Critical design aspects for reliability of 1200 KV UHV ac capacitor voltage transformer under severe system conditions Tiwari R.K., Kurre M., Mahendra S., Naik K.M., Dhamija A. Bharat Heavy Electricals Limited, Bhopal, India Online published on 27 May, 2013. Summary Indian Power system is expanding at an accelerated pace due to rapid industrialization. The Planning Commission projections indicated 3 times increase in peak demand by 2021–22. Power generating units are being installed more and more at remote places due to unevenly distributed energy sources in the country. Right of Way, High Transmission losses, economical transmission of bulk power over long distances etc are the main factors for considering the up-gradation of existing transmission system voltage in a country like India having dense population. 1200 kV is considered as the next level transmission voltage to overcome the above challenges.[1] Capacitor Voltage Transformer (CVT) is used in the power system for measurement of voltage, protection of Bus Bar against over voltage and PLCC (Power Line Carrier Communication) application. It is one of the most complicated equipment in the switchyard because of its sensitivity to the system transients. This paper discusses the critical design aspects of a reliable CVT considering the system severity and all system transient conditions like ferroresonance, Electrostatic field distribution, Air saturation at high switching transient voltages, Corona Suppression etc. This paper also illustrates the anticipated problems for reliable operation of the equipment and recommendations to overcome these problems. Some of the unique features of 1200 kV CVT discussed in this paper are internal and external design of Capacitor voltage divider, various methods of ferroresonance damping and the method adopted in 1200 kV CVT, electrostatic field distribution and design of corona shields. Apart from the above unique features, the 1200 kV CVT has to withstand many system transients in the system which can affect its performance. As the solid state relays are used, the CVT has to faithfully reproduce the changes on the primary voltage but this is also the time at which transients are produced in the systems. The CVT needs to be designed to take care of these transients, so that much superior transient response is guaranteed. Finally the approach for successful development and testing of 1200 kV Capacitor Voltage Transformer is illustrated in this paper. Top Keywords Capacitor Voltage Transformer, Capacitor Voltage Divider, Intermediate Voltage Transformer, Electrostatic Field Distribution, Ferroresonance, Damping, Air Saturation. Top |