A sensor for detecting residual magnetism of a converter transformer and a method for manufacturing the same

Abstract

The application belongs to the technical field of power equipment, and discloses a converter transformer residual magnetism detection sensor and a preparation method thereof; wherein the converter transformer residual magnetism detection sensor comprises a shell, a pressure sensor and an adsorption block; the pressure sensor and the adsorption block are both encapsulated in the shell; the shell is made of non-ferromagnetic material, and the adsorption block is made of ferromagnetic material; the pressure sensor is a flexible pressure sensor, which comprises a dielectric layer and electrode layers arranged on both sides of the dielectric layer respectively; the converter transformer residual magnetism detection sensor is used for being installed on a transformer oil tank; the pressure sensor is located between the core of the converter transformer and the adsorption block; the adsorption block is used for compressing the pressure sensor under the action of residual magnetism in the core; and the pressure sensor is used for outputting a pressure value signal under the compression of the adsorption block. The technical scheme disclosed by the application can be used for detecting the residual magnetism of the converter transformer, and has high residual magnetism detection precision and accuracy.

Description

Technical Field

[0001] This invention belongs to the field of power equipment technology, and specifically relates to a residual magnetism detection sensor for converter transformers and its preparation method. Background Technology

[0002] Ultra-high voltage direct current (UHVDC) transmission technology features large capacity, low loss, and reduced line corridor space, making it an economical and efficient power transmission method. The converter transformer is the core equipment of the UHVDC transmission system, directly affecting the safe and reliable operation of the entire system. Residual magnetism can accumulate in converter transformers after they are taken out of service or after DC resistance testing. Putting them back into operation under these conditions can generate inrush currents and overvoltages, seriously threatening the safety of the power grid and electrical equipment. Therefore, residual magnetism must be eliminated before putting converter transformers into operation.

[0003] Existing demagnetization methods for converter transformers mainly include DC method, power frequency AC method, and low frequency AC method. When eliminating residual magnetism in a converter transformer, it is generally necessary to detect the residual magnetism in the converter transformer first. However, a converter transformer is a complex combination of stray capacitance and linear / nonlinear inductance. Depending on the external load conditions, the core still has a complex magnetic process when and after the excitation is cut off, which leads to unreliable residual magnetism detection results and thus affects the demagnetization effect. Summary of the Invention

[0004] The purpose of this invention is to provide a residual magnetism detection sensor for converter transformers and its manufacturing method, thereby solving one or more of the aforementioned technical problems. The technical solution provided by this invention can detect the residual magnetism of converter transformers and has high accuracy and precision in residual magnetism detection.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a residual magnetism detection sensor for converter transformers, comprising: a housing, a pressure sensor, and an adsorption block;

[0007] The pressure sensor and the adsorption block are both encapsulated within the housing. One side of the pressure sensor is connected to the inner wall of the housing, and the adsorption block is disposed on the other side of the pressure sensor.

[0008] The shell is made of non-ferromagnetic material, and the adsorption block is made of ferromagnetic material;

[0009] The pressure sensor is a flexible pressure sensor, which includes a dielectric layer and electrode layers respectively disposed on both sides of the dielectric layer.

[0010] The residual magnetism detection sensor of the converter transformer is installed in the transformer oil tank. The pressure sensor is located between the iron core of the converter transformer and the adsorption block. The adsorption block is used to compress the pressure sensor under the action of residual magnetism in the iron core. The pressure sensor is used to output a pressure value signal under the compression of the adsorption block.

[0011] A further improvement of the present invention is that,

[0012] The housing includes a base and a cover, the cover being detachably mounted on the base;

[0013] The pressure sensor is equipped with a signal line, which is used to output the pressure value signal.

[0014] The base has a wire hole, through which the signal wire of the pressure sensor extends out of the housing, and the space between the signal wire and the wire hole is filled with sealant.

[0015] The base is provided with a guide post, and the adsorption block is provided with a guide hole. The adsorption block is sleeved and installed on the guide post through the guide hole.

[0016] A further improvement of the present invention is that,

[0017] An electric field shielding layer is provided on the outside of the housing.

[0018] A further improvement of the present invention is that,

[0019] The interior of the shell is a negative pressure environment.

[0020] A further improvement of the present invention is that,

[0021] The surface of the dielectric layer of the flexible pressure sensor has an arc-shaped protrusion structure.

[0022] A further improvement of the present invention is that it further includes:

[0023] A computing terminal is used to acquire the pressure value signal output by the pressure sensor and calculate the amount of residual magnetism in the core of the converter transformer based on the pressure value signal.

[0024] This invention provides a method for preparing a residual magnetism detection sensor for a converter transformer, comprising the following steps:

[0025] A pressure sensor is fabricated by attaching an adsorption block to the pressure sensor and then encapsulating the pressure sensor and the adsorption block in a housing.

[0026] The steps for preparing the pressure sensor include: adding a dielectric material dispersion to a polydimethylsiloxane dispersion to obtain a mixture; adding sodium chloride to the mixture, heating and stirring until a colloid is formed; adding a curing agent to the colloid, stirring evenly, and coating it onto a mold; drying and curing to obtain a thin film; washing the obtained thin film in deionized water to remove sodium chloride to obtain a porous thin film; and encapsulating the porous thin film between two electrode layers to prepare the pressure sensor.

[0027] A further improvement of the present invention is that,

[0028] The dielectric material is one or a mixture of two of carbon nanotubes and carbon black.

[0029] A further improvement of the present invention is that,

[0030] The specific steps for encapsulating the pressure sensor and the adsorption block into the housing include:

[0031] The pressure sensor and the adsorption block are assembled into the housing, with one end face of the pressure sensor connected to the inner wall of the housing and the other end face of the pressure sensor connected to the adsorption block.

[0032] The housing is subjected to a vacuum pore treatment, and after a negative pressure environment is formed inside the housing, the housing is sealed.

[0033] A further improvement of the present invention is that,

[0034] The surface of the mold is provided with wavy microgrooves, which are used to form an arc-shaped protrusion structure on the surface of the dielectric layer.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The residual magnetism detection sensor for converter transformers provided by this invention encapsulates a pressure sensor and a ferromagnetic adsorption block within a housing. The adsorption block compresses the pressure sensor based on the residual magnetism, and the amount of residual magnetism in the iron core can be determined by the pressure signal output by the pressure sensor under compression. This achieves high accuracy in detecting residual magnetism in converter transformers. Specifically, encapsulating the pressure sensor and adsorption block within the housing avoids the influence of transformer oil pressure changes on the sensor, ensuring its accuracy. Further, the improved accuracy in detecting residual magnetism in converter transformers contributes to improved accuracy in eliminating residual magnetism, thereby enhancing the safety of converter transformers during operation.

[0037] In this invention, the wire hole on the base facilitates the lead-out of the signal line while maintaining the integrity of the housing; the space between the signal line and the wire hole is filled with sealant, which effectively prevents transformer oil or other impurities from entering the housing and ensures the long-term stable operation of the sensor; the guide post on the base cooperates with the guide hole on the adsorption block to provide stable guidance for the adsorption block and ensure the accurate displacement of the adsorption block under the action of the magnetic field.

[0038] In this invention, the electric field shielding layer provided on the outside of the housing can effectively shield the influence of the external electric field on the sensor, improving the anti-interference capability of the detection; in addition, the electric field shielding layer also provides an extra layer of protection for the sensor, extending the service life of the sensor.

[0039] In this invention, the interior of the housing is a negative pressure environment, which eliminates the influence of internal air on the movement of the adsorption block and the detection accuracy of the pressure sensor, thereby improving the overall detection accuracy of the sensor.

[0040] In this invention, an arc-shaped protrusion structure is formed on the surface of the dielectric layer, which makes the pressure sensor very easy to compress, thereby greatly improving the sensitivity of the sensor. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0042] Figure 1 This is an exploded schematic diagram of a converter transformer residual magnetism detection sensor in an embodiment of the present invention;

[0043] Figure 2 yes Figure 1 The diagram shows the appearance of the embodiment.

[0044] Figure 3 yes Figure 1 A cross-sectional schematic diagram of the embodiment shown;

[0045] The explanations of the reference numerals in the figure are as follows:

[0046] 1. Housing; 11. Base; 111. Wiring hole; 12. Cover; 13. Guide post;

[0047] 2. Pressure sensor; 21. Dielectric layer; 22. Electrode layer; 23. Signal line;

[0048] 3. Adsorption block. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention; obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0050] Based on the technical solutions disclosed in the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices.

[0051] Please see Figures 1 to 3 This invention provides a residual magnetism detection sensor for a converter transformer, which can be installed inside the transformer tank. The sensor includes: a housing 1, a pressure sensor 2, and an adsorption block 3. The housing 1 is made of a non-ferromagnetic material, the pressure sensor 2 is a flexible pressure sensor, and the adsorption block 3 is made of a ferromagnetic material. Both the pressure sensor 2 and the adsorption block 3 are encapsulated within the housing 1. One end face of the pressure sensor 2 is connected to the inner wall of the housing 1, and the other end face of the pressure sensor 2 is connected to the adsorption block 3.

[0052] In a specific exemplary technical solution, the housing 1 includes a base 11 and a cover 12. A wire hole 111 is provided on the base 11, and the signal line 23 of the pressure sensor 2 extends out of the housing 1 through the wire hole 111. A sealant is filled between the signal line 23 and the wire hole 111. In a further preferred technical solution, a guide post 13 is provided on the base 11, and a guide hole is provided on the adsorption block 3. The adsorption block 3 is sleeved on the guide post 13 through the guide hole. An electric field shielding layer is provided on the outside of the housing 1. The inside of the housing 1 is a negative pressure environment. The flexible pressure sensor includes a dielectric layer 21 and electrode layers 22 disposed on both sides of the dielectric layer 21.

[0053] In the technical solution provided by this invention, a pressure sensor and a ferromagnetic adsorption block are encapsulated in a housing to form a novel residual magnetism detection device. This device utilizes the adsorption effect of residual magnetism on the adsorption block to compress the pressure sensor, and then indirectly determines the amount of residual magnetism in the iron core through the pressure value signal of the pressure sensor. This design of this invention effectively avoids the detection errors that may exist in traditional detection schemes and can significantly improve the accuracy of residual magnetism detection. Further, accurate residual magnetism detection provides a reliable basis for the elimination of residual magnetism in converter transformers, ensuring the safe use of converter transformers and reducing the risk of equipment failure caused by residual magnetism.

[0054] To further explain, in the technical solution of this invention, a non-ferromagnetic material is used to make the housing, avoiding the influence of the housing itself on the magnetic field and ensuring the accuracy of residual magnetism detection; a flexible pressure sensor is used, which can better adapt to the small displacement of the adsorption block and improve the sensitivity of detection; the ferromagnetic adsorption block has a strong response to residual magnetism, ensuring the effectiveness of detection; encapsulating both the pressure sensor and the adsorption block in the housing protects the sensor from interference from the external environment and improves the stability of detection; encapsulating the pressure sensor and the adsorption block in the housing provides a relatively stable working environment for the pressure sensor, and this encapsulation method effectively isolates the influence of transformer oil pressure changes on the pressure sensor, avoiding detection errors caused by oil pressure fluctuations; in addition, the flexible pressure sensor adopts a dielectric layer and electrode layer design, which has extremely high sensitivity to pressure changes, can better adapt to various complex detection environments, and improves the applicability of detection. In summary, the technical solution disclosed in this invention significantly improves the accuracy of residual magnetism detection, provides a strong guarantee for the accurate elimination of residual magnetism, and provides important technical support for the safe use of converter transformers.

[0055] In one embodiment of the present invention, the residual magnetism detection sensor of the converter transformer disclosed in this embodiment is installed inside the transformer oil tank. Specifically, it is installed on the top or side of the transformer oil tank through a flange, so that the end face of the residual magnetism detection sensor is flush with the inner wall of the oil tank. The pressure sensor 2 is located between the iron core and the adsorption block 3. When there is residual magnetism in the iron core, it will attract the adsorption block 3 to compress the pressure sensor 2, and different pressure values ​​will be formed according to the amount of residual magnetism. The amount of residual magnetism of the iron core can be calculated based on the pressure value.

[0056] In one embodiment of the present invention, the housing 1 includes a base 11 and a cover 12. The base 11 is a circular plate made of aluminum alloy, and the cover 12 is a cylindrical structure with one end open. The cover 12 is made of plastic, and the outer side of the cover 12 is covered with an electric field shielding layer, which can be a copper mesh or an aluminum alloy plating layer. The cover 12 is glued to the upper end surface of the base 11, thereby forming a cavity between the base 11 and the cover 12 for mounting the pressure sensor 2 and the adsorption block 3. The pressure sensor 2 is attached to the inner end face of the cover 12. The pressure sensor 2 includes a dielectric layer 21, an electrode layer 22, and signal lines 23. The dielectric layer 21 is made of porous material. Two electrode layers 22 are attached to opposite sides of the dielectric layer 21, and two signal lines 23 are electrically connected to the two electrode layers 22. A through-hole 111 is provided in the center of the base 11. The signal lines 23 of the pressure sensor 2 extend out of the housing 1 through the through-hole 111, and sealant is filled between the signal lines 23 and the through-hole 111 to ensure the airtightness of the housing 1 and prevent transformer oil from entering the housing 1. The adsorption block 3 is a steel disc attached to the other side of the pressure sensor 2. A guide hole is provided in the center of the adsorption block 3, and a guide post 13 is fixed in the center of the base 11. The adsorption block 3 is fitted onto the guide post 13 through the guide hole to prevent the adsorption block 3 from shifting and affecting the detection of the pressure sensor 2.

[0057] In a preferred embodiment of the invention, the wiring hole on the base facilitates the lead-out of the signal line while maintaining the integrity of the housing; the space between the signal line and the wiring hole is filled with sealant, effectively preventing transformer oil or other impurities from entering the housing and ensuring long-term stable operation of the sensor; the guide post on the base cooperates with the guide hole on the adsorption block to provide stable guidance for the adsorption block, ensuring accurate displacement of the adsorption block under the action of the magnetic field; the design of the guide post and guide hole also simplifies the sensor installation process and improves installation efficiency; the electric field shielding layer set on the outside of the housing can effectively shield the influence of the external electric field on the sensor, improving the anti-interference capability of the detection; in addition, the electric field shielding layer also provides an extra layer of protection for the sensor, extending the service life of the sensor.

[0058] In one embodiment of the present invention, a vacuum is applied inside the housing 1 to create a negative pressure environment, preventing air in the pores of the dielectric layer from affecting the compression of the dielectric layer and ensuring the measurement accuracy of the residual magnetism detection sensor. Further illustratively, the negative pressure environment inside the housing effectively eliminates the influence of internal air on the movement of the adsorption block and the detection accuracy of the pressure sensor; the negative pressure environment also enhances the sealing of the housing and improves the stability of the sensor.

[0059] In one specific embodiment of the present invention, the adsorption block 3 is a plurality of thin steel sheets, and the adsorption block 3 array is attached to one side of the pressure sensor 2.

[0060] In one embodiment of the present invention, a method for preparing a residual magnetism detection sensor for a converter transformer specifically includes the following steps:

[0061] Step S1: Fabricate the pressure sensor, specifically including:

[0062] Step S11: Prepare a dielectric material dispersion, wherein the dielectric material is a mixture of carbon nanotubes and carbon black; wherein, weigh carbon nanotubes and carbon black, add them to isopropanol solution, stir magnetically for 20 minutes and then ultrasonically disperse for 1.5 hours to obtain a suspension of carbon nanotubes and carbon black.

[0063] Step S12: Prepare polydimethylsiloxane dispersion, including: weighing polydimethylsiloxane and adding it to isopropanol solution, stirring magnetically for 30 min to obtain polydimethylsiloxane dispersion;

[0064] Step S13: Slowly add the dielectric material dispersion to the polydimethylsiloxane dispersion while magnetically stirring. After complete addition, continue stirring for 30 minutes to obtain a mixture of carbon nanotubes, carbon black and dimethylsiloxane.

[0065] Step S14: Add fully ground sodium chloride particles to the mixture obtained in step S13, heat to 80°C and stir until the solvent evaporates and the mixture becomes colloidal. Add curing agent at a ratio of 10:1 and continue stirring until homogeneous.

[0066] Step S15: Apply the colloid obtained in step S14 onto the mold and dry and cure it to obtain a thin film; wherein, the surface of the mold is provided with wavy microgrooves; the wavy microgrooves make the surface of the dielectric layer form an arc-shaped protrusion structure, which makes the pressure sensor very easy to compress, thereby greatly improving the sensitivity of the sensor.

[0067] Step S16: Place the membrane obtained in step S15 into deionized water, heat it to 70°C and stir continuously to wash away the sodium chloride particles in the membrane, and obtain a porous membrane.

[0068] Step S17: The porous film obtained in step S16 is cut into small particles, and conductive adhesive is attached to both sides as electrode layers. The electrodes are led out through copper wires to obtain a pressure sensor.

[0069] Step S2: Attach the adsorption block to the pressure sensor;

[0070] Step S3: Assemble the pressure sensor and the adsorption block into the housing, so that the pressure sensor is fixed to the inner wall of the housing;

[0071] Step S4: Drill a hole in the housing and then seal the housing.

[0072] In summary, this invention discloses a residual magnetism detection sensor for converter transformers and its fabrication method. The residual magnetism detection sensor is installed inside the transformer tank and includes a housing, a pressure sensor, and an adsorption block. The housing is made of a non-ferromagnetic material, the pressure sensor is a flexible pressure sensor, and the adsorption block is made of a ferromagnetic material. Both the pressure sensor and the adsorption block are encapsulated within the housing. One end of the pressure sensor is connected to the inner wall of the housing, and the other end is connected to the adsorption block. By encapsulating the pressure sensor and the ferromagnetic adsorption block within the housing, the residual magnetism can compress the pressure sensor by adsorbing the adsorption block. The amount of residual magnetism in the core can be determined by detecting the pressure value of the pressure sensor, thus improving the accuracy of residual magnetism detection and consequently improving the accuracy of residual magnetism elimination in converter transformers, thereby enhancing the operational safety of converter transformers.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A residual magnetism detection sensor for a converter transformer, characterized in that, include: Housing (1), pressure sensor (2), and adsorption block (3); The pressure sensor (2) and the adsorption block (3) are both encapsulated in the housing (1). One side of the pressure sensor (2) is connected to the inner wall of the housing (1), and the adsorption block (3) is disposed on the other side of the pressure sensor (2). The shell (1) is made of non-ferromagnetic material, and the adsorption block (3) is made of ferromagnetic material; The pressure sensor (2) is a flexible pressure sensor, which includes a dielectric layer (21) and electrode layers (22) respectively disposed on both sides of the dielectric layer (21); the dielectric layer (21) is a porous thin film, and an arc-shaped protrusion structure is formed on the surface of the dielectric layer (21); The residual magnetism detection sensor of the converter transformer is installed in the transformer oil tank. The pressure sensor (2) is located between the iron core of the converter transformer and the adsorption block (3). The adsorption block (3) is used to compress the pressure sensor (2) under the action of residual magnetism in the iron core. The pressure sensor (2) is used to output a pressure value signal under the compression of the adsorption block (3). The housing (1) includes a base (11) and a cover (12), the cover (12) being detachably mounted on the base (11); the pressure sensor (2) is provided with a signal line (23), the signal line (23) being used to output the pressure value signal; a wire hole (111) is provided on the base (11), the signal line (23) of the pressure sensor (2) extends out of the housing (1) through the wire hole (111), and a sealant is filled between the signal line (23) and the wire hole (111); a guide post (13) is provided on the base (11), a guide hole is provided on the adsorption block (3), and the adsorption block (3) is sleeved and mounted on the guide post (13) through the guide hole; An electric field shielding layer is provided on the outside of the housing (1); the inside of the housing (1) is a negative pressure environment.

2. The residual magnetism detection sensor for a converter transformer according to claim 1, characterized in that, Also includes: The computing terminal is used to acquire the pressure value signal output by the pressure sensor (2) and calculate the amount of residual magnetism in the core of the converter transformer based on the pressure value signal.

3. A method for preparing a converter transformer residual magnetism detection sensor as described in claim 1, characterized in that, Includes the following steps: Prepare a pressure sensor (2), attach an adsorption block (3) to the pressure sensor (2), and encapsulate the pressure sensor (2) and the adsorption block (3) into a housing (1); The steps for preparing the pressure sensor (2) include: adding the dielectric material dispersion to the polydimethylsiloxane dispersion to obtain a mixture; adding sodium chloride to the mixture, heating and stirring until a colloid is formed, adding a curing agent to the colloid, stirring evenly and coating it onto a mold, drying and curing to obtain a film; washing the obtained film in deionized water to remove sodium chloride to obtain a porous film; and encapsulating the porous film between two electrode layers (22) to prepare the pressure sensor (2).

4. The method for preparing a converter transformer residual magnetism detection sensor according to claim 3, characterized in that, The dielectric material is one or a mixture of two of carbon nanotubes and carbon black.

5. The method for preparing a converter transformer residual magnetism detection sensor according to claim 3, characterized in that, The specific steps of encapsulating the pressure sensor (2) and the adsorption block (3) into the housing (1) include: The pressure sensor (2) and the adsorption block (3) are assembled into the housing (1), one end face of the pressure sensor (2) is connected to the inner wall of the housing (1), and the other end face of the pressure sensor (2) is connected to the adsorption block (3). The housing (1) is subjected to a vacuum hole treatment, and the housing (1) is sealed after a negative pressure environment is formed inside the housing (1).

6. The method for preparing a converter transformer residual magnetism detection sensor according to claim 3, characterized in that, The surface of the mold is provided with wavy microgrooves, which are used to form an arc-shaped protrusion structure on the surface of the dielectric layer (21).

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