Analysis of transient signals in a substation capacitor bank system using an experimental setup

The capacitor bank system is one of the important systems in an electric utility, with the benefit of power factor correction and reactive power compensation for transmission and distribution systems. Installation of a capacitor bank system in a substation causes transient signals when switching occurs. The aim of this research is to study the transient signals that occur when the capacitor bank is switched in each step. A capacitor bank-switching experimental test unit has been built to create a downscale capacitor bank system in a distribution-level substation. This unit was modelled after the NongChok substation under the Electricity Generating Authority of Thailand (EGAT). The impact on the distribution system when the capacitor bank is switched has been studied, and phenomena such as inrush currents, voltage transience, and frequency oscillation are taken into consideration. A method to reduce transient issues has been discussed and implemented in the test unit to evaluate the performance impact of these methods on a switching capacitor bank system.