Uma técnica para compensação dinâmica de transformadores de potencial capacitivos.

Abstract

The aim of this work is to present a compensation technique to dynamically correct the disturbances produced by the coupling capacitor voltage transformers (CCVT) secondary voltage. The compensation technique is based on the recursive digital filter of the CCVT secondary voltage, whose frequency response is used as input data to a software that computes the linear elements of the CCVT model. The parameters of the compensator (recursive digital filter) are obtained from the CCVT transfer function and from a compensated CCVT model, whose parameters are estimated from a fitting process. The validation of the technique is carried out by means of digital simulations using the ATP (Alternative Transients Program) and the MODELS language, which provides a dynamic interaction with the ATP. The analysis of the dynamic compensation of two CCVT are presented: one CCVT unit of 138 kV reported in literature and one unit of 230 kV made available by Companhia Hidro Elétrica do São Francisco (CHESF). In order to evaluate the strategy of compensation in time and frequency domains, three case studies are analyzed: the CCVT response with the proposed compensator, the CCVT response without compensation and the response of an ideal voltage divider. The digital simulations show that the dynamic compensation of the CCVT may be used to improve the performance and reliability of measurement, protection and control systems.