Contactless current measurement for suspended overhead lines using a magnetic field sensor array

In this study, a long-distance non-contact current measurement method is proposed based on the non-contact sensor array measurement technology, combined with a new current algorithm. The sensor array is a vertical array composed of three three-axis magnetic field (MF) sensors that is placed on the ground plane below the measured overhead line. The proposed current algorithm can optimize the geometry of the overhead line using the spatial MF values measured by the sensor array and then the three-phase currents can be calculated. To improve the accuracy of current measurement, the spatial MF model in the algorithm considers the influence of cable sag. It enables a more accurate coupling matrix between the measured overhead line and the sensor array to be established. Additionally, the current algorithm architecture is designed using a composite algorithm to more optimally obtain the best three-phase current values. A scale-down overhead-line measurement system is developed to test the proposed current measurement method. The results show whether a cable sag exists when the three-phase currents are approximately balanced, with errors less than 2.0%. Moreover, it can be determined whether cable sag exists when the three-phase currents are unbalanced, with less than 3.4% errors. This study proposes a non-contact overhead line current measurement technology for suspended overhead lines. By simply placing a vertical sensor array on the ground to measure the spatial magnetic field and providing initial values based on the power company's overhead-line specification, the proposed composite current algorithm can accurately evaluate three-phase currents. image