JPS628925B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a naturally cooled induction electric device winding used for, for example, naturally cooled transformers and naturally cooled reactors.

FIG. 1 shows the structure of a conventional naturally cooled transformer disk winding with folding plates. A plurality of coils 1 made by winding insulated wires are connected to horizontal oil pipes 2, respectively.
The disk winding 3 is constructed by stacking the wires in the height direction via the wires. This disk winding 3 is inserted between an inner insulating tube 6 and an outer insulating tube 7, and an inner vertical oil passage 4 is inserted between the disk winding 3 and the inner insulating tube 6. An outer vertical oil passage 5 is formed between the outer insulating cylinder 7 and the outer insulating cylinder 7, respectively. These inner and outer vertical oil passages 4, 5 are
A plurality of folding sections are formed by alternately and sequentially closing a plurality of folding plates 8 arranged for each predetermined number of coils.

In the disc winding 3 in which the flow plate 8 is arranged in this way, the inner or outer vertical oil passage 4, as shown by the arrow,
The oil rising through the coils 5 flows in a zigzag pattern into the horizontal oil passages 2 between the coils, thereby cooling each coil 1. The state of oil circulation within this naturally cooled induction electric coil is different from the case of forced oil feeding using a pump or the like, and the circulating flow rate of oil per unit time is relatively small.

As shown in Fig. 1, when the width dimension of the coil 1 in the radial direction is L and the width dimension of the horizontal oil pipe 2 in the height direction is d, the dimension ratio L/d of both is in the range of 5 to 35. In the designed naturally cooled induction electric winding, the temperature distribution of the coil tends to be uneven within the folded section sandwiched between the two upper and lower folded plates 8,8. For example, as shown in FIG. 2, in one folding section sandwiched between the lower folding plate 8 and the upper folding plate 8, a plurality of coils 1 are arranged horizontally within the folding section. The temperature distribution in the case where the cooling oil placed through the oil pipe 2 and rising up the inner vertical oil pipe 4 further rises while flowing through each horizontal oil pipe 2 to the outer vertical oil pipe 5 side is described below. Shown in Figure 3. Straight line A in the figure corresponds to the abutting folded flow section obtained by connecting the actual oil temperature measurements at the inlet and outlet of winding 3 with a straight line, and is the average oil temperature in the folded flow section. It shows a significant increase. Further, curve B shows the temperature distribution of the coil. In addition. The temperature measurement position is the radial center of the coil. In conventional naturally cooled induction electric windings, no consideration has been given to the relationship between the number of coils in one folded flow section and the average flow velocity of oil in the horizontal oilway in that folded flow section. Therefore, as shown by curve B in FIG. 3, the temperature distribution of the coil tends to become non-uniform within the same folded flow section, and there is a tendency for the temperature to rise locally.

An object of the present invention is to provide an economical naturally cooled induction electric wire that efficiently prevents local temperature increases in the coil, has good cooling characteristics, and is economical.

In order to achieve this objective, the present invention examines various relationships between the number of coils arranged in one diversion section and the average flow velocity of oil in the horizontal oilway within that diversion section, and The number of coils arranged in the folded flow section is 5 to 15, and the average flow velocity (cm/sec) of oil in the horizontal oilway within the folded flow section is configured as shown in equation (1) below. shall be.

≒3.07×10 ^-4 q+0.28 ...(1) However, in the formula, q is the heat flux density (W/m ² ) on the coil surface.

Before deriving the above equation (1), the present inventors conducted a number of preliminary experiments using the naturally cooled induction electric winding shown in FIG. Forty coils 1 are stacked in the height direction via horizontal oil pipes 2 to form a disk winding 3, which is inserted into an insulating cylinder 7. The upper part of the disc winding 3 and the radiator 11 are connected to the upper pipe 9, and the radiator 11 and the lower part of the disc winding 3 are connected to the lower pipe 1.
0, and oil naturally circulates between the disc winding 3 and the radiator 11.

For example, one of the many preliminary experiments
Here, three folding plates 8 were used to form three folding sections. The placement location of this folding plate 8 is indicated by a bold line C on the vertical axis of FIG. The coil number on the vertical axis indicates the number of disk windings 3 along the oil flow.
These numbers are sequentially assigned from the lower coil 1 to the upper coil 1. The first folding plate 8 is between the coil with coil number 10 and the coil with coil number 11, the second folding plate 8 is between the coil with coil number 25 and the coil with coil number 26, and the third folding plate 8 is between the coil with coil number 25 and the coil with coil number 26. The folding plates 8 are arranged above the coil numbered 40, respectively. Therefore, ten coils 1 are arranged in the first folding section formed below the first folding plate 8.
A second folding section formed between the first folding plate 8 and the second folding plate 8, and a second folding section formed between the second folding plate 8 and the third folding plate 8. Fifteen coils 1 are arranged in each of the third folding sections.

Further, in another preliminary experiment 2, four folding plates 8 were used, and four folding sections were formed by the folding plates 8. The placement location of this folding plate 8 is indicated by a bold line C on the vertical axis of FIG. The first folding plate 8 has coil number 10
The second folding plate 8 is between the coil with coil number 20 and the coil with coil number 21, and the third folding plate 8 is between the coil with coil number 30 and the coil with coil number 11. The fourth folding plate 8 is disposed between the coil No. 31 and above the coil No. 40, respectively. Therefore, ten coils 1 are arranged in each folding section.

In preliminary experiments 1 and 2, the conditions such as the difference ΔH in center height between the disk winding 3 and the radiator 11 shown in Fig. 4, the thickness of the pipes 9 and 10, and the width dimension of the vertical oil pipe were the same. Thus, the number of installed folding plates 8 (the number of folded flow sections to be formed), in other words, the number of coils in one folded flow section was reached.

Comparing Preliminary Experiment 1 and Preliminary Experiment 2 under these conditions, in Preliminary Experiment 2, the number of installed flow plates 8 (number of folded flow sections) was increased compared to Preliminary Experiment 1. As a result, the number of coils in one fold section is reduced. and flow plate 8
As the number of installed disk windings 3 increases, the pressure loss in the oil circulation system throughout the disk winding 3 increases, and the oil circulation flow rate decreases slightly. However, up to an appropriate number of diversion sections, the reduction in the total flow cross-sectional area of the horizontal oilway within each diversion section is greater than the decrease in the oil circulation flow rate. As the average flow velocity increases, the difference in average flow velocity in each horizontal oilway becomes smaller. As a result, as is clear from comparing Figures 5 and 6, especially in preliminary experiment 2, there was no local temperature rise in the coil as shown by curve B, and the temperature distribution was averaged over the whole. Good cooling efficiency.

Through a number of preliminary experiments including these preliminary experiments 1 and 2, the number of coils in one folded flow section,
It was found that there is a correlation between the average flow velocity of oil in the horizontal oilway in the diversion section and the temperature distribution of the coil. In other words, in order to obtain a naturally cooled induction coil with an averaged temperature distribution without local temperature rise of the coil, the oil in the horizontal oil channel should be adjusted to correspond to the number of coils between one flow section. It is necessary to adjust the average flow velocity of Therefore, in Preliminary Experiment 1, other factors related to oil circulation, such as the difference ΔH in center height between the disk winding 3 and the radiator 11, the thickness of the upper pipe 9 and the lower pipe 10, and the width dimension of the vertical oil passage, were also examined. By changing the conditions and selecting an average flow velocity of oil that matches the number of coils in the folded flow section, the coils will not become locally hot.

As a result of further various experiments, the present inventors found that
Whether or not a local temperature increase occurs in the coils within the diversion section is determined mainly by the number of coils in the diversion section and the average oil flow velocity (cm/sec) in the horizontal oilway within the diversion section. , heat flux density q on the surface of the coil
(W/m ² ). FIG. 7 is a characteristic diagram summarizing the experimental results. In other words, the number of coils in one fold section is 5.
Create disk windings of 10 disks (marked with squares in the figure), 10 disks (marked with triangles in the figure), and 15 disks (marked with circles in the figure). Experiments were conducted by varying the average flow velocity of oil on the road and the heat flux density q of the coil, and it was determined whether a local temperature increase occurred in the coil. In the figure, black marks indicate a disk winding with a local temperature rise, and white marks indicate a disk winding with no local temperature rise. Straight line A in the figure is a permissible limit line drawn based on this experimental result. When the number of coils in one fold section is 5 to 15, if the design is made to have a flow velocity higher than the average flow velocity on straight line A, the local part of the coil However, if the average flow velocity is lower than this and the flow rate is reduced below a certain value, a sudden local temperature rise will occur in the coil.

The relationship between the average flow velocity on the straight line A and the heat flux density q can be expressed as follows.

= 3.07×10 ^-4 q + 0.28 Therefore, in order to prevent the local temperature rise of the coil, the number of coils arranged in one fold section should be 5 to 5.
15, it is necessary to configure the average flow velocity of oil in the horizontal oilway to be expressed by the following equation (1').

≧3.07×10 ^-4 q+0.28 ... (1') In order to configure the average flow velocity of oil in the horizontal oilway as in the above equation (1'), for example, the disc winding 3 and the radiator 11 The difference in center height ΔH (third
(see figure), the thickness of the upper pipe 9 and the lower pipe 10, the width of the vertical oil passages 4 and 5, and other conditions related to oil circulation can be adjusted.

On the other hand, in a natural circulation state, the range of possible flow velocities is naturally limited, but in order to increase the flow velocity during natural circulation, it is necessary to increase the difference ΔH between the center heights of the disc winding and the radiator. , it is necessary to make structural adjustments such as increasing the thickness of the piping between the transformer body and the radiator, and increasing the width of the vertical oil passage of the winding. However, such structural adjustments to increase the flow velocity are changes in the direction of increasing the dimensions and weight of the transformer, and from this point of view, it is not economical to increase the average flow velocity. do not have.

Therefore, it is desirable that the average flow velocity be as low as possible without causing a local temperature rise in the coil. That is, by configuring the coil so that the average flow velocity is a value determined by the above equation (1), it is possible to prevent a local temperature rise in the coil and obtain an economical naturally cooled transformer winding.

FIG. 8 is a sectional view of a naturally cooled induction electric winding according to an embodiment of the present invention. In this embodiment, a plurality of folding plates 8 are inserted so that the number of coils in each folding section is eight, and the average flow velocity of oil in each horizontal oilway 2 satisfies the above formula (1). The positional relationship between the disc winding and the radiator, the thickness of the upper and lower piping that communicates the disc winding and the radiator, and the width dimensions of the inner vertical oil passage 4 and outer vertical oil passage 5 within the disc winding. etc. are designed.

Although this embodiment shows a case in which the number of coils in each folding area is equal, the number of coils, etc. in each folding area may be unequal. In this case as well, the average flow velocity of oil in each flow section must be designed to satisfy the above equation (1).

Note that the present invention can be applied to helical windings as well as disk windings.

As explained above, according to the present invention, it is possible to prevent a local temperature rise in the coil, greatly improve the cooling efficiency of the entire winding, and to keep the average oil flow velocity as low as possible. Therefore, the winding can be manufactured economically.

[Brief explanation of the drawing]

Figures 1 and 2 are longitudinal cross-sectional views of conventional naturally cooled transformer disk windings, Figure 3 is a temperature distribution diagram of oil and coil within one fold section of the winding, and Figure 4 5 is a schematic configuration diagram of a naturally cooled induction electric winding used in a preliminary experiment of the present invention, FIGS. 5 and 6 are temperature distribution diagrams of oil and coil obtained in the preliminary experiment, and FIG.
The figure is a characteristic diagram showing the presence or absence of a local temperature rise in the coil under various conditions, and FIG. 8 is a longitudinal cross-sectional view of a disk winding of a naturally cooled transformer according to an embodiment of the present invention. 1... Coil, 2... Horizontal oil pipe, 3... Disc winding, 4... Inner vertical oil pipe, 5... Outer vertical oil pipe,
6... Inner insulating tube, 7... Outer insulating tube, 8... Folded flow plate.

Claims (1)

[Claims] 1. A plurality of coils are stacked in the height direction via horizontal oil pipes to form a disc-shaped winding, and this disc-shaped winding is connected between an inner insulating cylinder and an outer insulating cylinder. The inner and outer vertical oil passages are formed between the disc-shaped winding wire and each insulating cylinder, and the inner and outer vertical oil passages are alternately arranged by folding plates arranged for each predetermined number of coils. When the width of the coil in the radial direction is L and the width of the horizontal oilway in the height direction is d, the dimensional ratio L/d of the two is 5 to 5. 35, the number of coils arranged in the one folded flow section is 5 to 15, and the average flow velocity (cm/sec) of oil flowing through the horizontal oil pipe is A naturally cooled induction electric winding characterized by being configured to satisfy the following formula (1). ≒3.07×10 ^-4 q+0.28 ...(1) However, in the formula, q is the heat flux density (W/m ² ) on the coil surface.