A photovoltaic string cable tracing system and method based on conductor surface wave

Abstract

The application provides a photovoltaic string cable line searching system and method based on a conductor surface wave, which comprises a signal transmitter, a non-contact receiver and a high-frequency carrier signal. The signal transmitter is used for generating a high-frequency carrier signal and injecting the high-frequency carrier signal into a measured photovoltaic cable in a non-contact mode. The non-contact receiver is used for picking up the high-frequency signal flowing through the measured photovoltaic cable in a non-contact mode and sending a prompt when the high-frequency signal is identified. The high-frequency carrier signal is transmitted on the measured photovoltaic cable in the form of a conductor surface wave. The application realizes the long-distance identification and pairing tracing of a single cable without power-off and disconnection by injecting the high-frequency carrier signal in a non-contact mode, using the directional transmission of the conductor surface wave along the cable and picking up the leakage signal in a non-contact mode.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power plant operation and maintenance technology, and in particular to a photovoltaic string cable tracing system and method based on conductor surface waves. Background Technology

[0002] In the daily operation and maintenance of photovoltaic power plants, the number of DC cables of photovoltaic strings is huge, the laying path is long, and they are mostly arranged in a concentrated manner using cable trays, underground burial, and conduit. Due to long-term operation, the cable labels have aged and fallen off, the numbers are blurred, the wiring is chaotic, or due to human damage, construction errors, etc., dozens of red and black cables are often mixed on site, and it is impossible to intuitively distinguish which positive and negative wires belong to the same string, which brings great difficulties to fault diagnosis, string identification and maintenance. Currently, traditional maintenance methods for addressing this type of cable connection issue mainly rely on multimeter continuity testing. This requires disconnecting all string cables on the inverter side, short-circuiting the red and black wires, and then returning to the area where cables are mixed to test continuity one by one to determine if the positive and negative terminals belong to the same circuit. This method is cumbersome, labor-intensive, and requires power disconnection and cable removal, which not only severely affects power generation but also poses safety hazards such as short circuits and electric shocks in DC high-voltage environments. In addition, most commercially available cable locators use low-frequency magnetic field induction principles, which have poor resistance to DC bias and high-voltage interference. When the signal is transmitted along a single cable, it relies on a closed loop and cannot achieve stable long-distance transmission of a single cable. Furthermore, the signal attenuates severely in scenarios with shading such as underground installations and conduits, making it difficult to adapt to the long-distance, high-interference DC cable environment of photovoltaic power plants. Contact-type equipment requires stripping the insulation layer, which can easily damage the cable and introduce new fault points. Therefore, there is currently no cable tracing system in this field that is specifically designed for photovoltaic string scenarios, requires no power outage or cable disconnection, is non-contact, and can achieve long-distance traceability of a single cable. Summary of the Invention

[0003] This invention aims to provide a photovoltaic string cable tracing system and method based on conductor surface waves. By injecting high-frequency carrier signals in a non-contact manner, the system utilizes conductor surface waves to transmit directionally along the cable and picks up leakage signals in a non-contact manner, thereby achieving long-distance identification, pairing, and tracing of single cables without the need for power outages or cable disconnection.

[0004] On one hand, the present invention provides a photovoltaic string cable tracing system based on conductor surface waves, comprising: A signal transmitter is used to generate a high-frequency carrier signal and inject the high-frequency carrier signal into the photovoltaic cable under test in a non-contact manner. A non-contact receiver is used to pick up high-frequency signals flowing through the photovoltaic cable under test in a non-contact manner, and to issue a prompt when the high-frequency signal is detected; The high-frequency carrier signal is transmitted on the photovoltaic cable under test in the form of a conductor surface wave.

[0005] Preferably, the signal transmitter includes: A high-frequency oscillation unit is used to generate a high-frequency carrier signal at a specific frequency. A coupling plate, connected to the output terminal of the high-frequency oscillation unit, is used to inject the high-frequency carrier signal into the conductor of the photovoltaic cable under test by capacitive coupling. An isolation coupling unit is connected between the high-frequency oscillation unit and the coupling plate to achieve electrical isolation.

[0006] Preferably, the signal transmitter further includes: The main control unit is used to control the start and stop of the signal transmitter and the signal mode, and output the corresponding trigger signal to the high-frequency oscillation unit; A power amplifier unit, connected to the high-frequency oscillation unit, is used to amplify the power of the high-frequency carrier signal.

[0007] Preferably, the contactless receiver includes: A sensing probe is used to non-contactly pick up the high-frequency carrier signal transmitted on the surface of the photovoltaic cable under test; A frequency selective filtering unit, connected to the sensing probe, is used to filter out interference signals and retain only the high-frequency carrier signal with the same frequency as that emitted by the signal transmitter; A signal amplification unit, connected to the frequency selective filtering unit, is used to amplify the filtered weak high-frequency carrier signal. The detection unit, connected to the signal amplification unit, is used to demodulate the amplified high-frequency carrier signal and extract signal features; An audible and visual alarm unit is connected to the output terminal of the detector unit and is used to issue an audible and visual alarm when a valid signal is received.

[0008] Preferably, the detection unit is an envelope detection unit, and the contactless receiver further includes: A comparison driving unit is connected between the envelope detection unit and the audio-visual prompting unit. It is used to compare the detected signal characteristics with a preset threshold and drive the audio-visual prompting unit to work when it is determined that a valid signal exists.

[0009] On the other hand, the present invention provides a method for tracing photovoltaic string cables based on conductor surface waves, comprising the following steps: On the inverter side, the coupling plate of the signal transmitter is attached to the outside of the insulation layer of a cable of the photovoltaic string to be searched, and the signal transmitter is turned on to inject a high-frequency carrier signal. Scan multiple candidate cables remotely using a contactless receiver; When the contactless receiver approaches the target cable and picks up the high-frequency carrier signal, it issues a prompt to identify the same cable connected to the signal transmitter.

[0010] Preferably, the line-finding method also includes: After identifying the first cable connected to the signal transmitter, the coupling plate of the signal transmitter is switched to the outside of the insulation layer of the second cable, which corresponds to the first cable in the same input circuit on the inverter side, and the signal transmitter is turned on to inject a high-frequency carrier signal into the second cable. At a remote end, the contactless receiver is used to scan multiple candidate cables again to identify the target cable corresponding to the second cable. Based on the association between the first cable and the second cable on the inverter side corresponding to the same input circuit, the identified first cable and second cable are determined to be the positive and negative pole matching cables of the same photovoltaic string.

[0011] Preferably, before attaching the coupling plate of the signal transmitter to the outside of the insulation layer of a cable of the photovoltaic string to be located on the inverter side and turning on the signal transmitter to inject a high-frequency carrier signal, a breakpoint distance prediction step is further included: The coupling plate of the signal transmitter is attached to the outside of the insulation layer of the string cable to be searched. The main control unit switches the signal transmitter to pulse mode. The main control unit controls the high-frequency oscillation unit to generate a rectangular pulse signal, which is injected into the photovoltaic cable under test in a non-contact manner with capacitive coupling through the coupling plate. The rectangular pulse signal is transmitted to the far end along the photovoltaic cable under test in the form of a conductor surface wave. When the transmission reaches the break point, a reflected echo signal is generated. The reflected echo signal returns to the signal injection end along the original path. The induction probe of the contactless receiver picks up the reflected echo signal at the signal injection end and sends the picking timestamp to the main control unit; The main control unit compares the start time of the transmitted rectangular pulse signal with the arrival time of the reflected echo signal and records the time interval between the two. The main control unit calculates the distance from the signal injection end to the breakpoint based on the time interval and the propagation speed of the rectangular pulse signal on the cable under test, and outputs the predicted location of the breakpoint. ,include:

[0012]

[0013]

[0014] In the formula, The equivalent relative permittivity is the surface wave propagation constant of the photovoltaic cable conductor under test. The relative permittivity of the insulation layer of the cable under test is . The thickness of the insulation layer of the cable being tested. The diameter of the conductor of the cable being tested. This is the geometric correction factor. This represents the theoretical propagation speed of a rectangular pulse signal on the cable under test. The speed of electromagnetic wave propagation in a vacuum. The time interval is the specified time interval.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The signal transmitter in this invention injects signals via capacitive coupling through a coupling plate, and the receiver picks them up non-contactly using an inductive probe. The entire process requires no wire disconnection, stripping, or power interruption, completely avoiding the risks of short circuits and electric shocks under high DC voltage. Utilizing the skin effect of surface waves on high-frequency conductors, long-distance transmission is possible through a single cable. Signal energy can penetrate insulation layers and leak outwards, unaffected by obstructions from underground installations, conduits, or cable trays, making it suitable for long-distance scenarios of hundreds of meters in photovoltaic power plants. Simultaneously, maintenance personnel can quickly locate target cables by scanning along the cable route with a handheld receiver, reducing connection time and minimizing power generation losses. This invention is specifically designed for photovoltaic DC string cables, effectively solving the problem of unidentifiable cables due to confusing markings or malicious cutting, and can cover the cable inspection and traceability needs of centralized, string, and commercial / industrial photovoltaic power plants.

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention, but do not constitute a limitation thereof; in the drawings: Figure 1 This is a schematic diagram of the structure of the photovoltaic string cable tracing system provided in this embodiment; Figure 2 This is a flowchart illustrating the photovoltaic string cable tracing method provided in this embodiment; Figure 3 This is a flowchart illustrating the interruption point distance prediction operation of the photovoltaic string cable tracing method provided in this embodiment. Detailed Implementation

[0018] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention. This embodiment provides a photovoltaic string cable tracing system and method based on conductor surface waves, which is applied to scenarios in photovoltaic power plants where the corresponding relationships of string cables cannot be identified due to reasons such as cable label detachment, human damage, or messy wiring.

[0019] Example 1: Please refer to Figure 2 A photovoltaic string cable tracing system based on conductor surface waves includes a signal transmitter and a non-contact receiver; The signal transmitter is used to generate a high-frequency carrier signal and inject the high-frequency carrier signal into the photovoltaic cable under test in a non-contact manner; the non-contact receiver is used to pick up the high-frequency signal flowing through the photovoltaic cable under test in a non-contact manner and issue a prompt when the high-frequency signal is detected; wherein, the high-frequency carrier signal is transmitted on the photovoltaic cable under test in the form of a conductor surface wave. The so-called surface wave of a conductor refers to a high-frequency electromagnetic wave that, under the influence of the skin effect, is concentrated in an extremely thin layer near the interface between the conductor and the insulation layer and propagates directionally along the surface of the conductor. Its propagation does not depend on a closed loop, and a single cable can achieve stable long-distance signal transmission. Moreover, the signal energy can penetrate the insulation layer and leak outward, thus being picked up by an external non-contact receiver.

[0020] In a preferred embodiment, the signal transmitter includes: A high-frequency oscillation unit is used to generate a high-frequency carrier signal at a specific frequency. The coupling plate is connected to the output of the high-frequency oscillation unit and is used to inject the high-frequency carrier signal into the conductor of the photovoltaic cable under test by capacitive coupling. Capacitive coupling refers to a non-contact transmission method in which signal energy is transferred between two mutually insulated conductors through an electric field. There is a distributed capacitance between the two conductors. When the voltage on one conductor changes, a corresponding electrical signal is induced on the other conductor through the charging and discharging effect of the capacitor.

[0021] In the application scenario of this embodiment, the specific implementation method of capacitive coupling is as follows: The coupling plate of the signal transmitter (usually an arc-shaped or flat metal electrode) serves as the first electrode, the copper conductor inside the photovoltaic cable under test serves as the second electrode, and the cable insulation layer between the two serves as the coupling medium. The three together constitute a coupling capacitor. When the signal transmitter outputs a high-frequency carrier signal to the coupling plate, the high-frequency alternating voltage on the coupling plate passes through the equivalent capacitor and induces a high-frequency charge oscillation of the same frequency on the surface of the copper conductor, thereby injecting the high-frequency carrier signal into the cable conductor in a non-contact, non-physical connection manner. This process does not require stripping the insulation layer or direct contact of the conductor with metal contacts, thus realizing signal input under safe isolation conditions. An isolation coupling unit is connected between the high-frequency oscillation unit and the coupling plate to achieve electrical isolation, prevent high-frequency carrier signals from interfering with the DC bus of the photovoltaic system, and protect the internal circuitry of the signal transmitter. The main control unit is used to control the start and stop of the signal transmitter and the signal mode, and outputs the corresponding trigger signal to the high-frequency oscillation unit. In a preferred embodiment, the signal mode includes at least two modes: continuous carrier mode and pulse mode. The power amplifier unit, connected to the high-frequency oscillation unit, is used to amplify the power of the high-frequency carrier signal to increase the transmission distance, making it suitable for long-distance cable scenarios of hundreds of meters in photovoltaic power plants.

[0022] In a preferred embodiment, the contactless receiver includes: The induction probe is used to non-contactly pick up the high-frequency carrier signal transmitted on the surface of the photovoltaic cable under test. The induction probe adopts a capacitive plate or inductive coil structure. When in use, it is close to the surface of the cable insulation layer to inductively pick up the leaked high-frequency carrier signal. The frequency selective filtering unit, connected to the sensing probe, is used to filter out interference signals and retain only the high-frequency carrier signal with the same frequency as the signal transmitter. It can be implemented using a narrowband bandpass filter or a phase-locked loop circuit. The signal amplification unit, connected to the frequency selective filtering unit, is used to amplify the weak high-frequency carrier signal after filtering. The detector unit, connected to the signal amplification unit, is used to demodulate the amplified high-frequency carrier signal and extract signal features; the audible and visual alarm unit, connected to the output of the detector unit, is used to issue an audible and visual alarm when a valid signal is received. The detection unit is an envelope detection unit, used to extract the envelope waveform from the amplitude-modulated signal and restore the original modulation characteristics. The contactless receiver also includes a comparison drive unit, connected between the envelope detection unit and the audio-visual prompt unit, used to compare the detected signal characteristics with a preset threshold, and drive the audio-visual prompt unit to work when a valid signal is detected. The preset threshold is manually adjusted by the maintenance personnel according to the specific frequency of the high-frequency carrier signal.

[0023] The above embodiments provide a non-contact photovoltaic string cable tracing system based on conductor surface waves. A high-frequency carrier signal is injected non-contactly through a signal transmitter using capacitive coupling. The conductor surface waves are then transmitted over long distances along the cable. A non-contact receiver picks up the surface leakage field and issues an audible and visual alert. This solves the problems of traditional cable tracing methods, which require power disconnection and cable removal, rely on closed loops, are cumbersome to operate, and pose safety hazards. As a result, it achieves single-strand, non-contact, long-distance, and highly efficient identification and tracing of photovoltaic DC cables.

[0024] Example 2: Please refer to Figure 2This embodiment provides a photovoltaic string cable tracing method based on conductor surface waves, using the system of Embodiment 1. It is applied to scenarios where the cut location is determined and only the string correspondence needs to be identified from a jumbled cable. In this case, the main control unit selects a continuous carrier mode, including the following steps: On the inverter side, attach the coupling plate of the signal transmitter to the outside of the insulation layer of a cable of the photovoltaic string to be searched, and turn on the signal transmitter to inject a high-frequency carrier signal. Use a contactless receiver at a remote location to scan for multiple candidate cables at the cut point; When the contactless receiver approaches the target cable and picks up the high-frequency carrier signal, it issues a prompt to identify the same cable connected to the signal transmitter. After identifying the first cable connected to the signal transmitter, the coupling plate of the signal transmitter is switched to the outside of the insulation layer of the second cable, which corresponds to the first cable in the same input circuit on the inverter side, and the signal transmitter is turned on to inject a high-frequency carrier signal into the second cable. At a remote location, a non-contact receiver is used to scan multiple candidate cables again to identify the target cable corresponding to the second cable. Based on the association between the first and second cables on the inverter side corresponding to the same input circuit, the identified first and second cables are determined to be the positive and negative pole paired cables of the same photovoltaic string.

[0025] Similarly, the above steps can be repeated for the photovoltaic string side to achieve full-path string cable matching and tracing from the module side to the inverter side, and fully restore the entire string's path.

[0026] Example 3: This example provides a method for tracing photovoltaic string cables based on conductor surface waves. Using the system of Example 1, if the cut-off location is uncertain, maintenance personnel can use a handheld non-contact receiver to scan along the cable trench in the photovoltaic field, underground pipe opening, and cable tray location. When the non-contact receiver suddenly changes from a continuous alarm state to a silent state, or from a silent state to a continuous alarm state, the signal transition point is the cut-off location. In a preferred embodiment, please refer to Figure 3 To further improve screening efficiency and reduce the scope of blind scanning, this embodiment performs a breakpoint distance prediction operation before the method provided in Embodiment 2, including the following steps: On the inverter side, the coupling plate of the signal transmitter is attached to the outside of the insulation layer of the string cable to be searched. The main control unit switches the signal transmitter to pulse mode; the main control unit controls the high-frequency oscillation unit to generate a pulse with a width of [missing information]. The rectangular pulse signal is amplified by the power amplifier unit and then injected into the photovoltaic cable under test in a non-contact manner via a coupling plate using capacitive coupling. The rectangular pulse signal is transmitted to the far end along the photovoltaic cable under test in the form of a conductor surface wave. When it reaches the break point, the impedance changes abruptly due to the conductor interruption, that is, it changes from the characteristic impedance of the cable to an open circuit. The pulse signal generates a reflected echo at the impedance change point, and the reflected echo returns to the signal injection end along the original path. The induction probe of the contactless receiver picks up the reflected echo signal near the injection end and sends the pickup timestamp to the main control unit; The main control unit records the time interval between the start time of the transmitted pulse and the arrival time of the reflected echo. The unit is seconds (s). Predict the breakpoint distance using the following formula. :

[0027]

[0028]

[0029] in, Let be the equivalent relative permittivity of the surface wave propagation in the photovoltaic cable conductor under test. Since the electromagnetic field of high-frequency surface waves is not entirely confined within the insulation layer but is simultaneously distributed in the insulation layer and the external air, the actual permittivity experienced by the surface wave is a weighted mixture of the dielectric constant of the insulation layer and the dielectric constant of the air; where, The relative permittivity of the insulation layer of the photovoltaic cable under test can be obtained directly from the table in the cable specification book. The typical value for XLPE insulation material is 2.3. The thickness of the insulation layer of the photovoltaic cable under test is expressed in meters (m) and can be obtained from the cable specification sheet. The diameter of the conductor of the photovoltaic cable under test is in meters (m), which can be obtained from the cable specification sheet. Equivalent relative permittivity It is derived by summing the base value and the correction increment, as shown in the formula. In the middle, the first item It is the arithmetic mean of the dielectric constants of the insulating layer and air, representing the equivalent dielectric constant when the electromagnetic field energy is uniformly distributed in the two media, and serves as the benchmark for the entire weighted averaging process; This represents an upward correction to the baseline, pulling the equivalent dielectric constant from the average value to a value closer to that of the insulating layer itself. ; Here is the geometric correction factor, where The ratio of insulation thickness to conductor width represents the geometric characteristics of the cable. The larger the ratio, the thicker the insulation layer and the easier it is for the electromagnetic field to diffuse into the outside air. The smaller the ratio, the thinner the insulation layer and the easier it is for the electromagnetic field to be trapped inside the insulation layer. This represents the geometric correction factor, which determines the rate at which changes in geometric structure correct the equivalent dielectric constant. A value of 12 is preferred. The exponent represents a function relating the square root to the reciprocal, and this exponent causes the geometric correction factor to... When the value approaches 1, that is, the electromagnetic field is completely confined within the insulating layer. When the value approaches 0, the electromagnetic field energy is evenly distributed between the insulating layer and the air.

[0030] The theoretical propagation speed of high-frequency surface waves on the photovoltaic cable under test is expressed in m / s. The speed of electromagnetic wave propagation in a vacuum; The predicted distance from the signal injection point to the breakpoint is in meters. Based on the distance of the breakpoint Maintenance personnel travel along the cable trench laying path to the vicinity of the predicted location, then switch the signal transmitter to continuous carrier mode, and use a handheld non-contact receiver to perform a precise scan near the predicted location, confirming the precise location of the breakpoint through audio and visual prompts. After the breakpoint is accurately located, signals are injected sequentially and corresponding cables are identified one by one according to the method in Example 2 to complete the positive and negative pole pairing.

[0031] In a preferred embodiment, the pulse width of the rectangular pulse signal and repetition cycle The following constraints must be met to ensure the resolution and unambiguous measurement range of the ranging system: , The preset minimum resolvable breakpoint distance ensures that when the breakpoint distance is less than... At this time, the reflected echo will not overlap with the transmitted pulse, thus ensuring that the near-end blind zone does not exceed the design value; , The preset maximum detection range ensures that all reflected echoes within the maximum detection range return to the receiver before the next transmission pulse is emitted, thus avoiding ambiguity in distance measurement.

[0032] This embodiment solves the technical problems of traditional cable tracing methods, which require blindly scanning along the cable laying path, resulting in a large search area and long time consumption when the cut location is unknown. Maintenance personnel can first obtain the distance value between the cut point and the injection end, and then go directly to the predicted location for precise point-to-point investigation, reducing the search range from the entire power station area to a range of tens of meters near the predicted point, thereby improving the efficiency of cable cut point location.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A photovoltaic string cable tracing system based on conductor surface waves, characterized in that, include: A signal transmitter is used to generate a high-frequency carrier signal and inject the high-frequency carrier signal into the photovoltaic cable under test in a non-contact manner. A non-contact receiver is used to pick up high-frequency signals flowing through the photovoltaic cable under test in a non-contact manner, and to issue a prompt when the high-frequency signal is detected; The high-frequency carrier signal is transmitted on the photovoltaic cable under test in the form of a conductor surface wave.

2. The photovoltaic string cable tracing system based on conductor surface waves according to claim 1, characterized in that, The signal transmitter includes: A high-frequency oscillation unit is used to generate a high-frequency carrier signal at a specific frequency. A coupling plate, connected to the output terminal of the high-frequency oscillation unit, is used to inject the high-frequency carrier signal into the conductor of the photovoltaic cable under test by capacitive coupling. An isolation coupling unit is connected between the high-frequency oscillation unit and the coupling plate to achieve electrical isolation.

3. The photovoltaic string cable tracing system based on conductor surface waves according to claim 2, characterized in that, The signal transmitter also includes: The main control unit is used to control the start and stop of the signal transmitter and the signal mode, and output the corresponding trigger signal to the high-frequency oscillation unit; A power amplifier unit, connected to the high-frequency oscillation unit, is used to amplify the power of the high-frequency carrier signal.

4. The photovoltaic string cable tracing system based on conductor surface waves according to claim 1, characterized in that, The contactless receiver includes: A sensing probe is used to non-contactly pick up the high-frequency carrier signal transmitted on the surface of the photovoltaic cable under test; A frequency selective filtering unit, connected to the sensing probe, is used to filter out interference signals and retain only the high-frequency carrier signal with the same frequency as that emitted by the signal transmitter; A signal amplification unit, connected to the frequency selective filtering unit, is used to amplify the filtered weak high-frequency carrier signal. The detection unit, connected to the signal amplification unit, is used to demodulate the amplified high-frequency carrier signal and extract signal features; An audible and visual alarm unit is connected to the output of the detector unit and is used to issue an audible and visual alarm when a valid signal is received.

5. The photovoltaic string cable tracing system based on conductor surface waves according to claim 4, characterized in that, The detection unit is an envelope detection unit, and the contactless receiver further includes: A comparison driving unit is connected between the envelope detection unit and the audio-visual prompting unit. It is used to compare the detected signal characteristics with a preset threshold and drive the audio-visual prompting unit to work when it is determined that a valid signal exists.

6. The photovoltaic string cable tracing system based on conductor surface waves according to claim 3, characterized in that, The signal modes include at least continuous carrier mode and pulse mode.

7. A method for tracing photovoltaic string cables based on surface wave propagation, applied to the system described in any one of claims 1 to 6, characterized in that, Includes the following steps: On the inverter side, the coupling plate of the signal transmitter is attached to the outside of the insulation layer of a cable of the photovoltaic string to be searched, and the signal transmitter is turned on to inject a high-frequency carrier signal. Scan multiple candidate cables remotely using a contactless receiver; When the contactless receiver approaches the target cable and picks up the high-frequency carrier signal, it issues a prompt to identify the same cable connected to the signal transmitter.

8. The photovoltaic string cable tracing method based on conductor surface waves according to claim 7, characterized in that, Also includes: After identifying the first cable connected to the signal transmitter, the coupling plate of the signal transmitter is switched to the outside of the insulation layer of the second cable, which corresponds to the first cable in the same input circuit on the inverter side, and the signal transmitter is turned on to inject a high-frequency carrier signal into the second cable. At a remote end, the contactless receiver is used to scan multiple candidate cables again to identify the target cable corresponding to the second cable. Based on the association between the first cable and the second cable on the inverter side corresponding to the same input circuit, the identified first cable and second cable are determined to be the positive and negative pole matching cables of the same photovoltaic string.

9. The photovoltaic string cable tracing method based on conductor surface waves according to claim 7, characterized in that, Before attaching the coupling plate of the signal transmitter to the outside of the insulation layer of a cable of the photovoltaic string to be located on the inverter side and turning on the signal transmitter to inject a high-frequency carrier signal, a breakpoint distance prediction step is also included: The coupling plate of the signal transmitter is attached to the outside of the insulation layer of the string cable to be searched. The main control unit switches the signal transmitter to pulse mode. The main control unit controls the high-frequency oscillation unit to generate a rectangular pulse signal, which is injected into the photovoltaic cable under test in a non-contact manner with capacitive coupling through the coupling plate. The rectangular pulse signal is transmitted to the far end along the photovoltaic cable under test in the form of a conductor surface wave. When the transmission reaches the break point, a reflected echo signal is generated. The reflected echo signal returns to the signal injection end along the original path. The induction probe of the contactless receiver picks up the reflected echo signal at the signal injection end and sends the picking timestamp to the main control unit; The main control unit compares the start time of the transmitted rectangular pulse signal with the arrival time of the reflected echo signal and records the time interval between the two. The main control unit calculates the distance from the signal injection end to the breakpoint based on the time interval and the propagation speed of the rectangular pulse signal on the cable under test, and outputs the predicted location of the breakpoint. ,include: In the formula, The equivalent relative permittivity is the surface wave propagation constant of the photovoltaic cable conductor under test. The relative permittivity of the insulation layer of the cable under test is denoted as . The thickness of the insulation layer of the cable being tested. The diameter of the conductor of the cable being tested. This is the geometric correction factor. This represents the theoretical propagation speed of a rectangular pulse signal on the cable under test. The speed of electromagnetic wave propagation in a vacuum. The time interval is the specified time interval.

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