CN114843089B - Method for designing insulation in casting dry type transformer winding - Google Patents
Method for designing insulation in casting dry type transformer winding Download PDFInfo
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- CN114843089B CN114843089B CN202210451684.1A CN202210451684A CN114843089B CN 114843089 B CN114843089 B CN 114843089B CN 202210451684 A CN202210451684 A CN 202210451684A CN 114843089 B CN114843089 B CN 114843089B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/28—Coils; Windings; Conductive connections
- H01F27/32—Insulating of coils, windings, or parts thereof
- H01F27/323—Insulation between winding turns, between winding layers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/28—Coils; Windings; Conductive connections
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/04—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing coils
- H01F41/06—Coil winding
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/04—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing coils
- H01F41/12—Insulating of windings
- H01F41/122—Insulating between turns or between winding layers
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Abstract
The invention discloses a method for designing insulation in a cast dry type transformer winding, which is characterized in that an absolute safety zone and a relative safety zone which are not discharged by gas in the Paschen law are used for designing an insulation structure of the cast dry type transformer winding, and the insulation structure is combined with a corresponding winding method by reasonable segmentation to ensure that a partial discharge test voltage U specified by GB1094.11 is applied test When the highest potential difference distributed between any two wires in the winding is not more than U min The main factors of partial discharge inside the winding of the casting dry type transformer are eliminated, so that partial discharge can not occur even if gas exists inside the winding, the safety of insulation inside the winding is ensured, the whole quality and the service life of the dry type transformer are improved, and conditions are provided for thoroughly maintaining-free dry type transformers; meanwhile, the process quality requirement on the insulating material for winding casting is reduced, the production efficiency is improved, and the production cost is saved.
Description
Technical Field
The invention relates to a method for designing insulation in a casting dry-type transformer winding.
Background
The partial discharge of high-voltage electrical equipment in the atmosphere is caused by the relatively high voltage between conductors and the electric field and air formed by the relatively high voltage. The most harmful partial discharge of the dry-type transformer occurs in the vicinity of the internal wires of the winding, because this burns out the thin insulation of the wires, causing the winding turn-to-turn short circuit to cause serious faults of the transformer, which is also the main cause of shortening the life of the transformer, so thoroughly eliminating this hazard is extremely important for long-term safe operation of the transformer. Particularly in severe environments (such as high and low air pressure) or when winding insulation is defective (such as bubble or crack of solid medium), if partial discharge can be eliminated, the method is an ideal boundary pursued by dry-type transformer design and manufacture.
The casting dry-type transformer has the advantages that the insulation material in the winding can protect the internal insulation of the high-voltage winding from being damaged by mechanical forces such as vibration, external short circuit and the like, also prevent dust from being embedded in the winding or from being affected by moisture, and cause adverse effects on the internal insulation of the high-voltage winding, is very beneficial to lightning strike resistance of the transformer, ensures the safety performance of the high-voltage winding fully, and provides conditions for realizing thorough maintenance-free dry-type transformer.
The internal insulation of the dry-type transformer winding is divided into inter-turn insulation, interlayer insulation and inter-segment insulation, as in fig. 1, wherein the inter-turn insulation can not consider the partial discharge problem due to lower voltage, and the inter-layer and inter-segment needs to solve the partial discharge problem.
Measures for eliminating partial discharge inside a traditional epoxy resin cast few-segment layered winding are as follows: firstly, the voltage between the sections and the voltage between the layers are moderately reduced by adopting a few-section winding mode (4-12 sections of a 10kV transformer), and secondly, the air between the sections and the layers of the winding is removed by tightly casting epoxy resin. However, the high voltage still exists between the inner layers and the segments of the winding, and the formed electric field is enough to discharge the air existing nearby, so that the cast insulating material has no defects to prevent the partial discharge. This method can be referred to as passive elimination of partial discharge and requires that the epoxy casting process be perfect to eliminate the partial discharge. However, if the insulating material filled in the manufacturing process is defective (such as bubbles), or the insulating material is deformed or even cracked in the operation process to generate defects, the air entering the defects can easily meet the discharge condition, and larger partial discharge can be generated to seriously threaten the safety of the winding. In actual use, the transformer winding generates heat under load to generate high temperature, the temperature expansion coefficients of the epoxy resin material and the metal wire are greatly different, and when the temperature is greatly changed along with the load in operation, different thermal expansions of the wire and rigid objects with different properties of the insulating material are generated, so that great internal stress is generated at the joint interface, the insulating material is easily deformed and even cracked to cause insulation defects, and large partial discharge occurs due to air infiltration to cause internal faults of the high-voltage winding. Therefore, the epoxy resin transformer has extremely high requirements on the processing technology of the insulating material during winding manufacture, residual bubbles in the winding can be often caused by unstable technology, the cast winding is subjected to partial discharge exceeding standard, and the winding is scrapped and lost greatly. Even if the partial discharge quantity of the transformer is very small under the condition of room temperature before the winding leaves the factory, the frequent change of the temperature caused by the load still causes new defects of the insulating material in the running process, so that the insulation of the transformer is gradually deteriorated in the running process, and the partial discharge is gradually increased, thereby influencing the service life of the transformer. Therefore, the passive method for eliminating internal partial discharge by densely filling the windings of the traditional epoxy resin transformer with the insulating material has difficulty in manufacturing process and risks in operation, and increases the quality cost and the operation maintenance burden of the dry-type transformer.
Disclosure of Invention
The invention aims to: aiming at the defects of the prior art, the invention provides a casting type dry-type transformer winding internal insulation design method, which comprises the following steps:
step 1, determining the safety voltage of gas;
step 2, determining the rated bearing voltage of the winding;
step 3, determining the test voltage U of the partial discharge of the transformer test ；
Step 4, determining a wiring coefficient k w ；
Step 5, designing the minimum number of segments of the main winding;
step 6, designing a tapping winding;
and 7, designing a winding method of the winding wire and a final segmentation mode.
The step 1 comprises the following steps: obtaining the gas minimum discharge voltage U from the Paschen curve min . Here U min The other voltages refer to ac effective values for amplitude.
The step 2 comprises the following steps: determining M turns per volt of transformer winding according to transformer design principle U And rated turns M r ，M r ＝M U U r ，U r Rated voltage of the transformer;
determining the number of turns M of tap adjusting winding for non-excitation voltage regulation tc ；
Tap adjustment voltage range is expressed as n x + -U k In%, the number of tap windings is 2n (n is a natural number, determined by a user), and the rated regulated voltage received by each tap winding is U tc ＝U k ％U r ；
The voltage regulating range of the transformer is (1-nU) k ％)U r To (1+nU) k ％)U r The winding structure is now divided into a main winding and 2n tap-adjusting windings M tc The number of main winding turns m=m r -nM tc Rated voltage on main winding is U M ＝U r (1-nU k ％)。
The step 3 comprises the following steps: for dry transformers, provision is made for the partial discharge measurement voltage U of the transformer to be applied when the transformer winding taps are placed in the nominal voltage position according to GB1094.11 test ＝k test U r ，k test To be a multiple of the applied voltage relative to the nominal voltage at the time of measurement.
Step 4 comprises: according to the wiring mode of the winding, the winding actually bears the test voltage U w ＝k w U test ，k w For the connection coefficient k when the winding is delta-connected w =1, when the winding is Y-wired
The step 5 comprises the following steps: ensuring that the transformer is applied with a partial discharge test voltage U prescribed by GB1094.11 test The voltage being applied to each segment of the main windingThe minimum number of segments N of the main winding is:
or:
wherein int represents an integer, at which time the number of turns in the main winding segment is averagedWhen->When the number of turns of the main winding is non-integer, the number of the sections is increased after M is rounded so as to meet the requirement that the number of turns of the main winding is kept unchanged.
The step 6 comprises the following steps: the tap-adjusting windings have 2n groups, each tap-adjusting winding needs to meet the requirement of applying U to the transformer when being segmented test Each segment voltage is smaller thanIf the tap-adjusting winding applies U at the transformer test The bearing voltage is not more than%>No segmentation is required, otherwise segmentation is required.
The step 7 comprises the following steps: the wire in the section is wound in a layered manner or in a cake manner;
when the layered winding is adopted, each section is layered and continuous and clockwise from inside to outside;
when cake winding is adopted, adjacent cakes of the cake winding are selected continuously and smoothly from inside to outside, and the minimum cake dividing quantity is calculated according to a normal segmentation method; however, if adjacent cakes are subjected to a forward and reverse winding process, the minimum cake dividing quantity is doubled.
The invention provides a principle and a method for thoroughly eliminating partial discharge inside a cast transformer winding by utilizing a discharge safety zone based on a gas discharge rule, which can be called an active elimination partial discharge method, and has been widely verified in a silicon rubber cast dry transformer.
The beneficial effects are that: the invention provides a method for actively reducing the internal voltage of a winding to eliminate partial discharge, namely, an absolute safety area of gas non-discharge in the Paschen law is used for conducting insulation structural design on a casting type transformer winding, and the method is combined with a corresponding winding method through reasonable segmentation to ensure that the partial discharge test voltage U specified in GB1094.11 is applied test When the highest potential difference distributed between any two wires in the winding is not more than U min Eliminating internal part of cast dry transformer windingThe main factor of partial discharge is that partial discharge can not occur even if air exists in the winding, so that the safety of insulation in the winding is ensured, the integral quality and the service life of the dry-type transformer are greatly improved, and conditions are provided for thoroughly maintaining-free dry-type transformers; meanwhile, the process quality requirement on the insulating material for winding casting is reduced, the production efficiency is improved, and the production cost is saved. In a word, the invention effectively improves the safety reliability and economic benefit of the whole life cycle of the dry-type transformer.
Drawings
The foregoing and other advantages of the invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings and detailed description.
Fig. 1 is a schematic diagram of a dry-type transformer cast winding and its internal insulation.
Fig. 2 is a schematic representation of the curve expression of Paschen's law.
Fig. 3 is a schematic view of each segment (pancake) of the a-phase winding continuously and smoothly from inside to outside.
Fig. 4 is a schematic diagram of adjacent segments (pancake) of a phase winding using a forward and reverse winding method.
Detailed Description
The invention will be further described with reference to the accompanying drawings and examples.
The gas discharge law can be expressed by Paschen's law and the corresponding curve (fig. 2). In this experimental law, the air discharge voltage (Y-axis) is related to the product of air pressure and the distance between conductors (X-axis). The relationship has a minimum discharge voltage U min And the corresponding product delta 0 Higher than U min When the gas exists, the discharge is possible to occur under specific conditions; when the product delta between the air pressure and the conductor distance<δ 0 Time (delta in curve) 0 Right), initial discharge voltage U d Decreasing as the product δ decreases; while when delta<δ 0 Time (delta in curve) 0 Left) initial discharge voltage U d Instead, increases with decreasing product δ.
Although Paschen's law is an experimentally verified law carried out at low pressure, many people are under different gases, different pressuresAnd the analysis expression of the discharge curve under different intervals are modified greatly, so that the complex factors such as gas molecular ionization collision and electron emission are considered, but the conclusion has a common rule that the gas discharge has the lowest discharge voltage U min ，U min Is related to the gas species; the gas discharge curve can be divided into 3 zones: u (U) min The following is an absolute safety zone, U, where the gas is not discharged min And the relative safe area (left area and right area) of conditional discharge is between the two curves, and the discharge area is above the curves, as shown in figure 1.
In the design of the transformer windings, when the windings are subjected to the highest possible voltage, U is set up min As the design limit of any inter-conductor voltage peak value in the winding, the potential difference between any conductors in the winding will not exceed U when the transformer is operated min The inside of the winding is in an absolute safety area where gas is not discharged, namely, the gas discharge phenomenon cannot be generated under any condition, so that the problem of partial discharge inside the winding of the dry-type transformer is thoroughly solved, and particularly under special environments such as a plateau, even if insulating materials near a winding wire are defective, namely, air bubbles or cracks exist in insulation, the inside of the high-voltage winding of the transformer can be ensured not to be partially discharged, and thin insulation among turns, layers and sections of the wire cannot be burnt by partial discharge, so that the winding of the transformer has long service life.
The voltage between winding conductors is actively reduced by utilizing the Paschen gas discharge law, the effect that gas cannot be discharged is achieved, and partial discharge is eliminated without densely filling and removing the gas through an insulating medium, so that the method is called an active partial discharge elimination method.
Dry transformer winding design using air non-discharge region
Step 1: determining a safety voltage
Obtaining the minimum discharge voltage U from the Paschen curve min For air U, e.g min About 327 volts. Here U min The other voltages refer to ac effective values for amplitude.
Step 2: determining winding voltage
Determining the transformation according to the design principle of the transformerTurns per volt M of the winding U And rated turns M r ，M r ＝M U U r ，U r Rated voltage of the transformer; in addition, the number of turns M of the tap adjusting winding for non-excitation voltage regulation is determined tc . The tap adjustment voltage range is typically expressed as n x + -U k In%, the number of tap windings is 2n, and the rated regulating voltage born by each tap winding is U tc ＝U k ％U r The voltage regulating range of the transformer is (1-nU) k ％)U r To (1+nU) k ％)U r The winding structure is now divided into a main winding (M turns) and 2n tap-adjusting windings M tc M=m r -nM tc Rated voltage on main winding is U M ＝U r (1-nU k % of the total weight of the composition. For example, the transformer tap parameter is 2 x + -2.5%, then tap winding U at rated voltage tc ＝2.5％U r Main winding U M ＝95％U r A voltage.
Step 3: determination of the test voltage U of partial discharge of a transformer test
For dry transformers, the partial discharge measurement voltage U of the transformer is applied when the transformer winding tap is placed in the rated voltage position, as specified in national standard GB1094.11, 22 test ＝k test U r ，k test To be a multiple of the applied voltage relative to the nominal voltage at the time of measurement. Here U test And U r Are ac effective values.
Step 4: determining a wiring coefficient k w
According to the wiring mode of the winding, the winding actually bears the voltage U w ＝k w U test ，k w Is the connection coefficient, k when the winding is delta-connected w =1, when the winding is Y-wired
Step 5: designing main winding segments
It should be ensured that the partial discharge test voltage U prescribed in GB1094.11 is applied to the transformer test When each section of the main winding is subjected toVoltage (V)The number of segments N of the main winding is:
or:
wherein int represents an integer, at which time the number of turns in the main winding segment is averagedWhen->When the number of the main winding turns is non-integer, the number of the sections is increased after M is rounded so as to meet the requirement that the number of the main winding turns is kept unchanged. The number of turns required for adjustment can be adjusted on the basis of less than m according to the winding structure or the electrical insulation requirement in actual design, and the number of segments can be increased.
Step 6: design of tapping windings
The tap-adjusting windings have 2n groups, and each tap-adjusting winding is also required to meet the requirement of applying U to the transformer when being segmented test Each segment voltage is smaller thanThus if the tap-adjusting winding applies U at the transformer test The bearing voltage is not more than%>No segmentation is needed, otherwise segmentation is needed;
step 7: winding method for designing winding wire and final segmentation mode
The wires in the segments can be wound in layers or in cakes (only 1 turn of wire per layer). The turn-to-turn voltage of the lead is insufficient to generate partial discharge, thereby meetingThe voltage between the inner layers of the back sections of the steps 1 to 5 does not exceed U seg So that no partial discharge occurs between the layers. Whereas the inter-segment situation is related to the winding wire winding method.
First case: each segment or cake is continuously wound in a clockwise direction from the inside to the outside (fig. 3), so that the effect of the winding is that the potential difference distribution between adjacent segments or cakes dU=U seg Is approximately uniform, and the potential difference between any two wires between two sections or cakes does not exceed the section (cake) voltage U seg In the absolute safety zone, partial discharge is not generated between the segments.
Thus, even if gas exists between layers and between sections in the winding, discharge can not occur, and the electrical safety performance of insulation in the winding is ensured;
second case: the adjacent cakes of the cake winding adopt a forward and reverse winding process (figure 4), so that the potential difference distribution among the cakes forms a scissor difference shape, and the highest potential difference dU between the two cakes max =2du. At this time, in order to keep partial discharge when gas exists between cakes in the winding, the number of cakes is not less than 2N and the number of turns in each section is not less than 1Design with a relatively safe zone for conditional discharge of gas:
the insulation safety design in the winding can be performed in the relatively safe region of the Paschen curve according to the air pressure conditions determined in the use field and the insulation distance designed between the sections. Estimating the minimum air distance and the minimum atmospheric pressure which can be generated and encountered, finding the corresponding discharge voltage from the curve, and taking the margin, replacing the U with the reduced voltage value min The method can be designed as the basis of segmentation, so that the number of the segments is reduced, and the method has the advantages of improving the winding manufacturing efficiency and reducing the winding height.
When the winding is cast by the silicon rubber insulating material, the silicon rubber material is not adhered to the lead and other materials, so that the air in the winding cannot be discharged to a higher degree, and if the mode of actively reducing the voltage between the internal conductors is not adopted, harmful partial discharge cannot be eliminated, and the safe operation of the transformer is seriously endangered. The dry-type transformer formed by windings designed and manufactured by the principle can be suitable for any insulating material, so that partial discharge can not be generated among turns, layers and cakes in the windings which normally run in air, and the dry-type transformer is irrelevant to whether the insulating medium has defects or not and whether the periphery of a wire has air or not and can be suitable for internal insulation degradation phenomenon which occurs in long-term running of the dry-type transformer, thereby prolonging the service life of the dry-type transformer. This method of eliminating partial discharge by eliminating voltage or electric field factors may be called an active elimination partial discharge method.
Examples
(1) Distribution transformer U for three-phase experiment of 315kVA/10kV double-winding by casting silicon rubber r =10 kV; the high-voltage winding is delta-connection k w =1; with 2×±2.5% tap, nU% = 2×2.5% = 5%; the altitude of the test ground is not more than 100 m, and the partial discharge test voltage multiple k specified in GB1094.11 for a distribution transformer test The method is characterized in that the method comprises the following steps of (1.3), calculating to obtain N +.54, designing a high-voltage winding according to an absolute safety zone, wherein the design scheme is that a main winding component is 54 sections, each group of 4 tapping windings is designed to have 2 sections which are 8 sections in total, all the sections are layer windings, each layer is provided with 2 turns of wires, and the sections are directly and forward transited. And casting and solidifying the high-voltage winding by using liquid high-performance silicone rubber rich in air bubbles, and assembling the high-voltage winding, the three-phase low-voltage winding and the iron core into the three-phase distribution transformer. Partial discharge test was performed as specified in GB/T1094.11 standard when the test voltage increased to 1.8U r And fall back to the partial discharge test voltage of 1.3U r When the transformer does not have obvious partial discharge, the partial discharge amount is smaller than the qualification standard 10pC specified in GB1094.11, and the test is qualified.
(2) The silicon rubber is used for casting a 630kVA/10kV double-winding three-phase distribution transformer, a high-voltage winding is delta-connection, a tapping tap of 2 X+/-2.5% is arranged, and the altitude of an application area is not more than 100 meters. The design scheme of the high-voltage winding is that the high-voltage winding is mainly formed by 35 sections, each winding of the 4 tap windings is designed into 1 section which is 4 sections altogether, and all sections are wound in a layered mode, and direct transition and continuous forward winding are carried out among the sections. Defoaming and casting with liquid high-performance silicon rubber, and performing partial discharge test according to GB/T1094.11 standard until the test voltage rises to1.8U r And fall back to the partial discharge test voltage of 1.3U r When the transformer does not have obvious partial discharge, the partial discharge amount is smaller than the qualification standard 10pC specified in GB1094.11, and the test is qualified. The device is put into operation for more than 5 years so far, and no problem exists.
(3) The silicone rubber is used for casting a 2000kVA/10kV split low-voltage winding three-phase energy storage transformer, a high-voltage winding is delta-wiring, a 2 X+/-2.5% tapping tap is arranged, the altitude of an application area is not more than 200 meters, an air discharge relative safety area is applied, the design scheme of the high-voltage winding is 33 sections of a main winding component, 4 sections are designed for each group of 4 tapping tap windings, all the sections are pancake type unidirectional forward winding windings, and transition is carried out among cakes through wire bending. The liquid high-performance silicon rubber is used for defoaming casting, the test is carried out according to GB/T1094.11, when the test voltage is increased to 1.8Ur, obvious partial discharge occurs in the phase 3 of the transformer, when the test voltage is reduced to 1.3Ur, the partial discharge is smaller than 5pC and smaller than 10pC specified by the standard, and the factory test is qualified. The transformer is put into use in a user substation, and no problem occurs in 3 years.
(4) A transformer for a 30kVA/35kV double-winding transformer substation is cast from silicon rubber, a high-voltage winding is Y-connection, and the transformer is provided with a tapping tap of 2 X+/-2.5%, and the altitude of an application area is not more than 500 meters. The actual rated bearing voltage of the high-voltage winding is 35/. V3 kV, a relatively safe area of air discharge is applied, the design scheme is that the main winding is 74 sections, and the total of 2 sections of each winding is 8 sections of 4 tapping tap windings. All winding sections are wound in layers, and the sections are directly transited. And (5) defoaming and pouring with liquid high-performance silicone rubber. The transformer is qualified by testing partial discharge according to GB/T1094.11 before leaving the factory, and no problem occurs after the transformer is put into use for more than 4 years in a user substation.
The invention provides a method for designing insulation in a winding of a cast dry-type transformer, and the method and the way for realizing the technical scheme are numerous, the above description is only a preferred embodiment of the invention, and it should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the invention, and the improvements and modifications should be regarded as the protection scope of the invention. The components not explicitly described in this embodiment can be implemented by using the prior art.
Claims (8)
1. The method for designing the insulation in the casting dry-type transformer winding is characterized by comprising the following steps of:
step 1, determining the safety voltage of gas;
step 2, determining the rated bearing voltage of the winding;
step 3, determining the test voltage U of the partial discharge of the transformer test ；
Step 4, determining a wiring coefficient k w ；
Step 5, designing the minimum number of segments of the main winding;
step 6, designing a tapping winding;
and 7, designing a winding method of the winding wire and a final segmentation mode.
2. The method of claim 1, wherein step 1 comprises: obtaining the gas minimum discharge voltage U from the Paschen curve min 。
3. The method according to claim 2, wherein step 2 comprises: determining M turns per volt of transformer winding according to transformer design principle U And rated turns M r ，M r ＝M U U r ，U r The voltage is the rated voltage effective value of the transformer;
determining the number of turns M of tap adjusting winding for non-excitation voltage regulation tc ；
Tap adjustment voltage range is expressed as n x + -U k In%, the number of tap windings is 2n, and the rated regulating voltage born by each tap winding is U tc ＝U k ％U r ；
The voltage regulating range of the transformer is (1-nU) k ％)U r To (1+nU) k ％)U r The winding structure is now divided into a main winding and 2n tap-adjusting windings M tc The number of main winding turns m=m r -2nM tc The effective value of the rated voltage born on the main winding is U M ＝U r (1-nU k ％)。
4. A method according to claim 3, wherein step 3 comprises: for dry transformers, provision is made for the partial discharge measurement voltage U of the transformer to be applied when the transformer winding taps are placed in the nominal voltage position according to GB1094.11 test ＝k test U r ，k test To be a multiple of the applied voltage relative to the nominal voltage at the time of measurement.
5. The method of claim 4, wherein step 4 comprises: according to the wiring mode of the winding, the winding actually bears the test voltage U w ＝k w U test ，k w For the connection coefficient k when the winding is delta-connected w =1, when the winding is Y-wired
6. The method of claim 5, wherein step 5 comprises: ensuring that the transformer is applied with a partial discharge test voltage U prescribed by GB1094.11 test The voltage being applied to each segment of the main windingThe minimum number of segments N of the main winding is:
or:
wherein int represents an integer, at which time the number of turns in the main winding segment is averagedWhen->When the number of turns of the main winding is non-integer, the number of the sections is increased after M is rounded so as to meet the requirement that the number of turns of the main winding is kept unchanged.
7. The method of claim 6, wherein step 6 comprises: the tap-adjusting windings have 2n groups, each tap-adjusting winding needs to meet the requirement of applying U to the transformer when being segmented test Each segment voltage is smaller thanIf the tap-adjusting winding applies U at the transformer test The bearing voltage is not more than%>No segmentation is required, otherwise segmentation is required.
8. The method of claim 7, wherein step 7 comprises: the wire in the section is wound in a layered manner or in a cake manner;
when the layered winding is adopted, each section is layered and continuous and clockwise from inside to outside;
when cake winding is adopted, adjacent cakes of the cake winding are selected continuously and smoothly from inside to outside, and the minimum cake dividing quantity is calculated according to a normal segmentation method; however, if adjacent cakes are subjected to a forward and reverse winding process, the minimum cake dividing quantity is doubled.
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| CN106847482A (en) * | 2017-03-23 | 2017-06-13 | 江西特种变压器厂 | One kind has transverse air channel high pressure molded coil transformer and its manufacture method |
| CN106876130A (en) * | 2017-03-22 | 2017-06-20 | 海鸿电气有限公司 | A kind of loop construction and its technique for coiling of three dimensional wound core casting dry type transformer |
| CN111009401A (en) * | 2019-11-29 | 2020-04-14 | 广州智光电气技术有限公司 | Dry type converter transformer and design method thereof |
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2022
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106876130A (en) * | 2017-03-22 | 2017-06-20 | 海鸿电气有限公司 | A kind of loop construction and its technique for coiling of three dimensional wound core casting dry type transformer |
| CN106847482A (en) * | 2017-03-23 | 2017-06-13 | 江西特种变压器厂 | One kind has transverse air channel high pressure molded coil transformer and its manufacture method |
| CN111009401A (en) * | 2019-11-29 | 2020-04-14 | 广州智光电气技术有限公司 | Dry type converter transformer and design method thereof |
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