JP6833462B2 - Manufacturing method of naturally circulating vegetable oil-filled transformer - Google Patents

Description

The present invention relates to a method for manufacturing a vegetable oil-immersed transformer, which is designed and manufactured based on a natural-circulating mineral oil-filled transformer of the same type.

Conventionally, as this type of naturally circulating vegetable oil-filled transformer, as shown in Patent Document 1 below, a rapeseed oil-filled transformer by the inventor of the present application and the applicant of the present application is known.

According to such a rapeseed oil-filled transformer, it is possible to improve the airtightness of the transformer tank and prevent the moisture in the air from being absorbed by the rapeseed oil as the insulating oil.

Japanese Patent No. 5209581

Here, the inventor and the applicant of the present application, as a pioneer who has promoted the practical application and popularization of the vegetable oil-immersed transformer, are using the winding insulation for the winding while repeating the diligent test and research on the vegetable oil-immersed transformer. By focusing on paper, we came to the finding that it shows a characteristic superiority in design due to the difference from the existing mineral oil-immersed transformer.

In particular, vegetable oil has a higher viscosity (kinematic viscosity characteristic) than mineral oil, so it is not suitable for natural circulation compared to mineral oil, and it cannot be dealt with simply by changing mineral oil to vegetable oil. By paying attention, on the contrary, it was found that the difference from the existing mineral oil-immersed transformer shows a characteristic superiority in the design of the vegetable oil-filled transformer.

The present invention is based on such findings, and an object of the present invention is to provide a method for manufacturing a naturally circulating vegetable oil-filled transformer capable of maximizing the characteristics of vegetable oil by making a difference from the naturally circulating mineral oil-filled transformer. And.

The method for manufacturing a naturally circulating vegetable oil-filled transformer according to the first invention is a method for manufacturing a naturally circulating vegetable oil-filled transformer designed based on the naturally circulating mineral oil-filled transformer.
From the change over time in the average degree of polymerization of the winding insulating paper of the natural circulation type vegetable oil-filled transformer with respect to the change over time in the winding insulating paper of the natural circulation type mineral oil-filled transformer, the natural circulation type vegetable oil-filled transformer Expected life calculation process to calculate the expected life of the vessel and
A winding temperature setting process for setting the maximum winding temperature based on the relationship between the expected life calculated by the expected life calculation process and the maximum winding temperature .
An outer shape determining step of determining the outer shape of the naturally circulating vegetable oil-filled transformer so as to satisfy the maximum winding temperature set by the winding temperature setting step and the expected life corresponding to the maximum winding temperature. comprising a <br/>,
In the expected life calculation step, the time-dependent change in the average degree of polymerization between the mineral oil-filled insulating paper of the naturally circulating type mineral oil-filled transformer and the vegetable oil-filled insulating paper of the naturally circulating vegetable oil-filled transformer is accelerated and deteriorated. By the test, the expected life was calculated as the ratio of the winding insulating paper in vegetable oil to the winding insulating paper in mineral oil for the number of days until the average degree of polymerization residual ratio reached a predetermined value.
In the winding temperature setting step, the maximum winding temperature rise (K) that satisfies the multiplication factor of the expected life calculated in the expected life calculation step is set from the 6 ° C. temperature half rule of the life of the winding insulating paper. Calculate the maximum winding temperature,
In the external shape determination step, the maximum winding temperature rise (K) set by the winding temperature setting step and the maximum oil temperature rise (K) depending on the loss generated inside the naturally circulating vegetable oil-immersed transformer. ) And the difference (K) depending on the loss in the winding, the maximum oil temperature rise (K) is set by the following equation.
Maximum winding temperature rise (K) = Maximum oil temperature rise (K) + Difference (K)
The shape of the radiator is selected according to the oil maximum temperature rise (K), and the basic fixing position, terminal position, and control wiring position of the naturally circulating mineral oil-filled transformer are set to the naturally circulating vegetable oil-filled transformer. It is characterized in that it is designed to match the basic fixed position of the transformer, the terminal position, and the control wiring position.

Based on the above findings, according to the method for manufacturing a naturally circulating vegetable oil-filled transformer of the first invention, the naturally circulating vegetable oil-filled transformer with respect to the change over time in the average degree of polymerization of the winding insulating paper of the naturally circulating mineral oil-filled transformer. By grasping the change over time in the average degree of polymerization of the wound insulating paper, the expected life of the naturally circulating vegetable oil-filled transformer can be calculated. Then, the maximum winding temperature can be set from the relationship between the expected life and the maximum winding temperature.

By specifically setting the maximum winding temperature set here, it is possible to specifically realize a naturally circulating vegetable oil-immersed transformer with the desired expected life, making the best use of the characteristics of vegetable oil. , It is possible to increase the degree of freedom in design, such as extending the expected life of the transformer with mineral oil, or reducing the physique and weight of the transformer.

As described above, according to the method for manufacturing a naturally circulating vegetable oil-filled transformer of the first invention, the naturally circulating vegetable oil-filled transformer can make the best use of the characteristics of vegetable oil due to the difference from the naturally circulating mineral oil-filled transformer. The vessel can be designed and manufactured.

Further , according to the method for manufacturing a naturally circulating vegetable oil-filled transformer of the first invention, the maximum winding temperature and the expected life are determined from the relationship between the maximum winding temperature and the expected life of the naturally circulating vegetable oil-filled transformer. However, at this time, the outer shape of the naturally circulating vegetable oil-immersed transformer is determined so as to satisfy the determined maximum winding temperature and the expected life.

As a result, the characteristics of vegetable oil can be maximized, the degree of freedom in design can be increased, and the entire transformer can be made compact. In particular, from the relationship between the expected life of the vegetable oil-immersed transformer and the maximum winding temperature, it is possible to realize a design method that can control the extension of the expected life or the reduction and weight reduction of the physique compared to the mineral oil-immersed transformer. ..

As described above, according to the method for manufacturing a naturally circulating vegetable oil-filled transformer of the first invention, the natural-circulating vegetable oil-filled transformer can make the best use of the characteristics of vegetable oil due to the difference from the naturally-circulating mineral oil-filled transformer. The vessel can be specifically designed and manufactured.

Further , according to the method for manufacturing a naturally circulating vegetable oil-filled transformer of the first invention, when the naturally circulating mineral oil-filled transformer that is already in operation is replaced with a naturally circulating vegetable oil-filled transformer, it is already operated. Basic fixed position, bushing terminal position of natural circulation type mineral oil transformer, and basic fixed position, terminal of newly installed natural circulation type vegetable oil transformer at terminal stand position of control wiring of protective relay and tap switcher at load By matching the position and the terminal block position of the control wiring of the protective relay and the tap switcher under load, it is possible to shorten the on-site construction period for replacing the equipment. In addition, since it is possible to reduce the size and weight of the transformer compared to the naturally circulating mineral oil-filled transformer that is already in operation, the dimensional reserve capacity for reducing the size and the cross-sectional area of the iron core are increased. Therefore, it is possible to reduce the loss by reducing the magnetic flux density in the iron core and increasing the cross-sectional area of the copper wire used for the winding.

As described above, according to the method for manufacturing a naturally circulating vegetable oil-filled transformer of the first invention, the natural-circulating vegetable oil-filled transformer can make the best use of the characteristics of vegetable oil due to the difference from the naturally-circulating mineral oil-filled transformer. The vessel can be specifically designed and manufactured.

The plan view of the natural circulation type vegetable oil-filled transformer of this embodiment. The front view of the natural circulation type vegetable oil-filled transformer of this embodiment. The explanatory view of the expected life calculation process in the manufacturing method of the natural circulation type vegetable oil-filled transformer of this embodiment. The explanatory view of the winding temperature setting process in the manufacturing method of the natural circulation type vegetable oil-filled transformer of this embodiment. Top view of the existing naturally circulating mineral oil-filled transformer. Front view of the existing natural circulation type mineral oil transformer. The plan view which superposed the natural circulation type vegetable oil-filled transformer of this embodiment and the existing natural circulation type mineral oil-filled transformer. The front view which superposed the natural circulation type vegetable oil-filled transformer of this embodiment and the existing natural circulation type mineral oil-filled transformer. Top view of another naturally circulating vegetable oil-immersed transformer of the present embodiment. The front view of another natural circulation type vegetable oil-filled transformer of this embodiment.

As shown in FIG. 1, the naturally circulating vegetable oil-filled transformer 1 of the present embodiment accommodates a plurality of transformer bodies (not shown) in the transformer tank 2 as schematically shown in FIG. The structure is sealed with vegetable oil as an insulating liquid injected and impregnated inside.

The vegetable oil is typically rapeseed oil, but is not limited to this, for example, a part of soybean oil, sunflower oil, cottonseed oil, olive oil, safflower oil, jojoba oil, reskerella oil, veronia oil, etc. It may be all.

The transformer main body is configured by winding primary and secondary coils around an iron core, and the current flowing through the primary and secondary coils is switched by a tap changer (not shown) or the like housed in the transformer tank 2. It is possible.

The transformer tank 2 is provided with a radiator 3 for cooling on the opposite side and a conservator 4 on the upper part. Further, the transformer tank 2 is provided with a primary side connection terminal 51 on one of the remaining facing side portions and a secondary side connection terminal 52 on the other side.

The radiator 3 includes communication pipes 31 and 32 communicating with the inside of the transformer tank 2 at two locations above and below the side wall of the transformer tank 2, and a plurality of heat radiating plates 33 branched from the communication pipes 31 and 32, respectively. The vegetable oil in the transformer tank 2 is cooled by the heat radiating plate 33 by circulating through the communication pipes 31 and 32 at two locations above and below and the heat radiating plate 33. The circulation of vegetable oil may be natural circulation due to the temperature difference between the upper and lower communication pipes 31 and 32, or forced circulation by a circulation pump (not shown).

The conservator 4 is an auxiliary chamber into which the vegetable oil in the transformer tank 2 flows in. Even if the vegetable oil expands due to a temperature change, the conservator absorbs the amount of expanded oil, and the vegetable oil in the transformer tank 2 directly airs. It is possible to prevent contact with.

The primary side connection terminal 51 is a connection terminal connected to the primary coil of the transformer main body, and the secondary side connection terminal 52 is a connection terminal connected to the secondary coil of the transformer main body.

The above is the outline of the naturally circulating vegetable oil-immersed transformer 1 of the present embodiment.

Next, a method for designing and manufacturing the naturally circulating vegetable oil-immersed transformer 1 will be described with reference to FIGS. 1 to 5.

The method for designing and manufacturing the natural circulation type vegetable oil-filled transformer 1 of the present embodiment is a natural circulation type vegetable oil-filled transformer 1 designed and manufactured based on the natural circulation type mineral oil-filled transformer 1'. It is a manufacturing method of the input transformer 1, and includes an expected life calculation step, a winding temperature setting step, and an outer shape determination step.

First, in the expected life calculation process, the change over time in the average degree of polymerization of the winding insulating paper of the naturally circulating vegetable oil-filled transformer with respect to the time-dependent change in the winding insulating paper of the naturally circulating mineral oil-filled transformer. Calculate the expected life of a naturally circulating vegetable oil-immersed transformer.

As shown in FIG. 2, specifically, in the expected life calculation process, the winding insulating paper in the mineral oil of the naturally circulating mineral oil-filled transformer and the winding insulating paper in the vegetable oil of the naturally circulating vegetable oil-filled transformer are wound. The time-dependent change in the average degree of polymerization, which can quantitatively grasp the deterioration of the wire insulating paper, is calculated by the accelerated deterioration test.

According to the result of the accelerated deterioration test, it is the test result when the average polymerization degree residual ratio of the wound insulating paper before the start of the acceleration deterioration test is 80%, but the average polymerization degree residual ratio reaches up to 45%. The number of days is 9 times that of mineral oil medium winding insulating paper for vegetable oil (rapeseed oil) medium winding insulating paper, and from this, when the maximum winding temperature is the same, the initial winding average polymerization of the transformer operation If the residual ratio is 80%, it can be said that the vegetable oil (rapeseed oil) medium winding insulating paper has an expected life of 9 times that of the mineral oil medium winding insulating paper.

That is, by converting the insulating oil used for the transformer into vegetable oil, the expected life can be extended compared to the transformer using mineral oil as the insulating oil, and the extension is 9 times longer when the maximum winding temperature is the same. It becomes.

Next, in the winding temperature setting step, the maximum winding temperature is set from the relationship between the expected life calculated by the expected life calculation process and the maximum winding temperature.

Specifically, in the winding temperature setting process, the life of the winding insulating paper is "6 ° C temperature halving rule", that is, the life is halved (1/2) when the temperature rises by 6 ° C. To set.

That is, when the winding maximum temperature of the natural circulation type vegetable oil-filled transformer is increased by 19 (K) with respect to the winding maximum point temperature of the natural circulation type mineral oil-filled transformer, the natural circulation type mineral oil-filled transformer is regarded as The life of the naturally circulating vegetable oil-immersed transformer is the same.

In addition, when the winding maximum temperature of the natural circulation type vegetable oil-filled transformer is increased by 13 (K) with respect to the winding maximum point temperature of the natural circulation type mineral oil-filled transformer, the natural circulation type mineral oil-filled transformer becomes On the other hand, the life of the naturally circulating vegetable oil-immersed transformer is doubled.

From this, the natural circulation type vegetable oil-filled transformer has a natural circulation type vegetable oil-filled transformer so that the maximum winding point temperature of the natural circulation type vegetable oil-filled transformer is 13 (K) higher than the winding maximum temperature of the natural circulation type mineral oil-filled transformer. Select a radiator according to the loss generated inside the coil to determine the maximum oil temperature rise (K), and select the loss generated inside the winding, the size of the winding copper wire, and the size of the oil passage through which the oil flows. By doing so, the difference (K) with respect to the oil maximum temperature rise with respect to the winding maximum point temperature rise is determined, and the winding maximum point temperature rise (K) = oil maximum temperature rise (K) + oil with respect to the winding maximum point temperature rise. Since it is a difference (K) with respect to the maximum temperature rise, the winding maximum point temperature rise (K) can be set. As a result, it is possible to obtain a naturally circulating vegetable oil-filled transformer having twice the life of the naturally circulating mineral oil-filled transformer.

On the other hand, when the winding maximum temperature of the natural circulation type vegetable oil-filled transformer is increased by 13 (K) with respect to the winding maximum temperature of the natural circulation type mineral oil-filled transformer, the natural circulation type mineral oil-filled transformer is regarded as The life of the natural circulation type vegetable oil-filled transformer is doubled, but the winding maximum point temperature of the natural circulation type vegetable oil-filled transformer is 13 (K) with respect to the winding maximum point temperature of the natural circulation type mineral oil-filled transformer. ) By increasing the height, the amount of radiators according to the loss generated inside the naturally circulating vegetable oil-filled transformer can be reduced, and the number of radiators, the number of radiator panels, and the height of the radiator can be reduced. As a result, the naturally circulating vegetable oil-filled transformer can reduce the transformer physique as compared with the naturally circulating mineral oil-filled transformer.

Here, in the winding temperature setting step, the expected life corresponding to the maximum winding temperature is determined by setting the maximum winding temperature.

As shown in FIG. 3, for example, the relationship between the maximum winding temperature and the expected life (year) of the vegetable oil-immersed transformer when the equivalent ambient temperature is 25 ° C.
y = 39623065 × exp (-0.1155 × x)
Will be.

In FIG. 3, the maximum winding temperature (K) is a variable x, and the expected life (year) of the vegetable oil-immersed transformer is a variable y.

From the relationship between the maximum winding temperature and the expected life in FIG. 3, the maximum winding temperature and the corresponding expected life are specifically determined.

In the outer shape determination step, the outer shape of the naturally circulating vegetable oil-filled transformer is determined under each condition defined by the above expected life calculation process and winding temperature setting process.

Specifically, in the external shape determination process, the basic fixed position, terminal position, and control wiring position of the naturally circulating mineral oil-filled transformer are set to the basic fixed position, terminal position, and control wiring of the naturally circulating vegetable oil-filled transformer. Designed to match the position.

In such an external shape determination step, for example, FIG. 4 shows a conventional natural circulation type mineral oil-filled transformer 1', and FIG. 5 shows a natural circulation type vegetable oil-filled transformer 1 and an existing natural circulation type mineral oil-filled transformer 1'. As shown by superimposing the above, it has the advantage of making the best use of the following characteristics of vegetable oil. In FIGS. 4 and 5, the same components are designated by the same reference numerals and the description thereof will be omitted.

First, in the existing naturally circulating mineral oil-filled transformer 1'in FIG. 4, not only the volume of the transformer tank 2 is large, but also the radiator is large so as to cover the entire wide facing side surface of the transformer tank 2. Although it is a specification, in the naturally circulating vegetable oil-filled transformer 1 of the present embodiment of FIG. 1, the volume of the transformer tank 2 is small, and the radiator is also a small size that covers the central part of the side surface of the corresponding transformer tank. It is a specification.

On the other hand, as shown in FIG. 5, the positions of the primary side connection terminal 51 and the secondary side connection terminal 52 of the existing natural circulation type mineral oil-filled transformer 1'in FIG. 4 and the natural circulation of the present embodiment of FIG. The positions of the primary side connection terminal 51 and the secondary side connection terminal 52 of the type vegetable oil-immersed transformer 1 match. Similarly, by matching the foundation fixing position and the control wiring position, the construction work when the existing natural circulation type mineral oil-filled transformer and the natural circulation type vegetable oil-filled transformer of the present embodiment are replaced can be completed in a short period of time. It becomes possible to do.

As described in detail above, according to the method for manufacturing a naturally circulating vegetable oil-filled transformer of the present embodiment, the expected life is extended or transformed as compared with the mineral oil-filled transformer by making the best use of the characteristics of the vegetable oil. It is possible to increase the degree of freedom in design, such as reducing the physique and weight of the vessel.

As described above, according to the method for manufacturing a naturally circulating vegetable oil-filled transformer of the present embodiment, a naturally circulating vegetable oil-filled transformer that can maximize the characteristics of vegetable oil due to the difference from the mineral oil-filled transformer is designed. Can be manufactured.

That is, it is difficult for vegetable oil to correspond to a natural circulation type transformer as compared with mineral oil. For example, if the transformer structure is exactly the same, vegetable oil has a higher viscosity (kinematic viscosity characteristic) than mineral oil. Therefore, simply changing the mineral oil to vegetable oil will cause natural circulation in the winding during transformer operation. The flow velocity and the natural circulation velocity in the tank and radiator are lower in vegetable oil than in mineral oil.

As a result, the oil maximum temperature rise, the winding average temperature rise, and the winding maximum temperature rise,
The temperature of vegetable oil was higher than that of mineral oil as insulating oil, and it was not possible to meet the temperature rise limit specified in the standard.

In this way, where simply changing mineral oil to vegetable oil cannot be used for natural circulation transformers, the expected life is calculated by focusing on the winding insulating paper, and the relationship between the expected life and the maximum winding temperature is as follows. As described above, a characteristic advantage in design can be obtained in a naturally circulating vegetable oil-immersed transformer.

Specifically, the natural circulation is based on the change over time in the average degree of polymerization of the winding insulating paper of the naturally circulating vegetable oil-filled transformer with respect to the change over time in the winding insulating paper of the naturally circulating type ore-filled transformer. By the winding temperature setting process that sets the maximum winding temperature from the relationship between the expected life calculation process that calculates the expected life of the type vegetable oil-immersed transformer, the expected life calculated by the expected life calculation process, and the maximum winding temperature. , The maximum winding temperature can be raised, and the overall shape of the natural circulation type vegetable oil-immersed transformer, such as changing the panel shape of the radiator according to this, can be optimized, ensuring the degree of design freedom. It can be realized.

The naturally circulating vegetable oil-immersed transformer of the present embodiment is not limited to the above embodiment. For example, conventional transformers with low noise 50 dB specifications, tap changer specifications under load, transformer specifications that step down from a nominal voltage of 66 kV to a nominal voltage of 6.6 kV, and transformers with a rated capacity of 20 MVA specifications can all be installed due to restrictions on road transportation conditions. Although the carrying type could not be realized, as shown in FIG. 6, according to the design and manufacturing method of the naturally circulating vegetable oil-immersed transformer, as shown in FIGS. 6A and 6B, the radiator according to the kinematic viscosity characteristics of the vegetable oil. It can be arranged, the height of the transformer is 3600 mm or less, and it can be transported without disassembling the parts (all can be carried).

In FIG. 6, the same components as those in FIGS. 4 and 5 are designated by the same reference numerals, and the description thereof will be omitted.

1 ... Natural circulation type vegetable oil-filled transformer, 1'... Natural circulation type mineral oil-filled transformer, 2 ... Transformer tank, 3 ... Heater, 4 ... Conservator, 31, 32 ... Communication pipe, 33 ... Heat dissipation plate, 51 … Primary side connection terminal, 52… Secondary side connection terminal.

Claims (1)

It is a manufacturing method of a natural circulation type vegetable oil-filled transformer designed based on a natural circulation type mineral oil-filled transformer.
From the change over time in the average degree of polymerization of the winding insulating paper of the natural circulation type vegetable oil-filled transformer with respect to the change over time in the winding insulating paper of the natural circulation type mineral oil-filled transformer, the natural circulation type vegetable oil-filled transformer Expected life calculation process for calculating the expected life of the vessel and
A winding temperature setting process for setting the maximum winding temperature based on the relationship between the expected life calculated by the expected life calculation process and the maximum winding temperature .
An outer shape determining step of determining the outer shape of the naturally circulating vegetable oil-filled transformer so as to satisfy the maximum winding temperature set by the winding temperature setting step and the expected life corresponding to the maximum winding temperature. comprising a <br/>,
In the expected life calculation step, the time-dependent change in the average degree of polymerization between the mineral oil-filled insulating paper of the naturally circulating type mineral oil-filled transformer and the vegetable oil-filled insulating paper of the naturally circulating vegetable oil-filled transformer is accelerated and deteriorated. By the test, the expected life was calculated as the ratio of the winding insulating paper in vegetable oil to the winding insulating paper in mineral oil for the number of days until the average degree of polymerization residual ratio reached a predetermined value.
In the winding temperature setting step, the maximum winding temperature rise (K) that satisfies the multiplication factor of the expected life calculated in the expected life calculation step is set from the 6 ° C. temperature half rule of the life of the winding insulating paper. Calculate the maximum winding temperature,
In the external shape determination step, the maximum winding temperature rise (K) set by the winding temperature setting step and the maximum oil temperature rise (K) depending on the loss generated inside the naturally circulating vegetable oil-immersed transformer. ) And the difference (K) depending on the loss in the winding, the maximum oil temperature rise (K) is set by the following equation.
Maximum winding temperature rise (K) = Maximum oil temperature rise (K) + Difference (K)
The shape of the radiator is selected according to the oil maximum temperature rise (K), and the basic fixing position, terminal position, and control wiring position of the naturally circulating mineral oil-filled transformer are set to the naturally circulating vegetable oil-filled transformer. A method for manufacturing a naturally circulating vegetable oil-filled transformer, which is characterized in that it is designed to match the basic fixed position of the transformer, the terminal position, and the control wiring position.