阅读说明：本技术 一种高压电缆护层保护器选取的方法及系统 (Method and system for selecting high-voltage cable sheath protector ) 是由 李振强 周姣 李晓岚 娄颖 何慧雯 范冕 王磊 李志军 查志鹏 万磊 于 2021-05-31 设计创作，主要内容包括：本申请公开了一种高压电缆护层保护器选取的方法及系统。其中,该方法包括：根据电缆护层的绝缘水平,确定保护器的雷电冲击残压U-(1)的范围和操作冲击残压U-(2)的范围；根据电缆护层的工频短时耐受电压U-(p),确定保护器的额定电压U-(r)的范围和额定电压U-(r)的上限值U-(rb)；根据电缆故障下护层的最大工频过电压U-(fp)和保护器的工频电压耐受能力,确定保护器的耐受工频电压值和保护器的时间；根据保护器的额定电压U-(r)的范围,保护器的工频耐受电压值和时间,保护器的雷电冲击残压U-(1)的范围和操作冲击残压U-(2)的范围,确定最终的保护器。(The application discloses a method and a system for selecting high-voltage cable sheath protectors. Wherein, the method comprises the following steps: determining lightning impulse residual voltage U of the protector according to the insulation level of the cable sheath 1 Range and operating impact residual voltage U 2 A range of (d); power frequency short-time withstand voltage U according to cable sheath p Determining the rated voltage U of the protector r Range and rated voltage U of r Upper limit value U of rb (ii) a Maximum power frequency overvoltage U of protective layer under cable fault fp Determining the power frequency voltage tolerance value of the protector and the time of the protector; according to the rated voltage U of the protector r The power frequency withstand voltage value and time of the protector, and the lightning impulse residual voltage U of the protector 1 Range and operating impact residual voltage U 2 Determines the final protector.)

1. A method for selecting a high-voltage cable sheath protector is characterized by comprising the following steps:

determining lightning impulse residual voltage U of the protector according to the insulation level of the cable sheath₁Range and operating impact residual voltage U₂A range of (d);

power frequency short-time withstand voltage U according to cable sheath_pDetermining the rated voltage U of the protector_rRange and rated voltage U of_rUpper limit value U of_rb；

Maximum power frequency overvoltage U of protective layer under cable fault_fpDetermining the power frequency voltage tolerance value of the protector and the time of the protector;

according to the rated voltage U of the protector_rThe power frequency withstand voltage value and time of the protector, and the lightning impulse residual voltage U of the protector₁Range and operating impact residual voltage U₂Determines the final protector.

2. Method according to claim 1, characterized in that the lightning impulse residual voltage U of the protector is determined according to the insulation level of the sheath₁Range and operating impact residual voltage U₂Including:

determining lightning impulse withstand voltage U of cable sheath_lDetermining the power frequency short-time withstand voltage U of the cable sheath_p；

According to the lightning impulse withstand voltage U_lDetermining residual voltage U of lightning impulse₁In the range of U₁<U_l/k_l，k_lWithstand voltage coefficient for lightning impulse;

according to the power frequency short-time withstand voltage U_pDetermining the operating impact residual voltage U₂In the range of U₂<2U_p/k_p，k_pTo operate the impulse withstand voltage coefficient.

3. The method of claim 1, wherein the short-time withstand voltage U is determined according to the power frequency of the sheath_pDetermining the rated voltage U of the protector_rIncluding:

power frequency short-time withstand voltage U according to cable sheath_pDetermining the rated voltage U of the protector_rThe range of (A) is as follows:

4. a system for selecting high-voltage cable sheath protectors is characterized in that,

the residual voltage determining module is used for determining the lightning impulse residual voltage U of the protector according to the insulation level of the cable sheath₁Example (A) ofEnclose and operate and strike residual pressure U₂A range of (d);

a module for determining rated voltage for short-time withstand voltage U according to power frequency of the cable sheath_pDetermining the rated voltage U of the protector_rRange and rated voltage U of_rUpper limit value U of_rb；

Determining a power frequency withstand voltage module for determining a maximum power frequency overvoltage U of the sheath under a cable fault_fpDetermining the power frequency voltage tolerance value of the protector and the time of the protector;

determining a protector module for determining the rated voltage U of the protector_rThe power frequency withstand voltage value and time of the protector, and the lightning impulse residual voltage U of the protector₁Range and operating impact residual voltage U₂Determines the final protector.

5. The system of claim 1, wherein the determine the impulse residual voltage module comprises:

the sub-module for determining the lightning impulse withstand voltage is used for determining the lightning impulse withstand voltage U of the cable sheath_l；

Submodule for determining power frequency short-time withstand voltage U of cable sheath_p；

A submodule for determining the lightning impulse withstand voltage coefficient and used for determining the lightning impulse withstand voltage U_lDetermining residual voltage U of lightning impulse₁In the range of U₁<U_l/k_l，k_lWithstand voltage coefficient for lightning impulse;

a submodule for determining the operation impact tolerance voltage coefficient and used for determining the power frequency short-time tolerance voltage U_pDetermining the operating impact residual voltage U₂In the range of U₂<2U_p/k_p，k_pTo operate the impulse withstand voltage coefficient.

6. The system of claim 1, wherein the determine nominal voltage module comprises:

a submodule for determining the rated voltage range and used for short-time withstand voltage U according to the power frequency of the cable sheath_pDetermining the rated voltage U of the protector_rThe range of (A) is as follows:

Technical Field

The application relates to the technical field of power transmission and transformation, in particular to a method and a system for selecting a high-voltage cable sheath protector.

Background

In order to reduce the overvoltage of the power cable sheath, it is common to provide the sheath with a voltage limiter, known as a "protector". In actual operation, damage of the sheath protector occurs sometimes, and improper selection of the protector is a main cause of damage. The main parameters of the sheath protector include: rated voltage, power frequency voltage tolerance capability (amplitude and time of power frequency voltage tolerance), impact residual voltage and the like. The existing standards (GB 50217 and 2018 power engineering cable design standards) specify the following selection of protector parameters:

1. the residual voltage of the sheath voltage limiter under the action of the possible maximum impact current is not more than the value of the impact withstand voltage of the cable sheath divided by 1.4;

2. under the action of maximum power frequency induced overvoltage generated during system short circuit, the sheath voltage limiter can tolerate within the possible long fault time, and the fault removal time is calculated according to 2 s;

3. the sheath limiter must not be damaged after the possible maximum inrush current has been cumulatively applied 20 times.

The problems with the above provisions are as follows:

1. there is no clear indication of whether the maximum inrush current is a lightning or operational impulse, or both. Even if the two are combined, the protection ranges of the protector for lightning and operation overvoltage are different, and the uniform adoption of the coefficient of 1.4 is not reasonable because the frequency of the lightning overvoltage is high, the protection range of the protector is small, and the protection range of the protector for operation overvoltage is large.

2. In practical application, the product of the sheath protector only marks the residual voltage of lightning impulse under 10kA of lightning current, and the operation impulse level is unknown. In practice, the sheath protector is damaged in a short-circuit fault, which is an operating shock, and the current of the operating shock is much less than 10 kA. In addition, in addition to the different magnitudes, the test waveforms for lightning and operational impacts were also very different, with a lightning front time of 8/20 μ s and an operational front time of 30/60 μ s. Therefore, it is necessary to distinguish the parameters of the two.

3. Only the maximum power frequency induced overvoltage and the duration time of the maximum power frequency induced overvoltage resistant protector are explained, the protector is safe at the moment, but the insulation of the protective layer can be endangered by the overhigh power frequency overvoltage, so that the protector can act to protect the insulation of the protective layer under the overhigh power frequency overvoltage.

In summary, the specifications regarding the selection of parameters for the sheath protector in the existing standards are not comprehensive and are not easy to implement. This is one of the main reasons for the frequent damage of the cable sheath protector in actual operation, and therefore, the parameter selection of the protector needs to be further clarified so as to make the parameter selection of the protector more reasonable.

Disclosure of Invention

The embodiment of the disclosure provides a method for selecting a high-voltage cable sheath protector, which is used for solving the technical problems that in the prior art, the regulations related to the parameter selection of the cable sheath protector are not complete and are not easy to implement in the existing standard, so that the cable sheath protector is frequently damaged in actual operation.

According to an aspect of the embodiments of the present disclosure, there is provided a method for selecting a high voltage cable sheath protector, including: determining lightning impulse residual voltage U of the protector according to the insulation level of the cable sheath₁Range and operating impact residual voltage U₂A range of (d); power frequency short-time withstand voltage U according to cable sheath_pDetermining the rated voltage U of the protector_rRange and rated voltage U of_rUpper limit value U of_rb(ii) a According to the cableMaximum power frequency overvoltage U of protective layer under fault_fpDetermining the power frequency voltage tolerance value of the protector and the time of the protector; according to the rated voltage U of the protector_rThe power frequency withstand voltage value and time of the protector, and the lightning impulse residual voltage U of the protector₁Range and operating impact residual voltage U₂Selecting the final protector.

According to another aspect of the embodiments of the present disclosure, there is also provided a system for selecting a high voltage cable sheath protector, including: the residual voltage determining module is used for determining the lightning impulse residual voltage U of the protector according to the insulation level of the cable sheath₁Range and operating impact residual voltage U₂A range of (d); a module for determining rated voltage for short-time withstand voltage U according to power frequency of the cable sheath_pDetermining the rated voltage U of the protector_rRange and rated voltage U of_rUpper limit value U of_rb(ii) a Determining a power frequency withstand voltage module for determining a maximum power frequency overvoltage U of the sheath under a cable fault_fpDetermining the power frequency voltage tolerance value of the protector and the time of the protector; according to the rated voltage U of the protector_rRange of (1), power frequency withstand voltage value and time of the protector, lightning impulse residual voltage U of the protector₁Range and operating impact residual voltage U₂Selecting the final protector.

In the invention, a method for selecting main parameters of rated voltage, power frequency withstand voltage, lightning impulse residual voltage, operation impulse residual voltage and the like of the cable sheath protector is determined, the lightning impulse residual voltage is provided, the requirements of the rated voltage and the operation impulse residual voltage of the protector are also provided, the defects of the existing standard are overcome, a selection basis and a quantization index are provided, a proper protector is easy to select, and the damage of the protector and the sheath layer caused by improper selection of the protector parameters can be avoided.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the disclosure and together with the description serve to explain the disclosure and not to limit the disclosure. In the drawings:

fig. 1 is a schematic flow chart illustrating a method for selecting a high voltage cable sheath protector according to an embodiment of the disclosure;

fig. 2 is a schematic diagram of a system for selecting a high voltage cable sheath protector according to an embodiment of the disclosure.

Detailed Description

The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for full and complete disclosure of the invention and to fully convey the scope of the invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.

Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In addition, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.

According to a first aspect of the present embodiment, a method 100 for selecting a high voltage cable sheath protector is provided. Referring to fig. 1, the method 100 includes:

s102, determining the lightning impulse residual voltage U of the protector according to the insulation level of the cable sheath₁Range and operating impact residual voltage U₂A range of (d);

s104, according to the power frequency short-time withstand voltage U of the cable sheath_pDetermining the rated voltage U of the protector_rRange and rated voltage U of_rUpper limit value U of_rb；

S106, according to the maximum power frequency overvoltage U of the protective layer under the cable fault_fpAnd the power frequency voltage tolerance of the protector, and determining the tolerance of the protectorReceiving the power frequency voltage value and the protector time;

and S108, selecting the final protector according to the range of the rated voltage Ur of the protector, the power frequency withstand voltage value and time of the protector, the range of the lightning impulse residual voltage U1 of the protector and the range of the operation impulse residual voltage U2 of the protector.

In particular, the rated lightning impulse withstand voltage U of a certain 220kV cable sheath_l47.5kV, and the power frequency short-time withstand voltage U of the protective layer_p15kV (1 min); and calculating to obtain the power frequency overvoltage U with the largest protective layer_fpIs 6 kV. The parameters of the sheath protectors are selected according to the existing standards and the present invention, and table 1 lists the main parameters of the protectors of different models.

According to the existing standard GB 50217 and 2018, lightning impulse residual voltage U of the sheath protector₁Not more than 47.5/1.4-33.9 kV; the sheath voltage protector can resist the maximum power frequency induced overvoltage for 6kV for not less than 2 s. Therefore, the protectors of LHQ-220II, III and IV in the table can be selected.

According to the invention, the sheath protector needs to satisfy:

(1) lightning impulse residual voltage U₁The voltage is not more than 47.5/1.4-33.9 kV, and the power frequency withstand voltage value of the protector is not less than 6kV for not less than 2 s; this is in accordance with current standard regulations.

(2) Rated voltage of protectorNamely U_r≤ 9.2kV；

(3) Operation impact residual voltage U of protector₂<2U_p/kp＝2×15/1.15＝26kV。

Therefore, LHQ-220II and III can be selected to meet the requirements, and the operation impact residual voltage is verified to be less than 26 kV.

Main parameter (kV) of cable metal sheath overvoltage limiter

Therefore, the method for selecting the main parameters of the cable sheath protector, such as rated voltage, power frequency withstand voltage, lightning impulse residual voltage, operation impulse residual voltage and the like, is clear, not only is the lightning impulse residual voltage available, but also the requirements of the rated voltage of the protector and the operation impulse residual voltage thereof are provided, the defects of the existing standard are overcome, the selection basis and the quantization index are provided, the proper protector is easy to select, and the damage to the protector and the sheath caused by improper selection of the protector parameters can be avoided.

Optionally, the lightning impulse residual voltage U of the protector is determined according to the insulation level of the sheath₁Range and operating impact residual voltage U₂Including: determining lightning impulse withstand voltage U of cable sheath_lDetermining the power frequency short-time withstand voltage U of the cable sheath_p(ii) a According to the lightning impulse withstand voltage U_lDetermining residual voltage U of lightning impulse₁In the range of U₁<U_l/k_l，k_lWithstand voltage coefficient for lightning impulse; according to the power frequency short-time withstand voltage U_pDetermining the operating impact residual voltage U₂In the range of U₂<2U_p/k_p，k_pTo operate the impulse withstand voltage coefficient.

Optionally, the power frequency short-time withstand voltage U according to the sheath_pDetermining the rated voltage U of the protector_rIncluding:

power frequency short-time withstand voltage U according to cable sheath_pDetermining the rated voltage U of the protector_rThe range of (A) is as follows:

therefore, the method for selecting the main parameters of the cable sheath protector, such as rated voltage, power frequency withstand voltage, lightning impulse residual voltage, operation impulse residual voltage and the like, is clear, not only is the lightning impulse residual voltage available, but also the requirements of the rated voltage of the protector and the operation impulse residual voltage thereof are provided, the defects of the existing standard are overcome, the selection basis and the quantization index are provided, the proper protector is easy to select, and the damage to the protector and the sheath caused by improper selection of the protector parameters can be avoided.

In accordance with another aspect of the present embodiment, a system 200 for selecting a high voltage cable sheath protector is also provided. Referring to fig. 2, the system 200 includes: a residual voltage determining module 210 for determining the lightning residual voltage U of the protector according to the insulation level of the cable sheath₁Range and operating impact residual voltage U₂A range of (d); a voltage rating module 220 for determining a power frequency short-time withstand voltage U according to the sheath_pDetermining the rated voltage U of the protector_rRange and rated voltage U of_rUpper limit value U of_rb(ii) a Determining power frequency voltage tolerance module 230 for determining maximum power frequency overvoltage U of the sheath under the cable fault_fpDetermining the power frequency voltage tolerance value of the protector and the time of the protector; a protector module 240 for determining the rated voltage U of the protector_rThe power frequency withstand voltage value and time of the protector, and the lightning impulse residual voltage U of the protector₁Range and operating impact residual voltage U₂Determines the final protector.

Optionally, the determining the residual impulse pressure module 210 includes: the sub-module for determining the lightning impulse withstand voltage U of the cable sheath_l(ii) a Submodule for determining power frequency short-time withstand voltage U of cable sheath_p(ii) a A submodule for determining the lightning impulse withstand voltage coefficient and used for determining the lightning impulse withstand voltage U_lDetermining residual voltage U of lightning impulse₁In the range of U₁<U_l/k_l， k_lWithstand voltage coefficient for lightning impulse; a submodule for determining the operation impact tolerance voltage coefficient and used for short-time tolerance voltage U according to the power frequency_pDetermining the operating impact residual voltage U₂In the range of U₂<2U_p/k_p，k_pTo operate the impulse withstand voltage coefficient.

Optionally, the determine nominal voltage module 220 includes: a submodule for determining rated voltage range and used for power frequency short-time tolerance according to the cable sheathUnder voltage U_pDetermining the rated voltage U of the protector_rThe range of (A) is as follows:

the system 200 for selecting a high voltage cable sheath protector according to an embodiment of the present invention corresponds to the method 100 for selecting a high voltage cable sheath protector according to another embodiment of the present invention, and is not described herein again.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein. The scheme in the embodiment of the application can be implemented by adopting various computer languages, such as object-oriented programming language Java and transliterated scripting language JavaScript.

The present application has been described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

While the preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including the preferred embodiment and all changes and modifications that fall within the scope of the present application.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.