Designing a compensating electronic circuit to enhance capacitive voltage transformer characteristics

Abstract

Capacitive voltage transformer (CVT) is widely used to convert high voltage signals to low voltage ones for measurement, protection and control. It has poor dynamics which can lead to maloperation of protective relays. Moreover, CVT has a non-smooth frequency response and limited band width which make it inappropriate for system harmonic measurements. This paper proposes a new method for decreasing CVT voltage distortions and correcting CVT dynamic response as well as its steady state response. An electronic circuit is designed so as to reproduce CVT transients. The final output which is the summation of CVT voltage and the designed circuit voltage has considerably low distortions and is a replica of the input voltage. The proposed method is independent of the load and the Ferroresonance Suppression Circuit (FSC) connected to the CVT. Simulation results confirm the efficiency and accuracy of the proposed method. Finally, CVT percentage error for the proposed method is compared with the dynamic compensation method.