Stator coil manufacturing method of generator stator coil notch anti-corona structure

Abstract

The invention provides a method for manufacturing a stator coil of a generator stator coil notch anti-corona structure, and relates to the technical field of generator stator coils, the stator coil manufactured by the method has the advantages of simple anti-corona structure, convenient process and easy design and manufacture, the anti-corona effect at the notch of the coil can be improved, and the anti-corona effect of the notch of the coil can be improved. And by adopting the design of the multi-layer composite material, the corrosion resistance of the corona discharge structure is improved, the durability of the coil corona discharge layer is enhanced, the electric corrosion of the stator coil at the notch outlet is avoided, and the stability of the corona discharge performance of the stator coil is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of generator stator coils, in particular to a method for manufacturing a stator coil with a generator stator coil notch anti-corona structure. Background Art

[0002] The anti-corona coating of high-voltage generator stator coils prevents partial discharges in the coils in the air. The coil anti-corona coating is divided into a slot anti-corona layer and a coil end anti-corona layer. The slot anti-corona layer includes the slot inner layer and the slot exit anti-corona layer. The main coil insulation surface is made of a semiconductor anti-corona material with a resistance range of 200Ω to 100,000Ω. Common materials include anti-corona tape or anti-corona paint. The coil end anti-corona layer is typically made of nonlinear silicon carbide anti-corona material with a resistance range of 10×106Ω to 10×1012Ω at DC5000V.

[0003] As large-scale generator sets operate for longer periods of time, the stator coils of many generator sets begin to turn white at the slots due to the poor corrosion resistance of the anti-corona layer at the slots. Similar situations occur in some units at the beginning of operation. In severe cases, the main insulation is corroded, causing the coil to break down, seriously endangering the safe and stable operation of the generator.

[0004] Stator coil slot discharge is caused by unstable and unreasonable low-resistance anti-corona resistance values ​​in the stator coil, resulting in poor anti-corona effectiveness, as well as loosening and wear of the stator coil slot fixings. This creates a large potential difference between the stator coil and the core, sufficient to cause discharge in the air gap between the stator coil slot and the stator core. Typically, the stator coil slots are wrapped with a semiconductor low-resistance anti-corona material. This low-resistance material maintains the same potential as the grounded stator core, preventing corona discharge caused by gaps within the slots. Furthermore, to ensure adequate contact between the stator coil and the core, after the stator coil is embedded, semiconductor strips or semiconductor corrugated sheeting are used to fill the gap between the coil and the core slot walls. These measures ensure effective contact and fixation between the stator coil and the slot walls, preventing wear of the coil slots due to vibration and other factors, which can lead to slot discharge. However, improving the corrosion resistance and anti-corona effectiveness of the anti-corona layer at the slot exit remains an urgent problem in this field. Summary of the Invention

[0005] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a method for manufacturing a stator coil with an anti-corona structure for a generator stator coil slot. This stator coil has the advantages of a simple anti-corona structure, convenient process, and easy design and manufacturing. It can improve the anti-corona effect at the coil slot, protect the overlapping positions of multiple layers of anti-corona, enhance the durability of the coil anti-corona layer, avoid electrical corrosion of the stator coil at the slot, and ensure the stability of the stator coil anti-corona performance.

[0006] To achieve the above-mentioned purpose, the present invention is implemented through the following technical solutions:

[0007] A method for manufacturing a stator coil having a stator coil slot anti-corona structure for a generator comprises the following steps:

[0008] Step 1: Wrap a first epoxy multi-resistance mica tape with a thickness of d0 on the formed conductor as the main insulation material, and wrap a layer of first low-resistance anti-corona tape half-lap around the main insulation groove, wrapping it to the medium and low resistance overlap;

[0009] Step 2: The high-resistance anti-corona structure of the stator coil consists of a silicon carbide medium-resistance anti-corona tape, a silicon carbide high-resistance anti-corona tape, and the first epoxy multi-resistance mica tape. A layer of the silicon carbide medium-resistance anti-corona tape is overlapped at the end of the first low-resistance anti-corona tape in a half-lapped wrapping manner, and then a layer of the silicon carbide high-resistance anti-corona tape is overlapped at the end of the silicon carbide medium-resistance anti-corona tape in a half-lapped wrapping manner;

[0010] Step 3: Wrap a second epoxy multi-resin powder mica tape halfway around the first low-resistance anti-corona tape, with one end wrapped to the silicon carbide medium-resistance anti-corona tape and the other end wrapped to the stator core slot, extending a distance d2 = 80 mm in the stator core slot;

[0011] Step 4: Wrap a layer of the second low-resistance anti-corona tape half-over the first low-resistance anti-corona tape and the second epoxy multi-resistance mica tape on top of it, covering the second epoxy multi-resistance mica tape, and extending the two ends by d1 = 20 mm and d4 = 20 mm respectively;

[0012] Step 5: After the anti-corona structure of the sub-coil notch is wrapped, the molded conductor is heated and pressurized to solidify and then removed from the mold.

[0013] Preferably, in step 1, the first epoxy multi-resin powder mica tape has a thickness d0 = 0.14 mm, a width of 25 mm, a resin content of 37-40%, and a volume resistivity > 10 12 Ω·m;

[0014] The thickness of the first low-resistance anti-corona belt is 0.08mm, and the inherent surface resistivity is 10 3 ~10 4 Ω.

[0015] Preferably, in the step 2, the thickness of the silicon carbide medium resistance anti-corona tape is 0.12 mm, the width is 25 mm, and the inherent surface resistivity is 10 11 ~10 12 Ω, nonlinear coefficient 0.5~1.0cm / kV;

[0016] Silicon carbide high resistance anti-corona tape thickness 0.12mm, width 25mm, inherent resistivity 10 12 ~10 13Ω, nonlinear coefficient 3~5cm / kV.

[0017] Preferably, in the step 2, the axial distance d3 of the silicon carbide medium-resistance anti-corona band covering the first low-resistance anti-corona band is 25 mm;

[0018] The axial distance d5 of the silicon carbide high-resistance anti-corona band covering the silicon carbide medium-resistance anti-corona band is 25 mm.

[0019] Preferably, in step five, the shaped conductor is cured and formed by internal heating.

[0020] Preferably, in step five, the heating rate of the formed conductor is 1.5° C. / min.

[0021] Preferably, in step five, the mold is unmolded when the mold is naturally cooled to below 50°C.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. Improve corrosion resistance. The multi-layer composite material design effectively avoids the electrical corrosion phenomenon in traditional anti-corona structures and extends the service life of the stator coil.

[0024] 2. Enhance electrical insulation performance. By using high-performance materials such as epoxy multi-powder mica tape and silicon carbide, the electrical insulation strength of the stator coil can be effectively improved to prevent high-voltage electrical corrosion.

[0025] 3. Simple manufacturing process. This method has a simplified process flow and low production cost, and is easy to achieve large-scale production.

[0026] 4. Improve equipment stability: The anti-corona structure of the present invention can effectively prevent corona discharge at the stator coil slot, thereby improving the stability and safety of the generator during long-term operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic cross-sectional view of the stator coil of the generator stator coil slot anti-corona structure of the present invention.

[0028] Description of Reference Numerals

[0029] 1-formed conductor, 2-first epoxy multi-resistance mica tape, 3-stator core, 4-first low-resistance anti-corona tape, 5-silicon carbide medium-resistance anti-corona tape, 6-silicon carbide high-resistance anti-corona tape, 7-second low-resistance anti-corona tape, 8-second epoxy multi-resistance mica tape. DETAILED DESCRIPTION

[0030] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the application equally.

[0031] Please see the attached Figure 1 This embodiment provides a method for manufacturing a stator coil having a stator coil slot anti-corona structure for a generator, comprising the following steps:

[0032] Step 1: Wrap the first epoxy multi-resin powder mica tape 2 with a thickness of d0 on the formed conductor 1 as the main insulation material, and wrap a layer of first low-resistance anti-corona tape 4 half-lap around the main insulation groove, wrapping it to the medium and low resistance overlap. Among them, the first epoxy multi-resin powder mica tape 2 preferably has a thickness of d0 = 0.14mm, a width of 25mm, a glue content of 37-40%, and a volume resistivity of >10 12 Ω·m; the first low-resistance anti-corona belt 4 preferably has a thickness of 0.08 mm and an inherent surface resistivity of 10 3 ~10 4 Ω.

[0033] Step 2: The high-resistance anti-corona structure of the stator coil is composed of a silicon carbide medium-resistance anti-corona tape 5, a silicon carbide high-resistance anti-corona tape 6, and the first epoxy multi-resistance mica tape 2. A layer of the silicon carbide medium-resistance anti-corona tape 5 is overlapped at the end of the first low-resistance anti-corona tape 4 by half-wrap wrapping, and then a layer of the silicon carbide high-resistance anti-corona tape 6 is overlapped at the end of the silicon carbide medium-resistance anti-corona tape 5 by half-wrap wrapping. Among them, the silicon carbide medium-resistance anti-corona tape 5 is preferably 0.12mm thick, 25mm wide, and has an inherent surface resistivity of 10 11 ~10 12 Ω, nonlinear coefficient 0.5~1.0cm / kV; silicon carbide high resistance anti-corona tape 6 thickness 0.12mm, width 25mm, inherent resistivity 10 12 ~10 13 Ω, nonlinear coefficient 3-5 cm / kV. Specifically, in this step, the SiC medium-resistance anti-corona band 5 covers the first low-resistance anti-corona band 4 by an axial distance d3 = 25 mm; the SiC high-resistance anti-corona band 6 covers the SiC medium-resistance anti-corona band 5 by an axial distance d5 = 25 mm.

[0034] This method uses high-performance materials such as epoxy multi-powder mica tape and silicon carbide, which can effectively improve the electrical insulation strength of the stator coil and prevent high-voltage electrical corrosion.

[0035] Step 3: Wrap a layer of second epoxy multi-resistance mica tape 8 on the upper half of the first low-resistance anti-corona tape 4, wrap one end to the silicon carbide medium-resistance anti-corona tape 5, and the other end to the slot of the stator core 3, extending a distance d2 = 80 mm in the stator core slot.

[0036] Step 4: Half-wrap a layer of second low-resistance anti-corona tape 7 on top of the first low-resistance anti-corona tape 4 and the second epoxy multi-glue mica tape 8 thereon, covering the second epoxy multi-glue mica tape 8, and extend the two ends by d1=20mm and d4=20mm respectively.

[0037] In step 3 and step 4, the size and properties of the second epoxy multi-resistance mica tape 8 and the second low-resistance anti-corona tape 7 can refer to the first epoxy multi-resistance mica tape and the first low-resistance anti-corona tape.

[0038] This method uses a multi-layer composite material design to improve the corrosion resistance of the anti-corona structure, effectively avoids the electrical corrosion phenomenon in traditional anti-corona structures, and extends the service life of the stator coil.

[0039] Step 5: After the anti-corona structure of the sub-coil notch is wrapped, the molded conductor 1 is heated and pressurized to solidify and then removed from the mold.

[0040] Specifically, in this step, after the anti-corona structure of the coil notch is wrapped, the formed conductor 1 is heated and pressurized in the mold using internal heating and solidification, with a heating rate of 1.5°C / min. When the wire rod temperature reaches 170±5°C, the power is turned off after keeping the temperature for 5 hours, and the mold is removed when it naturally cools to below 50°C. This step uses the method of demolding after natural cooling to minimize residual stress inside the stator wire rod and improve coil performance.

[0041] The present invention is only an exemplary description of the present invention and does not limit its scope of protection. Those skilled in the art may also make partial changes thereto. As long as they do not exceed the spirit of the present invention, they are all within the scope of protection of the present invention.

Claims

1. A method for manufacturing a stator coil with a stator coil slot anti-corona structure for a generator, characterized in that: The steps include: Step 1: Wrap a first epoxy multi-resin powder mica tape (2) with a thickness of d0 on the formed conductor (1) as the main insulating material, and wrap a layer of first low-resistance anti-corona tape (4) half-lap around the main insulating groove, wrapping it to the middle and low resistance overlap; Step 2: The high-resistance anti-corona structure of the stator coil is composed of a silicon carbide medium-resistance anti-corona tape (5), a silicon carbide high-resistance anti-corona tape (6), and the first epoxy multi-resistance mica tape (2); a layer of the silicon carbide medium-resistance anti-corona tape (5) is overlapped at the end of the first low-resistance anti-corona tape (4) in a half-lapped wrapping manner, and then a layer of the silicon carbide high-resistance anti-corona tape (6) is overlapped at the end of the silicon carbide medium-resistance anti-corona tape (5); Step 3: Wrap a second epoxy multi-resin powder mica tape (8) on the upper half of the first low-resistance anti-corona tape (4), wrap one end of the tape to the silicon carbide medium-resistance anti-corona tape (5), and wrap the other end of the tape to the slot of the stator core (3), extending a distance d2 = 80 mm in the slot of the stator core (3); Step 4: wrap a layer of the second low-resistance anti-corona tape (7) half-over the first low-resistance anti-corona tape (4) and the second epoxy multi-resistance mica tape (8) thereon, covering the second epoxy multi-resistance mica tape (7), and extending the two ends by d1 = 20 mm and d4 = 20 mm respectively; Step 5: After the corona protection structure of the sub-coil slot is wrapped, the molded conductor (1) is heated and pressurized to solidify the mold and then removed from the mold.

2. The method for manufacturing a stator coil of a generator stator coil notch anti-corona structure according to claim 1, characterized in that: In the step 1, the first epoxy multi-glue mica tape (2) has a thickness d0=0.14 mm, a width of 25 mm, a glue content of 37-40%, and a volume resistivity>10 12 Ω·m; The thickness of the first low-resistance anti-corona belt (4) is 0.08 mm, and the inherent surface resistivity is 10 3 ~10 4 Ω.

3. The method for manufacturing a stator coil of a generator stator coil notch anti-corona structure according to claim 1, characterized in that: In the step 2, the silicon carbide medium resistance anti-corona tape (5) has a thickness of 0.12 mm, a width of 25 mm, and an inherent surface resistivity of 10 11 ~10 12 Ω, nonlinear coefficient 0.5~1.0cm / kV; Silicon carbide high resistance anti-corona tape (6) thickness 0.12mm, width 25mm, inherent resistivity 10 12 ~10 13 Ω, nonlinear coefficient 3~5cm / kV.

4. The method for manufacturing a stator coil of a generator stator coil notch anti-corona structure according to claim 1, characterized in that: In the step 2, the silicon carbide medium-resistance anti-corona belt (5) covers the first low-resistance anti-corona belt (4) at an axial distance d3 = 25 mm; The silicon carbide high-resistance anti-corona band (6) covers the silicon carbide medium-resistance anti-corona band (5) at an axial distance d5=25 mm.

5. The method for manufacturing a stator coil of a generator stator coil notch anti-corona structure according to claim 1, characterized in that: In the step five, the formed conductor (1) is cured and formed by internal heating.

6. The method for manufacturing a stator coil of a generator stator coil notch anti-corona structure according to claim 1, characterized in that: In the step 5, the heating rate of the formed conductor (1) is 1.5°C / min.

7. The method for manufacturing a stator coil of a generator stator coil notch anti-corona structure according to claim 1, characterized in that: In the step 5, the mold is unloaded when the mold is naturally cooled to below 50°C.

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