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

Abstract

The invention discloses a high-voltage live cable identification method and system based on a frequency mixing signal, and belongs to the technical field of cable detection, and the method comprises the steps: carrying out the signal collection of a to-be-identified cable based on an electromagnetic induction principle, and obtaining an electric signal; wherein the electric signal comprises a dual-frequency signal for identification and a power frequency noise signal; performing analog-to-digital conversion processing on the electric signal to obtain a digital signal; processing the digital signal based on a phase-sensitive detection technology, and respectively extracting the amplitude and phase of the target dual-frequency signal; and cable identification is completed based on the amplitude and the phase of the target dual-frequency signal. The method can solve the problem that when noise interference is strong, traditional cable identification equipment is affected and cannot accurately carry out cable identification, and the identification accuracy and the identification efficiency can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of cable detection, and in particular relates to a method and system for identifying high-voltage live cables based on mixed frequency signals. Background Art

[0002] At present, power grids generally use underground cables to transmit electricity. When conducting daily inspections or emergency repairs of underground cables, accurately identifying the target cable is a crucial task in cable engineering. Once cable identification errors occur in this process, it may cause huge economic losses and seriously threaten personal safety. In many cases, the power system needs to maintain continuous power supply and cannot be easily interrupted. Power outage identification may cause system interruption, affecting production, services and normal life.

[0003] Live identification means that signal detection must be carried out under strong electromagnetic interference. Under extreme conditions such as strong power frequency interference near cables, the intensity of power frequency interference can often reach dozens of times or even higher than the normal identification signal strength, making it difficult to pick up signals. Ordinary power outage cable identification equipment cannot work normally or even gets damaged, which brings great safety risks to cable inspection, maintenance, and census work, affecting work efficiency.

[0004] The most commonly used method for identifying cable live signals is the dual-frequency modulation method. Specifically, the signal transmitter couples the dual-frequency signal to the outer shielding layer of the cable through a coupling clamp at the beginning of the cable, and uses a current sensor to detect the change law of the magnetic field generated by different cables at the cable identification point, so as to analyze the positive and negative phases of the current waveform in the cable and identify the target cable. The extraction method of the dual-frequency signal is currently mainly to filter out the noise signal through a bandpass filter. However, under strong electromagnetic interference, the power frequency interference amplitude is large, and the power frequency harmonic noise is small compared to the target signal frequency, so it is difficult to achieve a good filtering effect, which affects the efficiency and accuracy of cable identification. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a method and system for identifying high-voltage live cables based on mixed frequency signals. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0006] In a first aspect, the present invention proposes a method for identifying a high-voltage live cable based on a mixing signal, comprising:

[0007] Based on the principle of electromagnetic induction, the signal of the cable to be identified is collected to obtain an electrical signal; wherein the electrical signal includes a dual-frequency signal for identification and an industrial frequency noise signal;

[0008] Perform analog-to-digital conversion on the electrical signal to obtain a digital signal;

[0009] The digital signal is processed based on phase-sensitive detection technology to extract the amplitude and phase of the target dual-frequency signal respectively;

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

[0011] In a second aspect, the present invention proposes a high-voltage live cable identification system based on a mixed frequency signal, which is used to implement the method proposed in the first aspect 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,

[0012] The signal acquisition module is equipped with a current sensor, which is used to collect signals from 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;

[0013] The analog-to-digital conversion module is used to perform analog-to-digital conversion processing on the electrical signal to obtain a digital signal;

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

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

[0016] Beneficial effects of the present invention:

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

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

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

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

[0022] Figure 2 It is a flow chart of a method for identifying a high-voltage live cable based on a mixing signal provided by an embodiment of the present invention;

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

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

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

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

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

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

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

[0030] Fig.10 is a schematic diagram of the relationship between the phase tolerance and frequency ratio of the dual-frequency signal provided by an embodiment of the present invention;

[0031] Fig.11 It is a structural schematic diagram of a high-voltage live cable identification system based on mixed frequency signals provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The first aspect of the present invention proposes a method for identifying high-voltage live cables based on mixed-frequency signals. The method mainly implements cable identification based on dual-frequency modulation. Figure 1 , Figure 1 This is a schematic diagram of the process of cable identification using the dual-frequency modulation method provided by an embodiment of the present invention. On the right, there is a signal transmitter that injects a current signal into a cable to be identified. This current signal is a dual-frequency modulation signal wave (referred to as a dual-frequency signal). There will be different current waveforms on the cables on the left. The three waveforms above are the current waveforms in the cable. The current sensor should be placed on the cable on the left. The target cable can be identified by judging the current waveform.

[0034] See also Figure 2 , Figure 2 1 is a flow chart of a method for identifying a high-voltage live cable based on a mixing signal provided by an embodiment of the present invention. The method mainly comprises the following steps:

[0035] Step 1: Based on the principle of electromagnetic induction, the signal of the cable to be identified is collected to obtain an electrical signal; wherein the electrical signal includes a dual-frequency signal for identification and an industrial frequency noise signal.

[0036] Specifically, a signal transmitter is used to couple the dual-frequency signal to the outer shielding layer of the cable through a coupling clamp at the beginning of the cable, and a current sensor is used to detect the change law of the magnetic field generated by different cables at the identification point of the cable to collect the electrical signal of the cable to be identified. Among them, the frequency ratio of the dual-frequency signal is set to an even number, and the specific reason is analyzed in detail in step 4. In this embodiment, the frequency ratio of the dual-frequency signal is preferably 2.

[0037] Optionally, as an implementation method, the present embodiment may use a flexible Rogowski coil to collect signals from the cable to be identified. Specifically, the flexible Rogowski coil may be used to surround the cable to be identified, and the magnetic field signal generated in the cable to be identified may be sensed to obtain an electrical signal.

[0038] It can be understood that the induced magnetic field signal or the collected electrical signal includes the dual-frequency signal for identification, the power frequency noise and its harmonics from the cable to be tested and the nearby high-voltage transmission line, and the high-frequency magnetic field generated by the radio communication equipment, among which the power frequency noise is the main noise component. Therefore, it can be considered that the collected electrical signal mainly includes the dual-frequency signal 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] It is understandable that before the analog-to-digital conversion of the electrical signal, 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 collected electrical signal is first low-pass filtered using an RC filter, the filtered signal is amplified by an operational amplifier circuit, and after amplification, it is transmitted to an A / D analog-to-digital conversion unit 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 respectively.

[0044] In this embodiment, the target dual-frequency signal can be extracted in two steps using the improved phase-sensitive detection technology for the digital signal 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 with a lower frequency based on the dual-frequency signal.

[0046] Specifically, according to the dual-frequency signal to be detected, the software calculates and generates a reference signal with a lower frequency of the two. The signal data generated for the first time needs to be calculated and stored. When the frequency of the dual-frequency signal remains unchanged, the reference signal does not need to be regenerated when it is calculated again, and the reference signal stored for the first time can be used directly.

[0047] In this embodiment, the generated reference signal is a group of orthogonal sinusoidal signals, and the expressions of the in-phase reference signal and the orthogonal reference signal in the orthogonal sinusoidal signals are respectively:

[0048] U i = sin(ω l t)

[0049] U o = cos(ω l t);

[0050] Where U i Represents the in-phase reference signal, U o represents the orthogonal reference signal, ω l 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, ω l It is also the angular frequency of the low-frequency signal, and t represents time.

[0051] 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 collected by the analog-to-digital conversion module, and the longer the signal length, the more accurate and stable the signal amplitude and phase finally extracted.

[0052] Step 32: Using the lower frequency signal in the dual-frequency signal as the low-frequency target signal, perform a first mixing process on 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 mixed signal.

[0053] Combine the following Figure 3 The schematic diagram of the signal extraction process based on phase-sensitive detection technology shown in the figure gives a detailed introduction to the dual-frequency signal extraction process, and takes the dual-frequency signal frequencies of 640Hz and 1280Hz as an example to simulate the signal waveforms involved in the extraction process.

[0054] Specifically, the collected electrical signal is composed of a dual-frequency signal U l , U h And the power frequency noise signal U p , then after the previous signal conditioning and analog-to-digital conversion, the obtained digital signal also includes the dual-frequency signal U l , U h And the power frequency noise signal U p , the digital signal here can also be considered as the original noisy signal. Figure 4-5 , Figure 4 is a schematic diagram of an original noisy signal waveform provided by an embodiment of the present invention, Figure 5 is a schematic diagram of the spectrum of an original noisy signal provided by an embodiment of the present invention, and Figure 5 The magnitudes in are logarithmic coordinates.

[0055] In this embodiment, the expressions of each signal are:

[0056]

[0057] Where U l Represents low-frequency signal, U h Represents high-frequency signal, U p Represents the power frequency noise signal, U c A represents the superposition signal of the above three signals. l Indicates the amplitude of the low-frequency signal, A h Represents the high-frequency signal amplitude, A p Indicates the amplitude of the power frequency noise signal, ω l represents the angular frequency of the low-frequency signal, Represents the initial phase of the low-frequency signal, ω h represents the angular frequency of high-frequency signals, Represents the initial phase of the high-frequency signal, ω p Indicates the angular frequency of the power frequency noise signal, Indicates the initial phase of the power frequency noise signal;

[0058] Step 32 may be implemented according to the following sub-steps 32a)-32c).

[0059] 32a) mixing the digital signal with the in-phase reference signal and the quadrature reference signal respectively, and obtaining a first in-phase output signal and a first quadrature output signal respectively; the first in-phase output signal and the first quadrature output signal constitute a first mixed signal;

[0060] Among them, the first in-phase output signal is expressed as:

[0061]

[0062] The first quadrature output signal is expressed as:

[0063]

[0064] 32b) performing low-frequency filtering or fast Fourier transform processing on the first in-phase output signal and the first quadrature output signal, and correspondingly obtaining two DC signals I1 and Q1 including amplitude and phase information of the low-frequency target signal.

[0065] Specifically, it can be seen from the formulas of the first in-phase output signal and the first quadrature output signal that after the first mixing, the signal spectrum of the target signal (low-frequency signal at this time) in the two groups of signals changes from ω l Moved to ω=0 and ω=2ω l The high frequency signal and the power frequency signal are moved to and At ω = 0, only the target signal spectrum information exists. At this time, the high-frequency term can be filtered out by a low-frequency filter or the amplitude of the spectrum at ω = 0 can be directly read by fast Fourier transform to obtain a DC signal including the amplitude and phase information of the low-frequency signal. and

[0066] See also Figure 6-7 , Figure 6 is a schematic diagram of a signal spectrum after the first mixing provided by an embodiment of the present invention, Figure 7 is a schematic diagram of a signal spectrum near a frequency of 0 after the first mixing provided by an embodiment of the present invention, Figure 6 and Figure 7 The amplitudes in are all 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.

[0067] 32c) Based on the values ​​of the DC signals I1 and Q1, the amplitude and phase of the low-frequency target signal are calculated.

[0068] Specifically, the signal after passing through the filter is an approximate DC signal, and the amplitude and phase of the low-frequency target signal can be directly calculated by numerical calculation of the DC data. The calculation formula is:

[0069]

[0070] In the formula, A L represents the calculated value of the low-frequency target signal amplitude, 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 on the first mixed signal and the reference signal, and calculate the amplitude and phase of the high-frequency target signal based on the obtained second mixed signal, thereby completing the amplitude and phase extraction of the target dual-frequency signal.

[0072] It should be noted that this step does not require regeneration of the reference signal of the corresponding frequency. It only needs to reuse the reference signal and a set of mixed signals that have been saved in the previous step, and mix the signals after the first mixing with the in-phase reference signal again. Step 33 can be implemented according to the following sub-steps 33a)-33c).

[0073] 33a) 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 correspondingly; the second in-phase output signal and the second quadrature output signal constitute a second mixed signal;

[0074] Among them, the second in-phase output signal is expressed as:

[0075]

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

[0077]

[0078] 33b) performing low-frequency filtering or fast Fourier transform processing on the second in-phase output signal and the second quadrature output signal, and correspondingly obtaining two DC signals I2 and Q2 including amplitude and phase information of the high-frequency target signal.

[0079] Specifically, it can be seen from the formulas of the second in-phase output signal and the second orthogonal output signal that the signal spectrum after the second mixing continues to be moved. At this time, only the spectrum information of the target signal exists at ω=0. At this time, other items can be filtered out by a low-frequency filter or the amplitude of the spectrum at ω=0 can be directly read by fast Fourier transform to obtain a DC signal including the amplitude and phase information of the high-frequency signal. and

[0080] See also Figure 8-9 , Figure 8 is a schematic diagram of a signal spectrum after the second mixing provided by an embodiment of the present invention; Fig. 9 is a schematic diagram of a signal spectrum near a frequency of 0 after the second frequency mixing provided by an embodiment of the present invention; Figure 8 and Fig. 9 The amplitudes in are all logarithmic coordinates. Fig. 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 the values ​​of DC signals I2 and Q2, the amplitude and phase of the high frequency target signal are calculated.

[0082] Specifically, the signal after passing through the filter is an approximate DC signal, and the amplitude and phase of the high-frequency target signal can be directly calculated by numerical calculation of the DC data. The calculation formula is:

[0083]

[0084] In the formula, A H represents the calculated value of the high-frequency target signal amplitude, Represents the calculated value of the phase of the high-frequency target signal.

[0085] Generally speaking, for a stable sinusoidal signal, the signal amplitude is fixed, while the phase changes in real time. Therefore, the A calculated here is H It is the initial A h , Then Different. Accordingly, the A calculated in step 32c) L That is, the initial A l , also with different.

[0086] The high-voltage live cable identification method based on mixed-frequency signals proposed in the present invention only needs to construct a lower-frequency reference signal when extracting dual-frequency signals to realize the extraction and identification of two frequency signals, which saves program storage space, speeds up the algorithm operation efficiency, and thus improves the detection speed and efficiency.

[0087] Step 4: Complete cable identification based on the amplitude and phase of the target dual-frequency signal.

[0088] Before introducing the specific implementation process of step 4, the basis for determining the frequency of the dual-frequency signal is first introduced.

[0089] In cable identification, the specific frequency of the dual-frequency signal is determined based on the phase shift and attenuation of the identification signal in 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:

[0090] Assume that the ratio of the two signal frequencies in the dual-frequency modulation signal is

[0091]

[0092] In the formula, ω h Represents the angular frequency of the high-frequency signal in the dual-frequency signal, ω l Indicates the angular frequency of the low-frequency signal in the dual-frequency signal.

[0093] When the initial phase of both is 0°, that is, the positive phase,

[0094]

[0095] In the formula, represents the positive phase of the high frequency signal, Indicates the positive phase of the low-frequency signal.

[0096] The results of phase difference calculation during identification are all in the interval [0,2π), so it is necessary to and Increase or decrease the phase of the whole cycle by 2π, and keep the phase in the interval [0,2π). At this time,

[0097]

[0098] In the formula, k1, k2 = 0, ±1, ±2….

[0099] Arranged:

[0100]

[0101] In order to make the positive and negative phase criterion more concise, it is necessary to Also keep in the interval [0,2π), the equation is rearranged as:

[0102]

[0103] Where k is an arbitrary integer that keeps the left-hand side in the interval [0,2π).

[0104] When the initial phases of both are -180°, that is, in the opposite phase,

[0105]

[0106] In the formula, Indicates the anti-phase of the high-frequency signal, Indicates the inverted phase of low-frequency signals.

[0107] The subsequent derivation is the same as that of the positive phase, and the results are:

[0108]

[0109] It can be seen from the above formula that the difference between the positive phase criterion and the negative phase criterion lies in the (m-1)π term of the negative phase criterion, and when m≥3,

[0110] (m-1)π=(n-1)π+2kπ(1≤n≤3);

[0111] In the formula, the (m-1)π term and the 2kπ term will be combined with the k·2π term to cancel each other out, so any frequency ratio of the dual-frequency signal can be summarized in the range of [1,3]. When and only when m is an odd number, the positive phase criterion is the same as the negative phase criterion, and the positive phase waveform and the negative phase waveform of the dual-frequency waveform are also completely consistent, making it impossible to identify the cable. Therefore, in practical applications, it is necessary to avoid using a dual-frequency signal with an odd frequency ratio for cable identification, that is, the frequency ratio of the dual-frequency signal needs to be set to an even number.

[0112] Furthermore, for different frequency ratios, the phase difference in the criterion is also different. Different numbers of criterion points are evenly distributed alternately in the interval [0,2π). The more criterion points there are, the closer the distance between adjacent criterions is, and the lower the recognition tolerance is, which is not conducive to cable recognition.

[0113] To calculate the distance between adjacent criteria, the positive and negative criteria are subtracted:

[0114]

[0115] In the formula, It is only related to the frequency ratio of the dual-frequency signal. The value of the frequency ratio m changes in the interval (1,3). In fact, when m>2, the phase difference between the two criteria has exceeded 180°. Since the phase difference of the criteria needs to be controlled in [0,2π), the tolerance decreases when the frequency ratio m increases in the interval (2,3). The relationship between the criterion tolerance and the frequency ratio is: Fig.10It can be seen that when the frequency ratio is an even multiple of 2, 4, 8, etc., the distance between the positive phase criterion and the reverse phase criterion reaches a peak of 180°. Using dual-frequency signals with this frequency ratio for cable identification can greatly improve the fault tolerance and accuracy of identification in interference scenarios.

[0116] In summary, in the process of cable identification, the basis for identification can be determined by the phase relationship between the two frequencies of the dual-frequency signal, with the direction from the transmitting end to the receiving end of the target cable as the positive direction, and the current waveforms in the target cable and the adjacent cable are the positive phase and the negative phase of the dual-frequency modulation signal respectively. Then step 4 may include:

[0117] Step 41, determining a positive discrimination basis and a negative discrimination basis according to the phase relationship between the two frequencies of the dual-frequency signal.

[0118] Based on the above derivation, the positive discrimination basis can be expressed as:

[0119]

[0120] In the formula, θ H represents the calculated value of the high-frequency target signal phase, represents the calculated value of the phase of the low-frequency target signal, m represents the ratio of the dual-frequency signal frequencies, k1, k2 = 0, ±1, ±2…;

[0121] The reverse discrimination basis can be expressed as:

[0122]

[0123] Step 42: When the phase relationship of the dual-frequency signal satisfies the positive discrimination criterion, the signal waveform is in a positive phase, and the corresponding cable is identified as a target cable;

[0124] When the phase relationship of the dual-frequency signals satisfies the reverse discrimination criteria, the signal waveform is inverted, and the corresponding cable is identified as an adjacent non-target cable.

[0125] By analyzing the signal phase relationship characteristics, the positive and negative phases of the current waveform can be inferred, thereby accurately identifying the cable.

[0126] The high-voltage live cable identification method based on mixed-frequency signals proposed in the present invention first collects signals from the cable to be identified to obtain an electrical signal including a dual-frequency signal for identification and an industrial frequency noise signal; then the electrical signal is converted into a digital signal, and the amplitude and phase of the target dual-frequency signal are extracted from the digital signal using phase-sensitive detection technology, and finally the cable identification is realized based on the amplitude and phase of the extracted dual-frequency signal. This method can accurately and efficiently extract the target signal from a signal with an extremely low signal-to-noise ratio in a strong industrial frequency magnetic field interference environment during live cable identification, and perform accurate cable identification.

[0127] The second aspect of the present invention provides a high-voltage live cable identification system based on a mixed frequency signal, which is used to implement the method provided by the first aspect of the present invention. Fig.11 , Fig.11 The structure diagram of a high-voltage live cable identification system based on a mixed frequency signal provided by an embodiment of the present invention is shown in FIG. The system includes a signal acquisition module, an analog-to-digital conversion module, a signal extraction module, and a cable identification module; wherein:

[0128] The signal acquisition module is equipped with a current sensor, which is used to collect signals from 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;

[0129] The analog-to-digital conversion module is used to perform analog-to-digital conversion processing on the electrical signal to obtain a digital signal;

[0130] The signal extraction module and the cable identification module are integrated in the microprocessor; the signal extraction module is used to process the digital signal based on the phase-sensitive detection technology, and respectively extract the amplitude and phase of the target dual-frequency signal;

[0131] The cable identification module is used to complete cable identification based on the amplitude and phase of the target dual-frequency signal.

[0132] Optionally, in this embodiment, the system further includes a signal conditioning unit, which is provided with a filtering circuit and an amplifying circuit for performing low-pass filtering and amplifying processing on the collected electrical signal before analog-to-digital conversion.

[0133] Optionally, in this embodiment, a digital filtering unit is also integrated in the microprocessor for performing noise reduction processing before signal extraction.

[0134] It is understandable that the system provided in this embodiment may also include a synchronous dynamic random-access memory (SDRAM) for storing reference signals and other intermediate information generated during the algorithm implementation process.

[0135] In addition, the system also includes an LCD screen, a button module, a GNSS (Global Navigation Satellite System) module, an audio amplifier module, etc. These modules are connected to a microprocessor, and the LCD screen can display the recognition data in real time, including the recognition results, phase relationship, signal amplitude, etc. The recognition results can be uploaded through the output unit and the WIFI module to communicate with the mobile host computer in real time, and the recognition results, phase relationship, signal amplitude, etc. and the positioning information of the GNSS module are uploaded to the host computer in real time to record the pipeline recognition information.

[0136] As for the recognition system embodiment of the second aspect, since it is basically similar to the recognition method embodiment of the first aspect, the description is relatively simple, and the relevant parts may refer to the partial description of the method embodiment of the first aspect.

[0137] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0138] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, devices (equipment), or computer program products. Therefore, the present application may adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware, which are collectively referred to as "modules" or "systems" herein. Moreover, the present application may adopt the form of computer program products implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program codes. The computer program is stored / distributed in a suitable medium, provided together with other hardware or as a part of hardware, or may adopt other distribution forms, such as by Internet or other wired or wireless telecommunication systems.

[0139] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A method for identifying high-voltage live cables based on mixed frequency signals, characterized in that: include: Based on the principle of electromagnetic induction, the signal of the cable to be identified is collected to obtain an electrical signal; wherein the electrical signal includes a dual-frequency signal for identification and an industrial frequency noise signal; Performing analog-to-digital conversion on the electrical signal to obtain a digital signal; The digital signal is processed based on phase-sensitive detection technology to extract the amplitude and phase of the target dual-frequency signal respectively; 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 is characterized in that: Based on the principle of electromagnetic induction, the signal of the cable to be identified is collected to obtain an electrical signal, which specifically includes: A flexible Rogowski coil is used to surround the cable to be identified, and the magnetic field signal generated in the cable to be identified is sensed to obtain an electrical signal.

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

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

5. The high-voltage live cable identification method based on mixed frequency signal according to claim 1 is characterized in that: The digital signal is processed based on the phase-sensitive detection technology to extract the amplitude and phase of the target dual-frequency signal respectively, specifically including: generating a reference signal of a lower frequency of the two based on the dual-frequency signal; Using the lower frequency signal in the dual-frequency signal as the low-frequency target signal, performing a first mixing process on the low-frequency signal in the digital signal and the reference signal, and calculating the amplitude and phase of the low-frequency target signal based on the obtained first mixing signal; The higher frequency signal in the dual-frequency signal is used as the high-frequency target signal, the first mixed signal and the reference signal are mixed for the second time, and the amplitude and phase of the high-frequency target signal are calculated based on the obtained second mixed signal, thereby completing the amplitude and phase extraction of the target dual-frequency signal.

6. The high-voltage live cable identification method based on mixed frequency signals according to claim 5 is characterized in that: The reference signal includes a set of orthogonal sinusoidal signals, which are expressed as follows: U i =sin(ω) l t) U o =cos(ω l t); Where U i Represents the in-phase reference signal, U o represents the orthogonal reference signal, ω l represents the angular frequency of the low-frequency signal, and t represents time.

7. The high-voltage live cable identification method based on mixed frequency signals according to claim 6 is characterized in that: The method further comprises: taking the lower frequency signal in the dual-frequency signal as the low-frequency target signal, performing a first mixing process on the low-frequency signal in the digital signal and the reference signal, and calculating the amplitude and phase of the low-frequency target signal based on the obtained first mixing signal, specifically comprising: The digital signal is mixed with the in-phase reference signal and the quadrature reference signal respectively, and a first in-phase output signal and a first quadrature output signal are obtained correspondingly; the first in-phase output signal and the first quadrature output signal constitute a first mixing signal; wherein the first in-phase output signal is expressed as: Where U l Represents low-frequency signal, U h Represents high-frequency signal, U p Represents the power frequency noise signal, U c A represents the superposition signal of the above three signals. l Indicates the amplitude of the low-frequency signal, A h Represents the high-frequency signal amplitude, A p Indicates the amplitude of the power frequency noise signal, ω l represents the angular frequency of the low-frequency signal, Represents the initial phase of the low-frequency signal, ω h represents the angular frequency of high-frequency signals, Represents the initial phase of the high-frequency signal, ω p 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 expressed as: Performing low-frequency filtering or fast Fourier transform processing on the first in-phase output signal and the first quadrature output signal, and correspondingly obtaining two DC signals I1 and Q1 including amplitude and phase information of low-frequency target signals; Based on the values ​​of the DC signals I1 and Q1, the amplitude and phase of the low-frequency target signal are calculated using the following formula: In the formula, A L represents the calculated value of the low-frequency target signal amplitude, Represents the calculated value of the phase of the low-frequency target signal.

8. The high-voltage live cable identification method based on mixed frequency signals according to claim 7 is characterized in that: The method further comprises: taking the higher frequency signal of the dual-frequency signal as the high-frequency target signal, performing a second mixing process on the first mixed signal and the reference signal, and calculating the amplitude and phase of the high-frequency target signal based on the obtained second mixed signal, specifically comprising: The first in-phase output signal and the first quadrature output signal are mixed with the in-phase reference signal respectively, and a second in-phase output signal and a second quadrature output signal are obtained correspondingly; the second in-phase output signal and the second quadrature output signal constitute a second mixed signal; wherein the second in-phase output signal is expressed as: The second quadrature output signal is expressed as: Performing low-frequency filtering or fast Fourier transform processing on the second in-phase output signal and the second quadrature output signal, and correspondingly obtaining two DC signals I2 and Q2 including amplitude and phase information of the high-frequency target signal; Based on the values ​​of the DC signals I2 and Q2, the amplitude and phase of the high-frequency target signal are calculated using the following formula: In the formula, A H represents the calculated value of the high-frequency target signal amplitude, θ H Represents the calculated value of the phase of the high-frequency target signal.

9. The method for identifying high-voltage live cables based on mixed frequency signals according to claim 1, characterized in that: The cable identification is completed based on the amplitude and phase of the target dual-frequency signal, including: The positive discrimination basis and the reverse discrimination basis are determined according to the phase relationship between the two frequencies of the dual-frequency signal; wherein, The positive discrimination basis is expressed as: In the formula, θ H represents the calculated value of the high-frequency target signal phase, represents the calculated value of the phase of the low-frequency target signal, m represents the ratio of the dual-frequency signal frequencies, k1, k2 = 0, ±1, ±2…; The reverse discrimination basis is expressed as: In the formula, k represents any integer; When the phase relationship of the dual-frequency signal satisfies the positive discrimination criterion, the signal waveform is in a positive phase, and the corresponding cable is identified as a target cable; When the phase relationship of the dual-frequency signals satisfies the reverse discrimination criterion, the signal waveform is inverted, and the corresponding cable is identified as an adjacent non-target cable.

10. A high-voltage live cable identification system based on mixed frequency signals, used to implement the method described in any one of claims 1 to 9, 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 collect 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 an industrial frequency noise signal; The analog-to-digital conversion module is used to perform analog-to-digital conversion processing 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 complete cable identification based on the amplitude and phase of the target dual-frequency signal.

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