CN115308544A - A transformer oil-paper insulation electric heating combined aging test device and using method thereof - Google Patents

Abstract

The invention belongs to the field of on-line monitoring and fault diagnosis of electrical equipment insulation, and in particular relates to a transformer inter-turn winding oil-paper insulation electric-heating combined aging test device and a method of using the same. The device includes a transformer component, a thermal stress component, and an aging tank component. The tank assembly provides electrical stress, the thermal stress component provides thermal stress for the aging tank assembly, the aging tank assembly includes a sealable tank body and a test device installed in the sealable tank body, the sealable tank body is provided with a gas valve through hole , the oil inlet valve through hole, the oil outlet valve through hole and the high pressure access through hole, the test device is a cage-shaped structure with holes in the sidewall, the upper bottom surface of the cage-shaped structure is an upper electrode plate, and the lower bottom surface is a The lower electrode plate, the upper electrode plate is connected to the high voltage end, the lower electrode plate is connected to the low voltage end, and a winding is connected between the upper electrode plate and the lower electrode plate; The study provides a representative sample.

Description

A transformer oil-paper insulation electric heating combined aging test device and its application method

technical field

The invention belongs to the field of on-line monitoring and fault diagnosis of electrical equipment insulation, and in particular relates to a transformer oil-paper insulation electric heating combined aging test device and a use method thereof.

Background technique

Oil-paper insulation is an important component of the internal insulation of oil-immersed transformers. During long-term operation, it is affected by multi-factor aging mainly caused by electrothermal stress, and the insulation performance decreases, which directly threatens the safe operation of the transformer. The aging problem has always been an important research topic in the insulation discipline. The insulation diagnosis and life prediction of electrical equipment are closely related to the safety and economy of power system operation.

Temperature and electric field have a great influence on various properties of insulating materials. IEC Publication No. 354, ANSI No. C57, No. 92 Standard and IEEE Standard have all expounded on the aging and aging rate of transformers. It is considered that the aging of oil-paper insulation During the operation of the transformer, it gradually develops under the combined action of electrical, thermal, mechanical and other stresses, and eventually leads to insulation failure. At the same time, it is considered that the main factor affecting the aging and expected life of transformer oil-paper insulation is thermal stress, followed by electrical stress. Therefore, most aging researches are carried out around thermal aging and electrical aging.

The research on condition monitoring of oil-paper insulation often involves the acquisition of samples in different aging states. Existing research mainly studies the aging process of transformer oil-paper insulation based on accelerated thermal aging. Due to the one-sidedness of this research method in considering factors, during the operation of transformers, the aging stress received is often not a single one, but two or more simultaneous effects and mutual influences. Therefore, an accurate assessment of the aging state of transformer oil-paper insulation is not up to the requirement. The invention proposes a transformer oil-paper insulation electrothermal combined aging test device, which can simulate the aging process of the oil-paper insulation under the combined action of electrothermal, which is more in line with the real operating conditions of the transformer, and the obtained samples are more representative.

The evaluation of transformer oil-paper insulation state is an important research content in the field of electric power. It not only provides theoretical reference and data for future transformer life prediction, but also provides a scientific basis for formulating reasonable operation, maintenance and renewal plans, and realizing transformer condition-based maintenance. , is an important guarantee to improve the availability and operational reliability of the transformer, and is undoubtedly a research topic with important practical significance and academic value. Carrying out a reasonable multi-factor joint aging experiment can provide experimental support for the above-mentioned subjects, and provide a scientific basis for the evaluation of the transformer oil-paper insulation state. Electrothermal factors are the two most common aging factors, so it is imperative to carry out multi-factor aging experiments based on electrothermal combined aging.

Experience has shown that the degree and rate of insulation aging depend on the physical and chemical properties of the material, the type and duration of the external stress, and the process used in the production process. Extensive and in-depth research on the aging behavior and the synergistic effect under various stresses to find out the aging law. Electrothermal combined stress aging is the most commonly used stress combination method in current research, because electrothermal factors are the two most common aging factors and are inevitable for most insulating materials. However, there are still some problems in the existing test platform, which makes the aging condition of the oil-paper insulation samples obtained through the test different from the actual aging condition.

Contents of the invention

In order to reduce the difference between the aging conditions of the oil-paper insulation samples obtained in the test and the real aging conditions of the oil-paper insulators, the present invention provides a transformer oil-paper insulation electric heating combined aging test device and its use method. The device includes transformer components, thermal stress Components, aging tank components, transformer components provide electrical stress for the aging tank components, thermal stress components provide thermal stress for the aging tank components, the aging tank components include a sealable tank and a test device installed in the sealable tank, the can The sealed tank body is provided with air valve through holes, oil inlet valve through holes, oil outlet valve through holes and high pressure access through holes. The test device is a cage structure with holes in the side wall. The upper bottom surface of the cage structure It is an upper electrode disk, and the lower bottom surface is a lower electrode disk. The upper electrode disk is connected to the high voltage end, the lower electrode disk is connected to the low voltage end, and a winding is connected between the upper electrode disk and the lower electrode disk.

Further, each winding is made of a copper core wrapped with kraft insulating paper, and two ends of the winding form two bifurcations, and an angle of 60-120 degrees is formed between the two bifurcations.

Further, the pipeline of the oil outlet valve goes deep into the bottom of the aging tank, and the pipeline of the gas valve enters the interior of the aging tank shallowly.

Further, a circulation pump is installed on the sealable tank, and the inlet and outlet of the circulation pump are respectively arranged on the left and right sides of the aging tank.

Further, the input nozzle and the output nozzle of the circulation pump are arranged staggered up and down, the input nozzle is arranged at the bottom, and the output nozzle is arranged at the top.

Further, the transformer assembly includes a transformer coil, a transformer resistor and a high-voltage terminal of the transformer, the transformer coil, the transformer resistor and the transformer high-voltage terminal are connected end to end in sequence, and the gap between the transformer resistor and the transformer high-voltage terminal is used as the upper electrode plate. High voltage connection.

Further, the high-voltage connection end of the upper electrode plate is connected to the variable voltage resistor and the high-voltage end of the transformer through the high-voltage access through hole, and the high-voltage access through hole is provided with a high-voltage bushing.

The present invention also provides a method of using a transformer oil-paper insulation electric heating combined aging test device. The use method of any one of the aforementioned transformer oil paper insulation electric heating combined aging test devices includes:

Add simethicone oil into the oil crucible, and use simethicone oil as a heat transfer medium to heat the sealable oil tank;

Install the processed insulating paper, insulating oil and winding in a transformer oil-paper insulation electrothermal combined aging test device, wherein the insulating paper and winding are set in the test device, the insulating oil is set in a sealable tank, and the insulating oil is covered Membrane testing device;

The aging test was carried out at a temperature of 130°C and a winding inter-turn voltage of 4kV/mm, respectively on the 3rd day of aging, the 5th day of aging, the 10th day of aging, the 15th day of aging, the 20th day of aging, and the 20th day of aging. Samples were taken on the 25th day, the 30th day of aging, and the 35th day of aging to obtain oil-paper insulation samples of different aging degrees.

Further, before starting the test, the insulating oil is passed through the oil inlet valve to the sealable tank, and the insulating oil floods the test device, and then nitrogen is filled into the sealable tank through the air valve.

Further, the insulating paper, insulating oil, and winding used in the experiment were dried at 90°C and 50Pa for 48 hours before use, and then the insulating paper and winding were immersed in insulating oil and immersed at 60°C and 50Pa. Oil for 48 hours.

The invention makes the oil-paper insulation samples obtained through tests closer to their real aging conditions in actual transformers, obtains representative oil-paper insulation samples in different aging states, and provides technical support for the monitoring and diagnosis research of the aging state of transformer oil-paper insulation.

Description of drawings

Fig. 1 is a device structural representation of the present invention;

Fig. 2 is a comparison of the degree of polymerization of the electrothermal aging sample and the aging time of the single thermal aging sample in an example of the present invention;

Among them, 1-test transformer transformer coil, 2-test transformer resistance, 3-test transformer high voltage end, 4-circulation pump, 5-oil inlet pump, 6-oil outlet pump, 7-oil inlet valve, 8-oil outlet valve, 9-temperature control module, 10-insulating oil, 11-iron cage with holes, 12-insulating paper, 13-winding, 14-air valve, 15-nitrogen, 16-dimethyl silicone oil, 17-oil bath, 18 - sealable tank body, 19 - upper electrode disc, 20 - lower electrode disc, 21 - high voltage bushing.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The invention provides a transformer oil-paper insulation electric heating combined aging test device and its use method. The device includes a transformer component, a thermal stress component, and an aging tank component. The transformer component provides electrical stress for the aging tank component, and the thermal stress component is the aging tank component. To provide thermal stress, the aging tank assembly includes a sealable tank body 18 and a test device installed in the sealable tank body, the sealable tank body is provided with an air valve through hole, an oil inlet valve through hole, and an oil outlet valve through hole and a high voltage access through hole, the test device is a cage structure with holes in the side wall, the upper bottom surface of the cage structure is an upper electrode disk 19, and the lower bottom surface is a lower electrode disk 20, and the upper electrode disk and the The high-voltage end is connected, the lower electrode disk is connected to the low-voltage end, and a winding is connected between the upper electrode disk and the lower electrode disk.

The electrical stress that affects the aging of oil-paper insulation is provided by the test transformer, which converts the 220V ordinary alternating current into a predetermined high voltage, and then transmits it to the winding through the high voltage bushing 21 and the upper electrode disc of the aging tank. The sealable tank body 18 (hereinafter referred to as the aging tank) adopted in this embodiment is made of stainless steel, uses dimethyl silicone oil as a heat transfer medium to heat the aging tank, and adopts a temperature control module arranged on the outer surface of the oil crucible to control the temperature. And oil crucible for heating and temperature control.

The transformer assembly in the present embodiment comprises test transformer transformation coil 1, test transformer transformation coil 2 and test transformer, as shown in Figure 1, one end of test transformer transformation coil 1 is connected with one end of test transformer transformation coil 2, and the other end Connect to one end of the test transformer, the other end of the test transformer transformer coil 2 is connected to the high voltage terminal 3 of the test transformer, the other end of the test transformer and the other end of the test transformer transformer coil 1 are grounded, and the high voltage terminal 3 of the test transformer is the transformer The oil-paper insulation electric heating combined aging test device provides high voltage electricity.

In order to realize the simulation of the inter-turn electrical stress of the oil-immersed power transformer winding, this implementation proposes a paper-wrapped copper structure winding inter-turn insulation model. In this embodiment, the number of windings is two, and the insulating oil paper to be tested is Placed between two windings, the winding in this embodiment consists of two copper strips wrapped with insulating kraft paper respectively, and the wrapped copper strips bind the two copper strips together through self-locking nylon cable ties, in order to simulate the winding in the transformer In the real bending situation inside, one end of each copper strip is bent outward at 45 degrees, forming a 90-degree angle between the two copper strips, and each end forms a "Y"-shaped structure, and the two copper strips are respectively connected to the upper electrode and the lower electrode. connect.

In this embodiment, the aging tank is located in the oil bath, used to store insulating oil, paper and windings, and provide a reaction place for oil-paper insulation aging.

The aging tank described in this embodiment is made of stainless steel as a whole, and a high-voltage bushing made of polytetrafluoroethylene is pre-installed on the top, which can provide electrical stress for the winding. The high-voltage end is connected to the upper electrode plate through the high-voltage bushing, and the lower motor plate is connected to the tank, the ground terminal of the test transformer and the earth.

In this embodiment, the aging tank is provided with an oil inlet valve 7, an oil inlet pump 5, an oil outlet valve 6, an oil outlet pump 8, and an air valve. The oil inlet and outlet can be carried out automatically through the cooperation of the valve and the pump, saving manpower; the air valve is used to fill nitrogen before the aging test to simulate the oil-paper insulation environment of the real transformer.

The aging tank described in this embodiment has a circulation pump 4 added, which can simulate the flow of insulating oil in a real transformer, and the flow rate can be adjusted within 100-500L/h; when circulating, the oil inlet of the circulation pump is opened at the oil outlet Under the opposite side of the mouth, it is ensured that the flow of the insulating oil 10 in the aging tank is not only a horizontal flow, but also a longitudinal flow due to the influence of gravity.

As an optional implementation mode, in this embodiment, the input nozzle and the output nozzle of the circulating pump are respectively arranged on the left and right sides of the aging tank, and the input nozzle and the output nozzle of the circulating pump are staggered up and down. It is set at the bottom, and the output pipe is set at the top. The air valve and the oil valve are respectively connected to the air pump and the oil pump to realize the automatic entry and exit of specific gas and transformer oil. Vacuum clean; the gas valve pipe only enters the aging tank shallowly, which is convenient for pumping nitrogen into the aging tank to seal it, and at the same time, it will not contaminate the transformer oil to prevent contamination of the gas valve.

In this embodiment, the aging tank is provided with a perforated iron cage 11, and the insulating paper 12 and the winding 13 are placed in the cage. During the aging process of the insulating oil, it can effectively prevent the flow of paper scraps from clogging the circulation pump, oil inlet pump, and oil outlet pump. . During the test, the insulating oil flooded the iron cage with holes, and the part of the aging tank not flooded by the insulating oil was filled with nitrogen gas 15 through the air valve 14 .

The temperature adjustment range of the oil bath described in this embodiment is 30-150° C., covering the temperature range of normal aging and accelerated aging of oil-paper insulation. In this embodiment, dimethyl silicone oil 16 is used for heat conduction, and the advantage of dimethyl silicone oil is non-toxic, high temperature resistance, and large specific heat capacity, so that the heating of the aging tank is uniform and stable, and at the same time it is environmentally friendly and healthy. In this embodiment, the temperature control module 9 pairs The oil crucible 17 is heated, and the aging tank is heated by conducting heat through the simethicone oil in the oil crucible, which can better simulate the influence of heat on the insulating oil paper in the real environment.

In this embodiment, No. 25 Karamay transformer oil is used as the insulating oil, cellulose kraft insulating paper is used as the insulating paper, and copper windings wrapped with ordinary transformer paper are used as the windings.

Utilize a kind of transformer oil-paper insulation electric heating combined aging test device provided by the present invention to carry out the steps of aging test as follows:

1. Insulating paper, insulating oil, and windings were dried at 90°C and 50Pa for 48 hours.

2. Immerse the insulating paper and the winding in the insulating oil, and immerse in the oil for 48 hours under the conditions of 60°C and 50Pa.

3. Put the processed insulating paper, insulating oil, and winding into the above-mentioned transformer oil-paper insulation electric heating combined aging test device. The aging test was carried out at a temperature of 130°C and a winding inter-turn voltage of 4kV/mm, respectively on the 3rd day of aging, the 5th day of aging, the 10th day of aging, the 15th day of aging, the 20th day of aging, and the 20th day of aging. Samples were taken on the 25th day, the 30th day of aging, and the 35th day of aging to obtain oil-paper insulation samples of different aging degrees.

4. For the obtained oil-paper insulation samples, the polymerization degree test and furfural test commonly used to judge the aging state of oil-paper insulation specified in the electric power industry standard DL/T 984-2018 were carried out to verify the effectiveness of the device.

The test results are shown in Figure 2. The changes in the degree of polymerization and furfural content conform to the law of aging of oil-paper insulation. The oil-paper insulation electric heating combined aging test device of the present invention can effectively obtain oil-paper insulation samples in different aging states.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (10)

1. The utility model provides a transformer oil paper insulation electric heat is ageing test device jointly, its characterized in that, including transformer subassembly, thermal stress subassembly, ageing tank subassembly, the transformer subassembly provides electric stress for ageing tank subassembly, and the thermal stress subassembly provides thermal stress for ageing tank subassembly, and ageing tank subassembly is including the sealable jar body and install the testing arrangement in the sealable jar body, but be provided with air valve through-hole on the sealable jar body, into oil valve through-hole, go out oil valve through-hole and high-voltage electricity and connect the through-hole, testing arrangement is the foraminiferous cage structure of lateral wall, and the last bottom surface of this cage structure is an upper electrode dish, and the bottom surface is a lower electrode dish down, upper electrode dish is connected with the high-voltage end, and lower electrode dish connects the low-voltage end, is connected with a plurality of windings between upper electrode dish and the lower electrode dish, and the insulating paper of awaiting measuring is placed between a plurality of windings.

2. The transformer oil-paper insulation electric-heat combined aging test device according to claim 1, wherein each winding is made of kraft insulation paper wrapping a copper core, two branches are formed at two ends of the winding, and an angle of 60-120 degrees is formed between the two branches.

3. The transformer oil-paper insulation electric-heating combined aging test device as claimed in claim 1, wherein the aging tank assembly is characterized in that the pipeline of the oil outlet valve extends into the bottom of the aging tank, and the pipeline well of the air valve extends into the aging tank shallowly.

4. The transformer oil-paper insulation electric-heat combined aging test device according to claim 1, wherein a circulating pump is mounted on the sealable tank body, and an inlet pipe orifice and an outlet pipe orifice of the circulating pump are respectively arranged on the left side and the right side of the aging tank.

5. The transformer oil-paper insulation electric-heat combined aging test device of claim 4, wherein the inlet pipe orifice and the outlet pipe orifice of the circulating pump are arranged in a staggered manner from top to bottom, the inlet pipe orifice is arranged at the lower part, and the outlet pipe orifice is arranged at the upper part.

6. The transformer oil-paper insulation electric-heat combined aging test device as claimed in claim 1, wherein the transformer assembly comprises a transformer coil, a transformer resistor and a transformer high-voltage end, the transformer coil, the transformer resistor and the transformer high-voltage end are sequentially connected end to end, and the transformer resistor and the transformer high-voltage end are used as the high-voltage connecting end of the upper electrode plate.

7. The transformer oil-paper insulation electric-heat combined aging test device as claimed in claim 6, wherein the high voltage connection end of the upper electrode plate is connected with the transformer resistor and the high voltage end of the transformer through a high voltage connection through hole, and the high voltage connection through hole is provided with a high voltage bushing.

8. A use method of a transformer oil paper insulation electric heating combined aging test device is characterized in that the use method of the transformer oil paper insulation electric heating combined aging test device according to any one of claims 1 to 7 comprises the following steps:

adding dimethyl silicone oil into the oil crucible, and heating the sealable oil tank by using the dimethyl silicone oil as a heat conduction medium;

installing the treated insulating paper, insulating oil and winding in a transformer oil-paper insulation electric-heat combined aging test device, wherein the insulating paper and the winding are arranged in the test device, the insulating oil is arranged in a sealable tank body, and the insulating oil is covered with a film for testing;

and carrying out an aging test under the conditions that the temperature is 130 ℃ and the turn-to-turn voltage of the winding is 4kV/mm, and respectively sampling on the 3 rd aging day, the 5 th aging day, the 10 th aging day, the 15 th aging day, the 20 th aging day, the 25 th aging day, the 30 th aging day and the 35 th aging day to obtain the oil paper insulation samples with different aging degrees.

9. The use method of the transformer oil-paper insulation electric-heat combined aging test device is characterized in that before the test is started, insulating oil is introduced into the sealable tank through the oil inlet valve, the testing device is submerged by the insulating oil, and then nitrogen is filled into the sealable tank through the gas valve.

10. The use method of the transformer oil-paper insulation electric-heat combined aging test device according to claim 8, characterized in that the insulation paper, the insulation oil and the winding used in the test are respectively dried at 90 ℃ and 50Pa for 48 hours before use, then immersed in the insulation oil and immersed in the oil at 60 ℃ and 50Pa for 48 hours.

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