A Method of Applying Switched and Fixed Capacitors for Voltage Control

This paper presents the method used by the Pennsylvania Power & Light Company (PP&L) to control voltage on the distribution system. This method utilizes a combination of switched and fixed capacitors on the distribution circuits and allows the exclusive use of tapless distribution transformers. The fixed capacitor requirements are determined on the basis of maintaining a nearly flat voltage profile at light-load circuit conditions and the switched capacitor requirements are determined on the basis of maintaining a nearly flat voltage profile at peak-load circuit conditions. Time recalibration control on the switched capacitors provides optimum voltage control over the daily load cycle. Some information is given concerning the distribution circuit losses and the overall system savings resulting from the use of capacitors.