Simulation Analysis and Measurement Verification of CVT Dielectric Loss for Its On-line Monitoring

Abstract

Capacitive voltage transformer (CVT) is an important high-voltage equipment and widely used in power systems for electric energy metering and relay protection. Dielectric loss can reflect the health of CVT. In order to obtain dielectric loss of CVT with non-stopping power, it is necessary to study the online monitoring method of CVT dielectric loss. In this paper, simulation analysis and measurement verification of CVT dielectric loss for its on-line monitoring were carried out. The on-line monitoring dielectric loss simulation model for 10 kV CVT was established. Dielectric loss values by changing the parallel resistance and the capacitance were simulated. Verification of simulation results by dielectric loss measurement on a 10kV CVT model was performed. Results show that the dielectric loss obtained by taking the phase of PT secondary voltage as the phase of CVT secondary voltage can reflect the actual dielectric loss change, but it is impossible to judge whether it is C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> or C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . The dielectric loss obtained from the phase of CVT secondary voltage itself can not reflect the actual dielectric loss change of C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> , but can reflect the actual dielectric loss change of C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . If the two methods are applied simultaneously, it can accurately determine on which part of the dielectric loss occurs. The actual measured dielectric loss of CVT is consistent with those simulated results. The method introduced in this paper provides theoretical support for on-line monitoring of CVT dielectric loss.