CN110780165A - Test device and test method for the deterioration of insulation material between overheating inter-turn of transformer winding - Google Patents

Abstract

The invention discloses a testing device and a testing method for the deterioration of insulating material between overheating inter-turns of transformer windings, comprising a device body with a transparent insulating box-shaped structure; the device body is connected to an oil pump through a circulating oil interface, and the oil pump is connected to an oil tank; Insulation fixing bracket for electrode and ground electrode; high-voltage electrode and ground electrode are arranged symmetrically on the left and right, and the ends of the high-voltage electrode and ground electrode are arranged in a circular arc structure. The electrode is connected to the external power supply, and the ground electrode is connected to the ground wire; the device body is provided with a temperature regulator for controlling its internal temperature; a heating and temperature measuring device is pasted under the ground electrode; The deterioration law of the material is convenient for the transformer to be shut down and repaired even if the overheating fault occurs, so as to avoid the breakdown and complete damage of the transformer caused by the high temperature deterioration.

Description

Test device and test method for the deterioration of insulation material between overheating inter-turn of transformer winding

technical field

The invention relates to the technical field of experiments on insulating materials of oil-immersed power transformers, in particular to a testing device and a testing method for the deterioration of insulating materials between overheated turns of transformer windings.

Background technique

The transformer is one of the key equipment in the power system. During the actual operation of the oil-immersed power transformer, when various unfavorable conditions such as external system failure, bad natural environment or transformer overload occur, the current flowing in the coil winding may change. A substantial increase. Since part of the loss in the transformer is proportional to the square of the current, it will cause excessive heat loss and cause overheating of the windings. The transformer fault caused by overheating of windings occupies a large proportion of all kinds of faults. With the continuous increase of transformer capacity in recent years, the problem of local overheating has become more prominent. High temperature will accelerate the deterioration of insulating materials and shorten their life, resulting in breakdown accidents.

At present, there are many experimental devices and methods for testing the state of insulating materials in transformers, but the research object is generally extruded cardboard for transformer phase-to-phase insulation. There are relatively few test devices and methods for winding inter-turn insulation multilayer kraft paper. At the same time, some experimental devices and methods take into account the influence of the internal temperature of the transformer, but in the actual situation, only the partial overheating of the windings, the entire heating of the transformer is not suitable for the actual operating conditions, nor can more accurate experimental results be obtained, and the adaptability is not strong. .

SUMMARY OF THE INVENTION

The invention provides a testing device and a testing method for the deterioration of insulating material between overheating turns of transformer windings, which can be used to evaluate the degree of deterioration of insulating materials under different temperatures when a local overheating fault develops.

The technical scheme adopted by the present invention is as follows: a device for testing the deterioration of insulating material between overheating turns of transformer windings, comprising a device body with a transparent and insulating box-shaped structure, the device body is provided with a box cover; the box cover is provided with a reserved lead outlet; The body is connected to the oil pump through the circulating oil interface, and the oil pump is connected to the oil tank; the device body is provided with an insulating fixing bracket for placing the high-voltage electrode and the ground electrode; the high-voltage electrode and the ground electrode are arranged symmetrically on the left and right, and the ends of the The arc of the arc part faces the side away from the ground electrode; the high voltage electrode is provided with an insulating layer; the ends of the high voltage electrode and the ground electrode are connected with metal pressure equalizing balls; the high voltage electrode is connected to the external power supply, and the ground electrode is connected to the ground wire; There is a temperature regulator for controlling its internal temperature; a heating and temperature measuring device is pasted under the ground electrode, and the heating and temperature measuring device includes a heating plate and a temperature sensor; both the heating and temperature measuring device and the temperature regulator are connected to the control device.

Further, the insulating layer is a multilayer insulating kraft paper.

Further, the device body is made of transparent epoxy resin.

Further, the box cover is detachably connected to the main body of the device through corner screws; the box cover is provided with four rectangular reserved lead outlets; they are the ground electrode outlet interface, the high voltage electrode outlet interface, and the temperature regulator outlet interface. And the outlet interface of heating and temperature measuring device.

Further, the insulating fixing bracket includes a left bracket and a right bracket with the same structure, and the left bracket includes two rectangular plates and two screws with nuts; one of the rectangular plates is arranged under the high-voltage electrode and the ground electrode; the other rectangular plate The plate is placed under the high voltage electrode and the ground electrode, and its two ends are respectively fixed with the lower rectangular plate by a screw with a nut.

A test method of a transformer winding overheating inter-turn insulation material deterioration test device, comprising the following steps:

Step 1: Immerse the high-voltage electrode provided with the insulating layer in the transformer oil, and put it into a vacuum drying box to dry;

Step 2: Fix the high-voltage electrode and the ground electrode attached to the heating and temperature measuring device with an insulating fixing bracket; put it into the device body filled with transformer oil; put the device body into a vacuum drying box for processing;

Step 3: Connect the high-voltage electrode to the external power supply, and the ground electrode to the ground wire; connect the device body to the oil pump through the circulating oil interface, and the oil pump to the oil tank; the control device controls the temperature inside the device body by controlling the temperature regulator; Heating; observe the changes of partial discharge and insulating layer at different temperatures; the control device controls the temperature of the heating plate to remain unchanged, and observe the changes of partial discharge and insulating layer over time.

The beneficial effects of the present invention are:

(1) The present invention can locally heat the insulating layer between turns of the transformer to make it fit the local overheating fault that occurs in the actual transformer;

(2) In the present invention, the heating and temperature measuring device is placed in the middle position under the ground electrode, which can not only make the two electrodes contact effectively, but also make the temperature evenly distributed on both ends of the ground electrode;

(3) In the present invention, the electrode structure is straight in the middle, and the two ends are arcs, which can effectively prevent the field strength at the corner from being too large, causing the preferential discharge at this point to have a greater impact on the test;

(4) In the present invention, the metal uniform balls at both ends of the two electrodes can equalize the voltage and avoid tip discharge caused by manufacturing or other processes.

Description of drawings

FIG. 1 is a schematic diagram of the structure of the device of the present invention.

In the picture: 1- Device body, 2- Temperature regulator, 3- Ground electrode lead wire, 4- High voltage electrode lead wire, 5- Circulating oil interface, 6- Metal pressure equalizing ball, 7- Insulation fixing bracket, 8- Heating And temperature measuring device, 9-heating sheet power cord, 10-temperature sensor wiring, 11-ground electrode, 12-high voltage electrode, 13-insulation layer.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

As shown in Figure 1, a transformer winding overheating inter-turn insulation material degradation test device includes a device body 1 with a transparent insulating box-shaped structure, and the device body 1 is provided with a box cover; It is fixed to the main body of the device body 1 . The box cover is provided with a reserved lead outlet, which are the outlet port of the ground electrode 11, the outlet port of the high voltage electrode 12, the outlet port of the temperature regulator 2, and the outlet port of the heating and temperature measuring device 8. A circulating oil interface 5 connected to an external oil tank is provided on the side of the device body 1 to provide circulating oil to the device body 1 to simulate the oil flow in an actual transformer.

The device body 1 is provided with an insulating fixing bracket 7 for placing the high-voltage electrode 12 and the ground electrode 11; the high-voltage electrode 12 and the ground electrode 11 are arranged symmetrically on the left and right, and their ends are arc-shaped structures; The side away from the ground electrode 11; the high voltage electrode 12 is provided with an insulating layer 13, and the insulating layer 13 is a multi-layer insulating paper; the high voltage electrode 12 is a copper strip, and the ground electrode 11 is a bare copper strip; The ends are arcs with larger radii. The ends of the high voltage electrode 12 and the ground electrode 11 are both connected with metal pressure equalizing balls 6 , and the metal pressure equalizing balls 6 play the role of equalizing the electric field to prevent the high and low voltage electrodes from generating partial discharge due to the tips. The high-voltage electrode 12 is connected to the external power supply through the high-voltage electrode lead wire 4, and the ground electrode 11 is connected to the ground wire through the ground electrode lead-out wire 3; the device body 1 is provided with a temperature regulator 2 for controlling the internal temperature; And the temperature measuring device 8, the heating and temperature measuring device 8 includes a heating plate and a temperature sensor; the heating plate and the temperature sensor are pasted in the middle position under the ground electrode 11 through thermal conductive glue, and they can be placed here to avoid contact with the high-voltage electrode 12, and at the same time To ensure effective contact between the two electrodes, on the other hand, placing it in the middle can make the temperature evenly distributed on both ends of the ground electrode 11, so as to locally heat the insulating kraft paper between turns of the transformer, making it fit the local overheating fault that occurs in the actual transformer. The heating and temperature measuring device 8 and the temperature regulator 2 are all connected to the control device; the temperature regulator 2 is used to control the temperature inside the entire device body 1 to remain unchanged to ensure that the test variables are unique.

The device body 1 is filled with transformer oil, which is made of epoxy resin material, namely plexiglass. The material is transparent, has good insulation, and has high corrosion resistance and heat resistance. It fully meets the requirements of high-voltage test experiments. . In addition, the device body 1 can be put into a vacuum drying box for ordinary experiments, and the air in the multilayer insulating paper can be removed by vacuuming, so as to avoid affecting the experimental results. The box cover is detachably connected to the main body of the device body 1. Open the cover when replacing electrodes or test sample insulating paper. During the test, the box cover must be fastened with screws to eliminate various hidden dangers during the test. There are four outlet ports reserved on the box cover, of which the heater power line 9 and the temperature sensor wiring 10 share one outlet port, and the shared port of the two outlet wires will not affect the test.

The larger the radius of the arc portion at both ends of the high voltage electrode 12 and the ground electrode 11 is, the more uniform the electric field here is and the better to avoid discharge there. The insulating fixing bracket 7 includes a left bracket and a right bracket with the same structure, and the left bracket includes two rectangular plates and two screws with nuts; one of the rectangular plates is arranged under the high-voltage electrode 12 and the ground electrode 11; the other rectangular plate is placed Below the high voltage electrode 12 and the ground electrode 11 , the two ends thereof are respectively fixed to the lower rectangular plate by screws with nuts. Both ends of the rectangular plate have a hole slightly larger than the diameter of the screw, and the rectangular plate is fixed near the arc of the high-voltage electrode 12 and the ground electrode 11 when fixing. The screw rod passes through the hole on the rectangular plate, and both sides are tightened with nuts to achieve the purpose of clamping the high-voltage electrode 12 and the ground electrode 11 .

A test method of a transformer winding overheating inter-turn insulation material deterioration test device, comprising the following steps:

Step 1: Immerse the high-voltage electrode 12 provided with the insulating layer 13 in the transformer oil, put it into a vacuum drying box to dry; set the temperature, vacuum degree and time, remove the moisture and other impurities in the insulating paper, and take out the wrapped insulating paper when the time is reached. High voltage electrode 12 of the paper.

Step 2: Fix the high voltage electrode 12 and the ground electrode 11 attached to the heating and temperature measuring device 8 with the insulating fixing bracket 7; the high voltage electrode 12 is connected to the high voltage electrode lead wire 4, and the ground electrode 11 is connected to the ground electrode lead wire 3; Put the insulating fixing bracket 7 of the high-voltage electrode 12 and the ground electrode 11 into the device body 1 filled with transformer oil; put the device body 1 into the vacuum drying box for processing; set the vacuum degree and the standing time to ensure that there is no multilayer insulating kraft paper. bubbles are present.

Step 3: Take the device body 1 out of the vacuum drying box, connect the high-voltage electrode 12 to the external power supply, and connect the ground electrode 11 to the ground wire; connect the device body 1 to the oil pump through the circulating oil interface 5, and the oil pump is connected to the oil tank to realize the circulating flow of the transformer oil; The control device controls the temperature in the device body 1 by controlling the temperature regulator 2 to ensure that the temperature in the entire device body 1 remains unchanged; the control device simultaneously controls the heating plate to heat, and sets a temperature gradient for the heating plate heating; observe the partial discharge at different temperatures and the insulating layer 13 changes; the control device controls the temperature of the heating plate to remain unchanged, and observes the changes of partial discharge and the insulating layer 13 over time.

The invention can realize local heating of the insulating kraft paper between the turns of the transformer, so as to fit the local overheating fault that occurs in the actual transformer. At the same time, the device is small in size and can be placed in a vacuum drying box for ordinary experiments, which can remove the air in the multi-layer insulating paper by vacuuming, so as to avoid affecting the experimental results. Placing the heating and temperature measuring device 8 in the middle of the ground electrode 11 not only enables the two electrodes to contact effectively, but also enables the temperature to be evenly distributed on both ends of the ground electrode 11 . The electrode structure is a straight arc in the middle with large radii at both ends, which can effectively avoid the excessive field strength at the corner, which causes the preferential discharge at this point to have a greater impact on the test. At the same time, the metal voltage equalizing ball 6 at the end of the electrode can equalize the voltage, so as to avoid tip discharge caused by manufacturing or other processes. The insulating fixing bracket 7 is small, and the transparent container is convenient to observe the phenomena generated during the experiment.

The invention can understand the deterioration rule of the insulating material when the local overheating fault occurs, and it is convenient for the transformer to be shut down and repaired even when the overheating fault occurs, so as to avoid the breakdown and complete damage of the transformer caused by the high temperature deterioration.

Claims (6)

1. The degradation testing device for the overheat interturn insulating material of the transformer winding is characterized by comprising a device body (1) with a transparent insulating box-shaped structure, wherein the device body (1) is provided with a box cover; a reserved lead outlet is arranged on the box cover; the device body (1) is connected with an oil pump through a circulating oil interface (5), and the oil pump is connected with an oil tank; an insulating fixed support (7) for placing a high-voltage electrode (11) and a ground electrode (11) is arranged in the device body (1); the high-voltage electrode (12) and the ground electrode (11) are arranged in bilateral symmetry, and the tail ends of the high-voltage electrode and the ground electrode are both arc-shaped structures; the radian of the arc part of the high-voltage electrode (12) faces to one side far away from the ground electrode (11); an insulating layer (13) is arranged outside the high-voltage electrode (12); the tail ends of the high-voltage electrode (12) and the ground electrode (11) are connected with metal voltage-equalizing balls (6); the high-voltage electrode (12) is connected with an external power supply, and the ground electrode (11) is connected with a ground wire; a temperature regulator (2) for controlling the internal temperature of the device body (1) is arranged in the device body; a heating and temperature measuring device (8) is adhered below the ground electrode (11), and the heating and temperature measuring device (8) comprises a heating sheet and a temperature sensor; the heating and temperature measuring device (8) and the temperature regulator (2) are both connected to the control device.

2. The degradation testing device for the overheat interturn insulating material of the transformer winding according to claim 1, wherein the insulating layer (13) is a multi-layer insulating kraft paper.

3. The degradation testing device of the overheat interturn insulating material of the transformer winding according to claim 1, wherein the device body (1) is made of transparent epoxy resin.

4. The transformer winding overheating interturn insulation material degradation testing device according to claim 1, characterized in that the box cover is detachably connected with the main body of the device body (1) through corner screws; four rectangular reserved lead outlets are arranged on the box cover; respectively is an outlet interface of the ground electrode (11), an outlet interface of the high-voltage electrode (12), an outlet interface of the temperature regulator (2) and an outlet interface of the heating and temperature measuring device (8).

5. The degradation testing device of the overheat interturn insulating material of the transformer winding according to claim 1, wherein the insulating fixing bracket (7) comprises a left bracket and a right bracket which have the same structure, and the left bracket comprises two rectangular plates and two screw rods with nuts; one rectangular plate is arranged below the high-voltage electrode (12) and the ground electrode (11); the other rectangular plate is placed below the high-voltage electrode (12) and the ground electrode (11), and two ends of the other rectangular plate are fixed with the rectangular plate below through screws with nuts.

6. The method for testing the degradation test device of the overheat interturn insulating material of the transformer winding according to any one of claims 1 to 5, comprising the following steps:

step 1: immersing a high-voltage electrode (12) provided with an insulating layer (13) into transformer oil, and putting the transformer oil into a vacuum drying oven for drying;

step 2: fixing a high-voltage electrode (12) and a ground electrode (11) attached with a heating and temperature measuring device (8) by using an insulating fixing support (7); putting the transformer oil into a device body (1) filled with transformer oil; putting the device body (1) into a vacuum drying oven for treatment;

and step 3: connecting the high-voltage electrode (12) with an external power supply, and connecting the ground electrode (11) with a ground wire; the device body (1) is connected with an oil pump through a circulating oil interface (5), and the oil pump is connected with an oil tank; the control device controls the temperature in the device body (1) by controlling the temperature regulator (2); the control device controls the heating sheets to heat at the same time; observing partial discharge and change of the insulating layer (13) at different temperatures; the control device controls the temperature of the heating sheet to be constant, and observes the change with time, the partial discharge and the change of the insulating layer (13).

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