Study on the Voltage Traveling Wave wavefront Detection for CVT

Voltage traveling wave wavefronts are essential for the traveling-wave based relays. capacitive voltage transformers (CVTs) are the predominant source of the voltage signals for the relays in HV/EHV/UHV power systems. To study the influence of the CVT on the detection of the voltage traveling wavefronts, this paper firstly analyzes the frequency response, especially the high frequency response of the CVT with the transfer function. The contributing factors to the high frequency response of the CVT are deeply studied. Then the companion model of the CVT is modeled and the wavelet transform is utilized to simulate and analyze the influence of the CVT on the voltage traveling wavefronts The study results show that the CVT causes severe attenuation and phase shift for the high frequency components, consequently it seriously suppresses and disturbs the voltage traveling wavefronts. Adjusting the parameters of the CVT can improve the wavefronts in the CVT´s output, but serious errors are still inevitable. Further study is needed to recover and detect the wavefronts precisely from the CVT´s output