The Impact of Zero-sequence Current Transformer Measuring Accuracy on High-impedance Earth Fault Detection in Distribution Networks (CICED2022)

Abstract

High-impedance earth faults in medium voltage distribution networks are very difficult to detect and isolate because of the negligible fault current. The reliability of high-impedance earth fault detection depends on the measuring accuracy of zero-sequence current transformers. There are many published studies in the field of earth fault detection in distribution networks, which lacks the research on engineering problems such as the influence of the measuring accuracy of the zero-sequence current transformer and its selection. This paper firstly analyzes the influence of zero-sequence current transformer measuring accuracy on detection. The paper then presents the measurement error test results on the common types of zero-sequence current transformers used in projects. Finally, combined with the measurement error test results, the paper proposes guidelines for the selection of the zero-sequence current transformer and the measures to be taken to improve its measurement accuracy. (Abstract)