Simulation Study of Non-contact Measurement of Three-core Cable Current Based on Magnetic Inversion
Due to the small laying workload,three-core cables are widely used in medium and low voltage power grid lines.The load current detection of three-core cables is of great significance for studying the power quality of the power grid and improving the fault diagnosis ability of the line.However,conventional current detection devices face many challenges when measuring the current of three-core cables.The current transformer has the disadvantage of requiring fixed installation and is difficult to a-chieve portable measurement.The magnetic field-based clamp current sensor has the characteristics of non-contact sensing and easy operation,and is widely used on site.However,during normal steady-state operation,the three-phase current vector sum of the three-core cable is zero,and conventional magnetic field-based current sensors cannot measure the current magnitude any-more.Therefore,this article proposes a current measurement method for three-core cables based on magnetic sensor arrays.To verify the correctness of this non-contact measurement method,COMSOL software was used to obtain the magnetic field distri-bution around the three-core cable.The results demonstrated that the magnetic field of the three-core cable exhibited a periodic distribution around the circumference,with the maximum value appearing at the closest position to the conductor.The magnetic field amplitude was influenced by the distance from the conductor and the current frequency.The farther the distance from the conductor,the higher the current frequency,and the smaller the magnetic field.Based on this distribution,a magnetic field-based current measurement method for three-core cables is proposed.The current of the three-core cables is obtained through inversion calculation based on the measurement results of the magnetic sensor array.This method can accurately measure the current of three-core cables,with a calculation error of less than 3％,providing a new approach for non-contact measurement of three-core cable current.
current monitoringmagnetic field sensingpower cablesnon-contact measurement
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