阅读说明：本技术 电缆温度检测装置、系统和方法 (Cable temperature detection device, system and method ) 是由 罗欣儿 于 2020-12-30 设计创作，主要内容包括：本申请涉及一种电缆温度检测装置、系统和方法。其中,电缆温度检测装置包括电压检测模组、电流检测模组和控制模组。电压检测模组设置于待测电缆,用于检测待测电缆的末端的谐波电压；电流检测模组设置于待测电缆的外侧,用于检测待测电缆的泄露电流；控制模组与电压检测模组和电流检测模组均连接,用于根据谐波电压和泄露电流,确定待测电缆的介电系数,并根据介电系数确定待测电缆的温度。本申请涉及的电缆温度检测装置通过不需要向待测电缆外加激励信息,能够提高对待测电缆的温度检测的准确性。(The application relates to a cable temperature detection device, system and method. Wherein, cable temperature-detecting device includes voltage detection module, current detection module and control module group. The voltage detection module is arranged on the cable to be detected and used for detecting the harmonic voltage at the tail end of the cable to be detected; the current detection module is arranged on the outer side of the cable to be detected and used for detecting leakage current of the cable to be detected; the control module is connected with the voltage detection module and the current detection module and used for determining the dielectric coefficient of the cable to be detected according to the harmonic voltage and the leakage current and determining the temperature of the cable to be detected according to the dielectric coefficient. The application relates to a cable temperature detection device can improve the accuracy of temperature detection of a cable to be detected by not adding excitation information to the cable to be detected.)

1. A cable temperature sensing device, comprising:

the voltage detection module is arranged on the cable to be detected and used for detecting the harmonic voltage at the tail end of the cable to be detected;

the current detection module is arranged on the outer side of the cable to be detected and used for detecting leakage current of the cable to be detected;

and the control module is connected with the voltage detection module and the current detection module and used for determining the dielectric coefficient of the cable to be detected according to the harmonic voltage and the leakage current and determining the temperature of the cable to be detected according to the dielectric coefficient.

2. The apparatus of claim 1, wherein the current detection module comprises:

the input end of the transconductance conversion circuit is connected with the outer side of the cable to be tested and is used for converting the leakage current into leakage voltage;

the voltage detection device is connected with the output end of the transconductance conversion circuit and is used for detecting the leakage voltage;

and the control device is connected with the voltage detection device and used for determining the leakage current according to the leakage voltage.

3. The apparatus of claim 2, wherein the transconductance conversion circuit comprises:

the first end of the resistor is connected with the outer side of the cable to be tested;

the first input end of the amplifying unit is connected with the first end of the resistor, the second input end of the amplifying unit is grounded, the output end of the amplifying unit is connected with the second end of the resistor, and the output end of the amplifying unit is connected with the voltage detection device.

4. The apparatus of claim 3, wherein the amplification unit is an operational amplifier.

5. The apparatus of claim 1, wherein the voltage detection module comprises a capacitive voltage divider.

6. A cable temperature sensing system, comprising:

the cable temperature detection device according to any one of claims 1 to 5;

and the control terminal is connected with the control module of the cable temperature detection device and used for receiving the temperature of the cable to be detected.

7. A method for detecting a temperature of a cable, comprising:

acquiring harmonic voltage of the tail end of the cable to be tested;

obtaining the leakage current of the cable to be tested;

determining the dielectric coefficient of the cable to be tested according to the harmonic voltage and the leakage current;

and determining the temperature of the cable to be tested according to the dielectric coefficient.

8. The method of claim 7, wherein said determining the temperature of the cable under test from the dielectric coefficient comprises:

acquiring a corresponding relation between a preset dielectric coefficient and a temperature value;

and determining the temperature value corresponding to the dielectric coefficient according to the corresponding relation to obtain the temperature of the cable to be measured.

9. The method of claim 7, wherein determining the dielectric coefficient of the cable under test from the harmonic voltage and the leakage current comprises:

determining an equivalent capacitance value of the cable to be tested according to the harmonic voltage and the leakage current;

and determining the dielectric coefficient of the cable to be tested according to the equivalent capacitance value of the cable to be tested.

10. The method of claim 7, wherein the obtaining the leakage current of the cable under test comprises:

acquiring leakage voltage of the cable to be detected;

determining the leakage current according to the leakage voltage.

Technical Field

The application relates to the technical field of electric power overhaul, in particular to a cable temperature detection device, system and method.

Background

With the development of urbanization and urban power grids, power cables have become the arteries of power transmission lines due to the advantages of no ground space occupation, reliable power supply, low possibility of electric shock, large distributed capacitance, maintenance workload and the like. The cable causes a temperature rise of the cable when the main insulation is aged or the load is large, and therefore, the detection of the temperature of the cable is very important.

In the conventional technology, the temperature of the cable is measured by an infrared temperature measurement technology, an optical fiber and photoelectronic technology or a distributed temperature measurement system utilizing the raman scattering principle. However, the temperature of the cable needs to be measured by an external excitation signal in the conventional technology, so that the measurement is inaccurate.

Disclosure of Invention

In view of the above, it is necessary to provide a cable temperature detection device, system and method.

In a first aspect, an embodiment of the present application provides a cable temperature detection apparatus, including:

the voltage detection module is arranged on the cable to be detected and used for detecting the harmonic voltage at the tail end of the cable to be detected;

the current detection module is arranged on the outer side of the cable to be detected and used for detecting leakage current of the cable to be detected;

and the control module is connected with the voltage detection module and the current detection module and used for determining the dielectric coefficient of the cable to be detected according to the harmonic voltage and the leakage current and determining the temperature of the cable to be detected according to the dielectric coefficient.

In one embodiment, the current detection module comprises:

the input end of the transconductance conversion circuit is connected with the outer side of the cable to be tested and used for converting leakage current into leakage voltage;

the voltage detection device is connected with the output end of the transconductance conversion circuit and used for detecting leakage voltage;

and the control device is connected with the voltage detection device and used for determining leakage current according to the leakage voltage.

In one embodiment, a transconductance conversion circuit includes:

the first end of the resistor is connected with the outer side of the cable to be tested;

and the first input end of the amplifying unit is connected with the first end of the resistor, the second input end of the amplifying unit is grounded, the output end of the amplifying unit is connected with the second end of the resistor, and the output end of the amplifying unit is connected with the voltage detection device.

In one embodiment, the amplifying unit is an operational amplifier.

In one embodiment, the voltage detection module includes a capacitive voltage divider.

In a second aspect, an embodiment of the present application provides a cable temperature detection system, including:

the cable temperature detection device provided in the above embodiment;

and the control terminal is connected with the control module of the cable temperature detection device and used for receiving the temperature of the cable to be detected.

In a third aspect, an embodiment of the present application further provides a cable temperature detection method, including:

acquiring harmonic voltage of the tail end of the cable to be tested;

acquiring leakage current of a cable to be detected;

determining the dielectric coefficient of the cable to be tested according to the harmonic voltage and the leakage current;

and determining the temperature of the cable to be measured according to the dielectric coefficient.

In one embodiment, determining the temperature of the cable under test based on the dielectric coefficient comprises:

acquiring a corresponding relation between a preset dielectric coefficient and a temperature value;

and determining a temperature value corresponding to the dielectric coefficient according to the corresponding relation to obtain the temperature of the cable to be measured.

In one embodiment, determining the dielectric coefficient of the cable to be tested according to the harmonic voltage and the leakage current comprises:

determining an equivalent capacitance value of the cable to be tested according to the harmonic voltage and the leakage current;

and determining the dielectric coefficient of the cable to be tested according to the equivalent capacitance value of the cable to be tested.

In one embodiment, obtaining the leakage current of the cable to be tested comprises:

acquiring leakage voltage of a cable to be detected;

the leakage current is determined from the leakage voltage.

The embodiment of the application provides a cable temperature detection device, a system and a method. The voltage detection module is arranged on the cable to be detected and used for detecting the harmonic voltage at the tail end of the cable to be detected; the current detection module is arranged on the outer side of the cable to be detected and used for detecting leakage current of the cable to be detected; the control module is connected with the voltage detection module and the current detection module and used for determining the dielectric coefficient of the cable to be detected according to the harmonic voltage and the leakage voltage and determining the temperature of the cable to be detected according to the dielectric coefficient. The cable temperature detection device provided by the embodiment of the application determines the dielectric coefficient of the cable to be detected by detecting the harmonic voltage and the leakage current generated when the cable to be detected runs, so that the temperature of the cable to be detected is determined. Therefore, excitation information does not need to be added to the cable to be detected, damage to the cable to be detected can be avoided, interference of external lines is avoided when the temperature of the cable to be detected is detected, and accuracy of temperature detection of the cable to be detected can be improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings needed to be used in the description of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without any creative work.

Fig. 1 is a schematic structural diagram of an equivalent circuit of a cable to be tested according to an embodiment of the present application;

fig. 2 is a schematic structural diagram of a cable temperature detection device according to an embodiment of the present application;

fig. 3 is a schematic structural diagram of a current detection module according to an embodiment of the present disclosure;

FIG. 4 is a schematic structural diagram of a cable temperature detection system according to an embodiment of the present application;

FIG. 5 is a schematic flow chart illustrating steps of a cable temperature detection method according to an embodiment of the present application;

FIG. 6 is a schematic flow chart illustrating steps of a cable temperature detection method according to an embodiment of the present application;

FIG. 7 is a schematic flow chart illustrating steps of a cable temperature detection method according to an embodiment of the present application;

fig. 8 is a schematic flowchart illustrating steps of a cable temperature detection method according to an embodiment of the present application.

Description of reference numerals:

10. a cable temperature detection device; 11. a cable to be tested; 20. a cable temperature detection system; 21. a control terminal; 100. a voltage detection module; 200. a current detection module; 210. a transconductance conversion circuit; 211. a resistance; 212. an amplifying unit; 220. a voltage detection device; 230. a control device; 300. a control module.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the present application are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is capable of embodiments in many different forms than those described herein and that modifications may be made by those skilled in the art without departing from the spirit and scope of the application, and it is therefore intended that this application not be limited to the particular embodiments disclosed below.

The following describes the technical solutions of the present application and how to solve the technical problems with the technical solutions of the present application in detail with specific embodiments. The following several specific embodiments may be combined with each other, and details of the same or similar concepts or processes may not be repeated in some embodiments. Embodiments of the present application will be described below with reference to the accompanying drawings.

The application provides a cable temperature monitoring device can set up in on-the-spot power cable ditch, detects the temperature of cable. According to the transmission line theory, a certain length of the cable line to be tested can be represented by a distributed parameter model. The cable to be tested can be assumed as n and infinitesimal length elements dx, and because the length elements dx are infinitesimal quantity, parameters can be concentrated in the range of the length elements, so that each length element can be abstracted into a lumped parameter circuit, and a chain circuit formed by cascading the lumped parameter circuits becomes a circuit model of the whole uniform cable to be tested. The structure of each lumped parameter circuit is shown in figure 1, R is singleThe method comprises the steps of measuring the equivalent resistance of a cable to be measured in a unit length, L is the equivalent inductance of the cable to be measured in the unit length, C is the equivalent capacitance of the cable to be measured in the unit length, V (x) represents the harmonic voltage of the head end of the cable to be measured in the unit length, and dV represents the variation of the harmonic voltage from the head end to the tail end of the cable to be measured in the unit length. From kirchhoff's voltage-current law, V ═ I (x) · (R + L), I₂(x)＝(V(x)+dV)·C，Wherein I (x) represents the current through the cable to be tested, I₂(x) Representing the harmonic current of the cable to be tested, namely the current passing through the equivalent capacitance of the cable to be tested, epsilon represents the dielectric coefficient of the cable to be tested, and r_sIndicating the inner radius, r, of the insulating layer of the cable to be tested_cRepresenting the inner radius of the core of the cable to be tested. According to the formula, the dielectric coefficient of the cable to be tested is irrelevant to the equivalent resistance and the equivalent inductance of the cable to be tested, and is only relevant to the equivalent capacitance of the cable to be tested. The temperature state of the cable to be measured is directly reflected on the dielectric coefficient. The cable temperature detection device 10 provided by the application can obtain the temperature of the cable to be detected by determining the dielectric coefficient of the cable to be detected.

Referring to fig. 2, an embodiment of the present application provides a cable temperature detecting apparatus 10, which includes a voltage detecting module 100, a current detecting module 200, and a control module 300. The voltage detection module 100 is disposed on the cable 11 to be detected, and is configured to detect a harmonic voltage at the end of the cable 11 to be detected. The cable 11 to be tested is a cable in the power cable trench, and the cable 11 to be tested includes a head end and a tail end. The first section and the tail end of the cable 11 to be tested can be determined according to the current transmission direction of the cable 11 to be tested, and the current is transmitted from the first end of the cable 11 to be tested to the second end of the cable 11 to be tested, so that the first end of the cable 11 to be tested is the head end of the cable 11 to be tested, and the second end of the cable 11 to be tested is the tail end of the cable 11 to be tested. The harmonic voltage is the voltage drop caused by the harmonic current and the impedance of the cable 11 under test. In an ideal situation, the ac power supply passing through the cable to be tested should have a pure sinusoidal waveform, but in a real application scenario, the waveform of the ac power supply is distorted due to the output impedance and the nonlinear load, so that harmonic current is generated. The voltage detection module 100 is disposed at the end of the cable 11 to be detected, so as to detect the harmonic voltage at the end of the cable 11 to be detected. The voltage detection module 100 may be a voltage sensor, a harmonic voltage sensor, or the like, and the present embodiment does not limit the kind, structure, and the like of the voltage detection module 100, as long as the function thereof can be achieved.

The current detection module 200 is disposed outside the cable 11 to be detected, and is configured to detect a leakage current of the cable 11 to be detected. The cable 11 to be tested typically comprises a core, an insulating layer, a shielding layer and a protective layer. Ideally, the cable 11 to be tested has no leakage current, but in practical application, no matter how much the material of the cable 11 to be tested is, the leakage current always exists. The current detection module 200 is arranged at the outer side of the cable 11 to be detected, and the current detection module 200 is arranged on the protective layer of the cable 11 to be detected, so that the current leaked from the cable 11 to be detected can be detected, and the leakage current of the cable 11 to be detected can be obtained. The current detection module 100 may be a current transformer or a rogowski coil current sensor, and the present embodiment does not limit the kind, structure, and the like of the current detection module 200, as long as the function thereof can be achieved.

The control module 300 is connected to the voltage detection module 100 and the current detection module 200, and is configured to determine the dielectric coefficient of the cable 11 to be detected according to the harmonic voltage and the leakage current, and determine the temperature of the cable 11 to be detected according to the dielectric coefficient. The control module 300 and the voltage detection module 100 may be connected by wire or wirelessly. Similarly, the control module 300 and the current detecting module 200 may be connected by wire or wirelessly. The connection manner between the control module 300 and the voltage detection module 100 and the current detection module 200 is not limited in this embodiment, as long as the transmission of signals between the control module 300 and the voltage detection module 100 and the current detection module 200 can be realized. The control module 300 may be a microprocessor chip or other device, and the present embodiment does not limit the kind and structure of the control module 300 as long as the functions thereof can be realized. In an alternative embodiment, the control module 300 may calculate an equivalent capacitance value of the cable 11 to be tested according to the harmonic voltage and the leakage current received to the cable 11 to be tested, and may determine the dielectric coefficient of the cable 11 to be tested according to the equivalent capacitance value. The dielectric coefficient of the cable 11 to be measured changes with the temperature, and the temperature of the cable 11 to be measured can be determined according to the dielectric coefficient of the cable 11 to be measured.

In an alternative embodiment, the memory of the control module 300 stores the corresponding relationship between the preset dielectric coefficients and the temperature values, i.e. one dielectric coefficient corresponds to one temperature value. After determining the dielectric coefficient of the cable 11 to be measured, the control module 300 traverses the preset dielectric coefficient in the memory, obtains the preset dielectric coefficient the same as the dielectric coefficient, obtains a temperature value corresponding to the preset dielectric coefficient, and determines the temperature value as the temperature of the cable 11 to be measured.

The working principle of the cable temperature detection device 10 provided by the embodiment of the application is as follows:

the user sets the voltage detection module 100 at the end of the cable 11 to be detected, and the harmonic voltage at the end of the cable 11 to be detected can be detected by the voltage detection module 100. The user sets up current detection module 200 in the outside of cable 11 that awaits measuring, can detect the leakage current of cable 11 that awaits measuring through current detection module 200. The control module 300 may determine the dielectric coefficient of the cable 11 to be tested according to the received harmonic voltage and the leakage current. The control module 300 can determine the temperature of the cable 11 to be measured according to the dielectric coefficient.

The cable temperature detection device 10 provided by the embodiment of the present application includes a voltage detection module 100, a current detection module 200 and a control module 300. The voltage detection module 100 is disposed on the cable 11 to be detected and is configured to detect a harmonic voltage at a tail end of the cable 11 to be detected; the current detection module 200 is disposed at an outer side of the cable 11 to be detected, and is configured to detect a leakage current of the cable 11 to be detected; the control module 300 is connected to both the voltage detection module 100 and the current detection module 200, and is configured to determine the dielectric coefficient of the cable 11 to be measured according to the harmonic voltage and the leakage current, and determine the temperature of the cable 11 to be measured according to the dielectric coefficient. The cable temperature detection device 10 provided by the embodiment of the application determines the dielectric coefficient of the cable 11 to be detected by detecting the harmonic voltage and the leakage current generated when the cable 11 to be detected runs, so as to determine the temperature of the cable 11 to be detected. Therefore, excitation information does not need to be added to the cable 11 to be detected, damage to the cable 11 to be detected can be avoided, interference of external circuits can be avoided when the temperature of the cable 11 to be detected is detected, and accuracy of temperature detection of the cable 11 to be detected can be improved. Meanwhile, the cable temperature detection device 10 provided by the embodiment of the application has the advantages of simple structure, easiness in installation, small occupied area and strong practicability.

Referring to fig. 3, in one embodiment, the current detection module 200 includes a transconductance conversion circuit 210, a voltage detection device 220, and a control device 230.

Transconductance conversion circuit 210 includes an input terminal and an output terminal. The input end of the transconductance conversion circuit 210 is connected to the outer side of the cable 11 to be tested, that is, the input end of the transconductance conversion circuit 210 is connected to the protection layer of the cable 11 to be tested. The transconductance conversion circuit 210 is configured to convert a leakage current of the cable 11 to be tested into a leakage voltage. The present embodiment does not set any limitation to the specific structure of the transconductance conversion circuit 210 as long as the function thereof can be achieved.

The voltage detection device 220 is connected to the output terminal of the transconductance conversion circuit 210, and is configured to detect a leakage voltage. Transconductance conversion circuit 210 converts the leakage current into a leakage voltage, which can be detected using voltage detection device 220. The voltage detection device 220 may be a voltage sensor or a voltage detection circuit, and the present embodiment does not limit the kind, structure, and the like of the voltage detection device 220 as long as the function thereof can be realized.

The control device 230 is connected to the voltage detection device 220 for determining a leakage current from the leakage voltage. The control device 230 and the voltage detection device 220 may be connected by wire or wirelessly. The present embodiment does not set any limitation on the connection manner between the control device 230 and the voltage detection device 220, as long as the leakage voltage detected by the voltage detection device 220 can be received. The control device 230 may be a microprocessor chip or a single chip, and the present embodiment does not limit the kind, structure, and the like of the control device 230, as long as the function thereof can be realized.

In the present embodiment, the transconductance conversion circuit 210 is used to convert the leakage current of the cable 11 to be tested into the leakage voltage that can be detected by the voltage detection device 220, and the control device 230 can leak the current according to the leakage voltage. Thus, the leakage current of the cable 11 to be detected can be detected more conveniently and accurately.

With continued reference to fig. 3, in one embodiment, the transconductance converting circuit 210 includes a resistor 211 and an amplifying unit 212. Resistor 211 includes a first terminal and a second terminal. The first end of the resistor 211 is connected to the outer side of the cable 11, that is, the first end of the resistor 211 is connected to the protection layer of the cable 11. The resistance of the resistor 211 is not limited in this embodiment, and the user can set the resistance according to the actual situation.

The amplifying unit 212 includes a first input terminal, a second input terminal, and an output terminal. A first input terminal of the amplifying unit 212 is connected to a first terminal of the resistor, a second input terminal of the amplifying unit 212 is grounded, an output terminal of the amplifying unit 212 is connected to a second terminal of the resistor 211, and an output terminal of the amplifying unit 212 is connected to the voltage detecting device 220. In other words, the amplifying unit 212 is connected in parallel with the resistor, and the voltage value of the resistor 211 can be obtained by detecting the voltage value of the amplifying unit 212. The leakage current of the cable 11 to be tested passes through the resistor 211, and the leakage current can be obtained according to the voltage value of the resistor 211 and the resistance value of the resistor 211. The present embodiment does not set any limit to the kind, structure, and the like of the amplifying unit 212 as long as the function thereof can be realized.

In an alternative embodiment, an oscilloscope may be used to connect to the output terminal of the amplifying unit 212, and the user may observe the leakage voltage of the cable 11 to be measured through the oscilloscope.

In one embodiment, the amplification unit 212 is an operational amplifier. An operational amplifier is a circuit unit having a very high amplification factor. The operational amplifier and the resistor 211 form a transconductance conversion circuit 210, which can realize the function of converting the leakage current into the leakage voltage. The output signal of the operational amplifier may be the result of a mathematical operation of adding, subtracting or differentiating, integrating, etc. the input signal. In this embodiment, the input signal of the operational amplifier is a leakage current, and a leakage voltage can be obtained through mathematical operation. The input bias current of the operational amplifier is small, so that a more accurate measurement result can be obtained, and more accurate leakage current can be obtained.

In one embodiment, the voltage detection module 100 includes a capacitive voltage divider. The capacitive voltage divider has high compressive strength and is not easy to break down, so that the voltage detection module 100 has higher reliability and practicability.

Referring to fig. 4, an embodiment of the present application provides a cable temperature detection system 20, which includes the cable temperature detection device 10 and the control terminal 21 provided in the above embodiment. The control terminal 21 is connected to the control module 300 in the cable temperature detecting device 10, and is configured to receive the temperature of the cable 11 to be measured. The control terminal 21 may be a computer device, which may be, but is not limited to, an industrial computer, a notebook computer, a smartphone, a tablet computer, a portable wearable device, and the like. The present embodiment does not set any limit to the kind of the control terminal 21 as long as the function thereof can be realized. Since the cable temperature detecting system 20 includes the cable temperature detecting device 10, the cable temperature detecting system 10 has all the structures and advantageous effects of the cable temperature detecting device 10. In this embodiment, the control terminal 21 may store the temperature of the cable 11 to be tested after receiving the temperature, and the worker may know whether the cable 11 to be tested has the insulation aging and other faults and the running state of the cable 11 to be tested by observing the temperature of the cable 11 to be tested.

In an optional embodiment, after receiving the temperature of the cable 11 to be tested, the control terminal 21 compares the temperature with a preset temperature threshold, and if the temperature is greater than the preset temperature threshold, it indicates that the temperature of the cable 11 to be tested is too high, and a safety accident is easy to occur, at this time, the control terminal 21 sends out warning information, so that a worker can timely maintain the cable 11 to be tested, and thus the safety of the cable 11 to be tested can be improved; if the temperature is lower than the preset temperature threshold, it indicates that the temperature of the cable 11 to be measured is normal, and the control terminal 21 only needs to store the temperature in the memory.

Referring to fig. 5, an embodiment of the present application provides a method for detecting a cable temperature, which is described by taking a control module 300 as an execution main body, and includes the following specific steps:

and step 100, obtaining the harmonic voltage at the tail end of the cable to be tested.

The harmonic voltage of the cable 11 to be tested can be detected in real time by using the voltage detection module 100. The voltage detection module 100 may transmit the detected harmonic voltage of the cable 11 to be detected to the control module 300, the control module 300 stores the received harmonic voltage in a memory, and the control module 300 may directly obtain the harmonic voltage in the memory when executing the cable temperature detection method. The specific description of the harmonic voltage and the end of the cable 11 to be tested can refer to the description of the above-mentioned embodiment of the cable temperature detection device 10, and will not be described herein again.

And 200, acquiring the leakage current of the cable to be detected.

The current detection module 200 can detect the leakage current of the cable 11 to be detected in real time. The current detection module 200 can transmit the detected leakage current of the cable 11 to be detected to the control module 300, the control module 300 stores the received leakage current in a memory, and the control module 300 can directly obtain the leakage current in the memory when executing the cable temperature detection method. For a detailed description of the leakage current of the cable 11 to be tested, reference may be made to the description of the above embodiment of the cable temperature detection device 10, and no further description is given here.

And step 300, determining the dielectric coefficient of the cable to be tested according to the harmonic voltage and the leakage current.

And step 400, determining the temperature of the cable to be measured according to the dielectric coefficient.

After obtaining the harmonic voltage at the end of the cable 11 to be measured and the leakage current of the cable 11 to be measured, the control module 300 calculates the dielectric coefficient of the cable 11 to be measured according to the harmonic voltage and the leakage current. If the temperature of the cable 11 to be measured changes and the dielectric coefficient of the cable 11 to be measured also changes, the control module 300 may determine the temperature of the cable 11 to be measured according to the dielectric coefficient of the cable 11 to be measured.

The cable temperature detection method provided by the embodiment of the application determines the dielectric coefficient of the cable 11 to be detected according to the harmonic voltage and the leakage voltage generated by the cable 11 to be detected, so as to determine the temperature of the cable 11 to be detected. The temperature of the cable 11 to be detected is directly determined according to the self-generated parameters of the cable 11 to be detected, an additional excitation signal is not needed, the accuracy of temperature detection of the cable 11 to be detected can be improved, and meanwhile, the cable 11 to be detected can be prevented from being damaged by the additional excitation signal.

Referring to fig. 6, in one embodiment, one possible implementation of the step 400 of determining the temperature of the cable to be tested according to the dielectric coefficient includes:

and step 410, acquiring a corresponding relation between a preset dielectric coefficient and a temperature value.

And step 420, determining a temperature value corresponding to the dielectric coefficient according to the corresponding relation, and obtaining the temperature of the cable to be measured.

The memory of the control module 300 stores a corresponding relationship between preset dielectric coefficients and temperature values in advance, that is, one preset dielectric coefficient corresponds to one temperature value. The pre-stored correspondence may be correspondence between different dielectric coefficients and temperature values of the cable 11 to be measured, which are obtained by a worker in advance according to a test. After obtaining the dielectric coefficient, the control module 300 may directly search the memory for the preset dielectric coefficient that is the same as the dielectric coefficient in a traversing manner, and determine the temperature value corresponding to the preset dielectric coefficient as the temperature of the cable 11 to be measured.

In this embodiment, the control module 300 determines the temperature corresponding to the dielectric coefficient rapidly through the pre-stored relationship between the dielectric coefficient and the temperature value, and both can determine the temperature of the cable 11 to be detected rapidly, so as to improve the efficiency of detecting the cable temperature.

Referring to fig. 7, one possible implementation of the step 300 of determining the dielectric constant of the cable to be tested according to the harmonic voltage and the leakage current includes:

and step 310, determining an equivalent capacitance value of the cable to be tested according to the harmonic voltage and the leakage current.

After receiving the harmonic voltage and the leakage current at the end of the cable 11 to be measured, the control module 300 may calculate the equivalent capacitance value of the cable 11 to be measured. Specifically, the control module 300 may be according to formula I₂＝V₂C calculating the equivalent capacitance value of the cable 11 to be measured, wherein I₂For leakage current, V, of the cable 11 to be tested₂Is the harmonic voltage at the end of the cable 11 to be measured, and C is the equivalent capacitance of the cable to be measured.

And 320, determining the dielectric coefficient of the cable to be tested according to the equivalent capacitance value of the cable to be tested.

After obtaining the equivalent capacitance value of the cable 11 to be measured, the control module 300 may obtain the dielectric coefficient of the cable 11 to be measured through calculation, specifically, the control module 300 may obtain the dielectric coefficient of the cable 11 to be measured according to a formulaCalculating the dielectric coefficient of the cable 11 to be measured, wherein epsilon represents the dielectric coefficient of the cable 11 to be measured, r_sRepresents the inner radius, r, of the insulating layer of the cable 11 to be tested_cRepresenting the inner radius of the core of the cable 11 to be tested.

Referring to fig. 8, one possible implementation manner of obtaining the leakage current of the cable to be tested in step 200 includes:

and step 210, obtaining the leakage voltage of the cable to be tested.

The leakage current of the cable 11 to be tested can be converted into the leakage voltage through the transconductance conversion circuit 210, and then the leakage voltage converted by the transconductance conversion circuit 210 can be detected by using the voltage detection device 220. For a detailed description of the transconductance conversion circuit 210 and the voltage detection device 220, reference may be made to the description of the above-mentioned embodiment of the cable temperature detection apparatus 10, and no further description is provided here.

Step 220, determining a leakage current according to the leakage voltage.

The control device 230 obtains the leakage voltage detected by the voltage detection device 220, and obtains the leakage current of the cable 11 to be tested according to the leakage voltage and the resistance value in the transconductance conversion circuit 210. The description of the control device 230 can refer to the description of the above-mentioned embodiment of the cable temperature detection apparatus 10, and will not be redundantly described here.

It should be understood that, although the steps in the flowcharts in the figures are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in a strict order unless explicitly stated herein, and may be performed in other orders. Moreover, at least some of the steps in the figures may include multiple sub-steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, and the order of performing the sub-steps or stages is not necessarily sequential, but may be performed alternately or in turns with other steps or at least some of the sub-steps or stages of other steps.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present application. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.