CN102682962B - Heat dissipation method for intermediate frequency amorphous alloy shell type transformer - Google Patents

Abstract

The invention discloses a heat dissipation method for an intermediate-frequency amorphous alloy shell-type transformer, specifically as follows: firstly, a heat-conducting thin plate is arranged close to the two iron core columns of the shell-type transformer, and the middle iron core The heat of the column is exported along the upper and lower sides of the heat conduction plate; second, the iron core with winding is placed in the middle of the oil tank, and the oil tank is filled with transformer oil, and the low-voltage and high-voltage windings are cooled through the transformer oil passage; third, finally through the outer surface of the oil tank and the air Convective heat transfer transfers the heat generated by the transformer to the external environment. The invention can effectively improve the heat dissipation conditions on the middle iron core column and the surrounding winding of the thin and tall medium-frequency amorphous alloy shell-type transformer, thereby reducing the maximum temperature rise of the transformer. The invention has a simple structure and process, the heat conduction plate itself does not generate heat, occupies a small space, and does not require an external power supply such as a cooling fan, and is suitable for harsh working conditions such as offshore wind power generation platforms.

Description

A heat dissipation method for an intermediate frequency amorphous alloy shell-type transformer

technical field

The invention relates to a heat dissipation technology for a transformer, in particular to a heat dissipation method for an intermediate frequency amorphous alloy shell type transformer.

Background technique

The use of renewable wind energy is shifting from land to sea. In offshore wind power generation, the AC transmission of submarine cables has large fluctuations in reactive power, and DC transmission can overcome this shortcoming, which will become the development trend of offshore power transmission in the future. In addition, the onshore distributed power generation system is easier to realize multi-terminal connection by using DC grid than AC grid. In order to realize low-voltage DC to high-voltage DC conversion, a kilohertz-level intermediate frequency transformer must be used. Under medium frequency conditions, amorphous alloys are thinner than electrical silicon steel strips, and have the characteristics of less loss than iron cores. Moreover, the power density of the intermediate frequency transformer is higher than that of the industrial frequency transformer. Under the same capacity condition, the volume of the intermediate frequency amorphous alloy transformer is significantly reduced and the weight is lighter, thereby saving resources and the overall equipment has the characteristics of miniaturization and light weight. Therefore, it will be a development trend in the future to use intermediate frequency amorphous alloy transformers as DC-DC transformers for offshore wind power generation. The temperature rise directly affects the performance of the transformer, which will accelerate the aging of the winding insulation, deteriorate the transformer oil, and shorten the service life of the transformer. Therefore, controlling temperature rise and maximum temperature is one of the key issues of transformer heat dissipation.

There are mainly two types of transformers: shell type and core type. Considering the heat dissipation of windings, most of them adopt core type structure. A search of existing technical literature found that the literature "1Megawatt, 20kHz, Isolated, Bidirectional 12kV to 1.2kV DC-DCConverter for Renewable Energy Applications" (The 2010 International Power Electronics Conference), proposed a single-phase core transformer heat dissipation structure, in each A water-cooled heat sink is placed between the iron core column and the low-voltage winding. The disadvantage of this heat dissipation method is that the leakage magnetic field on the heat dissipation structure causes eddy currents, which increases additional losses and heat. In addition, a water deionization device is required. This document also proposes a similar shell-type transformer, which adopts the heat dissipation method of aluminum plates and heat sinks on the upper and lower yokes respectively; the document also proposes another matrix transformer structure, in which each low-voltage winding is independent, and the high-voltage winding is shared and a layer is established. The two structures are not only bulky, but also the high-voltage winding layout process for establishing the ventilation channel is complicated. The above three heat dissipation structures are feasible for 12kV dry-type transformers, but the insulation strength of transformers with voltage levels higher than 35kV is insufficient.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a heat dissipation method with simple structure and process, good control of temperature rise and maximum temperature effect.

The purpose of the present invention is achieved through the following technical solutions:

A heat dissipation method for an intermediate frequency amorphous alloy shell-type transformer, specifically:

First, install heat-conducting thin plates close to the two iron core columns of the shell-type transformer, and export the heat of the middle iron core column along the upper and lower sides of the heat-conducting plate through the heat-conducting thin plates close to the iron core columns;

Second, the iron core with winding is placed in the middle of the oil tank, which is filled with transformer oil, and the low-voltage and high-voltage windings are cooled through the transformer oil passage;

Third, the heat generated by the transformer is transferred to the external environment through the convective heat exchange between the outer surface of the oil tank and the air.

Further, the heat conduction thin plates are arranged close to the two iron core columns of the shell-type transformer, and the specific operation steps are as follows:

(1) Prepare two heat-conducting sheets, one end of the two heat-conducting sheets is bent into an "L" shape, and the "L"-shaped heat-conducting plates are assembled back to back to form a "T"-shaped heat-conducting plate after the one end is bent;

(2) Sandwich the above-mentioned "T"-shaped heat conducting plate between two amorphous alloy iron core columns, and the bent part coincides with the non-open end of the window;

(3) Then install the shell-type transformer high and low voltage windings according to the normal process, and close the window;

(4) Bend the other end of the "T"-shaped heat conduction plate to form two back-to-back "C"-shaped heat conduction plates, and the length of the bent part extends to the middle of the iron core yoke;

(5) After completing the above steps, continue to follow the traditional amorphous alloy process to complete the rest of the process.

Preferably, the heat-conducting thin plate is closely attached to the two amorphous alloy iron cores, and the rounded bent parts at both ends extend to half of the width direction of the window of the iron core, and the heat-conducting thin plate is fully compatible with the iron core and the transformer oil. contact and contact area.

Preferably, the thermally conductive thin plate can be processed from a non-magnetic copper thin plate with good thermal conductivity.

Preferably, the thickness of the heat conducting thin plate is 0.3-1.5mm.

Compared with the prior art, the present invention has the following advantages:

First, the heat conduction plate is sandwiched between the two iron cores, which can effectively transfer the heat from the middle section of the iron core to the upper and lower ends through the heat conduction plate, and fully contact the oil layer for heat exchange, thereby significantly reducing the uneven temperature distribution of the middle iron core column .

Second, between the high-voltage and low-voltage windings, and between the high-voltage winding and the iron core column, there is a sufficient size of the oil circuit height, which reduces the resistance of the transformer core yoke to the oil rising path, and speeds up the flow of the high-voltage and low-voltage windings and the iron core column. The heat dissipation can effectively reduce the temperature rise of the transformer.

Third, the outer winding of the iron core has a sufficient area in contact with the oil to ensure heat dissipation at the end of the winding and ensure a lower temperature at the end.

Fourth, the heat conduction plate is sandwiched between the two iron cores to prevent the leakage magnetic field of the winding from generating eddy currents on the heat conduction plate, so the heat conduction plate will not generate additional heat.

Description of drawings

Fig. 1 is a structural schematic diagram (sectional view) of an intermediate frequency amorphous alloy transformer in an embodiment of the present invention;

Figure 2 is the front view of Figure 1

Fig. 3 is a side view of Fig. 1;

Fig. 4 is the top view of Fig. 1;

Fig. 5 is a schematic diagram of a heat conducting plate;

In the figure: 1-left heat conduction thin plate, 2-right heat conduction thin plate, 3-left iron core, 4-right iron core, 5-low voltage winding inner insulation 6-low voltage winding, 7-high voltage winding, 8-transformer oil tank, 9- Oil passage, 10-transformer oil.

Detailed ways

Embodiments of the present invention are described in detail below, and the present embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation and specific operation process are provided, but the protection scope of the present invention is not limited to the following embodiments.

The problem to be solved in this embodiment is to find a non-forced heat dissipation method with simple structure and process, small size and light weight, which can effectively reduce the maximum temperature of the inner core column and winding of the thin and tall shell type amorphous alloy transformer. Lift.

In this embodiment, the high-voltage winding of the medium-frequency amorphous alloy transformer is 50 kV, and the modular composite shell structure is adopted, which significantly reduces the height of the iron core and yoke, thereby reducing the unevenness of the magnetic field inside the iron core. Moreover, the size of the iron core is designed to be relatively flat, and the size of the iron core in the direction of the winding height is obviously larger than that of other two-dimensional spaces, which can effectively suppress the surrounding intermediate frequency electromagnetic field, thereby greatly reducing the additional loss and heat generated by the metal accessories of the transformer and the oil tank wall. It can also reduce the resistance of the internal transformer oil flow.

As shown in Figure 1-5, in the figure: left heat conduction thin plate 1, right heat conduction thin plate 2, left iron core 3, right iron core 4, low voltage winding to iron core insulating paper 5, low voltage winding 6, high voltage winding 7, transformer oil tank 8. Oil passages isolated by insulating cardboard between high and low voltage windings 9. Transformer oil 10.

The heat dissipation method of the shell-type transformer provided in this embodiment is specifically:

First, the left heat conduction thin plate 1 and the right heat conduction thin plate 2 are arranged close to the left iron core 3 and right iron core 4 of the shell-type transformer. Export along the upper and lower sides of the heat conduction plate;

Second, the iron core with winding is placed in the middle of the oil tank 8, and the oil tank 8 is filled with transformer oil 10, and the low-voltage winding 6 and the high-voltage winding 7 are cooled through the transformer oil passage 9;

Thirdly, the heat generated by the transformer is transferred to the external environment through the convective heat exchange between the outer surface of the oil tank 8 and the air.

In this embodiment, the left heat conduction thin plate 1 and the right heat conduction thin plate 2 are set according to the following steps:

(1) Bending one end of the heat-conducting thin plates 1 and 2 with a thickness of 0.5 mm and a width not exceeding the size of the side of the iron core respectively into an "L" shape, and then joining them back to back into a "T" shape, and connecting them with the amorphous alloy iron core 3, The non-open ends of 4 are matched, and the length of the bent part of the heat conduction plate extends to half the width of the iron core yoke.

(2) Open the window of the iron core, and bind the iron core columns close to both sides of the heat conduction plate with insulating tape. On the one hand, the iron core is fixed, and on the other hand, the low-voltage winding is insulated from the iron core columns.

(3) Then install the low-voltage winding 6, high-voltage winding 7, and insulating cardboard between the high-voltage and low-voltage windings according to the normal process, and form the oil passage 9, and then close the core window.

(4) Bending the other ends of the heat-conducting thin plates 1 and 2 to the side of the iron core 3 and 4 respectively, and the length of the bent part extends to the middle position of the iron core yoke, thus forming two "C"-shaped heat-conducting thin plates, These two "C"-shaped heat-conducting thin plates form an "I"-shaped heat dissipation structure back to back.

(5) Continue to complete the rest of the transformer assembly process according to the traditional process.

The assembled transformer core with windings is placed in the middle of the oil tank 8, and the oil tank 8 is filled with transformer oil 10, so that the transformer oil 10 can fully contact with the iron cores 3 and 4, the low-voltage winding 6, the high-voltage winding 7 and the extensions of the heat-conducting thin plates 1 and 2. Contact for efficient heat exchange. Transformer oil 10 is used as a heat transfer medium, and its density decreases with the increase of temperature, so that the hot oil rises under the action of gravity, and effectively transfers the heat of iron core 3, 4, winding 6, 7 to the inner wall of oil tank 8, and after another In heat exchange, the thermal transformer oil 10 at the inner wall of the oil tank is cooled, and its density increases, so that it flows downward, and the high temperature of the transformer oil rises and the low temperature drops to form a natural circulation. The fuel tank 8 conducts high-temperature heat from the inner wall to the outer wall with a lower temperature, and conducts convective heat exchange and heat radiation with the air outside the fuel tank, and finally transfers the heat to the external environment.

To sum up, the present invention can effectively improve the heat dissipation conditions on the middle iron core column and the surrounding winding of the thin and tall medium-frequency amorphous alloy shell-type transformer, thereby reducing the maximum temperature rise of the transformer. The invention has a simple structure and process, the heat conduction plate itself does not generate heat, occupies a small space, and does not require an external power supply such as a cooling fan, and is suitable for harsh working conditions such as offshore wind power generation platforms. After simulation calculation, it has obvious heat dissipation effect.

Although the content of the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as limiting the present invention. Various modifications and alterations to the present invention will become apparent to those skilled in the art upon reading the above disclosure. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims (4)

1. A method for heat dissipation of an intermediate frequency amorphous alloy shell-type transformer, characterized in that the method is specifically: First, install heat-conducting thin plates close to the two iron core columns of the shell-type transformer, and export the heat of the middle iron core column along the upper and lower sides of the heat-conducting plate through the heat-conducting thin plates close to the iron core columns; Second, the iron core with winding is placed in the middle of the oil tank, which is filled with transformer oil, and the low-voltage and high-voltage windings are cooled through the transformer oil passage; Third, finally transfer the heat generated by the transformer to the external environment through the convective heat exchange between the outer surface of the oil tank and the air; The heat-conducting thin plates are arranged close to the two iron core columns of the shell-type transformer, and the specific operation steps are as follows: (1) Prepare two heat-conducting thin plates, one end of the two heat-conducting plates is bent into an "L" shape, and the "L"-shaped heat-conducting plates are assembled back to back to form a "T"-shaped heat-conducting plate after one end is bent; (2) Sandwich the above-mentioned "T"-shaped heat conduction plate between two amorphous alloy iron core columns, and the bent part coincides with the non-open end of the window; (3) Then install the shell-type transformer high and low voltage windings according to the normal process, and close the window; (4) Bend the other end of the "T"-shaped heat conduction plate to form two back-to-back "C"-shaped heat conduction plates, and the length of the bent part extends to the middle of the iron core yoke; (5) After completing the above steps, continue to complete the rest of the process according to the traditional amorphous alloy process. 2. The heat dissipation method of a medium-frequency amorphous alloy shell-type transformer according to claim 1, wherein the heat-conducting thin plate is closely attached to two amorphous alloy iron cores, and the round corners at both ends are bent toward the iron cores. The width of the core window extends to half of the position, and the heat-conducting thin plate has sufficient contact and contact area with the iron core and transformer oil. 3. A method for heat dissipation of an intermediate frequency amorphous alloy shell-type transformer according to any one of claims 1-2, characterized in that the heat-conducting thin plate is made of a non-magnetic copper plate with good thermal conductivity. 4. The method for heat dissipation of an intermediate frequency amorphous alloy shell-type transformer according to any one of claims 1-2, wherein the thickness of the heat-conducting thin plate is 0.3-1.5mm.