A processing method for protecting the insulation of a water turbine stator winding in high-altitude areas

Abstract

This invention discloses a method for protecting the insulation of stator windings in high-altitude hydroelectric turbines, comprising the following steps: pre-treating the stator windings with anti-fouling agents, then placing the stator windings into an impregnation tank; evacuating the impregnation tank to achieve a near-vacuum state; injecting room-temperature curing epoxy resin impregnation liquid into the impregnation tank; after the impregnation liquid stabilizes, filling the impregnation tank with inert gas to pressurize and fully remove air bubbles; recovering the inert gas to restore the air pressure inside the impregnation tank to normal atmospheric pressure at high altitudes; removing the stator windings for initial condensation at room temperature at high altitudes, followed by heating and curing; coating the stator windings with room-temperature curing anti-corrosion varnish under heat radiation conditions; inspecting and repairing the insulation coating surface of the stator windings until the insulation coating surface is uniform and smooth. This invention can adapt to the harsh environmental conditions of low air pressure, large temperature differences, and strong ultraviolet radiation at high altitudes.

Description

Technical Field

[0001] This invention belongs to the field of stator winding insulation protection technology, and particularly relates to a treatment method for insulation protection of stator windings of hydro turbines in high-altitude areas. Background Technology

[0002] Currently, when insulating and protecting stator windings, the patent solution with publication number CN120768070A typically involves only routine impregnation, inspection, and sorting of the insulating varnish on the stator windings. The specific steps are as follows: S1, cleaning and drying the stator; S2, impregnating the pre-treated stator in the insulating varnish to form a preliminary varnish layer; S3, heating and curing the impregnated stator to form a solid varnish layer on the stator surface; S4, inspecting and sorting the cured stator.

[0003] However, the impregnation and curing process of this solution is relatively crude, with many hidden defects, and it cannot adapt to the harsher environmental conditions in high-altitude areas, such as low air pressure, large temperature differences, and strong ultraviolet radiation. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a treatment method for insulation protection of stator windings of hydro turbines in high-altitude areas, which can improve the quality of impregnation and curing.

[0005] The objective of this invention is achieved through the following technical solution: A method for insulation protection of stator windings of hydroelectric turbines in high-altitude areas includes the following steps: The stator windings are pre-treated to prevent contamination before being placed in an impregnation tank. The impregnation tank is evacuated to create a near-vacuum inside. Inject room temperature curing epoxy resin impregnation solution into the impregnation tank; After the impregnation solution stabilizes, inert gas is introduced into the impregnation tank to pressurize and fully remove air bubbles; The inert gas is recovered to restore the pressure inside the impregnation tank to the normal pressure state at high altitudes; Remove the stator windings and allow them to initially condense at room temperature in high-altitude areas before heating and solidifying them. Under thermal radiation conditions, the stator windings are coated with room temperature curing anti-corrosion paint; Inspect and repair the insulation covering of the stator winding until the insulation covering of the stator winding is uniform and smooth.

[0006] Furthermore, the anti-pollution pretreatment of the stator windings includes: Clean the stator windings with deionized water and / or volatile cleaning oil; Place the stator windings in an oven to dry them.

[0007] Furthermore, evacuating the impregnation tank to achieve a near-vacuum environment includes: Test the airtightness of the impregnation tank; Use a vacuum pump to evacuate the impregnation tank while monitoring the air pressure inside the tank until the gauge pressure inside the tank reaches a near-vacuum state. Maintain a near-vacuum state inside the impregnation tank for 30 to 60 minutes.

[0008] Furthermore, injecting room-temperature curing epoxy resin impregnation solution into the impregnation tank includes: Maintain a near-vacuum state inside the impregnation tank while injecting room temperature curing epoxy resin impregnation liquid into the impregnation tank.

[0009] Furthermore, after the impregnation solution has stabilized, inert gas is introduced into the impregnation tank to pressurize and fully remove air bubbles, including: Inspect the adhesion of the impregnating liquid on the surface of the stator winding; After the impregnation solution stabilizes, inert gas is introduced into the impregnation tank to make the pressure inside the impregnation tank reach a gauge pressure of 0.2MPa~0.6MPa and maintain it for 30min~90min.

[0010] Furthermore, the initial condensation at room temperature in high-altitude areas, followed by reheating and solidification, includes: Preliminary condensation at room temperature in high-altitude areas takes 12-24 hours, followed by heating and curing for 6-12 hours, referencing the curing characteristics of epoxy resin.

[0011] Furthermore, applying a room-temperature curing anti-corrosion varnish to the stator windings includes: Apply room temperature curing anti-corrosion paint to the ends of the stator windings, the outlet slots, the slot openings in the radial ventilation channels, the spaces between adjacent phase-differentiated bars at the ends, and the sides of the conductors inside the slots.

[0012] Furthermore, applying a room-temperature curing anti-corrosion varnish to the stator windings includes: The stator windings were coated with a multi-layer composite paint and pressure sprayed with room temperature curing anti-splatter paint using a brush and a pressure sprayer.

[0013] Furthermore, the inspection of the insulation covering surface of the stator winding includes: Inspect the uniformity and smoothness of the insulation coating on the stator winding; Repairing the insulation covering of the stator winding includes: Surface pretreatment is performed on the damaged or reinforced parts of the insulation covering on the stator winding; Use repair resin for drip coating or encapsulation reinforcement.

[0014] Furthermore, the inspection of the insulation covering surface of the stator winding includes: The insulation coating of the stator winding is inspected using both visual inspection and an optical roughness tester.

[0015] The beneficial effects of this invention are as follows: By creating a near-vacuum state, a pressure difference is constructed to reduce potential impurities and promote the transition of a small number of residual liquid surface molecules from the liquid phase to the gas phase, thereby improving impregnation efficiency. Pressure impregnation effectively removes fine air bubbles, reducing defects in the insulation coating surface. Preliminary condensation and heating at room temperature in high-altitude areas ensure stable impregnation and prevent damage to the insulation coating surface caused by rapid curing. Therefore, pressure impregnation in a near-vacuum state, combined with preliminary condensation and heating at room temperature in high-altitude areas, improves impregnation and curing quality, making it suitable for harsh environmental conditions such as low air pressure and large temperature differences in high-altitude regions. In addition, by applying extra anti-corona treatment to the stator windings, corona can be reduced, which helps to adapt to harsh environmental conditions such as strong ultraviolet radiation in high-altitude areas. Attached Figure Description

[0016] The invention will now be described in more detail with reference to embodiments and the accompanying drawings. Figure 1 A flowchart of the present invention is shown; In the accompanying drawings, the same parts use the same reference numerals. The drawings are not to scale. Detailed Implementation

[0017] The invention will now be further described with reference to the accompanying drawings.

[0018] This invention provides a method for insulation protection of stator windings of hydroelectric turbines in high-altitude areas, such as... Figure 1 As shown, it includes the following steps: The stator windings are pre-treated to prevent contamination before being placed in an impregnation tank. The impregnation tank is evacuated to create a near-vacuum inside. Inject room temperature curing epoxy resin impregnation solution into the impregnation tank; After the impregnation solution stabilizes, inert gas is introduced into the impregnation tank to pressurize and fully remove air bubbles; The inert gas is recovered to restore the pressure inside the impregnation tank to the normal pressure state at high altitudes; Remove the stator windings and allow them to initially condense at room temperature in high-altitude areas before heating and solidifying them. Under thermal radiation conditions, the stator windings are coated with room temperature curing anti-corrosion paint; Inspect and repair the insulation covering of the stator winding until the insulation covering of the stator winding is uniform and smooth.

[0019] It is understandable that by creating a near-vacuum state, a pressure difference is constructed to reduce potential impurities and promote the transition of a small number of residual liquid surface molecules from the liquid phase to the gas phase, thereby improving impregnation efficiency; by pressurizing the impregnation process, fine air bubbles are fully expelled to reduce defects in the insulation coating surface; and by performing preliminary condensation and heating curing at room temperature in high-altitude areas, stable curing of the impregnation is achieved, thus preventing damage to the insulation coating surface due to rapid curing. Therefore, by pressurizing the impregnation process under near-vacuum conditions and performing preliminary condensation and heating curing at room temperature in high-altitude areas, the quality of impregnation curing can be improved, which is beneficial for adapting to the harsh environmental conditions such as low air pressure and large temperature differences in high-altitude areas. In addition, by applying extra anti-corona treatment to the stator windings, corona can be reduced, which helps to adapt to harsh environmental conditions such as strong ultraviolet radiation in high-altitude areas.

[0020] In one embodiment, anti-pollution pretreatment of the stator winding includes: Clean the stator windings with deionized water and / or volatile cleaning oil that do not affect the stator winding materials; Place the stator windings in an oven to dry them.

[0021] It should be noted that the anti-pollution pretreatment of the stator winding is a cleaning process based on the physical and chemical properties of the stator winding to resist oxidation and deionization, so as to prevent impurities from affecting the uniformity of the insulation coating surface; the drying operation is to remove the influence of a small amount of adhering micro-water and volatile decontamination oil.

[0022] In one embodiment, evacuating the impregnation tank to bring it to near-vacuum includes: Test the airtightness of the impregnation tank; Use a vacuum pump to evacuate the impregnation tank while monitoring the air pressure inside the tank until the gauge pressure inside the tank reaches a near-vacuum state. Maintain a near-vacuum state inside the impregnation tank for 30 to 60 minutes.

[0023] It should be noted that near-vacuum state is when the gauge pressure measured inside the impregnation tank reaches 97% to 99% of the negative value of the local absolute atmospheric pressure. The vacuuming operation is to enable a small number of residual molecules on the surface of the liquid to gain enough kinetic energy to overcome intermolecular forces and surface tension, so that they can undergo a non-equilibrium phase transition from the liquid phase to the gas phase.

[0024] In one embodiment, injecting room temperature curing epoxy resin impregnation solution into the impregnation tank includes: Maintain a near-vacuum state inside the impregnation tank while injecting room temperature curing epoxy resin impregnation liquid into the impregnation tank.

[0025] Understandably, maintaining a near-vacuum state inside the impregnation tank is to eliminate the "resistance source" inside the impregnation tank and build a stable "pressure difference driving force" to solve the flow obstacles of room temperature curing epoxy resin between the stator windings, optimize the contact state between the room temperature curing epoxy resin and the stator windings, and achieve rapid and uniform penetration.

[0026] It should be noted that the room temperature curing epoxy resin impregnating liquid can be selected from room temperature curing epoxy resins such as DECJ1403, DECJ0139, DECJ0702, DECJ0301 and DECJ1316.

[0027] In one embodiment, after the impregnation solution has stabilized, inert gas is introduced into the impregnation tank to pressurize and fully remove air bubbles, including: Inspect the adhesion of the impregnating liquid on the surface of the stator winding; After the impregnation solution stabilizes, inert gas is introduced into the impregnation tank to make the pressure inside the impregnation tank reach a gauge pressure of 0.2MPa~0.6MPa and maintain it for 30min~90min.

[0028] It should be noted that the inert gas is a gas that has no effect on the physicochemical properties of room temperature curing epoxy resin under normal temperature and high pressure conditions in high-altitude areas. Nitrogen can be used as the inert gas. The pressurization operation is to actively pressurize and enhance the driving force for uniform flow of room temperature curing epoxy resin, which helps to overcome pore resistance, thereby eliminating fine air bubbles between the room temperature curing epoxy resin and the stator winding, thus improving insulation density and eliminating hidden defects. In addition, for transparent resin, artificial light inspection can be used as the criterion for completion of the operation. Specifically, the criterion for passing artificial light inspection is that transparent resin has no obvious local reflection under light conditions. For non-transparent resin, a certain pressurization time needs to be extended to fully expel air bubbles.

[0029] In one embodiment, recovering the inert gas to restore the pressure inside the impregnation tank to normal atmospheric pressure at high altitudes includes: The impregnation tank is slowly pressurized, and most of the inert gas is recovered using a vacuum tank to restore the gas pressure inside the impregnation tank to the normal pressure state at high altitudes.

[0030] In one embodiment, initial condensation at room temperature in high-altitude areas, followed by reheating and solidification, includes: Preliminary condensation at room temperature in high-altitude areas takes 12-24 hours, followed by heating and curing for 6-12 hours, referencing the curing characteristics of epoxy resin.

[0031] It should be noted that the environmental conditions of the stator winding need to be kept relatively stable during the initial condensation operation; the heating temperature during the heat curing operation should not have a significant impact on the insulation properties and stability of the epoxy resin.

[0032] In one embodiment, applying a room-temperature curing anti-corrosion varnish to the stator windings under thermal radiation conditions includes: Under the irradiation conditions of the thermal radiation heater, room temperature curing anti-corrosion paint is applied to specific areas such as the ends of the stator winding, the outlet slot, the slot opening in the radial ventilation duct, the area between adjacent non-phase wires at the ends, and the side of the conductor in the slot.

[0033] It should be noted that the use of a thermal radiation heater is to raise the temperature to the applicable temperature for room temperature curing of the anti-corrosion paint. The room temperature curing anti-corrosion paint is a double-layer anti-corrosion paint composite structure. The inner layer uses a specific anti-corrosion paint that is evenly applied to a specific area of ​​the stator winding, while the outer layer uses an anti-corrosion paint that liquefies at room temperature and high pressure and rapidly condenses at room temperature and pressure to be evenly sprayed. This reduces the surface non-uniformity of the high electric field intensity area of ​​the stator winding, thereby reducing the corona phenomenon.

[0034] It should be noted that room temperature curing anti-spot paints such as DECJ1344, DECJ1345, DECJ1348 and DECJ0701 can be selected.

[0035] In one embodiment, applying a room-temperature curing anti-corrosion varnish to the stator windings under thermal radiation conditions includes: A multi-layer composite coating and pressure spraying of room temperature curing anti-smudge paint were applied to the stator windings using a fine brush and a pressure sprayer.

[0036] In one embodiment, detecting the insulation covering surface of the stator winding includes: Inspect the uniformity and smoothness of the insulation coating on the stator winding; Repairing the insulation covering of the stator winding includes: Surface pretreatment is performed on the damaged or reinforced parts of the insulation covering on the stator winding; Use repair resin for drip coating or encapsulation reinforcement.

[0037] It should be noted that the operation of repairing the insulation coating of the stator winding is also applicable to repairing epoxy resin defects found during turbine troubleshooting in high-altitude areas.

[0038] It should also be noted that surface pretreatment includes cleaning the surface to remove deteriorated epoxy resin and epoxy resin that may hinder the repair process. The drip coating process is mainly used to repair micro-cracks, pinholes, and corona spots. The specific operation includes: drawing the mixed resin into the drip syringe, aligning the syringe with the defect area, and slowly squeezing the syringe to allow the resin to fall onto the defect. The amount of resin dripped should be sufficient to cover the defect perimeter by 1mm to 2mm after natural diffusion, to avoid sagging due to excessive amount. If the defect is a crack, multiple small drips of resin can be applied along the crack direction to allow the resin to gradually penetrate into the crack. If necessary, the resin can be gently stirred with the needle to assist penetration. The coating operation is mainly used for localized wear and large-area weak areas. The specific operation includes: taking an appropriate amount of resin with a scraper and evenly scraping it from the center to the edge of the repair area. The coating thickness is controlled at 0.2mm~0.5mm to ensure that there are no missed coatings, bubbles or scraper marks.

[0039] It should be noted that after the drop coating and coating reinforcement operations, the uniformity and smoothness of the insulation coating surface on the stator winding still need to be tested. The grinding operation should be carried out with reference to the test results until there are no protrusions or depressions on the insulation coating surface on the stator winding.

[0040] In one embodiment, inspecting the insulation covering of the stator winding includes: The insulation coating of the stator winding is inspected using both visual inspection and an optical roughness tester.

[0041] In the description of this invention, it should be understood that the terms "upper", "lower", "bottom", "top", "front", "rear", "inner", "outer", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0042] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A method for insulation protection of stator windings of hydroelectric turbines in high-altitude areas, characterized in that, Includes the following steps: The stator windings are pre-treated to prevent contamination before being placed in an impregnation tank. The impregnation tank is evacuated to create a near-vacuum inside. Inject room temperature curing epoxy resin impregnation solution into the impregnation tank; After the impregnation solution stabilizes, inert gas is introduced into the impregnation tank to pressurize and fully remove air bubbles; The inert gas is recovered to restore the pressure inside the impregnation tank to the normal pressure state at high altitudes; Remove the stator windings and allow them to initially condense at room temperature in high-altitude areas before heating and solidifying them. Under thermal radiation conditions, the stator windings are coated with room temperature curing anti-corrosion paint; Inspect and repair the insulation covering of the stator winding until the insulation covering of the stator winding is uniform and smooth.

2. The method for insulation protection of stator windings of hydroelectric turbines in high-altitude areas according to claim 1, characterized in that, The anti-pollution pretreatment of the stator winding includes: Clean the stator windings with deionized water and / or volatile cleaning oil; Place the stator windings in an oven to dry them.

3. The method for insulation protection of stator windings of hydroelectric turbines in high-altitude areas according to claim 1, characterized in that, The process of evacuating the impregnation tank to create a near-vacuum environment includes: Test the airtightness of the impregnation tank; Use a vacuum pump to evacuate the impregnation tank while monitoring the air pressure inside the tank until the gauge pressure inside the tank reaches a near-vacuum state. Maintain a near-vacuum state inside the impregnation tank for 30 to 60 minutes.

4. A method for insulation protection of stator windings of hydroelectric turbines in high-altitude areas according to claim 1 or 3, characterized in that, The process of injecting room-temperature curing epoxy resin impregnation solution into the impregnation tank includes: Maintain a near-vacuum state inside the impregnation tank while injecting room temperature curing epoxy resin impregnation liquid into the impregnation tank.

5. A method for insulation protection of stator windings of hydroelectric turbines in high-altitude areas according to claim 1, characterized in that, After the impregnation solution stabilizes, inert gas is introduced into the impregnation tank to pressurize and fully remove air bubbles, including: Inspect the adhesion of the impregnating liquid on the surface of the stator winding; After the impregnation solution stabilizes, inert gas is introduced into the impregnation tank to make the pressure inside the impregnation tank reach a gauge pressure of 0.2MPa~0.6MPa and maintain it for 30min~90min.

6. A method for insulation protection of stator windings of hydroelectric turbines in high-altitude areas according to claim 1, characterized in that, The process of initial condensation at room temperature in high-altitude areas, followed by reheating and solidification, includes: Preliminary condensation at room temperature in high-altitude areas takes 12-24 hours, followed by heating and curing for 6-12 hours, referencing the curing characteristics of epoxy resin.

7. A method for insulation protection of stator windings of hydroelectric turbines in high-altitude areas according to claim 1, characterized in that, The application of room temperature curing anti-corrosion paint to the stator windings includes: Apply room temperature curing anti-corrosion paint to the ends of the stator windings, the outlet slots, the slot openings in the radial ventilation channels, the spaces between adjacent phase-differentiated bars at the ends, and the sides of the conductors inside the slots.

8. A method for insulation protection of stator windings of hydroelectric turbines in high-altitude areas according to claim 1, characterized in that, The application of room temperature curing anti-corrosion paint to the stator windings includes: The stator windings were coated with a multi-layer composite paint and pressure sprayed with room temperature curing anti-splatter paint using a brush and a pressure sprayer.

9. A method for insulation protection of stator windings of hydroelectric turbines in high-altitude areas according to claim 1, characterized in that, The inspection of the insulation covering surface of the stator winding includes: Inspect the uniformity and smoothness of the insulation coating on the stator winding; Repairing the insulation covering of the stator winding includes: Surface pretreatment is performed on the damaged or reinforced parts of the insulation covering on the stator winding; Use repair resin for drip coating or encapsulation reinforcement.

10. A method for insulation protection of stator windings of hydroelectric turbines in high-altitude areas according to claim 1, characterized in that, The inspection of the insulation covering surface of the stator winding includes: The insulation coating of the stator winding is inspected using both visual inspection and an optical roughness tester.

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