An anti-interference current sensing fiber and a current sensing fiber loop made of the same

Abstract

The invention discloses an anti-interference current-sensing optical fiber. The sensing optical fiber is a double-refracting polarization-maintaining optical fiber, and the double-refracting polarization-maintaining optical fiber sequentially comprises a non-spiral area, a variable-speed spiral area and a constant-speed spiral area, wherein the tail end surface of the constant-speed spiral area is provided with a reflecting film, the variable-speed spiral area is in the shape of one ring or two rings, and the starting point and the ending point of the variable-speed spiral area are kept coincident at spatial positions. The invention also discloses a current-sensing optical-fiber ring made of the sensing optical fiber, wherein the tail end of the constant-speed spiral area and the starting point as well as the ending point of the variable-speed spiral area are kept coincident at the spatial positions. The anti-interference current-sensing optical fiber has the advantages of simple structure, light weight and easiness in realization, and the sensibility of the optical fiber at the variable-speed spiral area for an outside magnetic field can be inhibited to a great extent; the anti-interference current-sensing optical fiber is unrelated to the frequency of current or an electric field, so that the basic characteristics of the optical fiber at the variable-speed spiral area are equivalent to the characteristics of the optical fiber at the non-spiral area, and therefore the precision of a current transformer and the anti-interference property of the sensing optical-fiber ring are improved.

Description

technical field [0001] The invention relates to an anti-interference sensing optical fiber and a sensing optical fiber ring in a current sensor, in particular to a reflection-type all-optical fiber current sensor which is used for measuring current and performing relay protection in a high-voltage transmission line and has the ability to resist external electromagnetic interference. Sensing fiber or sensing fiber ring. Background technique [0002] As one of the key equipment of high-voltage transmission main line, all-fiber current sensor (or transformer) has been favored and valued more and more by the international electric power industry. Famous power equipment manufacturers at home and abroad, such as ABB, Alstom, NARI Aerospace, NARI Jibao, China Electric Power Research Institute, etc., hundreds of enterprises and research institutes have invested a lot of manpower, material and financial resources in competing for research and development. Although after several year...

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Problems solved by technology

[0005] For this reason, the patent CN202614975U proposes a method of using a magnetic field shielding tube to solve this problem, but this technology still has certain constraints in practical applications

First, the shielding ability of the same magnetic field shielding tube increases with the increase of the magnetic field frequency, that is to say, the shielding effect of the magnetic field shielding tube in high frequency is better, but the shielding effect for low frequency, especially DC, is poor. This phenomenon is It is often caused by the so-called "skin effect". The test results show that even if the shielding effect of the magnetic field shielding tube on the power frequency magnetic field reaches an accuracy of two thousandths, there is still a large distance from such accuracy for DC.

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