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Project: T083700 #3113

Shunt capacitor banks are applied universally on power transmission and distribution networks for power factor correction to regulate voltage and reduce losses. Their ratings typically range from 10 MVAr to 400 MVAr when applied at substations, depending on the level of reactive power compensation required. Because individual capacitor units are manufactured in ratings limited to about 20 kV, 1000 kVAr, numerous units need to be interconnected in series-parallel arrangements to support the desired voltage and to achieve the desired reactive power rating. Over the years, various capacitor bank arrangements have been configured and applied on utility networks, differing in banking arrangement and grounding practice, fusing of individual capacitor units, unbalance and surge protections, measures for accommodating multiple units at the station, primary and backup switching devices and configurations, switching strategy for minimizing system impact, and measures for limiting impact on nearby apparatus.

This report presents the findings of a project with the primary objective of reviewing and summarizing utility practices in the design and operation of shunt capacitor banks used at station buses for power factor correction. It also briefly reviews certain application issues warranting special attention based on a review of available published literature, a survey conducted among utilities, and firsthand knowledge of utility practices and experiences.

Keywords:Capacitor bank, reactive control, capacitor protections, capacitor switching