Phasor estimation technique to reduce the impact of coupling capacitor voltage transformer transients

A new least squares technique to reduce the impact of the transient response of coupling capacitor voltage transformers (CCVTs) on the performance of distance relays is described. Several factors that affect the frequency and time responses of CCVTs are considered. The effect of the transient response on the phasor-estimates is illustrated. An improved least squares technique, which uses the knowledge of the frequency of the CCVT transients while estimating the phasors, is presented. A case, taken from a set of studies, is included to demonstrate the performance of the proposed approach. The robustness of the method is verified by a CCVT parameter sensitivity study.