High-voltage live cable identification method and system based on mixed signal

Abstract

The application discloses a high-voltage live cable identification method and system based on a mixed signal, and belongs to the technical field of cable detection. The method comprises the following steps: collecting a signal of a cable to be identified based on an electromagnetic induction principle to obtain an electric signal; the electric signal comprises a double-frequency signal and a power frequency noise signal; performing analog-digital conversion on the electric signal to obtain a digital signal; processing the digital signal based on a phase-sensitive detection technology to extract an amplitude and a phase of a target double-frequency signal; and completing cable identification based on the amplitude and the phase of the target double-frequency signal. The method can solve the problem that a traditional cable identification device cannot accurately identify a cable when noise interference is strong, and can improve identification accuracy and identification efficiency.

Description

Technical Field

[0001] This invention belongs to the field of cable testing technology, specifically relating to a method and system for identifying high-voltage live cables based on mixed-frequency signals. Background Technology

[0002] Currently, power grids widely use underground cables to transmit electrical energy. Accurately identifying the target cable during routine inspections or emergency repairs is a crucial aspect of cable engineering. Misidentification during this process can lead to significant economic losses and seriously threaten personal safety. Furthermore, in many cases, power systems require continuous power supply and cannot be easily interrupted. Incorrect cable identification can cause system disruptions, affecting production, services, and daily life.

[0003] Live-line identification means that signal detection must be carried out under strong electromagnetic interference. However, under extreme conditions such as strong power frequency interference near cables, the intensity of power frequency interference can often reach tens of times or even higher than the intensity of normal identification signals, making it difficult to pick up signals. Ordinary power outage cable identification equipment cannot work properly or may even be damaged. This brings great safety risks to cable inspection, maintenance, and survey work and affects work efficiency.

[0004] Currently, the most commonly used method for identifying live cables is the dual-frequency modulation method. Specifically, the signal transmitter couples the dual-frequency signal to the outer shielding layer of the cable at the cable's beginning using coupling clamps. At the cable identification point, a current sensor detects the changes in the magnetic field generated by different cables, thereby analyzing the phase difference of the current waveform in the cable to identify the target cable. The extraction of the dual-frequency signal currently mainly involves filtering out noise signals using bandpass filters. However, under strong electromagnetic interference, the amplitude of power frequency interference is large, and the frequency difference between power frequency harmonic noise and the target signal is small, making it difficult to achieve a good filtering effect, thus affecting the efficiency and accuracy of cable identification. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, this invention provides a method and system for identifying high-voltage live cables based on mixed-frequency signals. The technical problem to be solved by this invention is achieved through the following technical solution:

[0006] In a first aspect, the present invention proposes a method for identifying high-voltage live cables based on mixed-frequency signals, comprising:

[0007] The signal of the cable to be identified is acquired based on the principle of electromagnetic induction to obtain an electrical signal; the electrical signal includes a dual-frequency signal for identification and a power frequency noise signal.

[0008] The electrical signal is converted from analog to digital to obtain a digital signal;

[0009] The digital signal is processed using phase-sensitive detection technology to extract the amplitude and phase of the target dual-frequency signal.

[0010] Cable identification is performed based on the amplitude and phase of the target dual-frequency signal.

[0011] Secondly, this invention proposes a high-voltage live cable identification system based on a mixed-frequency signal, used to implement the method proposed in the first aspect of this invention. The system includes a signal acquisition module, an analog-to-digital conversion module, a signal extraction module, and a cable identification module; wherein...

[0012] The signal acquisition module is equipped with a current sensor, which is used to acquire signals from the cable to be identified based on the principle of electromagnetic induction, and obtain electrical signals; the electrical signals include dual-frequency signals for identification and power frequency noise signals;

[0013] The analog-to-digital converter module is used to perform analog-to-digital conversion on electrical signals to obtain digital signals;

[0014] The signal extraction module and the cable identification module are integrated in the microprocessor; the signal extraction module is used to process digital signals based on phase-sensitive detection technology to extract the amplitude and phase of the target dual-frequency signal respectively;

[0015] The cable identification module is used to identify cables based on the amplitude and phase of the target dual-frequency signal.

[0016] The beneficial effects of this invention are:

[0017] 1. The high-voltage live cable identification method based on mixed-frequency signals proposed in this invention first acquires signals from the cable to be identified, obtaining electrical signals including dual-frequency signals for identification and power frequency noise signals; then, the electrical signals are converted into digital signals, and phase-sensitive detection technology is used to extract the amplitude and phase of the target dual-frequency signal from the digital signals; finally, cable identification is achieved based on the extracted amplitude and phase of the dual-frequency signal. This method can accurately and efficiently extract the target signal from signals with extremely low signal-to-noise ratio in strong power frequency magnetic field interference environments during live cable identification, and perform accurate cable identification.

[0018] 2. The high-voltage live cable identification method based on mixed-frequency signal proposed in this invention only needs to construct a lower-frequency reference signal to extract and identify the two frequency signals when extracting dual-frequency signals, which saves program storage space, speeds up algorithm operation efficiency, and thus improves detection speed and efficiency.

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the cable identification process using the dual-frequency modulation method provided in an embodiment of the present invention;

[0022] Figure 2 This is a flowchart illustrating a high-voltage live cable identification method based on a mixed-frequency signal provided in an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the signal extraction process based on phase-sensitive detection technology provided in an embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram of the original noisy signal waveform provided in an embodiment of the present invention;

[0025] Figure 5 This is a schematic diagram of the spectrum of the original noisy signal provided in an embodiment of the present invention;

[0026] Figure 6 This is a schematic diagram of the signal spectrum after the first mixing provided in an embodiment of the present invention;

[0027] Figure 7 This is a schematic diagram of the signal spectrum near 0 frequency after the first mixing provided in an embodiment of the present invention;

[0028] Figure 8 This is a schematic diagram of the signal spectrum after the second mixing provided in an embodiment of the present invention;

[0029] Figure 9 This is a schematic diagram of the signal spectrum near 0 frequency after the second mixing provided in an embodiment of the present invention;

[0030] Figure 10 This is a schematic diagram illustrating the relationship between phase tolerance and frequency ratio of a dual-frequency signal provided in an embodiment of the present invention;

[0031] Figure 11 This is a schematic diagram of a high-voltage live cable identification system based on a mixed-frequency signal provided in an embodiment of the present invention. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] The first aspect of this invention proposes a method for identifying high-voltage live cables based on mixed-frequency signals. This method primarily utilizes dual-frequency modulation to achieve cable identification. Please refer to... Figure 1 , Figure 1 This is a schematic diagram of the cable identification process using the dual-frequency modulation method provided in this embodiment of the invention. On the right, a signal transmitter injects a current signal into a cable to be identified; this current signal is the dual-frequency modulation signal wave (referred to as the dual-frequency signal). Different current waveforms will appear on the cables on the left; the three waveforms shown above represent the current waveforms in the cable in question. A current sensor is placed on the cable on the left, and the target cable can be identified by judging the current waveform.

[0034] Please see Figure 2 , Figure 2 This is a flowchart illustrating a high-voltage live cable identification method based on a mixed-frequency signal provided in an embodiment of the present invention. The method mainly includes the following steps:

[0035] Step 1: Based on the principle of electromagnetic induction, acquire signals from the cable to be identified to obtain electrical signals; the electrical signals include dual-frequency signals for identification and power frequency noise signals.

[0036] Specifically, a signal transmitter couples a dual-frequency signal to the outer shielding layer of the cable at its start using a coupling clamp. At the cable identification point, a current sensor detects the changes in the magnetic field generated by different cables, and collects the electrical signal of the cable to be identified. The frequency ratio of the dual-frequency signals is set to an even number; the reasons for this are explained in detail in step 4. In this embodiment, a frequency ratio of 2 is preferred.

[0037] Optionally, as one implementation method, this embodiment can use a flexible Rogowski coil to acquire signals from the cable to be identified. Specifically, a flexible Rogowski coil can be wrapped around the cable to be identified to sense the magnetic field signal generated in the cable, thereby obtaining an electrical signal.

[0038] It is understandable that the sensed magnetic field signal, or the collected electrical signal, includes the dual-frequency signal used for identification, power frequency noise and its harmonics from the cable under test and nearby high-voltage transmission lines, and high-frequency magnetic fields generated by radio communication equipment; among these, power frequency noise is the main noise component. Therefore, it can be considered that the collected electrical signal mainly includes the dual-frequency signal used for identification and the power frequency noise signal.

[0039] Step 2: Perform analog-to-digital conversion on the electrical signal to obtain a digital signal.

[0040] Understandably, before performing analog-to-digital conversion on electrical signals, the following steps are also included:

[0041] The electrical signal is conditioned, and the conditioning process includes low-pass filtering and amplification.

[0042] Specifically, the acquired electrical signal is first low-pass filtered using an RC filter. The filtered signal is then amplified by an operational amplifier circuit and transmitted to an A / D analog-to-digital converter to convert the electrical signal into a digital signal.

[0043] Step 3: Process the digital signal based on phase-sensitive detection technology to extract the amplitude and phase of the target dual-frequency signal.

[0044] In this embodiment, the target dual-frequency signal can be extracted in two steps using an improved phase-sensitive detection technique after analog-to-digital conversion. Specifically, step 3 can be implemented according to the following sub-steps 31-33.

[0045] Step 31: Generate a reference signal of the lower frequency of the two signals based on the dual-frequency signals.

[0046] Specifically, based on the dual-frequency signals to be detected, the software calculates and generates a reference signal of the lower frequency of the two signals. The initial generated signal data needs to be calculated and stored. Subsequently, if the frequencies of the dual-frequency signals remain unchanged, the reference signal does not need to be regenerated when calculating again, and the reference signal stored initially can be used directly.

[0047] In this embodiment, the generated reference signal is a set of quadrature sinusoidal signals. The expressions for the in-phase reference signal and the quadrature reference signal in the quadrature sinusoidal signals are as follows:

[0048] ;

[0049] In the formula, Indicates the in-phase reference signal. Indicates a quadrature reference signal. This represents the angular frequency of the reference signal. Since the reference signal is generated based on the lower frequency of the dual-frequency signal to be detected, therefore... It is also the angular frequency of low-frequency signals. Indicates time.

[0050] Optionally, to simplify the calculation process, the amplitude of the reference signal can be set to 1, the initial phase can be set to 0, and the signal length can be specified in advance. The length of the reference signal should be consistent with the length of the signal acquired by the analog-to-digital conversion module, and the longer the signal length, the more accurate and stable the final extracted signal amplitude and phase will be.

[0051] Step 32: Using the lower frequency signal in the dual-frequency signal as the low-frequency target signal, perform the first mixing process between the low-frequency signal in the digital signal and the reference signal, and calculate the amplitude and phase of the low-frequency target signal based on the obtained first mixing signal.

[0052] The following is combined with Figure 3 The diagram shown illustrates the signal extraction process based on phase-sensitive detection technology. It provides a detailed introduction to the dual-frequency signal extraction process and uses 640Hz and 1280Hz dual-frequency signals as examples to simulate the signal waveforms involved in the extraction process.

[0053] Specifically, let's assume the acquired electrical signal consists of a dual-frequency signal. , and power frequency noise signal Therefore, after the preceding signal conditioning and analog-to-digital conversion, the resulting digital signal also includes dual-frequency signals. , and power frequency noise signal The digital signal here can also be considered as the original noisy signal. Please see [link / reference]. Figure 4-5 , Figure 4 This is a schematic diagram of the original noisy signal waveform provided in an embodiment of the present invention. Figure 5 This is a schematic diagram of the spectrum of the original noisy signal provided in an embodiment of the present invention, and Figure 5 The amplitude values ​​are logarithmic coordinates.

[0054] In this embodiment, the expressions for each signal are:

[0055] ;

[0056] In the formula, Indicates a low-frequency signal. Indicates a high-frequency signal. Indicates power frequency noise signal, This represents the superposition of the aforementioned three signals. Indicates the amplitude of low-frequency signals. Indicates the amplitude of a high-frequency signal. Indicates the amplitude of the power frequency noise signal. Indicates the angular frequency of the low-frequency signal. Indicates the initial phase of the low-frequency signal. Indicates the angular frequency of a high-frequency signal. Indicates the initial phase of a high-frequency signal. Indicates the angular frequency of the power frequency noise signal. Indicates the initial phase of the power frequency noise signal;

[0057] Step 32 can be implemented as follows: sub-steps 32a)-32c).

[0058] 32a) The digital signal is mixed with the in-phase reference signal and the quadrature reference signal respectively to obtain the first in-phase output signal and the first quadrature output signal; the first in-phase output signal and the first quadrature output signal constitute the first mixing signal;

[0059] The first in-phase output signal is represented as:

[0060] ;

[0061] The first quadrature output signal is represented as:

[0062] ;

[0063] 32b) Perform low-frequency filtering or fast Fourier transform processing on the first in-phase output signal and the first quadrature output signal to obtain two DC signals containing amplitude and phase information of the low-frequency target signal. and .

[0064] Specifically, as can be seen from the formulas for the first in-phase output signal and the first quadrature output signal, after the first mixing, the signal spectrum of the target signal (which is now a low-frequency signal) in both sets of signals changes from... Moved to and At that location, both high-frequency and power frequency signals were moved to... , and , At, At this point, only the target signal spectrum information exists. In this case, a low-frequency filter can be used to filter out the high-frequency terms, or the spectrum can be directly read after a fast Fourier transform. The amplitude at that point can be used to obtain a DC signal that includes both the amplitude and phase information of the low-frequency signal. and .

[0065] Please see Figure 6-7 , Figure 6 This is a schematic diagram of the signal spectrum after the first mixing provided in an embodiment of the present invention. Figure 7 This is a schematic diagram of the signal spectrum near 0 frequency after the first mixing, provided in an embodiment of the present invention. Figure 6 and Figure 7 The amplitude values ​​are all on logarithmic coordinates. Figure 7 It can be seen that the amplitude when the spectrum is 0 is the amplitude of the DC component, and the DC component of the mixed signal can be obtained by fast Fourier transform.

[0066] 32c) Based on DC signal and The values ​​are used to calculate the amplitude and phase of the low-frequency target signal.

[0067] Specifically, the signal after filtering is an approximate DC signal. The amplitude and phase of the low-frequency target signal can be directly calculated from this DC data using the following formula:

[0068] ;

[0069] ;

[0070] In the formula, This represents the calculated value of the low-frequency target signal amplitude. This represents the calculated value of the phase of the low-frequency target signal.

[0071] Step 33: Using the higher frequency signal in the dual-frequency signal as the high-frequency target signal, perform a second mixing process between the first mixing signal and the reference signal, and calculate the amplitude and phase of the high-frequency target signal based on the obtained second mixing signal, thereby completing the extraction of the amplitude and phase of the target dual-frequency signal.

[0072] It should be noted that this step does not require regenerating the reference signal of the corresponding frequency. It only requires reusing the reference signal and the mixed signal already saved in the previous step, and mixing the mixed signal with the in-phase reference signal again. Then step 33 can be implemented according to the following sub-steps 33a)-33c).

[0073] 33a) The first in-phase output signal and the first quadrature output signal are mixed with the in-phase reference signal respectively to obtain the second in-phase output signal and the second quadrature output signal; the second in-phase output signal and the second quadrature output signal constitute the second mixed signal;

[0074] The second in-phase output signal is represented as:

[0075] ;

[0076] The second quadrature output signal is represented as:

[0077] ;

[0078] 33b) Perform low-frequency filtering or fast Fourier transform processing on the second in-phase output signal and the second quadrature output signal to obtain two DC signals containing amplitude and phase information of the high-frequency target signal. and .

[0079] Specifically, as can be seen from the formulas for the second in-phase output signal and the second quadrature output signal, the signal spectrum after the second mixing is further shifted. At this point, only the spectral information of the target signal exists. In this case, a low-frequency filter can be used to filter out other terms, or the spectrum can be directly read after a Fast Fourier Transform. The amplitude at that point can be used to obtain a DC signal that includes both the amplitude and phase information of the high-frequency signal. and .

[0080] Please see Figure 8-9 , Figure 8 This is a schematic diagram of the signal spectrum after the second mixing provided in an embodiment of the present invention; Figure 9 This is a schematic diagram of the signal spectrum near 0 frequency after the second mixing provided in an embodiment of the present invention; Figure 8 and Figure 9 The amplitude values ​​are all on logarithmic coordinates. Figure 9 It can be seen that the amplitude when the spectrum is 0 is the amplitude of the DC component, and the DC component of the mixed signal can be obtained by fast Fourier transform.

[0081] 33c) Based on DC signal and The values ​​are used to calculate the amplitude and phase of the high-frequency target signal.

[0082] Specifically, the signal after filtering is an approximate DC signal. The amplitude and phase of the high-frequency target signal can be directly calculated from this DC data using the following formula:

[0083] ;

[0084] ;

[0085] In the formula, This represents the calculated value of the high-frequency target signal amplitude. The calculated value representing the phase of the high-frequency target signal.

[0086] Generally speaking, for a stable sinusoidal signal, the signal amplitude is fixed, while the phase changes in real time. Therefore, the calculation here... That is the initial one , Then and Different. Accordingly, the calculation in step 32c) That is, the initial , also with different.

[0087] The high-voltage live cable identification method based on mixed-frequency signals proposed in this invention only requires the construction of a lower-frequency reference signal to extract and identify two frequency signals, saving program storage space, accelerating algorithm operation efficiency, and thus improving detection speed and efficiency.

[0088] Step 4: Complete cable identification based on the amplitude and phase of the target dual-frequency signal.

[0089] Before introducing the specific implementation process of step 4, let's first introduce the basis for determining the frequency of the dual-frequency signal.

[0090] In cable identification, the specific frequency determination of dual-frequency signals is based on factors including the phase shift and attenuation of the identification signal within the cable and the phase tolerance between the identification signal criteria. The theoretical derivation of the phase tolerance between the identification signal criteria is as follows:

[0091] Let the ratio of the two signal frequencies in the dual-frequency modulated signal be .

[0092] ;

[0093] In the formula, This indicates the angular frequency of the higher-frequency signal in a dual-frequency signal. This indicates the angular frequency of the lower frequency signal in a dual-frequency signal.

[0094] When both are initially in phase at 0°, i.e., in the case of being in phase,

[0095] ;

[0096] In the formula, Indicates the positive phase of a high-frequency signal. This indicates the positive phase of a low-frequency signal.

[0097] The phase difference calculation results during recognition are all within the interval [0, 2π), so it is necessary to... By increasing or decreasing the phase by 2π over an integer period, the phase remains within the interval [0, 2π).

[0098] ;

[0099] In the formula, .

[0100] Summarized as follows:

[0101] ;

[0102] To simplify the phase-to-phase criterion, it is necessary to... It also remains in the interval [0, 2π), and the equation can be rearranged as follows:

[0103] ;

[0104] In the formula, Let be any integer that keeps the left side of the expression in the interval [0, 2π).

[0105] When both are initially in phase -180°, i.e., out of phase,

[0106] ;

[0107] In the formula, Indicates the out-of-phase of a high-frequency signal. This indicates the out-of-phase of a low-frequency signal.

[0108] The subsequent derivation is similar to the positive case, and the simplified result is as follows:

[0109] ;

[0110] As can be seen from the above formula, the difference between the positive phase criterion and the negative phase criterion lies in the negative phase criterion. Item, and hour,

[0111] ;

[0112] In the formula, Item and Xiang Jiang and The terms are combined and canceled out, therefore any frequency ratio of a dual-frequency signal can be summarized as follows: Within the scope, if and only if When the frequency ratio is odd, the positive phase criterion is the same as the negative phase criterion, and the positive and negative phase waveforms of the dual-frequency waveform are completely identical, making cable identification impossible. Therefore, in practical applications, dual-frequency signals with an odd frequency ratio should be avoided for cable identification; that is, the frequency ratio of the dual-frequency signal should be set to an even number.

[0113] Furthermore, the phase difference in the criterion varies depending on the different frequency ratios. The interval is evenly distributed with different numbers of criteria points. The more criteria points there are, the closer the distance between adjacent criteria is, and the lower the tolerance of recognition, which is not conducive to cable recognition.

[0114] The distance between adjacent criteria is calculated by subtracting the positive and negative phase criteria:

[0115] ;

[0116] In the formula, It is only related to the ratio of the frequencies of the dual-frequency signals, the frequency ratio The value changes within the interval (1, 3). And so it changes. In fact, when Since the phase difference between the two criteria has exceeded 180°, and the phase difference of the criteria needs to be controlled within [0, 2π), the frequency ratio... The tolerance decreases as the interval (2,3) increases. The relationship between the criterion tolerance and the frequency ratio is as follows: Figure 10 This indicates that when the frequency ratio is an even multiple of 2, 4, 8, etc., the distance between the positive phase criterion and the negative phase criterion reaches a peak of 180°. Using dual-frequency signals with this frequency ratio for cable identification can significantly improve the fault tolerance and accuracy of identification in interference scenarios.

[0117] In summary, during cable identification, the discrimination criterion can be determined based on the phase relationship between the two frequencies of the dual-frequency signal. Taking the direction from the transmitting end to the receiving end of the target cable as the positive direction, the current waveforms in the target cable and adjacent cables represent the positive and negative phases of the dual-frequency modulation signal, respectively. Therefore, step 4 may include:

[0118] Step 41: Determine the criteria for positive phase discrimination and negative phase discrimination based on the phase relationship between the two frequencies of the dual-frequency signal.

[0119] Based on the above derivation, the criterion for positive phase discrimination can be expressed as:

[0120] ;

[0121] In the formula, The calculated value representing the phase of the high-frequency target signal. The calculated value representing the phase of the low-frequency target signal. This represents the ratio of the frequencies of the dual-frequency signals. ;

[0122] The criteria for phase reversal can be expressed as:

[0123] .

[0124] Step 42: When the phase relationship of the dual-frequency signals meets the positive phase discrimination criteria, the signal waveform is positive phase, and the corresponding cable is identified as the target cable.

[0125] When the phase relationship of the dual-frequency signals meets the inversion discrimination criteria, the signal waveform is inverted, and the corresponding cable is identified as a nearby non-target cable.

[0126] By analyzing the characteristics of signal phase relationships, the phase of the current waveform can be inferred, thereby enabling accurate identification of cables.

[0127] The high-voltage live cable identification method based on mixed-frequency signals proposed in this invention first acquires signals from the cable to be identified, obtaining electrical signals including a dual-frequency signal for identification and a power frequency noise signal. Then, the electrical signals are converted into digital signals, and phase-sensitive detection technology is used to extract the amplitude and phase of the target dual-frequency signal from the digital signals. Finally, cable identification is achieved based on the extracted amplitude and phase of the dual-frequency signal. This method can accurately and efficiently extract the target signal from signals with extremely low signal-to-noise ratios in strong power frequency magnetic field interference environments during live cable identification, and perform accurate cable identification.

[0128] A second aspect of the present invention provides a high-voltage live cable identification system based on a frequency mixing signal, used to implement the method provided in the first aspect of the present invention. Please refer to... Figure 11 , Figure 11 This is a schematic diagram of a high-voltage live cable identification system based on a mixed-frequency signal according to an embodiment of the present invention. The system includes a signal acquisition module, an analog-to-digital conversion module, a signal extraction module, and a cable identification module; wherein,

[0129] The signal acquisition module is equipped with a current sensor, which is used to acquire signals from the cable to be identified based on the principle of electromagnetic induction, and obtain electrical signals; the electrical signals include dual-frequency signals for identification and power frequency noise signals;

[0130] The analog-to-digital converter module is used to perform analog-to-digital conversion on electrical signals to obtain digital signals;

[0131] The signal extraction module and the cable identification module are integrated in the microprocessor; the signal extraction module is used to process digital signals based on phase-sensitive detection technology to extract the amplitude and phase of the target dual-frequency signal respectively;

[0132] The cable identification module is used to identify cables based on the amplitude and phase of the target dual-frequency signal.

[0133] Optionally, in this embodiment, the system further includes a signal conditioning unit, which is equipped with a filtering circuit and an amplification circuit, for performing low-pass filtering and amplification processing on the acquired electrical signal before analog-to-digital conversion.

[0134] Optionally, in this embodiment, the microprocessor also integrates a digital filtering unit for noise reduction processing before signal extraction.

[0135] It is understood that the system provided in this embodiment may also include synchronous dynamic random-access memory (SDRAM) for storing reference signals and other intermediate information generated during the algorithm implementation process.

[0136] In addition, the system includes an LCD screen, a button module, a GNSS (Global Navigation Satellite System) module, and an audio amplifier module. All these modules are connected to the microprocessor. The LCD screen can display the recognition data in real time, including the recognition results, phase relationship, and signal amplitude. The recognition results can be uploaded in real time via the output unit and the WIFI module to a connected mobile host computer, transmitting the recognition results, phase relationship, signal amplitude, and GNSS module positioning information to the host computer, thus recording the pipeline recognition information.

[0137] As for the second aspect of the identification system embodiment, since it is basically similar to the first aspect of the identification method embodiment, the description is relatively simple, and relevant details can be found in the description of the first aspect of the method embodiment.

[0138] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0139] Those skilled in the art will understand that embodiments of this application can be provided as methods, apparatus (devices), or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects, all of which are collectively referred to herein as "modules" or "systems." Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The computer program may be stored / distributed in a suitable medium, provided with or as part of other hardware, or may take other distribution forms, such as via the Internet or other wired or wireless telecommunications systems.

[0140] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for identifying high-voltage live cables based on mixed-frequency signals, characterized in that, include: The signal transmitter injects a current signal into a cable to be identified. This current signal is a dual-frequency signal with a frequency ratio of 2. Signal acquisition is performed on the cable to be identified based on the principle of electromagnetic induction to obtain electrical signals; wherein, the electrical signals include dual-frequency signals for identification and power frequency noise signals; the expressions for each signal are as follows: ； In the formula, Indicates a low-frequency signal. Indicates a high-frequency signal. Indicates power frequency noise signal, This represents the superposition of the aforementioned three signals. Indicates the amplitude of low-frequency signals. Indicates the amplitude of a high-frequency signal. Indicates the amplitude of the power frequency noise signal. Indicates the angular frequency of the low-frequency signal. Indicates the initial phase of the low-frequency signal. Indicates the angular frequency of a high-frequency signal. Indicates the initial phase of a high-frequency signal. Indicates the angular frequency of the power frequency noise signal. Indicates the initial phase of the power frequency noise signal; The electrical signal is subjected to analog-to-digital conversion to obtain a digital signal; The digital signal is processed using phase-sensitive detection technology to extract the amplitude and phase of the target dual-frequency signal, including: A reference signal of the lower frequency of the two signals is generated based on the dual-frequency signals; the reference signal includes a set of orthogonal sinusoidal signals, expressed by the formula: ； In the formula, Indicates the in-phase reference signal. Indicates a quadrature reference signal. Indicates the angular frequency of low-frequency signals. Indicates time; Using the lower frequency signal in the dual-frequency signal as the low-frequency target signal, the low-frequency signal in the digital signal is mixed with the reference signal for the first time, and the amplitude and phase of the low-frequency target signal are calculated based on the obtained first mixed signal. Specifically, this includes: mixing the digital signal with the in-phase reference signal and the quadrature reference signal respectively to obtain a first in-phase output signal and a first quadrature output signal; the first in-phase output signal and the first quadrature output signal constitute the first mixed signal; and performing low-frequency filtering or fast Fourier transform processing on the first in-phase output signal and the first quadrature output signal to obtain two DC signals including the amplitude and phase information of the low-frequency target signal. and Based on the DC signal and The values ​​are used to calculate the amplitude and phase of the low-frequency target signal; Using the higher frequency signal in the dual-frequency signal as the high-frequency target signal, the first mixing signal and the reference signal are mixed a second time, and the amplitude and phase of the high-frequency target signal are calculated based on the obtained second mixing signal, thereby completing the amplitude and phase extraction of the target dual-frequency signal; specifically, this includes: mixing the first in-phase output signal and the first quadrature output signal with the in-phase reference signal respectively to obtain a second in-phase output signal and a second quadrature output signal; the second in-phase output signal and the second quadrature output signal constitute the second mixing signal; and performing low-frequency filtering or fast Fourier transform processing on the second in-phase output signal and the second quadrature output signal to obtain two DC signals including the amplitude and phase information of the high-frequency target signal. and Based on the DC signal and The values ​​are used to calculate the amplitude and phase of the high-frequency target signal; Cable identification is performed based on the amplitude and phase of the target dual-frequency signal.

2. The high-voltage live cable identification method based on mixed-frequency signals according to claim 1, characterized in that, Based on the principle of electromagnetic induction, signal acquisition is performed on the cable to be identified to obtain electrical signals, specifically including: A flexible Rogowski coil is used to wrap around the cable to be identified, and the magnetic field signal generated in the cable is sensed to obtain an electrical signal.

3. The high-voltage live cable identification method based on mixed-frequency signals according to claim 1, characterized in that, Before performing analog-to-digital conversion on the electrical signal, the process further includes: The electrical signal is conditioned, and the conditioning process includes low-pass filtering and amplification.

4. The high-voltage live cable identification method based on mixed-frequency signals according to claim 1, characterized in that, Before processing the digital signal, the method further includes: The digital signal is then subjected to digital filtering.

5. The high-voltage live cable identification method based on mixed-frequency signals according to claim 1, characterized in that, The first in-phase output signal is represented as: ； In the formula, Indicates a low-frequency signal. Indicates a high-frequency signal. Indicates power frequency noise signal, This represents the superposition of the aforementioned three signals. Indicates the amplitude of low-frequency signals. Indicates the amplitude of a high-frequency signal. Indicates the amplitude of the power frequency noise signal. Indicates the angular frequency of the low-frequency signal. Indicates the initial phase of the low-frequency signal. Indicates the angular frequency of a high-frequency signal. Indicates the initial phase of a high-frequency signal. Indicates the angular frequency of the power frequency noise signal. Indicates the initial phase of the power frequency noise signal; The first quadrature output signal is represented as: ； The formulas for calculating the amplitude and phase of the low-frequency target signal are as follows: ； ； In the formula, This represents the calculated value of the low-frequency target signal amplitude. This represents the calculated value of the phase of the low-frequency target signal.

6. The high-voltage live cable identification method based on mixed-frequency signals according to claim 5, characterized in that, The second in-phase output signal is represented as: ； The second quadrature output signal is represented as: ； The formulas for calculating the amplitude and phase of the high-frequency target signal are as follows: ； ； In the formula, This represents the calculated value of the high-frequency target signal amplitude. The calculated value representing the phase of the high-frequency target signal.

7. The method for identifying high-voltage live cables based on mixed-frequency signals according to claim 1, characterized in that, Cable identification is performed based on the amplitude and phase of the target dual-frequency signal, including: The criteria for determining positive phase and negative phase are determined based on the phase relationship between the two frequencies of the dual-frequency signal; wherein, The positive phase discrimination criterion is expressed as follows: ； In the formula, The calculated value representing the phase of the high-frequency target signal. The calculated value representing the phase of the low-frequency target signal. This represents the ratio of the frequencies of the dual-frequency signals. ; The inverse discrimination criterion is expressed as follows: ； In the formula, Represents any integer; When the phase relationship of the dual-frequency signals meets the positive phase discrimination criteria, the signal waveform is positive phase, and the corresponding cable is identified as the target cable. When the phase relationship of the dual-frequency signals meets the inversion discrimination criteria, the signal waveform is inverted, and the corresponding cable is identified as a nearby non-target cable.

8. A high-voltage live cable identification system based on mixed-frequency signals, used to implement the method described in any one of claims 1-7, characterized in that, The system includes a signal acquisition module, an analog-to-digital conversion module, a signal extraction module, and a cable identification module; wherein, The signal acquisition module is equipped with a current sensor, which is used to acquire signals from the cable to be identified based on the principle of electromagnetic induction to obtain an electrical signal; wherein, the electrical signal includes a dual-frequency signal for identification and a power frequency noise signal; The analog-to-digital conversion module is used to perform analog-to-digital conversion on the electrical signal to obtain a digital signal; The signal extraction module and the cable identification module are integrated in a microprocessor; the signal extraction module is used to process the digital signal based on phase-sensitive detection technology to extract the amplitude and phase of the target dual-frequency signal respectively. The cable identification module is used to identify cables based on the amplitude and phase of the target dual-frequency signal.

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