discussed and the voltage sag duration is derived. The voltage sags in the MEA service area were surveyed by real time monitoring at both distribution substation and customers´ facility. The monitoring results were analyzed and were found to agree well with the simulation study. Each sag event was represented by a dot and was reported on the Computer Business Equipment Manufacturing Association (CBEMA) curve. From CBEMA curve, it can be concluded that appropriate setting of ride-through capability of the sensitive equipment can reduce the effect of disturbance from voltage sags.