FERNANDES JÚNIOR, D.; http://lattes.cnpq.br/3630883713661678; FERNANDES JÚNIOR, Damásio.
Résumé:
Electric utilities have reported unexpected overvoltage protective device
operations in several coupling capacitor voltage transformers (CCVT) leading to failures of
some units. Many works have been carried out to study the performance of the CCVT.
However, there are many problems to obtain correct models due to the small number of
available data found in literature, which are very important for validation purposes. The
current thesis presents a CCVT model for electromagnetic transient studies which
comprises linear and nonlinear elements. The following contributions are presented: a
methodology to estimate the linear parameters from frequency response data; an accurate
CCVT model in time-domain digital simulations, validated from laboratory measurements
of transient overvoltages. The proposed model may easily be used in connection with the
EMTP (Electromagnetic Transients Program). In the fitting process, constraints are needed
for a fine adjustment of some previously expected 60 Hz parameters. The results may be
used to predict the CCVT performance when it is submitted to transient overvoltages.
