JPH07336855A - Method and device for cooling power cable in duct - Google Patents

Abstract

PURPOSE:To more efficiently cool power cables to improve their transmission capacities and, at the same time, to easily lay the power cables. CONSTITUTION:A cooling water hose 6 which can expand and through which a coolant can flow is inserted into the space 5 between the inner peripheral surface 1a of a duct 1 and the outer peripheral surfaces 2a of power cables 2 in the duct 1 in which the power cables 2 are laid. Then the inserted hose 6 is expanded. As a result, the hose 6 expands to fill up the space 5 and the surface of the hose 6 presses the internal peripheral surface 1a of the duct 1 and outer peripheral surfaces 2a of the cables 2. Finally, the hose 6 closely adheres to the outer peripheral surfaces 2a of the cables 2. In addition, the cross section of the hollow section 7 of the hose 6 in the direction perpendicular to the length direction of the hose 6 becomes larger. While the hose 6 closely adheres to the cables 2, the cables 2 are cooled with cooling water flowing through the hose 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for improving the transmission capacity of a power cable drawn from a substation, for example, by applying it to a place where the power cable is laid in an underground conduit which is already connected to a manhole. The present invention relates to a method and an apparatus for cooling a power cable in a pipeline, which is suitable for effectively recovering the amount of heat generated by the cable.

[0002]

2. Description of the Related Art In order to increase the power transmission capacity of a power cable, it is necessary to increase the voltage and the current, and there are methods such as reducing the generated loss and adopting a cooling method for increasing the current. The first way to reduce the generated loss is to reduce the AC effective resistance by reducing the conductor loss by increasing the size of the conductor. However, there is a limitation in adopting a large conductor power cable in order to improve the transmission capacity. That is, for example, when laying a power cable in an underground pipe,
From the relationship between the drawing tension and the lateral pressure, as shown in FIG.
The outer diameter d of the power cable 2 with respect to the diameter D (inner diameter) is designed under the condition of d <D-30 (mm), as shown in FIG. Therefore, in general, the pipeline inner diameter of the substation lead-out portion is 6.6 (k) when the cable outer diameter is 95 (mm) in the SVP pipe (impact-resistant vinyl chloride pipe) of 130 (mm).
V) 3 × 500 (mm ² ) CVT (Triplex type cross-linked polyethylene insulated vinyl sheath cable) is laid. From the above design conditions, 6.6 kV, 3
A CVT of × 600 (mm ² ) has an outer diameter of 104 (mm) and is not laid.

In adopting a cooling method for improving the power transmission capacity, a method of circulating cooling water is generally known. When this method is adopted, the cooling water can be flowed by (1) a method of filling the entire inside of the conduit 1 with the cooling water 3 and circulating the cooling water 3 (shown in FIG. 4). (2) Insert a cooling pipe 4 made of plastic or vinyl having a circular cross-section with a fixed inner diameter of a hollow portion through which cooling water circulates into the pipe line 1 along the power cable 2 to cool the cooling pipe 4. A method of filling and circulating water 3 (shown in FIG. 5). Etc. have been adopted.

[0004]

By the way, the above (1)
The method (1) has an advantage that the cooling effect is large because a large cross section of flowing water can circulate a large amount of cooling water 3. However, when trying to adopt this method for existing pipelines,
The existing pipeline often has poor water-tightness, and there is a high risk of water leaking to the outside of the pipeline, which causes a problem that it is impossible to circulate and cool the water.

In addition, the method of (2) above, the cooling pipe 4
There is usually no problem with the airtightness of water, and it is possible to circulate water in the existing pipeline. However, in this method, since the cooling pipe 4 is passed through a narrow space, the diameter of the cooling pipe 4 that can be inserted is limited, so that the cooling effect is poor,
Furthermore, since the insertion length is also limited, the cooling length is shortened and the cooling efficiency is low, which is a problem.

The present invention has been made in order to solve the above-mentioned conventional problems. Cooling of the power cable in the pipeline which can improve the transmission capacity because the cooling efficiency of the power cable can be improved and can be easily installed. It is an object to provide a method and a device.

[0007]

In order to achieve the above-mentioned object, the present invention has the following constitution. That is, the invention of claim 1 is a method for cooling a power cable laid in a pipeline with a cooling medium, wherein the power cable is laid between the inner peripheral surface of the pipeline and the outer peripheral surface of the power cable. The step of inserting a pipe material capable of expansion and internal circulation of the cooling medium, the step of expanding the inserted pipe material to bring the pipe material into close contact with the outer peripheral surface of the power cable, and the cooling medium to flow inside the closely attached pipe material to generate power. And a step of cooling the cable.

According to a second aspect of the present invention, in an apparatus for cooling a power cable laid in a pipeline with a cooling medium, the inner peripheral surface of the pipeline and the outer peripheral surface of the power cable in the state where the power cable is laid. A pipe material that is located in a flat state between the pipe material and the pipe material that allows expansion and internal circulation of the cooling medium, and an internal pressure is applied to the inserted pipe material to expand it and bring the tube material into close contact with the outer peripheral surface of the power cable. And a cooling unit for cooling a power cable by circulating a cooling medium inside a closely adhered pipe material.

[0009]

In general, in the method of cooling by circulating a cooling medium such as cooling water, the following measures can be considered to improve the cooling efficiency. (1) To increase the cross-sectional area of the passage through which the cooling medium flows. (2) The contact area between the power medium, which is a heat source, and the cooling medium is large. On the other hand, when the cooling pipe is drawn into the narrow space between the existing power cable and the inner peripheral surface of the pipeline, the smaller the contact area with the cable, the better in order to reduce the frictional resistance.

The inventor has made the present invention as a result of various consideration of the above points. In the present invention, a pipe material that allows expansion and internal circulation of the cooling medium is inserted between the inner peripheral surface of the conduit in which the power cable is laid and the outer peripheral surface of the power cable. Since this inserted pipe material expands, before expansion, the hollow part is crushed and folded into a flat state in which the cross section perpendicular to the longitudinal direction of the pipe is small (for example, the external shape becomes a band shape). , Can be inserted between the inner peripheral surface of the conduit and the outer peripheral surface of the power cable. Therefore, the pipe material in this state has a small contact area with the power cable when it is inserted into the pipeline and has a small friction resistance, so that it can be easily pulled into the pipeline, and the insertion work can be smoothly performed with a small amount of labor. You can Therefore, it is suitable for laying long sections.

Further, the inserted pipe material is expanded by applying an internal pressure to its hollow with, for example, a gas body or a liquid. As a result, the vertical cross section of the hollow pipe in the longitudinal direction becomes large, and a large amount of cooling medium can be circulated in the hollow. Further, since the pipe material is brought into close contact with the outer peripheral surface of the power cable, the contact area with the power cable is increased and the thermal resistance can be reduced.
Therefore, good heat transfer from the power cable to the cooling medium is achieved. Therefore, when the cooling medium (cooling liquid such as cooling water or cooling oil, cooling gas) is circulated in the closely adhered pipe material to cool the power cable, a large flow rate of the cooling medium can be obtained and the thermal resistance can be improved. Since it is reduced, heat can be efficiently recovered.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. 1 and 2 are a cross-sectional view and a perspective view of a procedure explanatory diagram of a method for cooling a power cable according to an embodiment of the present invention. 1 and 2, the same parts as those in FIGS. 3 to 5 are designated by the same reference numerals and the description thereof is omitted. Further, the conduit 1 shows the edge of the inner peripheral surface 1a, and the power cable 2 does not have its internal structure.

First, the inner peripheral surface 1a of the conduit 1 and the outer peripheral surface 2 of the power cable 2 in the conduit 1 in which the power cable 2 is installed.
A flexible cooling water (example of cooling medium) hose or tube (hereinafter simply referred to as cooling water hose: example of pipe material) 6 capable of expansion and internal circulation of the cooling medium is inserted into a space 5 between a and a. To do. The details of this insertion are shown in FIG.
As shown in FIG. 2, the hollow portion 7 of the cooling water hose 6 is crushed so that the cross section of the hose 6 perpendicular to the longitudinal direction of the conduit 1 has a small flat state, for example, the appearance has a strip plate shape. The cooling water hose 6 is inserted into the space 5 after being folded. Therefore, the cooling water hose 6 is connected to the conduit 1
It is easy to pull it in, and the insertion work can be done smoothly with little effort. The cooling water is an example of the cooling medium, and the case where other cooling oil or cooling gas is used as the cooling medium is also included in the present invention. Further, the cooling water hose 6 may be made of, for example, airtight elastic rubber or plastic rubber.

Next, the inserted cooling water hose 6 is expanded. This expansion is performed by applying an internal pressure to the cooling water hose 6 by a pump (corresponding to an internal pressure applying section) 8 or the like with a liquid such as a gas body or water. And the cooling water hose 6
As it expands, it expands so as to fill the space 5 and the surface of the cooling water hose 6 presses the inner peripheral surface 1a of the conduit 1 and the outer peripheral surface 2a of the power cable 2 and fits into them. Finally, as shown in FIG. 1 (b), the cooling water hose 6 is in close contact with the outer peripheral surface 2a of the power cable 2. Further, the hollow portion 7 has a large vertical cross section in the longitudinal direction of the conduit.

Next, as described above, cooling water is filled in the cooling water hose 6 that is in close contact with the power cable 2, and this cooling water is circulated to cool the power cable. This cooling water takes away heat from the power cable once and the temperature rises,
The heat goes to the external heat exchanger 9, where the heat is taken away and the temperature drops, and the heat is circulated again to the cooling water hose 6 for circulation for cooling. As mentioned above, since the hollow portion 7 is large,
The cooling water hose 6 allows a large amount of cooling water to flow therein for effective cooling. Further, since the cooling water hose 6 is in close contact with the power cable, the contact area with the power cable is large and the thermal resistance can be reduced. Therefore, the heat conduction from the power cable 2 to the cooling water 3 is made good.

Therefore, according to this embodiment, when the cooling water 3 is circulated in the cooling water hose 6 which is in close contact with the power cable 2 to cool the power cable 2, a large flow rate of the cooling water 3 can be obtained. Moreover, since the thermal resistance is reduced, the heat can be efficiently recovered.

[0017]

As described above, according to the present invention, the adhesion between the power cable and the cooling medium distribution pipe material can be increased and a large amount of the cooling medium can be flown into the hollow, so that the cooling efficiency of the power cable is increased. Therefore, the transmission capacity can be improved. In addition, the cooling medium distribution pipe material has a free shape when installed,
For example, since the outer shape can be folded into a strip shape, it can be easily drawn into the pipeline, and is suitable for laying long sections.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining a procedure of a method for cooling a power cable according to an embodiment of the present invention.

FIG. 2 is a perspective view for explaining one procedure of the embodiment.

FIG. 3 is a diagram illustrating the conventional installation of a power cable in a pipeline.

FIG. 4 is an explanatory diagram of an example of a conventional cooling method for a power cable in a pipeline.

FIG. 5 is an explanatory diagram of another example of a conventional cooling method for a power cable in a pipeline.

[Explanation of symbols]

 1 Pipe Line 1a Pipe Inner Surface 2 Power Cable 2a Power Cable Outer Surface 3 Cooling Water 5 Space 6 Cooling Water Hose 7 Hollow Portion 8 Internal Pressure Applying Port 9 Heat Exchanger

Claims (2)

[Claims] 1. A method of cooling a power cable laid in a pipeline with a cooling medium, wherein an expansion and a cooling medium are provided between an inner peripheral surface of the pipeline in which the power cable is laid and an outer peripheral surface of the power cable. The step of inserting a pipe material capable of internal circulation, the step of expanding the inserted pipe material to bring the pipe material into close contact with the outer peripheral surface of the power cable, and the cooling medium being circulated inside the closely attached pipe material to cool the power cable. A method of cooling an in-pipe power cable, comprising: 2. A device for cooling a power cable laid in a pipeline with a cooling medium, wherein a flat state is provided between the inner peripheral surface of the pipeline and the outer peripheral surface of the power cable in the state where the power cable is laid. A pipe material that is capable of expansion and internal circulation of a cooling medium, an internal pressure applying section that applies an internal pressure to the inserted pipe material and expands it to bring the pipe material into close contact with the outer peripheral surface of the power cable, and the inside of the close contact pipe material And a cooling unit for circulating a cooling medium to cool the power cable.