BRIDGE CAPACITOR BANK DESIGN AND OPERATION

The concept of a bridge capacitor bank installation was presented in a previous paper [1]. This paper discusses design and operation aspects related to the installation of a bridge capacitor bank in a substatio n. The 138/69 kV bridge capacitor bank installation presented in [1] i s analized. An automatic switching control relay scheme for the same t est installation is also discussed. The control scheme takes into acco unt the dual effect a bridge capacitor installation has upon the elect rical power system: it generates reactive power on the station 138 kV bus and transfers reactive power from the 69 kV to the 138 kV bus. An unbalance protection scheme preventing the cascading type failure of t he capacitor units in the 138/69 kV bridge capacitor bank is also pres ented. An unbalance protection scheme for high voltage, large MVAr siz e bridge capacitor banks is also discussed. Simple analytical formulas with practical value to evaluate the magnitude and frequency of the v oltage transients generated by the energization of a bridge capacitor bank are presented. Recorded switching transient magnitudes and freque ncies are compared with calculated values.