Low-voltage cable insulation fault positioning method and device

Abstract

The invention discloses a low-voltage cable insulation fault positioning method and device. The method comprises the following steps: S1, short-circuiting the tail end of a normal phase of a cable and the tail end of a fault phase of the cable; s2, measuring a resistance value Rs between the starting end of the normal phase of the cable and the starting end of the fault phase of the cable, a resistance value R1 of the starting end of the normal phase of the cable from the fault point to the ground, and a resistance value R2 of the starting end of the fault phase of the cable from the fault point to the ground; and S3, calculating the distance D between the fault point and the initial end of the fault phase of the cable according to a formula. Due to the adoption of the technical scheme, compared with the prior art, the insulation fault positioning of the low-voltage cable can be realized only by using the resistance measuring device, the cost is low, the operation is convenient and safe, and the cable cannot be damaged. Secondly, fault leakage resistance is measured twice in different directions through R1 and R2, and system errors can be eliminated to a certain extent by calculating time difference, so that the measurement precision is improved, and the positioning accuracy is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of cable faults, and in particular to a method and device for locating insulation faults in a low-voltage cable. Background Art

[0002] Low-voltage cables, a crucial component of power transmission, particularly those used in photovoltaic power plants, are often buried deep underground. Once an insulation failure occurs, locating the fault becomes a challenging task during repair. Traditional cable fault detection methods suffer from low efficiency and operational complexity, particularly in buried environments.

[0003] Currently, existing cable fault detection technologies include the DC impulse method (pulse method), the step voltage method, the acousto-magnetic synchronous method, and the Ostwald resin impregnation method. However, these methods have certain limitations in practice. For example, the DC impulse method is only applicable to newly laid cables. For buried cables, additional acousto-magnetic or acousto-magnetic asynchronous method testers are required for measurement and location, and a high-voltage generator is also required. This is not only costly but also inconvenient and unsafe to operate. The step voltage method and the acousto-magnetic synchronous method rely on specific signal detection and may not be accurate enough in environments with high ambient noise. Although the Ostwald resin impregnation method can reveal the location of insulation faults, as a destructive detection technology, its application is limited.

[0004] Therefore, it is urgent to develop a method and device for locating insulation faults that is low in cost, convenient and safe to operate, and does not damage the cable. Summary of the Invention

[0005] The present invention provides a low-voltage cable insulation fault locating method and device to solve the technical problems of existing cable fault detection technologies, such as high detection cost, inconvenient operation, unsafe operation, and certain detection technologies causing damage to the cable.

[0006] To achieve the above-mentioned purpose, the present invention adopts the following technical solutions.

[0007] In one aspect, a method for locating a low-voltage cable insulation fault is provided, comprising the following steps:

[0008] S1. Short-circuit the end of the normal phase of the cable with the end of the faulty phase of the cable;

[0009] S2. Electrically connect the two measuring ends of the resistance measuring device to the starting end of the normal phase of the cable and the starting end of the faulty phase of the cable, respectively, and measure the resistance value Rs between the starting end of the normal phase of the cable and the starting end of the faulty phase of the cable;

[0010] Connect one measuring end of the resistance measuring device to the starting end of the normal phase of the cable, and ground the other measuring end. Measure the resistance value R1 from the starting end of the normal phase of the cable to the ground through the fault point.

[0011] Connect one measuring end of the resistance measuring device to the starting end of the cable fault phase and the other measuring end to ground, and measure the resistance value R2 from the starting end of the cable fault phase through the fault point to the ground;

[0012] S3. Calculate the distance D between the fault point and the beginning of the cable fault phase according to the following formula:

[0013]

[0014] Where L is the length of the faulty phase of the cable.

[0015] The above method can locate low-voltage cable insulation faults using only a resistance measurement device. It is not only low-cost, convenient and safe to operate, but also harmless to the cable. Secondly, by measuring the fault leakage resistance of R1 and R2 twice in different directions, the difference in calculation time can eliminate systematic errors to a certain extent, thereby improving measurement accuracy and increasing positioning accuracy.

[0016] In some embodiments,

[0017] When measuring Rs, the resistance measuring device is set to the low resistance gear and its power supply voltage is set to the low voltage gear;

[0018] When measuring R1 and R2, the resistance measuring device is set to a high resistance position and its power supply voltage is set to a high voltage position.

[0019] The present invention further improves the measurement accuracy by setting different resistance gears and voltage gears for different resistors. For example, when measuring high resistance above the megohm level, since the current passing through the measured resistor is very weak, it is easily affected by thermal noise, leakage current and the bias current of the measurement system itself, resulting in measurement errors. The power supply voltage is set to a high voltage gear to increase the excitation voltage applied to both ends of the measured resistor, thereby significantly increasing the current value flowing through the resistor. The increase in current is conducive to improving the signal-to-noise ratio, reducing relative error, and reducing the dependence of micro-current measurement on instrument resolution, thereby effectively improving the accuracy and stability of the entire system under high resistance measurement.

[0020] In yet another aspect, there is provided a low-voltage cable insulation fault locating device comprising a DC power supply, a resistance measuring device, and a calculation unit;

[0021] The DC power supply is used to supply power to the resistance measuring device;

[0022] The resistance measuring device is used to obtain the resistance value between two measuring ends;

[0023] The calculation unit is used to calculate the distance D between the fault point and the starting end of the faulty phase of the cable according to the following formula:

[0024]

[0025] Among them, Rs is the resistance value between the starting end of the normal phase of the cable and the starting end of the fault phase of the cable, which is measured by electrically connecting the two measuring ends of the resistance measuring device to the starting end of the normal phase of the cable and the starting end of the fault phase of the cable respectively; R1 is the resistance value from the starting end of the normal phase of the cable to the ground through the fault point, which is measured by electrically connecting one measuring end of the resistance measuring device to the starting end of the normal phase of the cable and the other measuring end to the ground; R2 is the resistance value from the starting end of the fault phase of the cable to the ground through the fault point, which is measured by electrically connecting one measuring end of the resistance measuring device to the starting end of the fault phase of the cable and the other measuring end to the ground; L is the length of the fault phase of the cable.

[0026] In some embodiments, the resistance measuring device is configured to be switchable between a low resistance gear and a high resistance gear, and the DC power supply is configured to be switchable between a low voltage gear and a high voltage gear;

[0027] When measuring Rs, the resistance measuring device is set to the low resistance gear and its power supply voltage is set to the low voltage gear;

[0028] When measuring R1 and R2, the resistance measuring device is set to a high resistance position and its power supply voltage is set to a high voltage position.

[0029] On the other hand, a computer device is provided, comprising a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the above method.

[0030] On the other hand, a computer-readable storage medium is provided, on which a computer program / instruction is stored, and when the computer program / instruction is executed by a processor, the steps of the above method are implemented.

[0031] In another aspect, a computer program product is provided, comprising a computer program / instruction, the computer

[0032] When the program / instructions are executed by a processor, the steps of the above method are implemented.

[0033] The present invention has at least the following technical effects or advantages:

[0034] 1. The present invention can locate insulation faults of low-voltage cables using only a resistance measuring device, which is not only low-cost, convenient and safe to operate, but also does not cause damage to the cable.

[0035] 2. The present invention measures the fault leakage resistance twice in different directions of R1 and R2, and can eliminate the system error to a certain extent by making a difference in calculation, thereby improving the measurement accuracy and increasing the positioning accuracy.

[0036] 3. The present invention further improves measurement accuracy by setting different resistance levels and voltage levels for different resistors. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of electrical connections when measuring Rs using the positioning method of the present invention;

[0038] Figure 2 Schematic diagram of electrical connections when measuring R1 using the positioning method of the present invention;

[0039] Figure 3 Schematic diagram of electrical connections when measuring R2 using the positioning method of the present invention. DETAILED DESCRIPTION

[0040] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0041] Example 1

[0042] See also Figure 1-Figure 3 A method for locating insulation faults in low-voltage cables comprises the following steps:

[0043] S1. Short-circuit the end of the normal phase of the cable with the end of the faulty phase of the cable;

[0044] S2. Electrically connect the two measuring ends of the resistance measuring device to the start of the normal phase of the cable and the start of the faulty phase of the cable, respectively, and measure the resistance value Rs between the start of the normal phase of the cable and the start of the faulty phase of the cable; this achieves the measurement of the cable conductor resistance, which serves as the basis for the subsequent "length measurement";

[0045] One measuring end of the resistance measuring device is electrically connected to the starting end of the normal phase of the cable, and the other measuring end is grounded. The resistance value R1 from the starting end of the normal phase of the cable through the fault point to the ground is measured. This realizes the measurement of the resistance of the normal phase cable conductor to the far end of the fault phase + the fault leakage resistance.

[0046] One measuring end of the resistance measuring device is electrically connected to the starting end of the cable fault phase, and the other measuring end is grounded. The resistance value R2 from the starting end of the cable fault phase through the fault point to the ground is measured. This realizes the measurement of the fault phase near-end resistance + fault leakage resistance.

[0047] S3. Calculate the distance D between the fault point and the beginning of the cable fault phase according to the following formula:

[0048]

[0049] Where L is the length of the faulty phase of the cable.

[0050] The above method measures the fault leakage resistance of R1 and R2 twice in different directions, and then eliminates the system error to a certain extent by calculating the difference, thereby improving the measurement accuracy and increasing the positioning accuracy.

[0051] Furthermore, in order to further improve the measurement accuracy, when measuring Rs, the resistance measuring device is set to the low resistance gear (1mΩ-1Ω) and its power supply voltage is set to the low voltage gear (24V); when measuring R1 and R2, the resistance measuring device is set to the high resistance gear (1kΩ-10MΩ) and its power supply voltage is set to the high voltage gear (240V).

[0052] Example 2

[0053] A low-voltage cable insulation fault locating device comprises a DC power supply, a resistance measuring device and a calculation unit;

[0054] The DC power supply is used to power the resistance measuring device;

[0055] The resistance measuring device is used to obtain the resistance value between two measuring terminals;

[0056] The calculation unit is used to calculate the distance D between the fault point and the starting end of the cable fault phase according to the following formula:

[0057]

[0058] Among them, Rs is the resistance value between the starting end of the normal phase of the cable and the starting end of the fault phase of the cable, which is measured by electrically connecting the two measuring ends of the resistance measuring device to the starting end of the normal phase of the cable and the starting end of the fault phase of the cable respectively; R1 is the resistance value from the starting end of the normal phase of the cable to the ground through the fault point, which is measured by electrically connecting one measuring end of the resistance measuring device to the starting end of the normal phase of the cable and the other measuring end to the ground; R2 is the resistance value from the starting end of the fault phase of the cable to the ground through the fault point, which is measured by electrically connecting one measuring end of the resistance measuring device to the starting end of the fault phase of the cable and the other measuring end to the ground; L is the length of the fault phase of the cable.

[0059] Furthermore, the resistance measuring device is configured to be switchable between a low resistance gear and a high resistance gear, for example, a bridge device with adjustable bridge arm resistance can be used to achieve switching between the low resistance gear and the high resistance gear. The DC power supply is configured to be switchable between a low voltage gear and a high voltage gear.

[0060] When measuring Rs, set the resistance measuring device to the low resistance position (1mΩ-1Ω) and its power supply voltage to the low voltage position (24V); when measuring R1 and R2, set the resistance measuring device to the high resistance position (1kΩ-10MΩ) and its power supply voltage to the high voltage position (240V).

[0061] Example 3

[0062] A computer device includes a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the above method.

[0063] Example 4

[0064] A computer-readable storage medium having a computer program / instruction stored thereon.

[0065] When the instructions are executed by the processor, the steps of the above method are implemented.

[0066] Example 5

[0067] A computer program product comprises a computer program / instruction, which implements the steps of the above method when executed by a processor.

[0068] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures, and techniques are not shown in detail so as not to obscure the understanding of this description.

[0069] Similarly, it should be understood that in order to streamline the present disclosure and aid understanding of one or more of the various inventive aspects, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, this disclosed method should not be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in less than all the features of the individual embodiments disclosed above. Accordingly, the claims that follow the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of the invention.

[0070] Those skilled in the art will appreciate that the modules, units, or groups of devices in the examples disclosed herein may be arranged in the device described in the embodiment, or alternatively may be located in one or more devices different from the devices in the examples. The modules in the aforementioned examples may be combined into one module or further divided into multiple submodules.

[0071] It will be appreciated by those skilled in the art that the modules in the devices of the embodiments may be adaptively changed and arranged in one or more devices different from the embodiments. The modules or units or groups in the embodiments may be combined into one module or unit or group, and furthermore they may be divided into a plurality of submodules or subunits or subgroups. All features disclosed in this specification (including the accompanying claims, abstracts and drawings) and all processes or units of any method or device disclosed herein may be combined in any combination, except that at least some of such features and / or processes or units are mutually exclusive. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstracts and drawings) may be replaced by an alternative feature providing the same, equivalent or similar purpose.

[0072] Furthermore, those skilled in the art will appreciate that although some embodiments described herein include certain features and not other features included in other embodiments, the combination of features from different embodiments is intended to be within the scope of the invention and to form different embodiments.

[0073] In addition, some of the embodiments are described herein as methods or combinations of method elements that can be implemented by a processor of a computer system or by other devices that perform the functions described. Thus, a processor having the necessary instructions for implementing the method or method element forms a device for implementing the method or method element. Furthermore, the elements described herein of the device embodiments are examples of devices for implementing the functions performed by the elements for the purpose of implementing the invention.

[0074] The various techniques described herein may be implemented in conjunction with hardware or software, or a combination thereof. Thus, the methods and apparatus of the present invention, or certain aspects or portions of the methods and apparatus of the present invention, may take the form of program code (i.e., instructions) embedded in a tangible medium, such as a floppy disk, CD-ROM, hard drive, or any other machine-readable storage medium, wherein when the program is loaded into a machine such as a computer and executed by the machine, the machine becomes an apparatus for practicing the present invention.

[0075] When the program code is executed on a programmable computer, the computing device generally includes a processor, a storage medium readable by the processor (including volatile and non-volatile memory and / or storage elements), at least one input device, and at least one output device. The memory is configured to store the program code; the processor is configured to execute the method of the present invention according to the instructions in the program code stored in the memory.

[0076] By way of example and not limitation, computer-readable media include computer storage media and communication media. Computer-readable media include computer storage media and communication media. Computer storage media stores information such as computer-readable instructions, data structures, program modules, or other data. Communication media generally embodies computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and includes any information delivery media. Combinations of any of the above are also included within the scope of computer-readable media.

[0077] As used herein, unless otherwise specified, the use of ordinal numbers "first," "second," "third," etc. to describe common objects merely indicates that different instances of similar objects are involved and are not intended to imply that the objects so described must have a given order in time, space, ranking, or in any other manner.

[0078] Although the present invention has been described with respect to a limited number of embodiments, it will be apparent to those skilled in the art, having benefit of the foregoing description, that other embodiments are contemplated within the scope of the invention thus described. Furthermore, it should be noted that the language used in this specification has been selected primarily for readability and didactic purposes, rather than for the purpose of explaining or limiting the subject matter of the present invention. Consequently, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the present invention is intended to be illustrative rather than restrictive of the scope of the invention, which is defined by the appended claims.

[0079] Finally, it should be noted that the present invention does not explain in detail the common knowledge recognized by technicians in this field. The above is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for locating insulation faults in low-voltage cables, characterized in that: The method comprises the following steps: S1. Short-circuit the end of the normal phase of the cable with the end of the faulty phase of the cable; S2. Electrically connect the two measuring ends of the resistance measuring device to the starting end of the normal phase of the cable and the starting end of the faulty phase of the cable, respectively, and measure the resistance value Rs between the starting end of the normal phase of the cable and the starting end of the faulty phase of the cable; Connect one measuring end of the resistance measuring device to the starting end of the normal phase of the cable, and ground the other measuring end. Measure the resistance value R1 from the starting end of the normal phase of the cable to the ground through the fault point. Connect one measuring end of the resistance measuring device to the starting end of the cable fault phase and the other measuring end to ground, and measure the resistance value R2 from the starting end of the cable fault phase through the fault point to the ground; S3. Calculate the distance D between the fault point and the beginning of the cable fault phase according to the following formula: Where L is the length of the faulty phase of the cable.

2. The low-voltage cable insulation fault location method according to claim 1, characterized in that: When measuring Rs, the resistance measuring device is set to the low resistance gear and its power supply voltage is set to the low voltage gear; When measuring R1 and R2, the resistance measuring device is set to a high resistance position and its power supply voltage is set to a high voltage position.

3. A low-voltage cable insulation fault location device, characterized by: It includes a DC power supply, a resistance measuring device and a calculation unit; The DC power supply is used to supply power to the resistance measuring device; The resistance measuring device is used to obtain the resistance value between two measuring ends; The calculation unit is used to calculate the distance D between the fault point and the starting end of the cable fault phase according to the following formula: Among them, Rs is the resistance value between the starting end of the normal phase of the cable and the starting end of the fault phase of the cable, which is measured by electrically connecting the two measuring ends of the resistance measuring device to the starting end of the normal phase of the cable and the starting end of the fault phase of the cable respectively; R1 is the resistance value from the starting end of the normal phase of the cable to the ground through the fault point, which is measured by electrically connecting one measuring end of the resistance measuring device to the starting end of the normal phase of the cable and the other measuring end to the ground; R2 is the resistance value from the starting end of the fault phase of the cable to the ground through the fault point, which is measured by electrically connecting one measuring end of the resistance measuring device to the starting end of the fault phase of the cable and the other measuring end to the ground; L is the length of the fault phase of the cable.

4. The low-voltage cable insulation fault locating device according to claim 3, characterized in that: The resistance measuring device is configured to be switchable between a low resistance gear and a high resistance gear, and the DC power supply is configured to be switchable between a low voltage gear and a high voltage gear; When measuring Rs, the resistance measuring device is set to the low resistance gear and its power supply voltage is set to the low voltage gear; When measuring R1 and R2, the resistance measuring device is set to a high resistance position and its power supply voltage is set to a high voltage position.

5. A computer device comprising a memory, a processor, and a computer program stored in the memory, wherein: The processor executes the computer program to implement the steps of the method according to claim 1 or 2.

6. A computer-readable storage medium having a computer program / instruction stored thereon, characterized in that: When the computer program / instructions are executed by a processor, the steps of the method according to claim 1 or 2 are implemented.

7. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the steps of the method according to claim 1 or 2 are implemented.

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