Precise positioning method and system for grounding fault of photovoltaic array cable

Abstract

The invention relates to the technical field of photovoltaic power generation monitoring, in particular to a photovoltaic array cable grounding fault accurate positioning method and system. The method comprises the following steps: acquiring a fault original signal, converting the fault original signal into a digital sequence, and obtaining a fault transient power flow by using discrete time-frequency integration; obtaining soil physical parameters based on the geographic partition index, and obtaining a partition filling rate operator for measuring the construction speed of a grounding interface charge layer by utilizing dynamic mapping; utilizing a virtual work projection relational expression, taking the power flow as a weight and combining with operator aggregation to obtain a physical fault distance; and finally, acquiring a drawing arrangement length, determining a reference length by using an electrical ranging calibration method based on traveling wave velocity equivalence, and performing scaling correction by using a space-time correlation correction relational expression. According to the invention, accumulative errors caused by transient initial phase slippage and cable sag are effectively eliminated, and accurate positioning in a complex wiring environment is realized.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power generation monitoring technology, and in particular to a method and system for accurately locating grounding faults in photovoltaic array cables. Background Technology

[0002] During the operation and maintenance of photovoltaic power generation systems, cables are prone to grounding faults due to their long-term exposure to extreme outdoor environments. Currently, the industry's common methods for locating cable faults include using discrete voltage or current signals for preliminary judgment, or manually carrying large testing equipment to the site for power outage testing. These methods either lack sufficient accuracy to accurately pinpoint the fault location, or require interrupting the power generation process, resulting in significant economic losses.

[0003] Most current online monitoring technologies are based on static calculation models. These models typically assume that the electromagnetic reflection characteristics are constant at the time of a fault. They use preset cable lengths and propagation speed constants to estimate the fault distance. However, in actual photovoltaic array grounding operations, the charge movement at the grounding point is a dynamic evolution process. When a fault occurs, the charge at the grounding interface is not distributed instantaneously, but rather undergoes a diffusion process.

[0004] This dynamic evolution causes the reflection characteristics of electromagnetic waves to shift in real time according to the charge distribution state. Existing computational models cannot capture this microscopic dynamic change, resulting in a lack of real-time correspondence between the calculated values ​​and the actual physical location, thus causing positioning errors. Therefore, the fundamental problem with existing technology lies in using fixed computational logic to describe the constantly changing grounding physical process. This mismatch between the computational reference and the actual physical state is the core reason why grounding faults cannot be accurately located in the early stages. Summary of the Invention

[0005] To address the problem that existing positioning methods use fixed calculation models to describe changing grounding processes, resulting in discrepancies between the calculated reference benchmark and the actual physical state, and consequently causing positioning deviations in the early transient stages, making it impossible to accurately pinpoint the true location of the fault point, this invention provides a method and system for accurate positioning of grounding faults in photovoltaic array cables.

[0006] In a first aspect, the present invention provides a method for accurately locating grounding faults in photovoltaic array cables, employing the following technical solution:

[0007] A method for accurately locating grounding faults in photovoltaic array cables, comprising the following steps: The original voltage and current signals of the faulty phase of the photovoltaic array cable are obtained and converted into digital voltage and digital current sequences. The digital voltage and digital current sequences are then processed using the discrete time-frequency integral relationship to obtain the fault transient power flow. Based on the cable geographic partition index, the corresponding soil physical parameters are obtained, and the rate of change of the digital current sequence over time is obtained; using the dynamic mapping relationship, the rate of change of the digital current sequence is nonlinearly mapped based on the soil physical parameters to obtain a partition filling rate operator for measuring the construction speed of the charge layer at the grounding interface. Based on the fault transient power flow and the partition fill rate operator, the instantaneous distance components at different times are nonlinearly aggregated using the virtual work projection relationship to obtain the physical fault distance. The length of the photovoltaic array cable layout is obtained from the drawing. The reference length is determined by the electrical ranging calibration method based on the equivalent traveling wave velocity. The physical fault distance is proportionally scaled and corrected using the spatiotemporal correlation correction formula with the drawing layout length as the benchmark, and the final fault distance is output to achieve fault location.

[0008] This invention establishes dynamic correction parameters for the grounding interface by introducing a partitioned fill rate operator that reflects the charge migration characteristics of the grounding interface. Furthermore, the partitioned fill rate operator is used to compensate for offsets in transient signals, eliminating the influence of charge distribution evolution on the location results. This solves the problem that calculated parameters cannot correspond to the physical state in real time, significantly improving the reliability of grounding fault location for photovoltaic array cables.

[0009] Preferably, the step of using discrete time-frequency integral equations to calculate and process the digital voltage sequence and the digital current sequence to obtain the fault transient power flow specifically satisfies the following equation:

[0010] In the formula, Indicates the first Fault transient power flow at each sampling time; Indicates the number of data points in the sub-sampling window; Indicates the first Within the sampling time, the first sampling time in the sub-sampling window Voltage values ​​at each sampling point; Indicates the first Within the sampling time, the first sampling time in the sub-sampling window The current value at each sampling point.

[0011] This invention effectively eliminates the interference of environmental clutter on basic data through energy aggregation processing in the time domain, providing a highly stable energy reference benchmark for subsequent calculation of the partition filling rate operator, and ensuring the accuracy of the positioning starting point.

[0012] Preferably, the dynamic mapping relationship is as follows:

[0013] In the formula, Indicates the first The cable geographic zone in the first Partition fill rate operator for each sampling time; Indicates the first Electrode geometry correction factor for each cable geographic region; Indicates the first The cable geographic zone in the first Soil electrical conductivity at each sampling time; Indicates the first The cable geographic zone in the first Real-time absolute temperature at each sampling moment; Indicates the first The rate of change of the digital current sequence over time at each sampling moment; This indicates the preset zero-prevention parameter.

[0014] This invention enables a quantitative description of the charge layer formation rate at the ground interface, providing core parameter support for negative feedback compensation of phase slip.

[0015] Preferably, the method for determining the electrode geometry correction factor includes: Get the The grounding contact area of ​​cables in each cable geographic zone; Calculate the ratio of the grounding contact area to the unit standard electrode contact area, and determine the obtained ratio as the electrode geometry correction factor.

[0016] Preferably, the method of using the virtual work projection relationship to perform nonlinear aggregation processing on the instantaneous distance components at different times to obtain the physical fault distance specifically satisfies the following relationship:

[0017] In the formula, Indicates the first Physical fault distance of each cable geographic zone; Indicates the total length of the sampling time sequence; Indicates the first Fault transient power flow at each sampling time; Indicates the first The cable geographic zone in the first The instantaneous distance component at each sampling moment; This represents the preset dimension adjustment coefficient; Indicates the first The cable geographic zone in the first Partition fill rate operator for each sampling time; Indicates the sampling step size.

[0018] This invention enhances the weight of effective signal moments through energy-weighted logic and dynamically offsets the reflection displacement in the very early transient state using operator correction terms, significantly improving the convergence speed of the positioning results to the physical true location.

[0019] Preferably, the method for obtaining the final fault distance is as follows:

[0020] In the formula, Indicates the first The final fault distance for each cable geographic zone; Indicates the first Physical fault distance of each cable geographic zone; For the first Actual cable laying length for each geographical region; For the first Reference length for each geographic region; This represents the total number of geographical partitions covered by the current fault path; This is the preset sag compensation factor.

[0021] This invention introduces a real physical scale to calibrate the electrical measurement distance. By eliminating the influence of wave velocity deviation and cable laying redundancy, it ensures a strict correspondence between the positioning results and the on-site support number.

[0022] Preferably, the method for determining the reference length includes: The standard wave velocity is calculated using the cable unit length distribution parameters, combined with the sampling period and the first The reference length is calculated from the number of sampling points in each geographical region.

[0023] Preferably, the method for obtaining the instantaneous distance component includes: Obtain the time difference between the digital voltage sequence and the digital current sequence at the arrival time of the reflected wave; The instantaneous distance component at the corresponding moment is determined by multiplying the standard traveling wave velocity of the geographical region with the time difference.

[0024] Preferably, the number of data points in the sub-sampling window is determined in the following way: The discharge duration is determined based on the grounding resistance evolution rate, and the soil polarization time constant is determined based on the soil resistivity and dielectric constant. The expected transient duration is obtained by weighted summation of the discharge duration and the soil polarization time constant using the transient envelope energy equivalent method. The number of data points in the sub-sampling window is determined based on the product of the expected transient duration and the sampling frequency.

[0025] Secondly, this invention provides a precise location system for grounding faults in photovoltaic array cables, employing the following technical solution: A precise location system for grounding faults in photovoltaic array cables includes a processor and a memory. The memory stores computer program instructions, and when the computer program instructions are executed by the processor, the aforementioned precise location method for grounding faults in photovoltaic array cables is implemented.

[0026] By adopting the above technical solution, a computer program is generated for the above-mentioned method for accurately locating grounding faults in photovoltaic array cables, and stored in a memory so that it can be loaded and executed by a processor. Terminal equipment can then be made based on the memory and processor for convenient use.

[0027] The present invention has the following technical effects: This invention introduces a partitioned filling rate operator to measure the dynamic construction process of the charge layer at the ground interface, solving the long-standing problem of transient initial reflection phase slip in the industry from a mechanistic perspective, and enabling the positioning algorithm to perceive microscopic physical characteristics.

[0028] Furthermore, this invention fully considers the complex wiring environment of photovoltaic arrays. By introducing a drawing layout length and sag compensation factor to scale the preliminary calculation results, it eliminates the spatial cumulative error caused by the natural sag deviation of the cables. This calibration method based on a physical scale ensures that the final output directly corresponds to the on-site support position, achieving meter-level spatial positioning accuracy.

[0029] Furthermore, this invention uses a geographic zoning index to differentiate soil physical parameters for different zones and combines the principle of virtual work projection to perform energy trade-offs on transient power flows. This architecture enables the solution to automatically adapt to various complex geological conditions and maintain high stability and reproducibility even under strong electromagnetic noise interference.

[0030] This invention eliminates the virtual image and drift commonly found in traditional methods, enabling maintenance personnel to directly locate fault points based on the coordinates fed back by the system. This significantly shortens fault response time, avoids losses caused by blind excavation, and has significant economic benefits. Attached Figure Description

[0031] Figure 1This is a flowchart of a method for accurately locating grounding faults in photovoltaic array cables provided in an embodiment of the present invention; Figure 2 This is a fault transient power flow distribution diagram provided in an embodiment of the present invention; Figure 3 This is an evolution diagram of the partition filling rate operator provided in an embodiment of the present invention; Figure 4 This is a physical fault distance aggregation solution diagram provided in an embodiment of the present invention; Figure 5 This is a spatiotemporal correlation correction positioning result diagram provided in an embodiment of the present invention. Detailed Implementation

[0032] This invention discloses a method for accurately locating grounding faults in photovoltaic array cables, referring to... Figure 1 This includes steps S1-S4: S1: Obtain the original voltage and current signals of the faulty phase of the photovoltaic array cable, convert them into digital voltage and digital current sequences, and use the discrete time-frequency integral relationship to calculate and process the digital voltage and digital current sequences to obtain the fault transient power flow.

[0033] It should be noted that the energy release generated instantaneously during a photovoltaic array grounding fault exhibits highly non-stationary characteristics. Directly using conventional RMS extraction methods can easily lead to the loss of crucial transient energy evolution information due to sampling bias. Therefore, the core objective of this step is to perform discrete-time domain energy aggregation operations to construct a basic energy scale that reflects the transient energy characteristics.

[0034] Preferably, as an example, the original voltage and current signals of the faulty phase of the photovoltaic array cable are acquired, converted into digital voltage and current sequences, and the digital voltage and current sequences are processed using discrete time-frequency integral formulas to obtain the fault transient power flow, including: First, the original voltage signal and the original current signal are acquired by a high-frequency sampling module installed at the beginning of the photovoltaic array cable; then, the original voltage signal and the original current signal are digitized using an analog-to-digital converter to obtain a digital voltage sequence and a digital current sequence.

[0035] Next, using the discrete time-frequency integral relationship, the data within the preset sub-sampling windows of the digital voltage sequence and the digital current sequence are multiplied and summed to obtain the fault transient power flow. The discrete time-frequency integral relationship is specifically as follows:

[0036] In the formula, Indicates the first The fault transient power flow obtained at each sampling time; Indicates the number of sampling points in the sub-sampling window; Indicates the first Within the sampling time, the first sampling time in the sub-sampling window Voltage values ​​at each sampling point; Indicates the first Within the sampling time, the first sampling time in the sub-sampling window The current value at each sampling point.

[0037] Understandably, the product term This characterizes the energy conversion intensity at the fault point during microsecond-level sampling. By calculating the product of instantaneous voltage and current, it can accurately capture the minute peaks of energy fluctuations during transient processes, avoiding the smoothing effect caused by average power calculations. The summation calculation is responsible for time-domain aggregation of the energy from dispersed sampling points. Its logical significance lies in transforming random voltage fluctuations into a continuous energy flow description, reflecting the trend of total work done by the fault within the sampling window.

[0038] It should be noted that the method for obtaining the number of sampling points in the sub-sampling window includes: The raw current signal at the instant of a ground fault is acquired, and the frequency component with the highest energy intensity in the raw current signal is identified using a Fast Fourier Transform (FFT) and recorded as the characteristic frequency. According to the Nyquist sampling theorem, 5 to 10 times the characteristic frequency is set as the minimum sampling frequency required by the system to ensure that the steep rising edge of the charge excitation at the instant of grounding can be captured.

[0039] The evolution sequence of grounding resistance at the grounding fault point is obtained. The evolution rate of the grounding resistance is determined by calculating the slope of the change from the initial breakdown resistance value to the steady-state grounding resistance value. Using the transient waveform gradient detection method, the duration for which the rate of change of resistance in the evolution sequence is greater than a preset threshold is determined as the discharge duration.

[0040] The soil resistivity and dielectric constant of the zone where the fault point is located are obtained. The soil polarization time constant is calculated by multiplying the two, which characterizes the damping effect of the medium on charge migration. Simultaneously, the evolution rate of the cable grounding resistance is obtained, which characterizes the macroscopic time from breakdown to stabilization of the discharge trajectory.

[0041] The expected transient duration is obtained by weighted summation of the soil polarization time constant and the discharge duration using the transient envelope energy equivalent method. This duration fully covers the total time from electromagnetic excitation to the point where the charge distribution tends to physical equilibrium. The weighting logic is as follows: the weight corresponding to the discharge duration is set to be positively correlated with the rise steepness of the grounding current, used to characterize the contribution ratio of the macroscopic discharge process to the waveform energy; the weight corresponding to the soil polarization time constant is set to be negatively correlated with the soil moisture content, used to characterize the influence ratio of the microscopic polarization process on the waveform tail.

[0042] The initial suggested number of sampling points is obtained by multiplying the minimum sampling frequency by the expected transient duration, and then rounding this initial suggested number of sampling points up to obtain the number of sampling points in the sub-sampling window. Determined by this method The value ensures that the sub-sampling window can completely contain the holographic energy information of the grounding transient process, effectively solving the problems of information loss due to an excessively small window or feature submersion due to an excessively large window.

[0043] S2: Obtain the corresponding soil physical parameters based on the cable geographic partition index, and obtain the rate of change of the digital current sequence over time; using the dynamic mapping relationship, perform nonlinear mapping processing on the rate of change of the digital current sequence based on the soil physical parameters to obtain a partition filling rate operator for measuring the construction speed of the charge layer at the grounding interface.

[0044] It should be noted that the formation rate of the ground interface charge layer directly determines the electromagnetic wave reflection characteristics of the grounding point. Since photovoltaic power plants cover vast areas, the soil moisture and mineral composition vary significantly across different zones. These differences in physical environment directly alter the damping effect of the grounding medium on charge migration, leading to varying formation rates of the ground interface charge layer in different zones. Because the charge layer formation process causes dynamic evolution of the interface equivalent impedance, when the formation rate of the ground interface charge layer is slow, the reflected wave will exhibit significant phase slip. If the physical environmental characteristics of the zones are ignored, the positioning model will be unable to identify the reflection slip pattern caused by the differences in the formation rate of the ground interface charge layer. Therefore, the core objective of this step is to use the aforementioned soil physical parameters as environmental constraints to perform nonlinear correction on the rate of change of the digital current sequence characterizing energy excitation, thereby establishing a zoned filling rate operator that can accurately measure the formation rate of the ground interface charge layer and provide a compensation basis for subsequent elimination of phase slip.

[0045] Preferably, as an example, the corresponding soil physical parameters are obtained based on the cable geographic zoning index, and the rate of change of the digital current sequence over time is obtained; using a dynamic mapping relationship, the rate of change of the digital current sequence is nonlinearly mapped based on the soil physical parameters to obtain a zoning fill rate operator for measuring the rate of charge layer formation at the grounding interface, including: First, the geographic partition index is retrieved based on the location of the faulty cable, and the corresponding soil conductivity and real-time absolute temperature are extracted from the preset environmental database using the geographic partition index.

[0046] Next, the differential algorithm is used to differentiate the digital current sequence to obtain the rate of change of the digital current sequence over time.

[0047] Subsequently, using the dynamic mapping relationship and a preset electrode geometry correction factor, nonlinear mapping processing is performed on the rate of change of the digital current sequence over time, the soil conductivity, and the real-time absolute temperature to obtain the partitioned filling rate operator. The specific calculation method of the partitioned filling rate operator is as follows:

[0048] In the formula, Indicates the first The cable geographic zone in the first Partition fill rate operator for each sampling time; Indicates the first Electrode geometry correction factor for each cable geographic region; Indicates the first The cable geographic zone in the first Soil electrical conductivity at each sampling time; Indicates the first The cable geographic zone in the first Real-time absolute temperature at each sampling moment; Indicates the first The rate of change of the digital current sequence over time at each sampling moment; This is the preset zero-prevention parameter.

[0049] Understandably, the rate of change term At the molecular level, the original driving force for the excitation of interfacial charges is characterized. The steeper the rise of the fault current, the stronger the driving force of the generated electric field, which directly accelerates the construction speed of the grounding interfacial charge layer.

[0050] Damping term In the denominator, this term represents the macroscopic resistance of the medium to charge migration. When the soil conductivity or temperature increases, the ion mobility in the medium increases, and the migration damping decreases accordingly. This results in a significant increase in the calculated construction speed of the grounding interface charge layer under the same current excitation.

[0051] Logarithmic mapping functions are used to simulate the saturation effect of charge migration. Physically, the charge filling rate does not increase linearly with the current magnitude. Through logarithmic transformation, the nonlinear physical trajectory of charge layer construction from rapid bursts to steady saturation is accurately described.

[0052] Correction factor As a proportional term, it reflects the amplification or reduction effect of contact geometry on charge flux.

[0053] The resulting partition-fill rate operator couples the complex physical environment and dynamic current changes into a single rate index, the magnitude of which directly characterizes the rate of charge layer formation at the ground interface at the current moment. This operator will serve as the core correction factor in the next step of virtual work projection calculation, used to offset the positioning drift caused by phase slip in the initial transient phase.

[0054] It should be noted that the soil electrical conductivity is obtained in real time by sensors buried in each zone.

[0055] It should also be noted that the method for obtaining the electrode geometry correction factor includes: Get the The actual grounding contact area of ​​the cable in each cable geographical zone; calculate the ratio of the grounding contact area to the unit standard electrode contact area, and determine the obtained ratio as the electrode geometry correction factor.

[0056] S3: Based on the fault transient power flow and the partition filling rate operator, the instantaneous distance components at different times are nonlinearly aggregated using the virtual work projection relationship to obtain the physical fault distance.

[0057] It should be noted that due to phase slip caused by charge migration, the instantaneous distance calculated at different times often fluctuates drastically. Directly averaging the values ​​would result in severe positioning drift. This data characteristic means that the dynamically changing reflection path must be projected back into a stable geometric space using an energy-weighted method. Therefore, the core objective of this step is to use the principle of virtual work projection to determine the true physical location with the largest energy contribution.

[0058] Preferably, as an example, based on the fault transient power flow and the partition fill rate operator, the instantaneous distance components at different times are nonlinearly aggregated using the virtual work projection relation to obtain the physical fault distance, including: First, the time difference between the digital voltage sequence and the digital current sequence at the arrival time of the reflected wave is obtained; then, the instantaneous distance component at the corresponding moment is determined by multiplying the standard traveling wave velocity of the geographical region with the time difference.

[0059] Next, using the virtual work projection relation, with the fault transient power flow as the weighting coefficient and the partition filling rate operator as the core of the phase correction factor, the instantaneous distance component is weighted, accumulated, and normalized to obtain the physical fault distance, specifically satisfying the following relation:

[0060] In the formula, Indicates the first Physical fault distance of each cable geographic zone; Indicates the total length of the sampling time sequence; Indicates the first Fault transient power flow at each sampling time; Indicates the first The cable geographic zone in the first The instantaneous distance component at each sampling moment; This is a preset dimension adjustment coefficient; Indicates the first The cable geographic zone in the first Partition fill rate operator for each sampling time; This is the sampling step size.

[0061] Understandably, the weighted numerator... This reflects energy weighting and fault energy. The larger the time, the clearer the fault point characteristic signal it contains. Through the product operation, the sampling time with concentrated energy dominates the final positioning result, and the noise interference of weak signal time is automatically suppressed.

[0062] Index correction term This is the core logic for correcting phase slip. When the partition fill rate operator... When the value is large, the exponent term approaches 0, and the correction bracket term in the denominator... Approaching 1; this means that the positioning weight at that moment is amplified as the interface charge layer fills faster and tends to stabilize.

[0063] Denominator adjustment term By adjusting The effective weights achieve negative feedback compensation for the very early transient phase slip. When When the charge layer is small, it has not yet formed, the denominator becomes large, thus reducing the impact of the fault moment on the final result. Its contribution effectively solved the positioning drift problem caused by the dynamic displacement of the reflector.

[0064] S4: Obtain the layout length of the photovoltaic array cable in the drawing, determine the reference length using the electrical ranging calibration method based on the equivalent traveling wave velocity, and use the spatiotemporal correlation correction formula to scale and correct the physical fault distance using the layout length in the drawing as the benchmark, and output the final fault distance to achieve fault location.

[0065] It's important to note that the physical fault distance calculated in the previous step was based on assumed wave velocity and sampling time. However, on the construction site, cables naturally sag on supports and have curvature at bends, causing discrepancies between the computer-calculated distance and the actual measured distance on the ground, resulting in errors of several meters or even tens of meters. The core purpose of this step is to use the actual dimensions on the construction drawings as a ruler to scale the calculated physical fault distance back to the actual cable path.

[0066] Preferably, as an example, the length of the photovoltaic array cable layout on the drawing is obtained, a reference length is determined using an electrical ranging calibration method based on traveling wave velocity equivalence, and a spatiotemporal correlation correction formula is used to scale and correct the physical fault distance using the drawing layout length as a benchmark, outputting the final fault distance to achieve fault location, including:

[0067] In the formula, Indicates the first The final fault distance for each cable geographic zone; Indicates the first Physical fault distance of each cable geographic zone; For the first Actual cable laying length for each geographical region; For the first Reference length for each geographic region; This represents the total number of geographical partitions covered by the current fault path; This is the preset sag compensation factor.

[0068] Understandable, This reflects the conversion ratio between the actual physical distance in meters and the distance calculated by the algorithm. The initial distance... Multiplying by this conversion ratio eliminates the cumulative errors caused by cable sag, bending, and model wave velocity deviations, ensuring... It directly corresponds to the actual geographical location of the stent.

[0069] It should be noted that the methods for obtaining the reference length include: First, obtain the number The cable material parameters for each geographical region, including inductance and capacitance per unit length, are determined; the theoretical traveling wave velocity for that geographical region is calculated using the electromagnetic wave propagation speed formula. ; Next, obtain the sampling period. ; Finally, using relational expressions The reference length is calculated, where, This represents the number of sampling points for the corresponding regional partition.

[0070] To demonstrate the effectiveness of the solution, relevant experiments were conducted. Below are the images obtained from the experiments: Figure 2 This is a fault transient power flow distribution map. The horizontal axis represents the sampling time after the fault occurs, and the vertical axis represents the fault transient power flow. The image shows a clear nonlinear oscillating rise process, accurately capturing the energy conversion peak in the very early transient state. This rich temporal characteristic provides a high signal-to-noise ratio benchmark for subsequent localization.

[0071] Figure 3 The graph shows the evolution of the partitioned filling rate operator, with time on the horizontal axis and the partitioned filling rate operator on the vertical axis. The graph reveals that the curve starts at a high level, then declines in a wave-like pattern and eventually stabilizes, fully simulating the trajectory of the charge layer at the ground interface from rapid excitation and filling to dynamic equilibrium saturation. The fluctuations in the curve reflect the damping effect of the soil medium on charge migration, demonstrating that complex microscopic physical parameters have been transformed into quantifiable rate indicators.

[0072] Figure 4 This is a graph showing the aggregated solution of physical fault distance. The horizontal axis represents time, and the vertical axis represents distance. There are two main curves in the graph: the dashed line describes the instantaneous distance component calculated at the arrival time of the reflected wave; the solid line describes the physical fault distance after aggregation processing using the virtual work projection formula.

[0073] The image shows that although the instantaneous sampled values ​​fluctuate drastically due to phase slip, the aggregated curve converges rapidly and remains stable. This proves that the virtual power projection algorithm, which uses power flow as weight and the fill rate operator as the phase correction factor, can effectively suppress the positioning drift in the very early transient stage and project the dynamically changing reflection path back to a stable geometric space.

[0074] Figure 5 This is a map showing the spatiotemporal correlation-corrected location results. The horizontal axis represents time, and the vertical axis represents distance. The solid line describes the final fault distance sequence after topology correction; the dashed line describes the actual fault distance detected at the photovoltaic power station site.

[0075] The image shows that the final calculated fault distance curve, after convergence, perfectly coincides with the horizontal dashed line representing the actual location on site. This proves that by scaling the actual laying length to the reference length, the cumulative errors caused by cable sag, path curvature, and wave velocity deviation were successfully eliminated, achieving precise fault location within a meter-level accuracy range.

[0076] This invention also discloses a precise location system for grounding faults in photovoltaic array cables, including a processor and a memory. The memory stores computer program instructions, and when the computer program instructions are executed by the processor, a precise location method for grounding faults in photovoltaic array cables according to the present invention is implemented.

[0077] The system also includes other components well known to those skilled in the art, such as communication buses and communication interfaces, the settings and functions of which are known in the art and will not be described in detail here.

[0078] In this invention, the aforementioned memory can be any tangible medium containing or storing a program that can be used or combined with an instruction execution system, apparatus, or device. For example, a computer-readable storage medium can be any suitable magnetic or magneto-optical storage medium, such as resistive random access memory (DRAM), dynamic random access memory (DRAM), static random access memory (SRAM), enhanced dynamic random access memory (DRAM), high-bandwidth memory, hybrid memory cube, etc., or any other medium that can be used to store desired information and can be accessed by an application, module, or both. Any such computer storage medium can be part of a device or accessible to or connected to a device.

Claims

1. A method for accurately locating grounding faults in photovoltaic array cables, characterized in that, Including the following steps: The original voltage and current signals of the faulty phase of the photovoltaic array cable are obtained and converted into digital voltage and digital current sequences. The digital voltage and digital current sequences are then processed using the discrete time-frequency integral relationship to obtain the fault transient power flow. Based on the cable geographic zoning index, the corresponding soil physical parameters are obtained, and the rate of change of the digital current sequence over time is obtained. Using the dynamic mapping relationship, the rate of change of the digital current sequence is nonlinearly mapped based on the soil physical parameters to obtain a partitioned filling rate operator for measuring the construction speed of the charge layer at the grounding interface. Based on the fault transient power flow and the partition fill rate operator, the instantaneous distance components at different times are nonlinearly aggregated using the virtual work projection relationship to obtain the physical fault distance. The length of the photovoltaic array cable layout is obtained from the drawing. The reference length is determined by the electrical ranging calibration method based on the equivalent traveling wave velocity. The physical fault distance is proportionally scaled and corrected using the spatiotemporal correlation correction formula with the drawing layout length as the benchmark, and the final fault distance is output to achieve fault location.

2. The method for accurately locating grounding faults in photovoltaic array cables according to claim 1, characterized in that, The digital voltage sequence and the digital current sequence are calculated and processed using the discrete time-frequency integral relationship to obtain the fault transient power flow, which specifically satisfies the following relationship: In the formula, Indicates the first Fault transient power flow at each sampling time; Indicates the number of data points in the sub-sampling window; Indicates the first Within the sampling time, the first sampling time in the sub-sampling window Voltage values ​​at each sampling point; Indicates the first Within the sampling time, the first sampling time in the sub-sampling window The current value at each sampling point.

3. The method for accurately locating grounding faults in photovoltaic array cables according to claim 1, characterized in that, The specific dynamic mapping relationship is as follows: In the formula, Indicates the first The cable geographic zone in the first Partition fill rate operator for each sampling time; Indicates the first Electrode geometry correction factor for each cable geographic region; Indicates the first The cable geographic zone in the first Soil electrical conductivity at each sampling time; Indicates the first The cable geographic zone in the first Real-time absolute temperature at each sampling moment; Indicates the first The rate of change of the digital current sequence over time at each sampling moment; This indicates the preset zero-prevention parameter.

4. The method for accurately locating grounding faults in photovoltaic array cables according to claim 3, characterized in that, The method for determining the electrode geometry correction factor includes: Get the The grounding contact area of ​​cables in each cable geographic zone; Calculate the ratio of the grounding contact area to the unit standard electrode contact area, and determine the obtained ratio as the electrode geometry correction factor.

5. The method for accurately locating grounding faults in photovoltaic array cables according to claim 1, characterized in that, The instantaneous distance components at different times are nonlinearly aggregated using the virtual work projection relationship to obtain the physical fault distance, specifically satisfying the following relationship: In the formula, Indicates the first Physical fault distance of each cable geographic zone; Indicates the total length of the sampling time sequence; Indicates the first Fault transient power flow at each sampling time; Indicates the first The cable geographic zone in the first The instantaneous distance component at each sampling moment; This represents the preset dimension adjustment coefficient; Indicates the first The cable geographic zone in the first Partition fill rate operator for each sampling time; Indicates the sampling step size.

6. The method for accurately locating grounding faults in photovoltaic array cables according to claim 1, characterized in that, The method for obtaining the final fault distance is as follows: In the formula, Indicates the first Final fault distance for each cable geographic zone; Indicates the first Physical fault distance of each cable geographic zone; For the first Actual cable laying length for each geographical region; For the first Reference length for each geographic region; This represents the total number of geographical partitions covered by the current fault path; This is the preset sag compensation factor.

7. The method for accurately locating grounding faults in photovoltaic array cables according to claim 6, characterized in that, The methods for determining the reference length include: The standard wave velocity is calculated using the cable unit length distribution parameters, combined with the sampling period and the first The reference length is calculated from the number of sampling points in each geographical region.

8. The method for accurately locating grounding faults in photovoltaic array cables according to claim 5, characterized in that, The method for obtaining the instantaneous distance component includes: Obtain the time difference between the digital voltage sequence and the digital current sequence at the arrival time of the reflected wave; The instantaneous distance component at the corresponding moment is determined by multiplying the standard traveling wave velocity of the geographical region with the time difference.

9. The method for accurately locating grounding faults in photovoltaic array cables according to claim 2, characterized in that, The number of data points in the sub-sampling window is determined in the following way: The discharge duration is determined based on the grounding resistance evolution rate, and the soil polarization time constant is determined based on the soil resistivity and dielectric constant. The expected transient duration is obtained by weighted summation of the discharge duration and the soil polarization time constant using the transient envelope energy equivalent method. The number of data points in the sub-sampling window is determined based on the product of the expected transient duration and the sampling frequency.

10. A precise location system for grounding faults in photovoltaic array cables, characterized in that, include: A processor and a memory, wherein the memory stores computer program instructions that, when executed by the processor, implement a method for accurately locating grounding faults in photovoltaic array cables according to any one of claims 1-9.

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