Distribution transformer winding deformation mechanical vibration test method

Abstract

The invention discloses a distribution transformer winding deformation mechanical vibration test method. Relates to the technical field of electrical testing, and applies a test model which comprises a distribution transformer, an expandable insulation capsule and a driving assembly for driving the insulation capsule to expand. The distribution transformer comprises a shell and a pancake winding arranged in the shell, the pancake winding comprises multiple layers of stacked insulation coils, the number of the insulation capsules is multiple, the insulation capsules are arranged between every two adjacent insulation coils, and the multiple insulation capsules are arranged at intervals in the radial direction of the insulation coils; the insulating capsule is driven to expand through the driving assembly, and pressure is applied to the cake-type winding, so that the cake-type winding reaches a preset mechanical deformation amount; then carrying out a power-on test on the winding, and obtaining vibration test data through a vibration sensor; the normal winding, the iron core, the clamping piece and the like of the transformer are consistent with those of a normal transformer, and the overall mechanical property is well consistent with that of a 10kV real-type distribution transformer; accurate mechanical vibration testing can be carried out on the distribution transformer winding through the model.

Description

Technical Field

[0001] This invention relates to the field of electrical testing technology, and in particular to a method for testing the mechanical vibration deformation of distribution transformer windings. Background Technology

[0002] During operation, distribution transformers are subjected to electrodynamic and mechanical forces, especially short-circuit impacts, causing irreversible deformation of the windings. This deformation can be categorized into axial and radial deformation. After deformation, changes are observed in parameters such as stray inductance and capacitance, as well as mechanical vibration characteristics. Currently, the main methods for simulating transformer winding deformation are the frequency response method and the short-circuit impedance method. Both methods are based on the principle that stray inductance and capacitance parameters of the windings change. Therefore, most current transformer winding deformation defect models simulate deformation using equivalent circuits of capacitors, inductors, and resistors, such as CN202887569U and CN204347165U. These defect models can only simulate electrical quantities and cannot simulate changes in mechanical quantities, thus hindering the study of their mechanical vibration characteristics. Summary of the Invention

[0003] In order to test the mechanical vibration of backup transformers, this application provides a method for testing the mechanical vibration of distribution transformer winding deformation.

[0004] This application provides a method for testing the mechanical vibration of distribution transformer winding deformation, employing the following technical solution:

[0005] A method for testing the mechanical vibration deformation of a distribution transformer winding includes a test model comprising a distribution transformer, an expandable insulating bladder, and a drive assembly for inflating the insulating bladder. The distribution transformer includes a housing and a disc-shaped winding disposed inside the housing. The disc-shaped winding comprises multiple layers of stacked insulated coils. Multiple insulating bladders are provided, positioned between adjacent insulated coils and spaced apart radially along the insulated coils. During testing, the drive assembly inflates the insulating bladders, applying pressure to the disc-shaped winding to achieve a preset mechanical deformation. Subsequently, the winding is energized for testing, and vibration test data is acquired using a vibration sensor.

[0006] Optionally, the drive assembly includes a hydraulic pipe, a hydraulic gauge, a regulating valve group, and a bidirectional pump connected in sequence, all of which are located on the outside of the housing. The bidirectional pump is connected to the insulating capsule through the hydraulic pipe and drives the insulating capsule to expand or contract by filling it with hydraulic oil.

[0007] Optionally, the distribution transformer includes two parts: a normal winding and a modified winding. The low-voltage winding coil material of the normal winding is paper-insulated flat copper wire, and the high-voltage winding coil material is enameled round copper wire. Both the low-voltage and high-voltage windings are made using a brushing process, and support strips are used between adjacent layers. The process and materials of the normal winding part are consistent with those of a real distribution transformer.

[0008] Optionally, in the deformed winding portion of the distribution transformer, an insulating capsule is provided between two adjacent winding layers; the deformed low-voltage winding coil uses paper-insulated flat copper wire, and the high-voltage winding coil uses paper-insulated enameled round copper wire to improve its insulation strength, and no glue is applied to the outer layer of the winding.

[0009] Optionally, pressure P is applied to the disc winding through the insulating capsule. n At that time, the following conditions need to be met.

[0010] P n >δ K , and δ 0.2 <P n <1.1δ 0.2 ；

[0011]

[0012] δ 0.5（n+1） The tensile stress along the line disc towards the middle conductor;

[0013] K δ The coefficient for uneven distribution of tensile stress along the line disc in the auxiliary direction;

[0014] n is the number of conductors along the auxiliary direction of the line disc;

[0015] δ 0.2 This represents the allowable tensile stress of the conductor.

[0016] Optionally, during pressurization, the bidirectional pump gradually applies pressure to the insulating capsules on the inner or outer side of the deformable winding. At the same time, the bidirectional pump simultaneously reduces the pressure of the insulating capsules in adjacent layers of the deformable winding. The regulating valve group adjusts the pressure during the pressure application process and monitors the pressure change in real time through the hydraulic gauge, guiding the winding to be deformed to gradually deform until the pressure increases to the set value.

[0017] In summary, this application includes the following beneficial technical effects:

[0018] 1. The normal windings, core, and clamps of the transformer are consistent with those of a normal transformer, and the overall mechanical characteristics are consistent with those of a 10kV true distribution transformer.

[0019] 2. The high and low voltage windings have good insulation strength and can withstand normal operating voltage and current, thus meeting the research needs of vibration characteristics of transformers under different operating conditions;

[0020] 3. The installation position and quantity of insulating capsules can be selected in advance. Both high-voltage and low-voltage windings can be set, and the deformation of the deformation section winding can be freely adjusted by adjusting the pressure of the bidirectional pump. The deformation state is well controllable and flexible. Attached Figure Description

[0021] Figure 1 This is an overall system diagram of the present invention;

[0022] Figure 2 This is a top view schematic diagram of the winding arrangement inside the distribution transformer according to the present invention;

[0023] Figure 3 This is a schematic diagram of the arrangement of the present invention outside the distribution transformer.

[0024] Explanation of reference numerals in the attached figures:

[0025] 1. Control box; 2. Two-way pump; 3. Regulating valve group; 4. Hydraulic gauge; 5. Hydraulic pipe; 6. Insulating bladder; 7. High voltage winding; 8. Support curtain; 9. Control cabinet. Detailed Implementation

[0026] The following is in conjunction with the appendix Figure 1-3 This application will be described in further detail.

[0027] This application discloses a method for testing the mechanical vibration of a distribution transformer winding deformation. The method uses a dedicated test model, which includes a distribution transformer, an expandable insulating capsule, and a drive assembly for expanding the insulating capsule. The distribution transformer includes a housing and a disc winding disposed inside the housing. The disc winding includes multiple layers of stacked insulating coils. Multiple insulating capsules are provided and disposed between two adjacent insulating coils, and the multiple insulating capsules are spaced apart along the radial direction of the insulating coils.

[0028] The drive assembly includes a hydraulic pipe, a hydraulic gauge, a regulating valve group, and a bidirectional pump connected in sequence, all of which are located on the outside of the housing. The bidirectional pump is connected to the insulating capsule through the hydraulic pipe and drives the insulating capsule to expand or contract by filling it with hydraulic oil.

[0029] In this embodiment, the distribution transformer is model S13-M-400 / 10, with a capacity of 400kVA and connection group Dyn11. The low-voltage winding uses paper-insulated flat copper wire, 4.3×12mm in size, with a total of 26 turns. The high-voltage winding uses enameled round copper wire φ2.24mm, with a total of 12 layers. The first 11 layers each have 98 turns, and the 12th layer has 104 turns, for a total of 1182 turns. A winding deformation section is set between turns 200-210 of the third layer of the high-voltage winding. Except for the third layer, the remaining windings are all coated with adhesive. Three support bars are added between the third layer and the deformation sections of the second and fourth layers. The support bars 8 in the normal winding section have a size of 3.0×10×368mm, and the support bars 8 in the deformation section have a size of 1.8×5×368mm, with 3 bars on each side, for a total of 6 bars.

[0030] The insulating capsule is made of ternary 23-type fluororubber, which has good insulation, ductility, and solvent resistance. The hydraulic hoses are nitrile rubber high-pressure hoses, φ10mm, capable of withstanding 100MPa pressure. A standard hydraulic gauge is used. The bidirectional pump is an electric hydraulic pump with high / low pressure of 70MPa / 7MPa and a flow rate of 1L / 5Lmin; the regulating valve parameters are matched to the bidirectional pump; control box 1 is used to set the applied oil pressure. The hydraulic oil used is Karamay No. 25 transformer oil.

[0031] The steps for using this device are as follows:

[0032] (1) Calculate the applied pressure value P based on the position of the deformed section winding and the estimated deformation. n ;

[0033] The applied pressure value P n The tensile stress δ generated in the Kth turn of the pancake winding is related to the tensile stress δ generated in the pancake winding. K And the allowable tensile stress δ corresponding to a residual (permanent) deformation of 0.2% in the transformer conductor. 0.2 related.

[0034] Where, δ K The approximate calculation formula is as follows:

[0035]

[0036] δ 0.5（n+1） The tensile stress along the line disc towards the middle conductor is generally close to the average tensile stress.

[0037] K δ It is the uneven distribution coefficient of tensile stress along the conductor coil, which is related to the elastic modulus of the conductor coil insulation and the geometric dimensions of the conductor coil.

[0038] n is the number of conductors along the auxiliary direction of the line disc.

[0039] Allowable tensile stress δ 0.2The δ value is related to the conductor material. For the copper wire in the deformed winding section of the high-voltage winding of a distribution transformer, its... 0.2 Between 10-12 MPa; in the normal winding section of the copper wire (resin impregnation process to enhance deformation stress), its δ 0.2 Between 20-24 MPa.

[0040] Considering the feasibility of repeated use of the defect model, the applied pressure value P n The principles for selecting values ​​are as follows:

[0041] P n >δ K , and δ 0.2 <P n <1.1δ 0.2 .

[0042] (2) Set the pressure value in the control box, and the bidirectional pump gradually applies pressure to the insulating capsules on the inner or outer side of the deformed section winding (either the inner or outer side is acceptable, and the pressure can be applied according to the set deformation direction). At the same time, the bidirectional pump synchronously reduces the pressure of the insulating capsules of the adjacent layers of the deformed section winding. The regulating valve group adjusts the pressure during the pressure application process, and the pressure change is observed in real time through the hydraulic gauge to guide the winding to be deformed to gradually deform until the pressure increases to the set value.

[0043] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for mechanical vibration testing of distribution transformer winding deformation, characterized in that: The application has a test model, which comprises a distribution transformer, inflatable insulation capsules and a driving assembly for driving the insulation capsules to expand; the distribution transformer comprises a shell and a disc winding arranged inside the shell, the disc winding comprises a plurality of insulation coils arranged in a multi-layer stack, the insulation capsules are arranged between two adjacent insulation coils, and the plurality of insulation capsules are arranged at intervals along the radial direction of the insulation coils; during the test, the insulation capsules are driven to expand by the driving assembly to apply pressure to the disc winding, so that the disc winding reaches a preset mechanical deformation amount; then the winding is tested for power supply, and vibration test data is obtained by a vibration sensor.

2. The method of claim 1, wherein: The driving assembly comprises a hydraulic pipe, a hydraulic gauge, an adjusting valve group and a bidirectional pump connected in sequence, which are all arranged outside the shell, the bidirectional pump is connected with the insulation capsules through the hydraulic pipe, and the insulation capsules are driven to expand or contract by filling hydraulic oil.

3. The method of claim 2, wherein the method further comprises: The distribution transformer comprises two parts of a normal winding and a deformed winding, the low-voltage winding coil material of the normal winding adopts paper-wrapped flat copper wire, the high-voltage winding coil material adopts enameled round copper wire, and the low-voltage and high-voltage windings as a whole adopt a brushing glue process, and a stay curtain is used between adjacent layers, the process and material of the normal winding part are consistent with those of a true distribution transformer.

4. The method of claim 3, wherein the method further comprises: The deformed winding part of the distribution transformer is provided with insulation capsules between two adjacent layers of windings; the deformed low-voltage winding coil adopts paper-wrapped flat copper wire, and the high-voltage winding coil adopts paper-wrapped enameled round copper wire, so as to improve the insulation strength, and the outer layer of the winding is not brushed with glue.

5. The method of claim 4, wherein the method further comprises: When the pressure P is applied to the pancake winding by the insulating capsule n the following conditions need to be met P n >δ K , and δ 0.2 <P n <1.1δ 0.2 ； δ 0.5（n+1） The tensile stress along the line disc towards the middle conductor; K δ K is the coefficient of non-uniformity of the tensile stress distribution along the line of the piezoelectric element; n is the number of conductors along the line cake auxiliary direction; delta 0.2 Tensile stress of the wire for the purpose of resistance.

6. The method of claim 5, wherein the method further comprises: When pressure is applied, the bidirectional pump gradually applies pressure to the insulation capsules inside or outside the deformed winding, while the bidirectional pump simultaneously reduces the pressure of the insulation capsules of adjacent layers of the deformed winding, the adjusting valve group adjusts the pressure during the pressure application process, and the pressure change is observed in real time through the hydraulic gauge, so as to guide the deformed winding to gradually deform until the pressure increases to a set value.

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