Integrated volt/var control using single-phase capacitor bank switching

Abstract

Electric utility distribution power systems as operated today are rarely perfectly balanced. While feeders with single-phase voltage regulators (VR) tend to be more balanced, feeders with substation transformers that have load tap changer (LTC) or line capacitors only for voltage control are more challenging to balance. BGE distribution system has very few LTCs and VRs. Both voltage and VAr control is done by utilizing the line capacitor banks that are switched as a function of substation transformer loading and low side bus voltage. Utilizing this approach, voltage balancing on feeders results in a set of unique challenges. As a result, BGE developed new approach that includes the use of capacitor bank controllers that support single phase capacitor bank switching along with singlephase voltage and current sensors installed at capacitor bank locations for voltage and current measurements. Capacitor banks controllers will be equipped with an internal battery and will also serve as fault circuit indicators. This paper introduces a new approach for integrated volt/VAr control that has two objectives: minimizing the overall energy demand known as Conservation Voltage Reduction (CVR) and improving the voltage balancing index (VBI) along the feeder based on singlephase capacitor bank switching. BGE intends to use the internally developed IVVC algorithms for the approach and is in the process of piloting this solution at two of its substations.