A novel non-invasion magnetic sensor array based measurement method of large current

Abstract

The development of smart grid calls for pervasive deployment of current measurement in the power transmission and distribution system, serving for monitoring, control and protection purpose. However, traditional methods fail to measure current with bandwidth from direct current to kHz and are inconvenient to install or dismount. In this paper, a novel current measurement method with a clamp-like structure is proposed to alleviate the magnetic interference from random sources. This method is based on a special magnetic sensor array which consists of three pairs of sensors. In each pair, the sensitive directions of the sensors are opposite. Besides, positioning calibration of the conductor under measurement is considered in order to reduce the error contributed by the displacement uncertainty of the conductor. The proposed design is tested by numerical simulation and finite element analysis (FEA). For peak current up to 500 A, the maximum error is 0.6532%. A prototype is then implemented and tested in laboratory experiments to demonstrate the performance of the proposed approach for measurement and protective purpose. From the results, the maximum error is 1.73%, which is compatible with standard IEC 60044-8:2002 accuracy classes for protective electronic current transformer.