Auto-reclose performance on 275 kV and 132 kV transmission line in Malaysia

Most faults on a transmission overhead line are transient in nature. Malaysia, with a high isokeraunic level of about 180 thunder day/year suffers many high transient faults which if not looked into affects reliability and quality of supply to the customers. Auto-reclosures are used on the transmission lines to carry out this duty. On the 275 kV lines single and three-pole auto-reclosure are used whilst on the 132 kV only three-pole auto-reclose is used. The percentage of three-pole auto-reclose failure has traditionally been high. This paper highlights the steps taken to improve the performance of the three-pole auto-reclose as follows: (a) look into the inherent characteristic of the synchronism-check relay especially the built in time in order to successfully synchronize the system; (b) simulation done on certain parts of the line due to large angle difference when a double circuit fault occurs; (c) look into the setting of the auto-recloser to suit the configuration of the system during disturbances; (d) and multi-pole recloser for critical lines according to joint study by TEPCO-TNB.