An Interference-Rejection Strategy for Measurement of Small Current Under Strong Interference With Magnetic Sensor Array

Abstract

Traditional infrastructure and instrumentation methods in power system are transforming to cater the needs of modern and smart grid applications. In this process, contactless broad range electric current measurement has emerged as a hot research field. Under this background, an improved strategy of current measurement has been proposed in this paper to solve the problem of large crosstalk error in scenarios where the measured current is much smaller than the interfering current. In the proposed strategy, two magnetic sensors with a piece of curved magnetic shielding layer constitute the measurement structure, in which the effect contributed by the interference is damped by summing up the magnetic field detected by the two sensors with the opposite sensitive direction and by the magnetic shielding. It has been demonstrated by experiments that this improved strategy can estimate the targeted current with the minimum drift of 0.19 A when the real value of the targeted current is 0 A. The finite-element analysis proves that the deviation is 0.21 A, while the interfering current changes from 1 to 10 kA. Based on these results, the proposed easily installed structure with high accuracy proves its immense potential application of current measurement in smart grid.