Towards a Three Phase Local Substation IT Calibrator using PMU Data

Abstract

Under URTDSM project, instrument transformers in 400 kV and 765 kV substations are to be calibrated using PMU data. This paper reviews existing methods for soft calibration using synchrophasors and discusses practical difficulties encountered in this activity. The paper suggests that it is feasible to develop a local substation based CT and CVT calibration system using data centric approach. This approach will be both simpler and superior vis-à-vis existing paradigm. Such calibrator can be implemented with ease provided substation transformer and shunt reactor CTs are wired to PMUs. Sensitivity analysis is carried out to bring out the importance of this activity and feasibility of carrying out physical CT calibration is also discussed.