CN107895609B - A method of increasing high voltage power cable service voltage type - Google Patents
A method of increasing high voltage power cable service voltage type Download PDFInfo
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- CN107895609B CN107895609B CN201711131094.6A CN201711131094A CN107895609B CN 107895609 B CN107895609 B CN 107895609B CN 201711131094 A CN201711131094 A CN 201711131094A CN 107895609 B CN107895609 B CN 107895609B
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- 238000000034 method Methods 0.000 title claims abstract description 12
- 239000002184 metal Substances 0.000 claims abstract description 69
- 239000004020 conductor Substances 0.000 claims abstract description 29
- 230000005540 biological transmission Effects 0.000 claims description 4
- 238000004364 calculation method Methods 0.000 claims description 4
- 230000015556 catabolic process Effects 0.000 claims description 2
- 238000010276 construction Methods 0.000 abstract description 5
- 239000000463 material Substances 0.000 abstract description 3
- 230000000694 effects Effects 0.000 abstract 1
- 230000005611 electricity Effects 0.000 abstract 1
- 230000005684 electric field Effects 0.000 description 3
- NMFHJNAPXOMSRX-PUPDPRJKSA-N [(1r)-3-(3,4-dimethoxyphenyl)-1-[3-(2-morpholin-4-ylethoxy)phenyl]propyl] (2s)-1-[(2s)-2-(3,4,5-trimethoxyphenyl)butanoyl]piperidine-2-carboxylate Chemical compound C([C@@H](OC(=O)[C@@H]1CCCCN1C(=O)[C@@H](CC)C=1C=C(OC)C(OC)=C(OC)C=1)C=1C=C(OCCN2CCOCC2)C=CC=1)CC1=CC=C(OC)C(OC)=C1 NMFHJNAPXOMSRX-PUPDPRJKSA-N 0.000 description 2
- 239000011810 insulating material Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 229920003020 cross-linked polyethylene Polymers 0.000 description 1
- 239000004703 cross-linked polyethylene Substances 0.000 description 1
- 238000009795 derivation Methods 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 239000004800 polyvinyl chloride Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B9/00—Power cables
- H01B9/02—Power cables with screens or conductive layers, e.g. for avoiding large potential gradients
- H01B9/028—Power cables with screens or conductive layers, e.g. for avoiding large potential gradients with screen grounding means, e.g. drain wires
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Abstract
A method of increasing high voltage power cable service voltage type.It include cylinder single high voltage power cable insulating layer inside radius be c position add a metal sleeve；The center of circle of the normal direction projection circle of metal sleeve is overlapped with the center of circle of conductor；Metal sleeve built in cylinder single high voltage power cable is connect by connecting terminal with low-voltage device in switchgear, as low-voltage alternating current power supply to low-voltage device power supply.Effect of the present invention: low-voltage alternating current power supply needed for low-voltage device directly draws from high-tension cable built-in metal casing and connects in switchgear, can simplify low-pressure system in original substation, saves the costs of equipment such as station local coordinate frame, low-voltage alternating-current screen；Control number of cables and its fee of material and operating expenses are greatly reduced, electricity transmitting and converting construction cost of investment is effectively reduced；Prevent to lead to the accident risk of low-voltage device power loss in switchgear because the low-tension supply in substation breaks down.
Description
Technical Field
The invention belongs to the technical field of power supply, and particularly relates to a method for increasing the supply voltage types of a high-voltage power cable.
Background
The currently common cylindrical single-core high-voltage power cable mainly comprises a conductor, an insulating layer and a grounding metal shielding layer, wherein the insulating layer is coated outside the conductor, and the grounding metal shielding layer is coated outside the insulating layer. However, such a conventional cylindrical single-core high-voltage power cable can only provide an operating voltage which determines the thickness of the insulating layer and is numerically proportional to the logarithm of the thickness of the insulating layer. For the switch cabinets arranged at two ends of a high-voltage power cable, power supplies required by various low-voltage devices in the switch cabinets cannot be directly supplied through the cable, and low-voltage power supplies in a transformer substation need to be led. This can cause two problems: firstly, secondary wiring in the transformer substation is complicated, and the investment cost is increased due to wiring materials and construction; if a low-voltage power supply in the transformer substation breaks down, all devices in the switch cabinet lose power, switch misoperation or switch failure is easily caused, the accident range is enlarged, and unnecessary loss is caused. National nets are therefore subject to huge losses almost every year.
Disclosure of Invention
In order to solve the above problems, an object of the present invention is to provide a method of increasing the kind of supply voltage of a high voltage power cable.
In order to achieve the above object, the present invention provides a method for increasing the kind of supply voltage of a high voltage power cable, comprising the following steps performed in sequence:
step 1) adding a metal sleeve at a position with a radius of c in an insulating layer of a cylindrical single-core high-voltage power cable consisting of the conductor, the insulating layer coated outside the conductor and a grounding metal shielding layer coated outside the insulating layer; the center of a normal projection circle of the metal sleeve coincides with the center of a conductor, and the voltage value between the metal sleeve and the grounding metal shielding layer can be changed by adjusting the radius c of the metal sleeve, so that the single cylindrical single-core high-voltage power cable can provide multiple voltages at the same time;
step 2) connecting a metal sleeve arranged in the cylindrical single-core high-voltage power cable with a low-voltage device in a switch cabinet through a wiring terminal, and supplying power to the low-voltage device as a low-voltage alternating-current power supply; the low-voltage device inside the switch cabinet at two ends is supplied with power through the built-in metal sleeve while the high-voltage power transmission requirement is met.
In step 1), the calculation formula of the radius c of the metal sleeve is as follows:
in the formula: u shape2: the voltage value between the metal sleeve and the grounding metal shielding layer is calculated according to the following formula:
Umax: the maximum working voltage between the conductor and the grounding metal shielding layer is calculated according to the following formula:
a: radius of conductor
b: radius of the grounded metal shield.
The method for increasing the supply voltage variety of the high-voltage power cable provided by the invention has the following beneficial effects:
firstly, a low-voltage alternating-current power supply required by a low-voltage device in a switch cabinet is directly led from a metal sleeve arranged in a high-voltage cable, so that an original low-voltage system in a transformer substation can be simplified, and the cost of equipment such as a transformer for the substation, a low-voltage alternating-current screen and the like is saved; the number of control cables, the material cost and the construction cost of the control cables are greatly reduced, and the construction investment cost of the power transmission and transformation project is effectively reduced;
and secondly, the accident risk of power loss of the low-voltage device in the switch cabinet caused by the fault of the low-voltage power supply in the transformer substation is avoided. Each cable supplies power independently, so that the accident that all substations are powered off due to the fault of a certain line cannot occur;
and thirdly, secondary wiring in the transformer substation is simplified, the wiring error rate is reduced, and the project construction progress is accelerated.
Drawings
Fig. 1 is a normal projection view of a cylindrical single-core high-voltage power cable to which the method for increasing the types of supply voltages of high-voltage power cables according to the present invention is applied.
In the figure: 1. the grounding metal shielding layer 2, the insulating layer 3, the conductor 4 and the built-in sleeve.
Detailed Description
The method for increasing the type of the supply voltage of the high-voltage power cable provided by the invention is described in detail below with reference to the accompanying drawings and specific embodiments.
The method for increasing the supply voltage variety of the high-voltage power cable comprises the following steps in sequence:
step 1) adding a metal sleeve 4 at a position with the radius of c in an insulating layer 2 of a cylindrical single-core high-voltage power cable which is composed of a conductor, an insulating layer coated outside the conductor and a grounding metal shielding layer coated outside the insulating layer and is shown in figure 1; the center of the normal projection circle of the metal sleeve 4 is coincident with the center of the conductor 3, and the distribution condition of the voltage extreme value in the insulating layer 2 can be changed by adjusting the radius c of the metal sleeve 4 under the premise of not changing the using amount of the insulating material, so that the cylindrical single-core high-voltage power cable can provide various voltages at the same time;
step 2), connecting a metal sleeve 4 arranged in the cylindrical single-core high-voltage power cable with a low-voltage device in a switch cabinet through a wiring terminal, and supplying power to the low-voltage device as a low-voltage alternating-current power supply; and when the high-voltage power transmission requirement is met, the low-voltage devices in the switch cabinets at two ends are supplied with power through the built-in metal sleeves 4.
In step 1), the radius c of the metal sleeve 4 is calculated as follows:
the following parameters were first set:
a: the radius of the conductor 3;
b: the radius of the grounded metal shield 1;
EM: breakdown electric field intensity of the insulating layer 2;
τ: the charge per unit length of the conductor 3;
epsilon: the dielectric constant of the insulating layer 2 is,
σb: the surface charge density of the inner surface of the grounding metal shielding layer 1;
c: the radius of the metal sleeve 4;
u: the voltage between the conductor 3 and the grounded metal shield layer 1;
U2: voltage between the metal sleeve 4 and the grounding metal shielding layer 1;
1.1) calculating the maximum working voltage of the inner conductor 3 of the cylindrical single-core high-voltage power cable when no metal sleeve is arranged:
the electric field strength of the conductor 3 at a radius r is:
wherein,is a unit direction vector whose direction is directed from the center of the conductor 3 to infinity.
The electric field strength extrema obtained at the edges of the conductor 3 are:
voltage between the conductor 3 and the grounded metal shield layer 1:
to make full use of the insulating material, make Emax＝EMThen, the maximum operating voltage between the conductor 3 and the grounded metal shielding layer 1 is:
1.2) calculating a voltage extreme value between the metal sleeve 4 and the grounding metal shielding layer 1 after the built-in metal sleeve 4 is built in:
the calculation formula of the voltage between the metal sleeve 4 and the grounding metal shielding layer 1 is as follows:
when r is c, the voltage value between the metal sleeve 4 and the grounded metal shielding layer 1 is:
from formula ⑥, U2The voltage value U between the metal sleeve 4 and the grounding metal shielding layer 1 can be changed by adjusting the radius c of the metal sleeve 4 only in relation to the radius c of the metal sleeve 42The numerical value of (c).
By derivation, the calculation formula for determining the radius c of the metal sleeve 4 is:
in the formula: u shape2: the voltage value between the metal sleeve 4 and the grounding metal shielding layer 1 is calculated according to the following formula:
Umax: the maximum operating voltage between the conductor 3 and the grounded metal shielding layer 1 is calculated as follows:
a: radius of conductor 3
b: radius of the grounded metal shield 1.
The following description will be given by taking an example of a copper-core crosslinked polyethylene insulated polyvinyl chloride sheath power cable YJV-35kV-1 × 50, in which the main parameters are that a is 4mm and b is 39mm, and the cable is obtained by formula ③:
assuming that the voltage required by the low-voltage device inside the switch cabinet is 220V, the voltage is obtained by equation ⑥:
in conclusion, a layer of metal sleeve 4 with the radius of 38.04mm is added in the insulating layer 2 of the cylindrical single-core high-voltage power cable, the metal sleeve 4 can provide 220V voltage, and the metal sleeve can be used by a low-voltage device in a switch cabinet after being connected through a busbar.
Claims (1)
1. A method of increasing the type of supply voltage of a high voltage power cable, characterized by: the method for increasing the supply voltage category of the high-voltage power cable comprises the following steps which are carried out in sequence:
step 1) adding a metal sleeve (4) at a position with an inner radius of c in an insulating layer (2) of a cylindrical single-core high-voltage power cable consisting of a conductor, an insulating layer coated outside the conductor and a grounding metal shielding layer coated outside the insulating layer; the center of a normal projection circle of the metal sleeve (4) coincides with the center of a conductor (3), and the voltage value between the metal sleeve (4) and the grounding metal shielding layer (1) can be changed by adjusting the radius c of the metal sleeve (4), so that a single cylindrical single-core high-voltage power cable can provide multiple voltages at the same time;
step 2), a metal sleeve (4) arranged in the cylindrical single-core high-voltage power cable is connected with a low-voltage device in a switch cabinet through a wiring terminal and used as a low-voltage alternating-current power supply to supply power to the low-voltage device; when the high-voltage power transmission requirement is met, the low-voltage devices in the switch cabinets at two ends are supplied with power through the built-in metal sleeves (4);
in the step 1), the calculation formula of the radius c of the metal sleeve (4) is as follows:
in the formula: u shape2: the voltage value between the metal sleeve (4) and the grounding metal shielding layer (1) is calculated according to the following formula:
τ: -the charge per unit length of the conductor (3);
epsilon: the dielectric constant of the insulating layer (2);
Umax: the maximum working voltage between the conductor (3) and the grounding metal shielding layer (1) is calculated according to the following formula:
a: radius of the conductor (3)
b: radius of the grounded metal shield (1)
EM: breakdown field strength of the insulating layer (2).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711131094.6A CN107895609B (en) | 2017-11-15 | 2017-11-15 | A method of increasing high voltage power cable service voltage type |
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| CN201711131094.6A CN107895609B (en) | 2017-11-15 | 2017-11-15 | A method of increasing high voltage power cable service voltage type |
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| Publication Number | Publication Date |
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| CN107895609A CN107895609A (en) | 2018-04-10 |
| CN107895609B true CN107895609B (en) | 2019-05-28 |
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105375376A (en) * | 2015-09-01 | 2016-03-02 | 上海大华电器设备有限公司 | Combined substation electrical switch cabinet |
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- 2017-11-15 CN CN201711131094.6A patent/CN107895609B/en active Active
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105375376A (en) * | 2015-09-01 | 2016-03-02 | 上海大华电器设备有限公司 | Combined substation electrical switch cabinet |
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