CAPACITIVE VOLTAGE TRANSFORMER MODELS FOR OPTIMAL DISTANCE RELAYING PROTECTION SCHEME

Abstract

Transient in capacitive voltage transformers (CVTs) usually employed as  instrument transformer for high voltage, long distance transmission line protections have been causing a lot of damage. This is due to false or non-triggering of protective relays. A lot of techinques have been identified for reduction of the transinets such as use of high value capacitors application of ferroresonance suppressed circuits resulting to the linear models of CVT (Active and Passive Ferroresonance suppressed circuits AFSC and PFSC). This work employs AFSC and PFSC models and investigates how the system impedence ration (SIR) employed CVT transient detection logic can be further used to reduce the CVT transients for optimal long distance relays protection scheme. The result shows an improved CVT transient detection using the SIR and transient detection logic whic is more precise than the past detection methods and does not penalize distance protection speed for close-in-faults