Large diameter and high sensitivity high voltage DC cable leakage current detection sensor

Abstract

The invention discloses a novel large caliber high sensitivity leakage current detection sensor for a high voltage cable. The detection sensor comprises a closed loop cross-core annular core, measurement coils and a current signal acquisition processing circuit. The fluxgate technology is utilized to design a closed annular core utilizing high magnetic permeability and low coercive force material, a center caliber of the annular core is made not to be smaller than 40mm for penetration of the to-be-detected high voltage DC cable, a four-quadrant symmetric winding method is employed in an excitation coil to wind on the annular core, a response coil is symmetrically wound on the annular core, and the current signal acquisition processing circuit employs closed loop feedback control to form a deep negative feedback circuit. The leakage current detection sensor has advantages of high precision, good stability and strong anti-interference capability, DC leakage currents in a range of hundreds of microampere to tens of milliampere can be measured, sensitivity can reach 100 microampere, and purposes of leakage current measurement and insulation state evaluation of the high voltage DC cable can be realized.

Description

technical field [0001] The invention relates to the field of power system signal acquisition, in particular to a large-caliber high-sensitivity high-voltage direct current cable leakage current detection sensor. Background technique [0002] With the gradual development of power grid construction, HVDC transmission has been paid more and more attention due to its advantages of low cost and no magnetic induction loss. However, during the operation of high-voltage DC cables, intermittent power outages are likely to form a large amount of space charge. According to the electric tree breakdown theory of XLPE cables, this long-term local electric field action causes the electric tree in the insulating layer to grow continuously to form a discharge channel, coupled with the uneven existence of XLPE insulation materials in the manufacturing process , eventually leading to a decrease in insulation resistance or even a risk of breakdown. Therefore, the development of high-voltage d...

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Problems solved by technology

[0005] According to the characteristics of the high-voltage DC cable line, the common weak current sensor has a small measurement caliber. In the engineering application site, the diameter of the grounding cable must be smaller than the inner diameter of the current sensor, and the high-voltage DC cable shielding cable has a larger outer diameter, so this type of small caliber Weak current sensors cannot be applied to the measurement site for leakage current detection

In addition, when the high-voltage DC cable is in normal operation, the leakage current is usually in the microampere level, which is extremely small. However, the detection accuracy of the existing common weak current transmission is generally in the milliampere level. The detection sensitivity is low and the accuracy is poor. The purpose of leakage current measurement. At the same time, when the environmental noise of the transmission line is greatly affected, its measurement effect will be worse. Therefore, the common weak current sensor cannot be applied to the on-site high-voltage DC cable leakage current measurement and insulation state assessment.

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