Feasibility analysis on capacitor Bank Installed in Tenaga Nasional Berhad Substation

Abstract

Generally, reactive power is correlated with voltage in power system. In the high voltage substation, capacitor bank is used to increase back voltage that has been dropped due to high load or long transmission line used for transmitting electricity. In this work, it will describe in general on operation of capacitor bank in the system and details on analysis on performance of capacitor bank especially during failure of capacitor units or elements. In the capacitor bank design, it contains several capacitor units which have been arranged in specified configuration to provide reactive power to the system. A unit of capacitor bank itself contains many capacitor elements that provide capacitance value. There are many designs for arrangement of capacitor units and elements for capacitor bank by the Original Equipments Manufacturer (OEM). As usual, for any electrical equipment that installed in power system, it is protected with protection devices in order to avoid any damaged to the equipment during fault occurred. For failure of capacitor units or elements, it must be detected as well since it will contribute to the unbalance on capacitance value, current and voltage. There are two techniques of detecting failures of capacitor units or elements which are current and voltage techniques. In Tenaga Nasional Berhad (TNB) substation, current technique is most preferable since the lack of voltage technique which is easy influenced by voltage grid system. Two models of capacitor bank that have been installed in TNB substation presently are modeled in PSCAD software for performance analysis aligns with allowable voltage tolerance stated in IEEE Std 18- 1992 and Std 1036-1992. As conclusion, based on performance analysis of capacitor bank during failure of capacitor units or elements, the design of arrangement for capacitor units is very important since the failure of capacitor unit or element will lead to unbalance current in capacitor bank. Furthermore, from the analysis, the numbers of failure capacitor elements which produces to unbalance in the system can be predicted so that alarm and tripping will be triggered to avoid further damages.