An online self-correction method to improve accuracy of split-core current transformer in low-voltage distribution networks

Teng, Jie, Wang, Shaorong, Jiang, Lin ORCID: 0000-0001-6531-2791, Xie, Wei, Fang, Chen and Liu, Shu (2022) An online self-correction method to improve accuracy of split-core current transformer in low-voltage distribution networks. Measurement, 195. p. 111052.

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Abstract

Split-core current transformer (CT) has been widely used in low-voltage distribution networks due to the merit of live-line installation. However, as the air gaps of the iron core exist, there is a possibly varying magnetizing error, which will severely degrade the accuracy of split-core CT, caused by manual installation deviation, vibration, and temperature variation in field operation. To tackle this issue, this paper proposes an online self-correction method to improve the measurement accuracy of split-core CT. The proposed method contains (1) an auxiliary winding loop (AWL) added to the split-core CT, to temporarily and intermittently operate in on/off modes; and (2) a self-correction algorithm (SCA) based on the operation of the AWL, to online determine the varying errors and then to give corrected measurement results. Moreover, a low-cost solution for embedding the proposed method in multiple split-core CTs in low-voltage distribution network is provided via series-connecting the AWLs. For validation, a prototype embedded with the proposed method is implemented, and is tested versus different applied primary currents and burdens. The test results exhibit that the proposed method effectively improves the measurement accuracy to a high class (0.2). Also, the proposed method’s robustness to varying gap lengths and temperatures is verified. Notably, even under the extreme condition with a 0.520 mm gap, the measurement errors are reduced from the inherent values up to 30.9% and 648 mrad to a satisfactory range below 0.195% and 0.295 mrad, respectively.

Item Type:	Article
Uncontrolled Keywords:	Split-core current transformer, Varying magnetizing error, Auxiliary winding loop, Self-correction algorithm, Low-cost implementation
Divisions:	Faculty of Science and Engineering > School of Electrical Engineering, Electronics and Computer Science
Depositing User:	Symplectic Admin
Date Deposited:	05 Apr 2022 14:44
Last Modified:	29 Mar 2023 01:30
DOI:	10.1016/j.measurement.2022.111052
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3152175