JPS58136219A - Power cable forcibly cooling facility - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to power cable equipment, and in particular to power cable forced cooling equipment configured to forcibly apply a cooling action in response to fluctuations in the energized load on the power cable. .

Conventionally, most of this type of power cable forced cooling equipment flows a refrigerant such as air, water, or oil in the longitudinal direction of the power cable inside, through, or outside, to reduce the heat generated when the power cable is energized. It is designed to remove directly or indirectly, and has the following drawbacks.

(1) Even if the refrigerant starts flowing, a cooling effect can be expected over the entire length only after the refrigerant reaches the exit or turning point, so there is a time delay before the desired cooling effect is achieved. This time delay depends on the length of the cooling section and the amount of refrigerant, but it takes from several minutes to several hours.

(2) Therefore, it is difficult to control the temperature, flow rate, etc. of the refrigerant in response to load fluctuations, and normally the power cable is operated so that the temperature is below the allowable temperature no matter when the maximum load is applied. Because of this necessity, the Kamikapuru system is always operated at a low temperature that allows for a margin above the maximum allowable temperature. In other words, more cooling than necessary is being performed.

(3) Refrigerators are also becoming larger and have a capacity that can handle continuous energization at maximum load.

For such refrigerators, since the energizing load is small during normal operation, low-efficiency operations such as small-capacity energizing operation or intermittent operation are performed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cooling method for a power cable that eliminates the above-mentioned drawbacks and can operate with a small capacity and high cooling efficiency.

The present invention provides power cable equipment that is configured to forcibly perform a cooling action in response to fluctuations in the energized load.
A heat storage body filled with a substance that maintains a solid state at normal energizing temperatures and melts at a pilot load energizing temperature is attached along the power cable.

Hereinafter, one embodiment of the present invention will be described based on the drawings. FIG. 1 is a cross-sectional view of a cooling equipment for a power cable according to the present invention, in which 1 is a trough, 2 is a power cable, 3 is a cooling pipe through which cooling water flows, 4 is a space inside the trough 1, and 5 is a tubular section. The heat storage body, 6 is a return pipe, and the cooling pipe 6 is configured so that a cooling effect is forcibly activated in response to fluctuations in the energizing load of the power cable 2.
Moreover, along the power cable 2, there is a heat storage body filled with ζ rough-in, which is a substance that maintains a solid state at normal energizing temperatures and melts at large load energizing temperatures. 5 is the attached equipment.

Hereinafter, this embodiment will be specifically explained in comparison with the conventional one. The conventional cables used for comparison here are as follows: (1) OF cables 2 of 275iv x 1600- are laid in three bales in an FRP disaster prevention trough, and the inner diameter is aOS+
Two cooling pipes 6 with a thickness of 8 cm are accommodated.

(2) The length of the cooling section is 2.5km1, and the cooling water inlet temperature is 10
°C, the secondary system generated loss is 2 w/cm.

(3) The depth of the tunnel is 20 m, the size is 6 m in diameter, and the wind cooling speed is 2 m/5ll IC.

(4) For power cable 203 line installation, inner diameter 15
Two return pipes 6 with a thickness of 15 mm are provided. (The state where the heat storage body 5 is not attached.) In the case of this comparative example, the normal maximum current carrying capacity of the power cable 2 is 460 MVA/act, the overload current carrying capacity is 1.5 times 680 MVA/cct, and the atmospheric temperature 3
When the temperature is assumed to be 2°C, the conductor temperature of the power cable 2 and the maximum temperature of the trough space 4 are as shown in FIG. In other words, the cooling water flow rate during normal energization is 2t/
-・cct also has a considerable margin of conductor temperature compared to the normal allowable temperature (assumed to be 85℃), but when overload current is applied,
Because the temperature significantly exceeds the short-term allowable temperature (assumed to be 95℃),
A cooling water flow rate of about 6 t/ec-CCt is required in order to maintain the temperature within the permissible range even if an overload energization state occurs.

On the other hand, in the embodiment of the present invention, paraffin (having a carbon number of 23 to
A tubular heat storage body 5 filled with methane-based hydrocarbon (57) is attached along the power cable 2.

That is, melting point 45°C to 65°C, heat of fusion 35, I C
at/71 specific gravity 0.9 t/CC (D paraffin, two heat storage bodies 5 filled in a pipe with an inner diameter of 80 m are attached.Then, the cooling water flow rate during normal energization is 2t/74m/a)
ct, the maximum temperature of the trough space 4 is 47°C, and if the paraffin in the heat storage body 5 has a melting point of 50°C, it maintains a solid state.

When the temperature in the sit trough space 4 exceeds 50° C. from this state to overload energization operation, the paraffin melts. The amount of heat stored for 5.2 of these heat storage tubes is 15506, r, z6n, and the amount of heat generated during normal energization per CCt is 0.960.
w/crIL, overload energization characteristic heat generation is 1.886vrA
Therefore, the temperature in the trough space 4 can be maintained at about 50° C. for about 14,680 seconds (about 41 hours). Therefore, the temperature of the conductor of the power cable 2 can be maintained at 90° C. or lower.

Therefore, as in this embodiment, the heat storage body 5 is connected to the power cable 2.
By attaching it along the line, a small flow rate of cooling water can be used to cope with overload energization.

That is, the change in the conductor temperature of the power cable 2 when the heat storage body 5 is used in combination with indirect cooling using only the cooling water in the trough space 4 is as shown in FIGS. 3 and 4.

The system shown in Fig. 3 is a case where the cooling water flow rate is kept constant even if the current load increases.The temperature in the trough space 4 increases as the current load increases, but in the conventional type, it is determined from the heat generated by the cable. On the other hand, in the heat storage body 5 combination type of this embodiment, the temperature reaches saturation at the melting temperature of the paraffin in the heat storage body 5, and there is no temperature change until all the paraffin melts. Figure 4 shows a case where the temperature rise in the trough space 4 due to an increase in the energized load is detected and the cooling water flow rate is increased.
Even in the conventional type, the maximum temperature of the trough space 4 is lower than that shown in FIG.

However, there is a certain time delay before the cooling water flow rate increases, and effective cooling of the entire length begins only after the cooling water reaches the turning point, so some overshoot in the temperature of the trough space 4 is unavoidable.

Therefore, since it is possible to maintain the temperature of the trough space 4 below a certain temperature by using the heat storage body 5 of this embodiment,
Efficient operation is possible without changing the flow rate of cooling water and without having to maintain a significantly low temperature during normal energization.

In indirect cooling in the trough, there is a temperature distribution in the longitudinal direction of the power cable, and the temperature is highest near the cooling turn point, and the cooling conditions are determined by the temperature at this part. Therefore, it is also effective to attach a heat storage body 5 along the power cable 2 in a part near the cooling water turning point.

Further, it can be used together with the heat storage body 5 inside the tunnel, and in this case, a material with a low melting point close to the permissible temperature inside the tunnel is suitable as the heat storage material.

Furthermore, it can be similarly used for naturally cooled power cables, and the shape of the heat storage body 5 is not limited to a tubular body.
Platy bodies, elongated bodies, and small-sized bodies can also be applied.

As explained above, according to the present invention, it is possible to provide electric cable equipment that has a small capacity and can be operated with high cooling efficiency, and can produce excellent industrial effects.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of the cooling equipment for a power cable according to an embodiment of the present invention, Figure 2 is a diagram showing the conductor temperature of the power cable and the maximum temperature in the trough space, and Figures 3 and 4 are diagrams showing cooling water. FIG. 4 is a diagram illustrating changes in the conductor temperature of the power cable when a heat storage body is used in combination with indirect cooling by cooling alone. 1 Nidraft, 2: Electric cable, 3: Cooling pipe, 4 Nidraft space, 5: Heat storage body, 6: Return pipe. -1 (T5's o 4-

Claims (1)

[Claims] 1. In a power cable facility configured to forcibly perform a cooling action in response to fluctuations in the energized load, the power cable along the power cable maintains a solid state at normal energizing temperatures, and when large loads are energized. An electric cable forced cooling equipment characterized by being attached with a heat storage body filled with a substance that melts at a temperature of