A method for budgeting the height of a transformer coil

Abstract

The present invention belongs to the technical field of transformer production and manufacturing, and specifically relates to a method for budgeting the height of a transformer coil. The basic information of the coil size is statistically analyzed, the wire and spacer samples used for winding the coil are prepared, the compression rate of the spacer under pressure is measured, the size of the wire after compression in the pressurized state of the wire and spacer combination is measured, the budget height of the coil is calculated based on the measured and calculated data, and the winding height size of the coil is pre-adjusted according to the deviation between the budget height of the coil and the designed height of the coil. The method for budgeting the height of the transformer coil provided by the present invention accurately budgets the height of the coil during the coil winding stage, avoids adjusting the height after the coil is baked, and the deviation between the budget result and the actual result is within ±3 mm.

Description

Technical Field

[0001] The present invention belongs to the technical field of transformer production and manufacturing, and particularly relates to a method for budgeting the height of a transformer coil, which is used for pre-adjusting the winding height of the coil during the winding process of the transformer coil. Background Art

[0002] The adjustment and control of the transformer coil height is a key link in the coil manufacturing process, and the coil height tolerance is generally required to be controlled within ±3 mm. The general technological process adopted by transformer manufacturers is: coil winding - coil mold lifting and pre-pressing - coil drying - coil compaction - coil height dimension inspection and adjustment - coil transfer.

[0003] With the gradual increase in the capacity and voltage of power transformers, the number of coil turns, the coil weight, and the radial dimension also increase accordingly, resulting in difficulty in opening the operating gap required to adjust the thickness of the oil duct spacer between the coil pancakes, making the subsequent coil height adjustment work more and more difficult and the operation time longer and longer. For example, when winding a coil of 750 kV voltage class, the coil height adjustment operation requires 2 people to operate for 12 hours, which will affect the accurate execution of the production plan. At the same time, since the wire is a self-adhesive wire, it is difficult to change its shape after baking and curing. In the height adjustment, tools such as wedge-shaped paddles are needed to open the pancake gap and change the wire shape, which affects the tightness of the pancake. At the same time, it is easy to cause insulation damage to the coil during operation and it is difficult to repair. Summary of the Invention

[0004] Based on the technical problem that there is currently no accurate method for budgeting the coil height, the present invention provides a new method for budgeting the height of a transformer coil, which can be used for accurate budgeting of the height of various structural coils. The technical solution of the present invention to achieve the above object is:

[0005] A method for budgeting the height of a transformer coil, comprising the following steps:

[0006] Step 1. Statistically analyze the basic information of the coil dimensions. The basic information of the coil dimensions includes: data information such as coil type, coil compaction force, number of coil stalls, thickness of the spacer between pancakes, total thickness of the coil spacers, height dimension of the end ring, size of the insulation wrapping of the pancake, number of coil turns, number of parallel-wound wires in the radial direction, and designed height of the coil. The coil is wound by multiple pancakes, and a spacer is arranged between each layer of pancakes. The total thickness of the coil spacers refers to the total thickness of all the spacers between the pancakes. For example, if there are one hundred layers of pancakes and the thickness of one spacer between the pancakes is 2 mm, then the total thickness of the coil spacers is 99 * 2 mm.

[0007] Step 2. Prepare the wire and spacer samples for winding the coil. It is necessary to prepare three sets of samples each that can meet the spacer pressure measurement and the combined pressure measurement of the wire and spacer.

[0008] Step 3. Dry treatment of the wire and spacer samples.

[0009] Step 4. Measure the compression rate of the spacer under pressure.

[0010] Stack the three groups of spacer samples into a column respectively, and apply an axial compression pressure F1. F1 is calculated according to the compression area of the spacer and the coil clamping force. The calculation formula is: compression pressure F1 = coil clamping force / (number of coils * number of positions) * (actual measured compression area of the spacer / area used in the coil clamping force calculation), with the unit of kN; the displacement speed of the pressure platform is a constant speed of 5 mm / min. The compression area of the spacer is obtained through calculation. Compression area of the spacer = actual measured compression area of the spacer / area used in the coil clamping force calculation. The actual measured compression area of the spacer refers to the area actually compressed during coil winding. The area used in the coil clamping force calculation refers to the area of the spacer actually pressed by the pressure mold of the pressurizing equipment during the coil test in actual production. The size of the pressure mold of the pressurizing equipment is generally 150 mm * 150 mm. If the length of the spacer exceeds the size of the pressure mold of the pressurizing equipment, that is, the mold size (150 * 150) is smaller than the coil radial direction, some spacers will not be pressed during the test. At this time, the area used in the coil clamping force calculation = width of the spacer * size of the pressure mold of the pressurizing equipment (width of the spacer * 150 mm); if the length of the spacer is less than the size of the pressure mold of the pressurizing equipment, then the area used in the coil clamping force calculation = width of the spacer * length of the spacer.

[0011] After applying the pressure to reach F1, measure the total thickness of the spacer samples in the pressurized state for the three groups respectively, calculate the average value of the total thickness of the spacer samples in the pressurized state and the spacer compression rate. Spacer compression rate = (total thickness of the spacer samples in the non-pressurized state - average value of the total thickness of the spacer samples in the pressurized state) / total thickness of the spacer samples in the non-pressurized state * 100%.

[0012] Step 5. Measure the size of the wire after compression in the pressurized state of the wire and spacer combination.

[0013] Combine the three groups of wire and spacer samples into an up-and-down arrangement structure of "spacer + horizontally arranged wire + spacer + horizontally arranged wire + spacer", and apply an axial pressure F2. F2 is calculated according to the axial compression pressure F1 of the spacer, the number of radially parallel wires, and the compression area. F2 = F1 * (width of the wire / actual measured compression length of the spacer). Measure the total thickness of the wire and spacer sample combination in the pressurized state for the three groups respectively, calculate the average value of the total thickness of the wire and spacer sample combination in the pressurized state, and finally calculate the size of the wire after compression. Size of the wire after compression = (average value of the total thickness of the wire and spacer sample combination in the pressurized state - total thickness of the spacer sample * (1 - spacer compression rate)) / 2.

[0014] Step 6. Calculate the coil budget height based on the measured and calculated data. The calculation formula is: Coil budget height = Dimension of the compressed wire * Number of coil turns + (Total thickness of coil spacers + Dimension of the insulation wrapping of the coil disk) * (1 - Compression rate of spacer pressing), with the unit of mm.

[0015] Step 7. Pre-adjust the coil design height dimension.

[0016] Based on the deviation between the coil budget height and the coil design height, pre-adjust the winding height dimension of the coil. Coil height adjustment dimension = (Coil budget height - Coil design height) / (1 - Compression rate of spacer pressing), with the unit of mm.

[0017] Advantages of the present invention:

[0018] The budget method for the transformer coil height provided by the present invention accurately budgets the coil height during the coil winding stage, avoiding readjusting the height after coil baking. The deviation between the budget result and the actual result is within ±3 mm. Description of the drawings

[0019] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some specific embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings within the scope of protection of this application can also be obtained based on these drawings.

[0020] Figure 1 is the step flow chart of the embodiment of the present invention;

[0021] Figure 2 is the schematic layout diagram when measuring the combined compression rate of the wire and the spacer in the embodiment of the present invention;

[0022] In the figure, 1 - spacer, 2 - wire. Specific embodiments

[0023] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention.

[0024] To fully illustrate the technical solutions of the present invention, take a 500 kV low-voltage coil as an example and illustrate as follows:

[0025] As Figure 1 shown, it is the step flow chart of the embodiment of the present invention. A budget method for the transformer coil height includes the following steps:

[0026] Step 1. Statistically analyze the basic information of the coil dimensions.

[0027] Taking a certain 500 kV low-voltage coil as an example, the basic information of the coil structure is shown in the following table:

[0028]

[0029] Step 2. Prepare the wire and spacer samples for winding the coil.

[0030] Among them, if the same wire gauge is used in multiple reels, samples need to be taken from each reel; if the coil uses wires of multiple wire gauges, samples need to be taken from each wire gauge. After wire sampling, it is necessary to perform a flattening treatment by knocking to avoid the influence of the irregular shape of the wire on the measurement results and make the measurement results more accurate.

[0031] Step 3. Dry the wire and spacer samples.

[0032] The samples are dried using a hot air oven. The drying parameters are: drying temperature 120 °C, drying duration 36 hours, and the drying time for the spacers after densification treatment is 48 hours. After drying, measurement should be carried out as soon as possible or moisture-proof measures should be taken to avoid the samples absorbing moisture, as moisture absorption of the samples will affect the accuracy of the budget.

[0033] Step 4. Measure the compression rate of the spacers under pressure.

[0034] Stack the first group of spacer samples in a column. The total thickness of the spacer samples in the unpressurized state is usually 15 - 20 mm; apply an axial compression force F1.

[0035] Pressing process: After applying the pressure to reach F1, hold for 30 s to fully apply the pressure to the spacers, record the total thickness of the spacers in the pressurized state, release the pressure to 0, hold for 10 s, and then apply the pressure F1 again. Repeat this process until the deviation between the total thickness of the spacer samples in the pressurized state at F1 pressure and the previous measurement data is ≤ 0.01 mm, and record the total thickness of the spacer samples in the pressurized state measured this time. According to the above steps, respectively measure and obtain the total thickness of the spacer samples in the pressurized state of the second group and the third group of spacer samples, and calculate the average value of the total thickness of the spacer samples in the pressurized state of the three groups and the compression rate of the spacers under pressure. Taking a certain 500 kV low-voltage coil as an example, the actual measured compressed area of the spacers of this product is 1451 mm 2 , and the area used in the calculation of the coil pressing force is 1302 mm 2 , then the compression force F1 is (224.28 / 2) / 28 * (1451 / 1302) kN = 4.46 kN. Since the actual radial wires of the coil are two, and in this embodiment, only one wire is tested during the actual test, therefore, when calculating with the formula, the coil pressing force should be divided by 2.

[0036] The calculation test data is as follows:

[0037]

[0038] The compression rate of the pad block under pressure (%) = (the total thickness of the pad block sample in the unpressurized state is 16 mm - the average total thickness of the pad block sample in the pressurized state is 14.634 mm) / the total thickness of the pad block sample in the unpressurized state is 16 mm * 100% = 8.533%.

[0039] In the embodiment of the present invention, a WDW-300E electronic universal testing machine is used to perform the pressure test.

[0040] Step 5. Measure the compressed dimensions of the wire in the pressurized state of the wire and spacer assembly.

[0041] Combine the first set of wire and spacer samples into a top-to-bottom arrangement of "spacer + horizontally arranged wire + spacer + horizontally arranged wire + spacer," with the wires and spacers forming a cross. The thickness of the spacer in the middle refers to the "spacer thickness between wire coils" in the basic information of the coil size, and the thickness of the spacers in the top and bottom positions refers to the "spacer thickness between wire coils + 2-4mm." The number of horizontally arranged wires refers to the "number of radially wound wires" in the basic information of the coil size. The number of horizontally arranged wires can be reduced based on the size of the pressurizing equipment. The pressurizing equipment die is only 150mm*150mm in size. During the test, the pressurizing equipment die is required to completely cover the wires in the width direction. If there are too many wires arranged side by side based on the actual coil size, it may not be possible to completely cover the wires that have already been wound, so it should be reduced. Apply axial pressure F2, following the same pressurization process as the spacer compression rate pressurization process. Repeat the above process until the total thickness of the conductor and spacer sample combination under pressure F2 deviates from the last measured data by ≤0.02mm. Record the total thickness of the first conductor and spacer sample combination under the pressurized state measured this time. Following the above steps, measure the total thickness of the second and third conductor and spacer sample combinations under pressurization, respectively. Calculate the average total thickness of the three conductor and spacer sample combinations under pressurization, and ultimately calculate the conductor dimensions after compression.

[0042] The calculation test data is as follows:

[0043]

[0044]

[0045] The calculation formula for the conductor pressure F2 in the table is: F2 = F1 * (conductor width / actual measured compressed length of the pad).

[0046] The size of the wire after compression is (44.116 - 20*(1 - 8.533%)) / 2 mm = 12.911 mm. Finally, it is divided by 2 because two layers of wires are used in the measurement.

[0047] Step 6. According to the data measured and calculated in the previous steps, calculate the budget height of the coil. The budget height of the coil = the size of the wire after compression * the number of turns of the coil + (the total thickness of the coil pads + the size of the insulation wrapping of the coil cake) * (1 - the compression rate of the pad under pressure) = 12.911 * 141 + (387 + 4) * (1 - 8.533%) mm = 2178 mm.

[0048] In the embodiment of the present invention, the end coil height is not added in all calculations because the end coil height is a relatively independent measurement and can be adjusted separately. The end coil is a circular ring or a layer of paper ring and a layer of pad. The drawings have clear height requirements. When the coil is actually measured and adjusted after being pressed, the adjustment of the end coil height is very simple and can be directly laid in the next process. The technical problem to be solved by the present invention is mainly that during the winding process of the coil cake, the pads can be increased or decreased according to the budgeted size, reducing the adjustment of the coil after baking and making the coil more firm.

[0049] Step 7. Pre-adjust the size of the designed height of the coil. The adjusted size of the coil height = (the budget height of the coil - the designed height of the coil) / (1 - the compression rate of the pad under pressure) = (2178 - 2180) / (1 - 8.53%) mm = -2.19 mm. Take the adjusted size of the coil height as -2.19 mm. That is: the budgeted height of the coil is 2.19 mm shorter than the designed height on the drawing, so 2.19 mm should be added during the winding process.

[0050] In the embodiment of the present invention, by using the above-mentioned method for budgeting the height of the transformer coil, the coil height is pre-adjusted during the winding process. Finally, after the coils of phases A, B, and C are taken out of the tank, the measured height under pressure is 2181 - 2182 mm, and the budget deviation ≤ 3 mm, meeting the process requirements.

[0051] Finally, it should be noted that: the above embodiments are only specific implementation manners of the present invention, used to illustrate the technical solutions of the present invention, rather than limiting it. The protection scope of the present invention is not limited thereto. Those skilled in the art should understand that: any person skilled in the art within the technical scope disclosed by the present invention can modify the technical solutions recorded in the foregoing embodiments, or can easily think of changes, or perform equivalent replacements on some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the protection scope of the present invention.

Claims

1. A method for budgeting the height of a transformer coil, characterized in that, It includes the following steps: Step 1. Statistically analyze the basic information of the coil dimensions, including: coil type, coil pressing force, number of coil steps, thickness of the spacers between disk coils, total thickness of the coil spacers, height dimension of the end coil, insulation wrapping dimension of the disk coils, number of coil turns, number of parallel conductors in the radial direction, and designed height of the coil; Step 2. Prepare the wire and spacer samples for winding the coil. Three sets of each of the spacer samples and wire samples that meet the quantity requirements for pressure measurement need to be prepared; Step 3. Conduct drying treatment on the wire and spacer samples; Step 4. Measure the pressure compression rate of the spacers; Stack the three sets of spacer samples into a column respectively, and apply an axial pressure F1. F1 is calculated based on the pressure-receiving area of the spacers and the coil pressing force. The calculation formula is: applied pressure F1 = coil pressing force / (number of coils * number of steps) * (actually measured pressure-receiving area of the spacers / pressure-receiving area used in the coil pressing force calculation); the displacement speed of the pressure platform is a constant speed of 5 mm / min. After applying the pressure to reach F1, measure the total thickness of the spacer samples in the pressurized state for the three sets of spacer samples respectively, calculate the average value of the total thickness of the spacer samples in the pressurized state for the three sets of spacer samples and the spacer pressure compression rate. The spacer pressure compression rate = (total thickness of the spacer samples in the non-pressurized state - average value of the total thickness of the spacer samples in the pressurized state) / total thickness of the spacer samples in the non-pressurized state * 100%; Step 5. Measure the size of the wire after compression in the pressurized state of the wire and spacer combination; Combine each set of wire and spacer samples into an up-and-down arrangement structure of "spacer + horizontal arrangement of wire + spacer + horizontal arrangement of wire + spacer", and apply an axial pressure F2. F2 is calculated based on the axial pressure F1 of the spacer, the number of parallel conductors in the radial direction, and the pressure-receiving area. F2 = F1 * (width of the wire / actually measured pressure-receiving length of the spacer). Measure the total thickness of the wire and spacer sample combinations in the pressurized state for the three sets of wire and spacer sample combinations respectively, calculate the average value of the total thickness of the wire and spacer sample combinations in the pressurized state for the three sets of wire and spacer sample combinations, and finally calculate the size of the wire after compression. The size of the wire after compression = (average value of the total thickness of the wire and spacer sample combinations in the pressurized state - total thickness of the spacer samples * (1 - spacer pressure compression rate)) / 2; Step 6. According to the data obtained from measurement and calculation, calculate the budget height of the coil. The calculation formula is: budget height of the coil = size of the wire after compression * number of coil turns + (total thickness of the coil spacers + insulation wrapping dimension of the disk coils) * (1 - spacer pressure compression rate); Step 7. According to the deviation between the budget height of the coil and the designed height of the coil, make a preliminary adjustment to the winding height dimension of the coil. The coil height adjustment dimension = (budget height of the coil - designed height of the coil) / (1 - spacer pressure compression rate).

2. The budget method for the height of a transformer coil according to claim 1, wherein In Step 2, if the same wire gauge is used in multiple coils, samples need to be taken from each coil of wire; if the coil uses wires of multiple wire gauges, samples need to be taken from the wires of each wire gauge; after sampling the wire, it needs to be beaten and flattened.

3. A method for estimating the height of a transformer coil according to claim 1, characterized in that In Step 3, the drying treatment parameters are: drying temperature 120°C, drying duration 36 hours, and the drying time for the spacers that have undergone densification treatment is 48 hours.

4. The budget method for the height of a transformer coil according to claim 1, characterized in that, In Step 4, after applying pressure until it reaches F1, maintain it for 30 s to fully apply pressure to the spacer block, record the total thickness of the spacer block under the pressurized state, release the pressure until it reaches 0, maintain it for 10 s, and then apply pressure F1 again. Repeat this process until the deviation between the total thickness of the spacer block sample under the pressurized state of F1 pressure and the previous measurement data is ≤0.01 mm, and record the total thickness of the spacer block sample under the pressurized state measured this time.

5. A method for budgeting the height of a transformer coil according to claim 4, characterized in that, An electronic universal testing machine is used for the pressure application test.

6. The budget method for the height of a transformer coil according to claim 1, wherein In Step 5, the thickness of the spacer block at the middle position refers to the thickness of the spacer block between the pancakes in the basic information of the coil size. The thickness of the spacer blocks at the upper and lower positions is the thickness of the spacer block between the pancakes + 2 - 4 mm. The number of horizontally arranged wires refers to the number of radially parallel wires in the basic information of the coil size, and the number of horizontally arranged wires is reduced according to the size of the pressure application equipment.

7. A method for budgeting the height of a transformer coil according to claim 6, characterized in that, Apply axial pressure F2 until the deviation between the total thickness of the combination of the wire and the spacer block sample under the pressure of F2 and the previous measurement data is ≤0.02 mm, and record the total thickness of the combination of the wire and the spacer block sample under the pressurized state measured this time.

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