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CN-122025387-A - Electromagnetic shielding structure of wide-range current transformer

CN122025387ACN 122025387 ACN122025387 ACN 122025387ACN-122025387-A

Abstract

The invention discloses an electromagnetic shielding structure of a wide-range current transformer, which comprises a cover plate 1, a spliced shielding shell body 2, a magnetic circuit optimization structure 5, a high-conductivity shielding layer 302, a composite damping layer 303, a winding shielding assembly 4, a magnetic circuit optimization structure 501, a magnetic flux concentrator 502 and a primary conductor 503, wherein the cover plate 1 is connected with the spliced shielding shell body 2 through a hinge 101, the spliced shielding shell body 2 comprises a first spliced body 201 and a second spliced body 202, three layers of trapezoidal grooves are symmetrically formed in the inner walls of the first spliced body 201 and the second spliced body 202, the multilayer composite shielding layer 3 comprises a high-permeability shielding layer 301, the high-conductivity shielding layer 302 and the composite damping layer 303 are sequentially embedded in the three layers of trapezoidal grooves from inside to outside. The invention realizes the organic unification of wide-range high-precision measurement and strong anti-interference capability, and remarkably improves the long-term stability and engineering practicability of the product.

Inventors

  • CHEN QINGHUI
  • Tang Hezhong
  • WANG JUNRONG
  • YANG JING
  • SONG QIANG
  • ZHANG YUPING
  • CHEN BO
  • LI PENGCHENG
  • HUA TAO
  • QU ZHIYI
  • Pan Zuliang
  • YANG XIUJIANG
  • Wei longxiang
  • LI JINYOU
  • XU HONGWEI

Assignees

  • 贵州电网有限责任公司

Dates

Publication Date
20260512
Application Date
20251105

Claims (10)

  1. 1. An electromagnetic shielding structure of a wide-range current transformer is characterized by comprising, The cover plate (1) is connected with the spliced shielding shell body (2) through a hinge (101); The spliced shielding shell body (2) comprises a first spliced body (201) and a second spliced body (202), wherein the second spliced body (202) is symmetrically arranged with the first spliced body (201) and is detachably connected with the first spliced body through a mortise-tenon structure (203) and a magnetic locking structure (204), a complete cylindrical shielding cavity is formed after connection, and three layers of trapezoidal grooves are symmetrically formed in the inner walls of the first spliced body (201) and the second spliced body (202); The multi-layer composite shielding layer (3) comprises a high magnetic conduction shielding layer (301), a high electric conduction shielding layer (302) and a composite damping layer (303) which are sequentially embedded in the three-layer trapezoidal grooves from inside to outside; the winding shielding assembly (4) comprises a secondary winding (401) with a concentric multi-layer structure, an aluminum foil shielding layer (402) arranged between the secondary winding layers, and voltage equalizing windings (403) arranged at the head end and the tail end of the secondary winding; a magnetic circuit optimizing structure (5) comprising a ring-shaped iron core (501), a magnetic flux concentrator (502), and a primary conductor (503); wherein an elastic supporting piece (6) is arranged between the high magnetic conduction shielding layer (301) and the annular iron core (501).
  2. 2. The electromagnetic shielding structure of the wide-range current transformer according to claim 1, wherein the magnetic flux concentrator (502) consists of a magnetic conduction sheet and a fixed bracket, and the magnetic conduction sheet is made of an iron-based nanocrystalline alloy.
  3. 3. The electromagnetic shielding structure of the wide-range current transformer according to claim 2, wherein the air gap distance between the intrados of the magnetic conductive sheet and the primary conductor (503) is 1-2 mm.
  4. 4. The electromagnetic shielding structure of the wide-range current transformer according to claim 1, wherein the elastic supporting piece (6) is made of memory alloy.
  5. 5. The electromagnetic shielding structure of the wide-range current transformer according to claim 1, wherein the high magnetic conductive shielding layer (301) is made of silicon steel sheets, and the silicon steel sheets are arranged in a spiral winding mode.
  6. 6. The electromagnetic shielding structure of the wide-range current transformer of claim 5, wherein the thickness of the silicon steel sheet is 0.3-0.4 mm.
  7. 7. The electromagnetic shielding structure of a wide range current transformer according to claim 1, wherein the material of the high conductive shielding layer (302) is oxygen-free copper foil.
  8. 8. The electromagnetic shielding structure of the wide-range current transformer of claim 7, wherein the surface of the oxygen-free copper foil is of a diamond concave-convex structure.
  9. 9. The electromagnetic shielding structure of wide range current transformer according to claim 1, wherein the material of the composite damping layer (303) is a magnetic rubber composite material, The magnetic rubber composite material comprises, by mass fraction of raw materials, 60-65wt% of nitrile rubber matrix, 25-30wt% of ferrite magnetic powder, 4-6wt% of carbon nanotubes, 2-3wt% of vulcanizing agent and 2-3wt% of stabilizing agent.
  10. 10. The electromagnetic shielding structure of the wide-range current transformer of claim 9, wherein the magnetic rubber composite material comprises, by mass fraction of raw materials, 60wt% of a nitrile rubber matrix, 30wt% of ferrite magnetic powder, 5wt% of carbon nanotubes, 3wt% of a vulcanizing agent and 2wt% of a stabilizer.

Description

Electromagnetic shielding structure of wide-range current transformer Technical Field The invention belongs to the technical field of power measurement equipment, and particularly relates to an electromagnetic shielding structure of a wide-range current transformer. Background The current transformer is used as key measuring equipment in a power system and plays important roles of current signal acquisition, metering, protection, monitoring and the like. With the deep promotion of smart grid construction and large-scale grid connection of new energy, the operation working condition of an electric power system is more and more complex, and the performance requirement on a current transformer is continuously improved. The modern power grid not only needs the transformer to keep high-precision measurement in normal operation, but also needs the transformer to stably work under the extreme working conditions of fault heavy current impact, harmonic interference, high-frequency transient state and the like. However, the electromagnetic shielding structure of the conventional current transformer exposes a plurality of technical bottlenecks when facing to the wide-range measurement requirement, and severely restricts the application of the electromagnetic shielding structure in a novel power system. The existing current transformer generally adopts a single-layer metal shielding cylinder structure, and the design has fundamental defects when dealing with complex electromagnetic environments. Firstly, the contradiction between the measuring range and the precision is prominent, the traditional shielding cylinder is easy to saturate when the rated current is more than 150%, the error is rapidly increased to +/-2% after the magnetic density is more than 1.8T, and when the magnetic density is less than 0.5% of the rated current, the magnetic leakage is serious due to poor shielding effect, the signal to noise ratio is rapidly reduced, and the phase error exceeds 1 degree. Secondly, the frequency response characteristic is poor, the single-layer copper shield is almost ineffective to magnetic field interference below 10kHz, the shielding effectiveness is less than 20dB, and the broadband interference suppression requirement generated by power electronic equipment cannot be met. More serious, electromagnetic resonance is easy to generate in a 15-25 kHz frequency band in a gap between the shielding cylinder and the winding, so that measurement noise is increased, and ageing of an insulating material is accelerated. In addition, the problem of temperature stability is not ignored, and when the ambient temperature exceeds 70 ℃, the thermal expansion deformation rate of the shielding layer reaches 0.1 mm/DEG C, so that the symmetry of the magnetic circuit is broken, and the measurement accuracy is further deteriorated. In view of the above technical challenges, the power industry is in urgent need for developing novel electromagnetic shielding technology for wide-range current transformers. The technology must be capable of maintaining stable measurement accuracy in the ultra-wide current range of 0.1% to 300%, and simultaneously has electromagnetic interference suppression capability covering the full frequency range from direct current to 50 kHz. In view of the severe operating environments of outdoor substations and new energy stations, the novel shielding structure is also required to have excellent temperature adaptability and long-term stability. Therefore, the novel electromagnetic shielding structure of the current transformer, which can realize wide-range high-precision measurement, strong anti-interference capability, excellent environmental adaptability and engineering practicability, is researched, and has important significance in promoting the technical progress of the intelligent power grid and guaranteeing the safe and stable operation of a power system. Disclosure of Invention This section is intended to outline some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section as well as in the description of the invention and in the title of the invention, which may not be used to limit the scope of the invention. The present invention has been made in view of the above and/or problems occurring in the prior art. Therefore, the invention aims to overcome the defects in the prior art and provide the electromagnetic shielding structure of the wide-range current transformer. In order to solve the technical problems, the invention provides the following technical proposal that comprises, The cover plate 1 is connected with the spliced shielding shell body 2 through a hinge 101; The spliced shielding shell body 2 comprises a first spliced body 201 and a second spliced body 202, wherein the second spliced body 202 and the first spliced body 201 are symmetrically arranged and detachably connected through a mortise-tenon j