EQUIVALENT-CIRCUIT MODELING OF A CAPACITIVE VOLTAGE TRANSFORMER FOR POWER-SYSTEM HARMONIC FREQUENCIES

This piper presents a lumped parameter equivalent circuit for a practi cal cvt for the frequency band associated with power system harmonics. Measured parameter values are presented for a commercial 400 kV unit. Measured and simulated frequency responses are given tar a practical cvt and the observed resonant modes are interpreted with reference to the equivalent circuit parameters. It is shown that the frequency resp onse of a practical cvt exhibits marked bandpass and bandstop characte ristics due to resonances associated with the capacitive divider, the intermediate voltage inductor and stray capacitive elements, particula rly the winding capacitances of the intermediate voltage inductor and the intermediate voltage transformer. The role of the transient dampin g arrangement and the secondary burden is discussed with reference to the Q-factors of the observed resonance perks in the overall frequency response.