A method and device for identifying broken strands of overhead conductors

Abstract

The present invention provides a method and device for identifying broken strands in an overhead conductor. The overhead conductor is twisted together by multiple strands of aluminum monofilaments / aluminum alloy monofilaments and multiple strands of steel monofilaments. The fault current of the overhead conductor is processed to obtain a first current spectrum. The first current spectrum is processed based on a pre-set spectrum line amplitude corresponding to a fault signal to obtain a spectrum containing the fault signal. If a spectrum corresponding to the set fault signal exists on the spectrum containing the fault signal, the overhead conductor is broken, thereby improving the ability to identify broken strands in the overhead conductor and having few limitations on identifying broken strands in the overhead conductor. The technical solution provided by the present invention can amplify the fault frequency of the current of the broken strand of the overhead conductor, can promptly detect fatigue broken strands of the overhead conductor, and avoid the overall breakage of the overhead conductor. The method can also be applied to real-time online monitoring of broken strands of the conductor due to breeze vibration, thereby avoiding serious damage to the transmission line.

Description

Technical Field

[0001] The present invention relates to the technical field of power transmission and distribution, and in particular to a method and device for identifying broken strands of overhead conductors. Background Art

[0002] In recent years, with the rapid construction of long-distance, high-capacity transmission lines, the safe operation of these lines has received considerable attention. Conductors within transmission lines are a crucial component in ensuring the safe operation of power systems. Because conductors operate outdoors for extended periods, they are often affected by natural conditions such as wind, rain, ice, snow, lightning, and other external factors, making them susceptible to various accidents. Wind-induced vibration is a common cause of these accidents, as wind forces conductors to be constantly in motion. Wind-induced vibration can be categorized into three types based on amplitude and frequency: breeze vibration, sub-span vibration, and galloping, with breeze vibration being the most frequent.

[0003] Breeze vibration poses a serious threat to the safe operation of China's overhead transmission lines, especially those with long spans. However, due to a lack of real-time vibration data, power companies are unable to accurately assess the vibration level of the conductors, assess their fatigue life, or predict the occurrence of fatigue accidents. Furthermore, after long-term operation, the parameters of vibration isolation devices change, weakening their vibration reduction performance, making accurate assessment difficult. This can cause strain values at certain clamping points on the conductors to exceed the specified value. The direct consequence of long-term excessive breeze vibration on conductors is fatigue damage and fatigue strand breakage. Once a strand breaks, the overall strength of the conductor decreases, potentially leading to a disconnection, posing a significant threat to the safe and stable operation of the power grid.

[0004] Transmission line inspections can effectively eliminate possible hidden dangers or losses and ensure the safe operation of the power grid. Traditional transmission line inspections are mainly carried out by staff going to the line site for manual visual inspections. The inspection efficiency is low, the labor intensity is high, and there are inspection blind spots. Especially for lines that cross mountains and rivers, the terrain is steep and the roads are rugged, which makes inspections difficult. Accidents of conductor strand breakage caused by breeze vibration fatigue are difficult to detect visually due to the high position of the conductors and the hidden form of damage, and hidden dangers cannot be eliminated in time. In response to this kind of inspection difficulty, inspections using GPS intelligent inspection instruments, helicopters, unmanned helicopters, intelligent inspection robots, etc. cannot detect overhead conductor fatigue breakage in time, that is, the ability to identify overhead conductor strand breakage is poor, resulting in overhead conductor breakage. In addition, none of the above inspection measures can achieve real-time online monitoring of conductor strand breakage accidents, and there are great limitations in identifying overhead conductor strand breakage. Summary of the Invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art in that the ability to identify broken overhead conductors is poor and the identification limitations are large, the present invention provides a method for identifying broken overhead conductors, wherein the overhead conductor is twisted together from multiple strands of aluminum monofilaments / aluminum alloy monofilaments and multiple strands of steel monofilaments; the fault current of the overhead conductor is processed to obtain a first current spectrum; the first current spectrum is processed based on a spectrum line amplitude corresponding to a preset fault signal to obtain a spectrum containing the fault signal; if the spectrum containing the fault signal contains a spectrum corresponding to a preset fault signal, the overhead conductor is broken, thereby improving the ability to identify broken overhead conductors and reducing the limitations on identifying broken overhead conductors.

[0006] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0007] In one aspect, the present invention provides a method for identifying broken strands in an overhead conductor, wherein the overhead conductor is formed by twisting multiple strands of aluminum monofilaments / aluminum alloy monofilaments and multiple strands of steel monofilaments; the method comprises:

[0008] Processing the fault current of the overhead conductor to obtain a first current spectrum;

[0009] Processing the first current spectrum based on a preset spectrum line amplitude corresponding to the fault signal to obtain a spectrum containing the fault signal;

[0010] If a spectrum line corresponding to the fault signal exists on the spectrum containing the fault signal, then the overhead wire is broken.

[0011] The processing of the fault current of the overhead conductor to obtain a first current spectrum includes:

[0012] Performing Fourier transform on the fault current of the overhead conductor to obtain a first current spectrum of the overhead conductor.

[0013] The step of processing the first current spectrum based on the first current spectrum with a spectrum line amplitude corresponding to a preset fault signal to obtain a spectrum containing the fault signal includes:

[0014] Taking the logarithm of the first current spectrum with the amplitude of the spectrum line corresponding to the preset fault signal as the base, to obtain a second current spectrum of the overhead conductor;

[0015] determining a third current spectrum of the overhead conductor based on the second current spectrum;

[0016] The spectrum line amplitude corresponding to the preset fault signal is the spectrum line amplitude corresponding to the current change in the first current spectrum when one strand of the aluminum monofilament / aluminum alloy monofilament is broken.

[0017] The determining of a third current spectrum of the overhead conductor based on the second current spectrum includes:

[0018] If the amplitude of the spectrum line on the second current spectrum is less than 0, the ordinate value corresponding to the spectrum line is set to 0; if the amplitude of the spectrum line on the second current spectrum is greater than 0, the ordinate value corresponding to the spectrum line is retained;

[0019] A third current spectrum amplitude of the overhead conductor is obtained based on the ordinate value corresponding to the spectrum line, and a third current spectrum is determined based on the third current spectrum amplitude.

[0020] The spectral line amplitude corresponding to the current change in the first current spectrum when one strand of the aluminum monofilament / aluminum alloy monofilament is broken based on the resistance of the aluminum monofilament / aluminum alloy monofilament is determined by the following formula:

[0021]

[0022] Where, f ΔI1 is the spectral line amplitude corresponding to the current change in the first current spectrum when one strand of aluminum monofilament / aluminum alloy monofilament is broken; N is the number of sampling points; ΔI1 is the current change when one strand of aluminum monofilament / aluminum alloy monofilament is broken in the overhead conductor, and R a is the electrical resistance of aluminum monofilament / aluminum alloy monofilament.

[0023] On the other hand, the present invention also provides a device for identifying broken strands of an overhead conductor, wherein the overhead conductor is formed by twisting multiple strands of aluminum monofilaments / aluminum alloy monofilaments and multiple strands of steel monofilaments; the device comprises:

[0024] A first processing module is used to process the fault current of the overhead conductor to obtain a first current spectrum;

[0025] A second processing module, configured to process the first current spectrum based on a preset spectrum line amplitude corresponding to a fault signal to obtain a spectrum containing the fault signal;

[0026] The identification module is used to determine whether there is a spectrum line corresponding to the fault signal on the spectrum containing the fault signal. If so, the overhead wire is broken.

[0027] The first processing module is specifically configured to:

[0028] Performing Fourier transform on the fault current of the overhead conductor to obtain a first current spectrum of the overhead conductor.

[0029] The second processing module includes:

[0030] a first determining unit, configured to take the logarithm of the first current spectrum with a preset spectrum line amplitude corresponding to the fault signal as a base to obtain a second current spectrum of the overhead conductor;

[0031] a second determining unit, configured to determine a third current spectrum of the overhead conductor based on the second current spectrum;

[0032] The spectral line amplitude corresponding to the preset fault signal is the spectral line amplitude corresponding to the current change in the first current spectrum when one strand of the aluminum monofilament / aluminum alloy monofilament is broken, which is determined by the following formula:

[0033]

[0034] Where, f ΔI1 is the spectral line amplitude corresponding to the current change in the first current spectrum when one strand of aluminum monofilament / aluminum alloy monofilament is broken; N is the number of sampling points; ΔI1 is the current change when one strand of aluminum monofilament / aluminum alloy monofilament is broken in the overhead conductor, and R a is the electrical resistance of aluminum monofilament / aluminum alloy monofilament.

[0035] The second determining unit is specifically configured to:

[0036] If the amplitude of the spectrum line on the second current spectrum is less than 0, the ordinate value corresponding to the spectrum line is set to 0; if the amplitude of the spectrum line on the second current spectrum is greater than 0, the ordinate value corresponding to the spectrum line is retained;

[0037] A third current spectrum amplitude of the overhead conductor is obtained based on the ordinate value corresponding to the spectrum line, and a third current spectrum is determined based on the third current spectrum amplitude.

[0038] Compared with the closest existing technology, the technical solution provided by the present invention has the following beneficial effects:

[0039] In the overhead conductor broken strand identification method provided by the present invention, the overhead conductor is twisted together from multiple strands of aluminum monofilaments / aluminum alloy monofilaments and multiple strands of steel monofilaments; the fault current of the overhead conductor is processed to obtain a first current spectrum; the first current spectrum is processed based on a preset spectrum line amplitude corresponding to a fault signal to obtain a spectrum containing the fault signal; if a spectrum corresponding to the preset fault signal exists on the spectrum containing the fault signal, the overhead conductor is broken, thereby improving the ability to identify broken overhead conductors and reducing the limitations of identifying broken overhead conductors;

[0040] The technical solution provided by the present invention can amplify the current fault frequency of overhead conductor broken strands, can timely detect fatigue broken strands of overhead conductors, avoid the overall breakage of overhead conductors, and can be applied to real-time online monitoring of conductor broken strands caused by breeze vibration, avoiding serious damage to transmission lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a flow chart of a method for identifying broken strands of overhead conductors according to an embodiment of the present invention;

[0042] Figure 2is a time domain diagram of a normal current signal of an overhead conductor in an embodiment of the present invention;

[0043] Figure 3 is a time domain diagram of a current variation signal of an overhead conductor in an embodiment of the present invention;

[0044] Figure 4 is a time domain diagram of an overhead conductor current signal containing a fault component in an embodiment of the present invention;

[0045] Figure 5 is a normal current spectrum diagram of an overhead conductor in an embodiment of the present invention;

[0046] Figure 6 is a spectrum diagram of current variation of an overhead conductor in an embodiment of the present invention;

[0047] Figure 7 is a Fourier spectrum diagram of the overhead conductor current containing a fault component in an embodiment of the present invention;

[0048] Figure 8 This is a new spectrum diagram of the overhead conductor current including the fault component in the embodiment of the present invention. DETAILED DESCRIPTION

[0049] The present invention will be described in further detail below with reference to the accompanying drawings.

[0050] Example 1

[0051] Embodiment 1 of the present invention provides a method for identifying broken strands of overhead conductors, the specific flow chart of which is as follows: Figure 1 The specific process is as follows:

[0052] S101: Processing the fault current of the overhead conductor to obtain a first current spectrum;

[0053] S102: Processing the first current spectrum based on a preset spectrum line amplitude corresponding to a fault signal to obtain a spectrum containing the fault signal;

[0054] S103: If a spectrum line corresponding to the fault signal exists on the spectrum containing the fault signal, then the overhead conductor is broken. The overhead conductor breakage refers to the breakage of aluminum monofilaments / aluminum alloy monofilaments in the overhead conductor, and the steel monofilaments will not be broken.

[0055] The overhead conductor is made of multiple strands of aluminum monofilament / aluminum alloy monofilament and multiple strands of steel monofilament. Considering the gaps between each strand and each layer, the resistance of the overhead conductor under ideal conditions is R 总 Expressed as:

[0056]

[0057] Among them, R a is the resistance of aluminum monofilament / aluminum alloy, Rs is the resistance of the steel monofilament, n a is the number of strands of aluminum monofilament / aluminum alloy monofilament, n s is the number of strands of steel monofilament.

[0058] Assuming that the voltage across the overhead conductor is unit voltage, the current I in the overhead conductor can be expressed as:

[0059]

[0060] Assume that x strands of aluminum monofilament / aluminum alloy monofilament in the overhead conductor are broken, the resistance of the overhead conductor is Then the current I′ in the overhead conductor is:

[0061]

[0062] When x strands of aluminum monofilament / aluminum alloy monofilament of overhead conductor are broken, the current change of overhead conductor satisfies I is B times ΔI, that is, because ρ s is the resistivity of the steel monofilament, ρ a is the resistivity of aluminum monofilament, L s is the length of the steel monofilament, L a is the length of the aluminum monofilament / aluminum alloy monofilament. The length of the steel monofilament is equal to the length of the aluminum monofilament / aluminum alloy monofilament, and both are equal to the length of the overhead conductor. s is the cross-sectional area of the steel monofilament, S a is the cross-sectional area of aluminum monofilament / aluminum alloy monofilament; thus Since ρ a / ρ s =0.29, so for overhead conductors made of multiple strands of steel monofilament and aluminum monofilament / aluminum alloy monofilament, For aluminum stranded wire / aluminum alloy stranded wire made of only aluminum monofilament / aluminum alloy monofilament, there are

[0063] In summary, if a single aluminum or aluminum alloy strand breaks on the outer surface of an overhead conductor, I will be several dozen times ΔI. If multiple strands break, the multiple will decrease accordingly. Therefore, in the early stages of a strand break, it is difficult to detect the potential for a break based on current changes.

[0064] When the current I0 containing the normal current I and the fault component is transformed into the frequency domain, the first current spectrum f of the overhead conductor is obtained. p1 The spectrum amplitudes corresponding to the current change ΔI when multiple strands of aluminum monofilaments / aluminum alloy monofilaments are broken in overhead conductors are both amplified by N / 2 times. Under the influence of the I spectrum line, the ΔI spectrum line is still difficult to distinguish. p1The spectral line amplitude corresponding to I is The spectral line amplitude corresponding to ΔI is

[0065] Processing the fault current of the overhead conductor to obtain a first current spectrum includes:

[0066] Perform Fourier transform on the fault current of the overhead conductor to obtain the first current spectrum f of the overhead conductor p1 .

[0067] Based on the first current spectrum, the first current spectrum is processed with a spectrum line amplitude corresponding to a preset fault signal to obtain a spectrum containing the fault signal, including:

[0068] The logarithm of the first current spectrum is taken with the amplitude of the spectrum line corresponding to the preset fault signal as the base to obtain the second current spectrum f of the overhead conductor. p2 ;

[0069] Based on the second current spectrum f p2 Determine the third current spectrum f of the overhead conductor p3 ;

[0070] The spectral line amplitude corresponding to the fault signal is preset to be the spectral line amplitude corresponding to the current change in the first current spectrum when one strand of the aluminum monofilament / aluminum alloy monofilament is broken, and is determined by the following formula:

[0071]

[0072] Where, f ΔI1 is the spectral line amplitude corresponding to the current change in the first current spectrum when one strand of aluminum monofilament / aluminum alloy monofilament is broken; N is the number of sampling points; ΔI1 is the current change when one strand of aluminum monofilament / aluminum alloy monofilament is broken in the overhead conductor, and R a is the electrical resistance of aluminum monofilament / aluminum alloy monofilament.

[0073] f p2 The spectral line amplitude corresponding to I is f I ,and f p2 The spectral line amplitude corresponding to ΔI is f ΔI ,and

[0074] Determining a third current spectrum of the overhead conductor based on the second current spectrum includes:

[0075] If the second current spectrum f p2 If the amplitude of the spectrum line on the current spectrum line is less than 0, the vertical coordinate value corresponding to the spectrum line is set to 0. If the second current spectrum f p2 If the amplitude of the spectrum line on is greater than 0, the vertical coordinate value corresponding to the spectrum line is retained;

[0076] The third current spectrum amplitude of the overhead conductor is obtained based on the vertical coordinate value corresponding to the spectrum line, and the third current spectrum f is determined based on the third current spectrum amplitude. p3 .

[0077] Example 2

[0078] Based on the same inventive concept, embodiment 2 of the present invention further provides an overhead conductor broken strand identification device, wherein the overhead conductor is formed by twisting multiple strands of aluminum monofilaments / aluminum alloy monofilaments and multiple strands of steel monofilaments. The functions of each component are described in detail below:

[0079] A first processing module is used to process the fault current of the overhead conductor to obtain a first current spectrum;

[0080] A second processing module is used to process the first current spectrum based on a preset spectrum line amplitude corresponding to the fault signal to obtain a spectrum containing the fault signal;

[0081] The identification module is used to determine whether there is a spectrum line corresponding to the fault signal on the spectrum containing the fault signal. If so, the overhead wire is broken.

[0082] The first processing module is specifically configured to:

[0083] Performing Fourier transform on the fault current of the overhead conductor to obtain a first current spectrum of the overhead conductor.

[0084] The second processing module is specifically configured to:

[0085] a first determining unit, configured to take the logarithm of the first current spectrum with a preset spectrum line amplitude corresponding to the fault signal as a base to obtain a second current spectrum of the overhead conductor;

[0086] a second determining unit, configured to determine a third current spectrum of the overhead conductor based on the second current spectrum;

[0087] The spectral line amplitude corresponding to the fault signal is preset as the spectral line amplitude corresponding to the current change in the first current spectrum when one strand of the aluminum monofilament / aluminum alloy monofilament is broken, which is determined by the following formula:

[0088]

[0089] Where, f ΔI1 is the spectral line amplitude corresponding to the current change in the first current spectrum when one strand of aluminum monofilament / aluminum alloy monofilament is broken; N is the number of sampling points; ΔI1 is the current change when one strand of aluminum monofilament / aluminum alloy monofilament is broken in the overhead conductor, and R a is the electrical resistance of aluminum monofilament / aluminum alloy monofilament.

[0090] The second determining unit is specifically configured to:

[0091] If the amplitude of the spectrum line on the second current spectrum is less than 0, the ordinate value corresponding to the spectrum line is set to 0; if the amplitude of the spectrum line on the second current spectrum is greater than 0, the ordinate value corresponding to the spectrum line is retained;

[0092] A third current spectrum amplitude of the overhead conductor is obtained based on the ordinate value corresponding to the spectrum line, and a third current spectrum is determined based on the third current spectrum amplitude.

[0093] Example 3

[0094] In the method for identifying broken strands of overhead conductors provided in Example 3 of the present invention, taking the JL / G1A-400 / 35-48 / 7 conductor as an example: the diameter of the aluminum monofilament is d a =3.22mm, steel monofilament diameter d s =2.5mm, aluminum resistivity ρ a =2.85×10 -8 Ω·m, steel resistivity ρ s =9.78×10 -8 Ω·m. Assuming the voltage across the overhead conductor is 1V, the overhead conductor is 35.2m long, and one aluminum monofilament breaks, we have:

[0095]

[0096]

[0097]

[0098] The power frequency (50Hz) current flowing through the conductor normally, if a conductor strand breaks and there is a 30Hz breeze vibration, the vibration signal sampling frequency is 512Hz, then there will be the following Figure 2 and Figure 3 The 50Hz and 30Hz signals shown (the corresponding spectrum is as Figure 5 and Figure 6 As shown, they are named x1(t) and x2(t) signals respectively), and the two signals are superimposed to form Figure 4 The third signal x3(t) is obtained from the time domain signal and the traditional Fourier transform spectrum (such as Figure 7 The broken strand fault feature cannot be seen in the image (shown). The superimposed signal is processed as follows:

[0099] (1) Perform Fourier transform on the superimposed signal x3(t) and find its spectrum.

[0100] (2) Take the logarithm of the spectrum to form a new spectrum;

[0101] (3) Perform a positive operation on the new spectrum.

[0102] Get as Figure 8 The spectrum of each signal shown is Figure 8 MF spectrum and Figure 5 The power frequency signal shown in Figure 6 The spectrum of the fault signal shown in . Figure 8 The new spectrum of x3(t) can easily show the broken strand fault frequency component (30Hz) and its multiple frequency components (60Hz, 90Hz, ...), thereby determining that the overhead wire has broken strands.

[0103] For the convenience of description, the various parts of the above-mentioned device are divided into various modules or units according to their functions and described separately. Of course, when implementing this application, the functions of each module or unit can be implemented in the same or multiple software or hardware.

[0104] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0105] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0106] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0107] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Ordinary technicians in the relevant field can still modify or replace the specific implementation methods of the present invention with equivalents by referring to the above embodiments. Any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are within the scope of protection of the claims of the present invention to be approved.

Claims

1. A method for identifying broken strands in an overhead conductor, wherein the overhead conductor is formed by twisting multiple strands of aluminum monofilaments / aluminum alloy monofilaments and multiple strands of steel monofilaments; characterized in that: The method comprises: Processing the fault current of the overhead conductor to obtain a first current spectrum; Processing the first current spectrum based on a preset spectrum line amplitude corresponding to the fault signal to obtain a spectrum containing the fault signal; If a spectrum line corresponding to the fault signal exists on the spectrum containing the fault signal, then the overhead wire is broken; The processing of the first current spectrum based on the preset spectrum line amplitude corresponding to the fault signal to obtain a spectrum containing the fault signal includes: Taking the logarithm of the first current spectrum with the amplitude of the spectrum line corresponding to the preset fault signal as the base, to obtain a second current spectrum of the overhead conductor; determining a third current spectrum of the overhead conductor based on the second current spectrum; The spectral line amplitude corresponding to the preset fault signal is the spectral line amplitude corresponding to the current change in the first current spectrum when one strand of the aluminum monofilament / aluminum alloy monofilament is broken; The spectral line amplitude corresponding to the current variation in the first fault current spectrum when one strand of the aluminum monofilament / aluminum alloy monofilament is broken is determined by the following formula: Where, f ΔI1 is the spectral line amplitude corresponding to the current change in the first current spectrum when one strand of aluminum monofilament / aluminum alloy monofilament is broken; N is the number of sampling points; ΔI1 is the current change when one strand of aluminum monofilament / aluminum alloy monofilament is broken in the overhead conductor, and R a is the electrical resistance of aluminum monofilament / aluminum alloy monofilament.

2. The method for identifying broken overhead conductor strands according to claim 1, wherein: The processing of the fault current of the overhead conductor to obtain a first current spectrum includes: Performing Fourier transform on the fault current of the overhead conductor to obtain a first current spectrum of the overhead conductor.

3. The method for identifying broken overhead conductor strands according to claim 1, wherein: The determining of a third current spectrum of the overhead conductor based on the second current spectrum includes: If the amplitude of the spectrum line on the second current spectrum is less than 0, the ordinate value corresponding to the spectrum line is set to 0; if the amplitude of the spectrum line on the second current spectrum is greater than 0, the ordinate value corresponding to the spectrum line is retained; A third current spectrum amplitude of the overhead conductor is obtained based on the ordinate value corresponding to the spectrum line, and a third current spectrum is determined based on the third current spectrum amplitude.

4. A device for identifying broken strands of an overhead conductor, wherein the overhead conductor is formed by twisting multiple strands of aluminum monofilaments / aluminum alloy monofilaments and multiple strands of steel monofilaments; characterized in that: The device comprises: A first processing module is used to process the fault current of the overhead conductor to obtain a first current spectrum; A second processing module, configured to process the first current spectrum based on a preset spectrum line amplitude corresponding to a fault signal to obtain a spectrum containing the fault signal; an identification module, configured to determine whether a spectrum line corresponding to the fault signal exists on the spectrum containing the fault signal, and if so, a strand of the overhead wire is broken; The second processing module includes: a first determining unit, configured to take the logarithm of the first current spectrum with a preset spectrum line amplitude corresponding to the fault signal as a base to obtain a second current spectrum of the overhead conductor; a second determining unit, configured to determine a third current spectrum of the overhead conductor based on the second current spectrum; The spectral line amplitude corresponding to the preset fault signal is the spectral line amplitude corresponding to the current change in the first current spectrum when one strand of the aluminum monofilament / aluminum alloy monofilament is broken, which is determined by the following formula: Where, f ΔI1 is the spectral line amplitude corresponding to the current change in the first current spectrum when one strand of aluminum monofilament / aluminum alloy monofilament is broken; N is the number of sampling points; ΔI1 is the current change when one strand of aluminum monofilament / aluminum alloy monofilament is broken in the overhead conductor, and R a is the resistance of aluminum monofilament / aluminum alloy monofilament; The first determining unit is specifically configured to: The second current spectrum of the overhead conductor is obtained by taking the spectrum line amplitude corresponding to the current change in the first current spectrum when one strand of the aluminum monofilament / aluminum alloy monofilament is broken as the base and taking the logarithm of the first current spectrum.

5. The overhead conductor broken strand identification device according to claim 4, characterized in that: The first processing module is specifically configured to: Performing Fourier transform on the fault current of the overhead conductor to obtain a first current spectrum of the overhead conductor.

6. The overhead conductor broken strand identification device according to claim 4, characterized in that: The second determining unit is specifically configured to: If the amplitude of the spectrum line on the second current spectrum is less than 0, the ordinate value corresponding to the spectrum line is set to 0; if the amplitude of the spectrum line on the second current spectrum is greater than 0, the ordinate value corresponding to the spectrum line is retained; A third current spectrum amplitude of the overhead conductor is obtained based on the ordinate value corresponding to the spectrum line, and a third current spectrum is determined based on the third current spectrum amplitude.

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