Insulation cushion block aging test device and deterioration performance evaluation method

Abstract

The invention provides an insulation cushion block aging test device and a deterioration performance evaluation method, and relates to the technical field of transformers, the insulation cushion block aging test device is characterized in that a heating chamber is defined in an aging oven; the oil tank is arranged in the aging box, and a containing cavity is defined in the oil tank and can be filled with transformer oil; the pre-tightening force applying mechanism is arranged in the accommodating cavity and is used for clamping the insulating cushion block and applying pre-tightening force to the insulating cushion block; and the pre-tightening force detection mechanism is used for detecting the pre-tightening force loaded by the insulating cushion block. Pre-tightening force is applied to the insulation cushion block through the pressing plate, the oil tank and the insulation cushion block are integrally heated through the aging oven, oil immersion and pre-tightening force-thermal aging conditions in a real working environment of the transformer are simulated, the magnitude of the pre-tightening force required by testing is accurately controlled, and the testing accuracy is improved. The dielectric constant and the refractive index of the insulation cushion block winding are obtained through calculation according to the terahertz frequency of the insulation cushion block after thermal aging, and then the degradation performance of the insulation cushion block is evaluated.

Description

Technical Field

[0001] The present invention relates to the technical field of transformers, and in particular to an insulating spacer aging test device and a degradation performance evaluation method. Background Art

[0002] High-voltage transformers are widely used in power transmission and distribution networks, industrial fields, infrastructure, and power load management. In high-voltage transformers, insulating pads are distributed between the layers of the transformer coils to provide the necessary electrical isolation and ensure that there is no accidental electrical contact between the different conductive parts of the transformer, thereby preventing short circuits and arcs. During the long-term operation of the transformer, the insulating pads will inevitably be impacted by various short-circuit faults. When a short-circuit fault occurs, the insulating pads will age due to the synergistic effect of preload and thermal stress, resulting in a decrease in axial preload and a decrease in the winding's ability to resist short circuits, thereby reducing the transformer's service life and operational reliability. Therefore, accurately detecting the insulation state of the insulating pads under the synergistic effect of preload and thermal aging and evaluating the degradation performance of the insulating pads are of great significance for judging the stability of the transformer.

[0003] The existing technology uses an accelerated thermal aging test device and method for insulation pads for testing. Due to the limitations of sensor conditions, the experimental operation is complicated and the accuracy is insufficient. Other testing methods include tensile strength test, polymerization degree test, Fourier infrared spectroscopy analysis and scanning electron microscopy, etc. These methods judge the aging state of cellulose insulation pads based on polymerization degree. However, the operation is also complicated and will cause damage to the sample.

[0004] In view of this, how to provide a device that is simple to operate, does not damage samples, accurately measures the insulation state of insulating gaskets under the synergistic effect of preload-heat aging, and evaluates the degradation performance of insulating gaskets is a problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] The purpose of the present invention is to provide an insulating spacer aging test device and a degradation performance evaluation method to solve the problems existing in the prior art.

[0006] To achieve the above object, the present invention provides an insulating spacer aging test device, comprising:

[0007] An aging box, defining a heating chamber therein;

[0008] An oil tank is arranged in the aging box, and defines a receiving cavity inside thereof and can be filled with transformer oil;

[0009] A pre-tightening force applying mechanism is arranged in the accommodating cavity and is used to clamp the insulating spacer and apply a pre-tightening force to the insulating spacer;

[0010] A preload detection mechanism, used to detect the preload of the insulating spacer load;

[0011] The processor is electrically connected to the preload force detection mechanism and is used to receive the preload force data of the insulating spacer load and display it on a display screen.

[0012] Furthermore, the preload force applying mechanism comprises:

[0013] A screw rod is vertically arranged in the accommodating cavity and fixed to the bottom surface of the oil tank through a base;

[0014] A plurality of pressing plates are slidably connected with the screw rod; the insulating spacer is clamped between two adjacent pressing plates;

[0015] The nut is threadably connected to the screw rod and is close to the clamping plate, and is used to drive the clamping plate to move toward the insulating spacer.

[0016] Furthermore, the clamping plate includes a first clamping plate, a second clamping plate and a third clamping plate which are arranged in sequence from top to bottom, the insulating pad is arranged between the second clamping plate and the third clamping plate, and the preload force detection mechanism is arranged between the first clamping plate and the second clamping plate; a first nut is arranged on the upper surface of the first clamping plate, and a second nut is arranged on the lower surface of the third clamping plate.

[0017] Furthermore, the preload force detection mechanism comprises:

[0018] The pressure sensor is arranged between the first pressing plate and the second pressing plate, and a polyimide film is sheathed on the outer surface of the pressure sensor;

[0019] A high temperature resistant tube, wherein the pressure sensor is fixedly connected to one end of the high temperature resistant tube through a thermoplastic tube, a transmission line is arranged inside the high temperature resistant tube, and the transmission line is electrically connected to the pressure sensor; the other end of the high temperature resistant tube extends outside the aging box, and the transmission line is electrically connected to the processor.

[0020] Furthermore, the high temperature resistant pipe is connected to the aging box through a fixing clamp and a sealing gasket.

[0021] The present invention also provides a method for evaluating the degradation performance of an insulating spacer block, using an insulating spacer block aging test device, comprising the following steps:

[0022] S1: placing an insulating spacer on the third pressing plate, rotating the first nut and the second nut to squeeze the insulating spacer from the upper and lower directions, and uploading the preload data of the insulating spacer load to the processor through the pressure sensor;

[0023] S2: Add transformer oil into the accommodating cavity, set the temperature of the aging box, heat the insulating pad, and start thermal aging of the insulating pad while maintaining the preload;

[0024] S3: After the aging is completed, the insulating spacer is taken out and a terahertz frequency test is performed on the insulating spacer;

[0025] S4: Evaluate the degradation performance of the insulating spacer according to the terahertz frequency.

[0026] Furthermore, in step S2, the thermal aging conditions of the insulating spacer are: thermal aging is performed at different aging times under the same preload condition; or thermal aging is performed at different preload conditions under the same aging time.

[0027] Furthermore, in step S3, the dielectric constant and the refractive index of the insulating spacer winding are calculated according to the terahertz frequency of the insulating spacer.

[0028] The present invention discloses the following technical effects:

[0029] The present invention applies preload force to the insulating spacer through a clamping plate, heats the oil tank and the insulating spacer as a whole through an aging box, simulates the oil immersion, preload force and thermal aging conditions in the real working environment of the transformer, and detects the preload force of the insulating spacer load through a preload force detection mechanism, accurately controls the preload force required for the test, and improves the test accuracy; after the aging is completed, the terahertz frequency of the insulating spacer is tested, and the dielectric constant and refractive index of the insulating spacer winding are calculated according to the terahertz frequency of the insulating spacer, and then the degradation performance of the insulating spacer is evaluated. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 It is a schematic diagram of the structure of the present invention;

[0032] Figure 2 This is a schematic diagram of the internal structure of the fuel tank;

[0033] Figure 3 This is a schematic diagram of the pressure sensor connection;

[0034] Figure 4 It is a schematic diagram of the fitting curve represented by the first relationship equation;

[0035] Figure 5 A schematic diagram of a fitting curve representing the second relationship equation;

[0036] Figure 6 It is a schematic diagram of the fitting curve represented by the third relationship equation;

[0037] Figure 7 is a schematic diagram of a fitting curve represented by the fourth relationship equation;

[0038] Among them, 1. fixing clamp; 2. sealing gasket; 3. high temperature resistant pipe; 4. transmission line; 5. aging box; 6. oil tank; 7. screw; 8. handle; 9. first nut; 10. first clamping plate; 11. polyimide film; 12. pressure sensor; 13. thermoplastic pipe; 14. second clamping plate; 15. insulating pad; 16. third clamping plate; 17. second nut; 18. base. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] Example 1

[0042] An embodiment of the present invention provides an insulating pad aging test device, comprising: an aging box 5, which defines a heating chamber inside; an oil tank 6, which is arranged in the aging box 5, defines a accommodating chamber inside and can be filled with transformer oil, and a handle 8 is provided on the outside of the oil tank 6 for opening, closing the oil tank 6 and putting the oil tank 6 in or out; a preload applying mechanism, which is arranged in the accommodating chamber and is used to clamp the insulating pad 15 and apply a preload to the insulating pad 15; a preload detecting mechanism, which is used to detect the preload of the insulating pad 15 load; and a processor, which is electrically connected to the preload detecting mechanism and is used to receive the preload data of the insulating pad 15 load and display it on a display screen.

[0043] In this embodiment, the preload force applying mechanism includes: a screw rod 7, which is vertically arranged in the accommodating cavity and fixed to the bottom surface of the oil tank 6 through a base 18; a plurality of clamping plates, which are slidably connected to the screw rod 7; an insulating pad 15 is clamped between two adjacent clamping plates; and a nut, which is threadedly connected to the screw rod 7 and is close to the clamping plate, and is used to drive the clamping plate to move in a direction close to the insulating pad 15.

[0044] In this embodiment, the clamping plate includes a first clamping plate 10, a second clamping plate 14 and a third clamping plate 16 arranged in sequence from top to bottom, and an insulating pad 15 is arranged between the second clamping plate 14 and the third clamping plate 16. The insulating pad 15 can be cut to a set size according to actual conditions, and multiple layers of insulating pads 15 can be stacked together, and the thickness of each layer of insulating pads 15 is 1.5 mm. The preload detection mechanism is arranged between the first clamping plate 10 and the second clamping plate 14; the upper surface of the first clamping plate 10 is provided with a first nut 9, and the lower surface of the third clamping plate 16 is provided with a second nut 17.

[0045] In this embodiment, there are four screw rods 7, the first clamping plate 10, the second clamping plate 14 and the third clamping plate 16 are square, through holes are respectively set at the corners of the three clamping plates corresponding to the four screw rods 7, the base 18 is set with mounting screw holes corresponding to the four screw rods 7, the lower end of the screw rod 7 is inserted into the mounting screw hole and threadedly connected thereto; the base 18 can improve the overall stability of the device, and provide additional buffering and shock absorption effects, protect the device from vibration, ensure that the device does not shake during the experiment, and improve the test accuracy. The first nut 9 and the second nut 17 limit and clamp the three clamping plates from the upper and lower directions respectively, so as to achieve the effect of applying pre-tightening force to the insulating spacer 15.

[0046] In this embodiment, the preload force detection mechanism includes: a pressure sensor 12, which is arranged between the first pressing plate 10 and the second pressing plate 14, and a polyimide film 11 is sleeved on its outer surface. The function of the polyimide film 11 is to seal the pressure sensor 12 to prevent transformer oil from entering the pressure sensor 12, and to prevent the aging temperature set by the aging box 5 from exceeding the temperature (-20-70°C) that the sensor itself can withstand and fail; a high temperature resistant tube 3, the pressure sensor 12 is fixedly connected to one end of the high temperature resistant tube 3 through a thermoplastic tube 13, and a transmission line 4 is arranged inside the high temperature resistant tube 3, and the transmission line 4 is electrically connected to the pressure sensor 12; the other end of the high temperature resistant tube 3 extends outside the aging box 5, and the transmission line 4 is electrically connected to the processor, and the high temperature resistant tube 3 is connected to the aging box 5 through a fixing clamp 1 and a sealing pad 2. The function of the high temperature resistant tube 3 is to wrap the transmission line 4, so that the transmission line 4 can be used normally under high oil heat conditions, and the thermoplastic tube 13 is used to ensure the connection sealing in a high temperature environment and play a protective effect.

[0047] The embodiment of the present invention also provides a method for evaluating the degradation performance of an insulating spacer, using an aging test device for an insulating spacer 15, comprising the following steps:

[0048] S1: Arrange the insulating spacer 15 on the third pressing plate 16, rotate the first nut 9 and the second nut 17 to squeeze the insulating spacer 15 from the upper and lower directions, and upload the preload data of the insulating spacer 15 to the processor through the pressure sensor 12 to confirm the preload size. In this embodiment, the preload is set to 2000N;

[0049] S2: adding transformer oil into the accommodating cavity, setting the temperature of the aging box 5, heating the insulating pad 15, and setting the heating temperature to 130 degrees Celsius, so that the insulating pad 15 starts thermal aging under the condition of maintaining the preload; the thermal aging step is performed six times in total, and the six thermal aging times are 0h, 120h, 240h, 360h, 480h, and 600h respectively;

[0050] S3: After the aging is completed, the insulating spacer 15 is taken out and a terahertz frequency test is performed on the insulating spacer 15;

[0051] S4: Evaluate the degradation performance of the insulating spacer 15 according to the terahertz frequency.

[0052] The processor makes a fitting curve of the dielectric constant and the terahertz frequency according to the dielectric constant and the terahertz frequency of the insulating spacer 15, and obtains the first relationship equation between the dielectric constant and the terahertz frequency of the insulating spacer 15 after six thermal agings:

[0053] y1=-0.05797x+2.74907

[0054] y2=-0.09107x+2.7797

[0055] y3=-0.07297x+2.79736

[0056] y4=-0.10287x+2.83267

[0057] y5=-0.11584x+2.86161

[0058] y6=-0.06811x+2.83356

[0059] Among them, y1, y2, y3, y4, y5, and y6 are the dielectric constants of the insulating spacer 15 after thermal aging for 0 h, 120 h, 240 h, 360 h, 480 h, and 600 h under a preload of 2000 N, respectively, and x is the terahertz frequency.

[0060] It is found through experiments that the buoyancy generated by transformer oil is very small and has little impact on the experimental results. Therefore, the buoyancy generated by transformer oil is used as the test result in this embodiment to simplify the calculation.

[0061] Example 2

[0062] The difference between this embodiment and embodiment 1 is that the heat aging conditions are different. Specifically, under the condition of a heat aging time of 600 h, the insulation spacer 15 is heat aged with a preload of 0 N, 1000 N, and 2000 N, respectively.

[0063] The processor makes a fitting curve of the dielectric constant and the terahertz frequency according to the dielectric constant and the terahertz frequency of the insulating spacer 15, and obtains the second relationship equation between the dielectric constant and the terahertz frequency of the insulating spacer 15 after three thermal aging steps after fitting:

[0064] y7=-0.13128x+2.92004

[0065] y8=-0.07047x+2.8612

[0066] y9=-0.06804x+2.83351

[0067] Among them, y 7、 y 8、 y9 is the dielectric constant of the insulating spacer 15 with preload of 0N, 1000N and 2000N and thermal aging for 600h, and x is the terahertz frequency.

[0068] Example 3

[0069] The test conditions of this embodiment are the same as those of embodiment 1. The processor makes a fitting curve of the refractive index and the terahertz frequency according to the refractive index and the terahertz frequency of the insulating spacer 15. After fitting, the third relationship equation between the refractive index and the terahertz frequency of the insulating spacer 15 after six thermal agings is obtained:

[0070] y 10 =-0.02319x+1.66028

[0071] y 11 =-0.02005x+1.66413

[0072] y 12 =-0.01783x+1.66629

[0073] y 13 =-0.03922x+1.69596

[0074] y 14 =-0.02555x+1.69562

[0075] y 15 =-0.01794x+1.69039

[0076] Among them, y 10 ,y 11 ,y 12 ,y13 ,y 14 ,y 15 They are the refractive indices of the insulating spacer 15 aged for 0 h, 120 h, 240 h, 360 h, 480 h and 600 h under a preload of 2000 N, respectively, and x is the terahertz frequency.

[0077] Example 4

[0078] The test conditions of this embodiment are the same as those of embodiment 2. The processor makes a fitting curve of the refractive index and the terahertz frequency according to the refractive index and the terahertz frequency of the insulating spacer 15. After fitting, the fourth relationship equation between the refractive index and the terahertz frequency of the insulating spacer 15 after three thermal agings is obtained:

[0079] y 16 =-0.03116x+1.71018

[0080] y 17 =-0.03045x+1.70549

[0081] y 18 =-0.01794x+1.69039

[0082] Among them, y 16 ,y 17 ,y 18 are the refractive indices of the insulating spacer 15 with preloads of 0 N, 1000 N, and 2000 N respectively and thermally aged for 600 h, and x is the terahertz frequency.

[0083] By performing a thermal aging test on the insulating spacer 15 through Examples 1 to 4, the preload-terahertz frequency after thermal aging and the above-mentioned fitting curve can be obtained, thereby providing guidance for evaluating the insulation state and degradation performance of the oil-immersed transformer.

[0084] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0085] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. An insulating spacer aging test device, characterized in that: include: An aging box (5) defines a heating chamber therein; An oil tank (6) is arranged in the aging box (5), and defines a receiving cavity therein and can be filled with transformer oil; A pre-tightening force applying mechanism is arranged in the accommodating cavity and is used to clamp the insulating spacer (15) and apply a pre-tightening force to the insulating spacer (15); A preload force detection mechanism, used for detecting the preload force of the insulating spacer (15); The processor is electrically connected to the preload force detection mechanism and is used to receive preload force data of the insulating spacer (15) load and display it on a display screen.

2. The insulating spacer aging test device according to claim 1, characterized in that: The preload force applying mechanism comprises: A screw rod (7) is vertically arranged in the accommodating cavity and fixed on the bottom surface of the oil tank (6) through a base (18); A plurality of clamping plates are slidably connected to the screw rod (7); the insulating pad (15) is clamped between two adjacent clamping plates; A nut is threadedly connected to the screw rod (7) and is close to the clamping plate, and is used to drive the clamping plate to move in a direction close to the insulating pad (15).

3. The insulating spacer aging test device according to claim 2, characterized in that: The clamping plate comprises a first clamping plate (10), a second clamping plate (14) and a third clamping plate (16) which are arranged in sequence from top to bottom; the insulating pad (15) is arranged between the second clamping plate (14) and the third clamping plate (16); the preload force detection mechanism is arranged between the first clamping plate (10) and the second clamping plate (14); a first nut (9) is arranged on the upper surface of the first clamping plate (10), and a second nut (17) is arranged on the lower surface of the third clamping plate (16).

4. The insulating spacer aging test device according to claim 3, characterized in that: The preload force detection mechanism comprises: A pressure sensor (12) is arranged between the first pressing plate (10) and the second pressing plate (14), and a polyimide film (11) is sleeved on the outer surface of the pressure sensor; A high temperature resistant tube (3), wherein the pressure sensor (12) is fixedly connected to one end of the high temperature resistant tube (3) via a thermoplastic tube (13); a transmission line (4) is arranged inside the high temperature resistant tube (3), and the transmission line (4) is electrically connected to the pressure sensor (12); the other end of the high temperature resistant tube (3) extends outside the aging box (5), and the transmission line (4) is electrically connected to the processor.

5. The insulating spacer aging test device according to claim 4, characterized in that: The high temperature resistant pipe (3) is connected to the aging box (5) via a fixing clamp (1) and a sealing gasket (2).

6. A method for evaluating the degradation performance of an insulating spacer, using the insulating spacer (15) aging test device according to claim 4, characterized in that: The following steps are involved: S1: placing an insulating spacer (15) on a third pressing plate (16), rotating a first nut (9) and a second nut (17) to squeeze the insulating spacer (15) from upper and lower directions, and uploading preload data of the insulating spacer (15) to a processor via a pressure sensor (12); S2: adding transformer oil into the containing cavity, setting the temperature of the aging box (5), heating the insulating pad (15), and causing the insulating pad (15) to start thermal aging while maintaining the preload; S3: After the aging is completed, the insulating spacer (15) is taken out and a terahertz frequency test is performed on the insulating spacer (15); S4: Evaluate the degradation performance of the insulating spacer (15) according to the terahertz frequency.

7. The method for evaluating the degradation performance of an insulating spacer according to claim 6, characterized in that: In step S2, the thermal aging conditions of the insulating spacer (15) are: thermal aging is performed at different aging times under the same preload condition; or thermal aging is performed at different preload conditions under the same aging time.

8. The method for evaluating the degradation performance of an insulating spacer according to claim 6, characterized in that: In step S3, the dielectric constant and the refractive index of the winding of the insulating spacer (15) are calculated based on the terahertz frequency of the insulating spacer (15).

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