Photovoltaic array ground fault fast detection and location device

Abstract

The embodiment of the application relates to the field of new energy power generation control of a power system, in particular to a photovoltaic array ground fault rapid detection and positioning device, which comprises a fault signal acquisition unit, a fault feature extraction unit, a distributed positioning unit and a main control unit; wherein the fault signal acquisition unit covers different areas of a direct current bus and a grounding net through double-interface synchronization, ensures the comprehensiveness of fault feature information acquisition, the fault feature extraction unit generates standardized characteristic values based on multidimensional global parameters, avoids the limitation of single impedance parameter analysis, and the distributed positioning unit realizes full-link coverage of head and tail ends and intermediate nodes through a component string multi-node interface, can accurately lock the specific component string and node position where the fault is located after receiving a positioning instruction, and solves the pain point that the prior art can only preliminarily identify a fault area and cannot meet precise operation and maintenance disposal.

Description

Technical Field

[0001] This invention relates to the field of power system technology, and in particular to a rapid detection and location device for grounding faults in photovoltaic arrays. Background Technology

[0002] In recent years, the global energy transition has accelerated, and the photovoltaic (PV) industry, as a core pillar of clean energy utilization, has achieved rapid development on a large scale and at high density. The installation scenarios for PV arrays have expanded from centralized power plants to distributed rooftops, mountainous and hilly environments, and other complex conditions. During operation, PV arrays are highly susceptible to grounding faults due to factors such as component aging, severe weather (e.g., thunderstorms, high temperature and humidity), mechanical wear, and interference from external objects. These faults can not only cause equipment damage such as component burnout and inverter shutdown, but also pose significant safety hazards such as electric shock and fire, while also leading to a substantial decrease in the power generation efficiency of the PV system, resulting in significant economic losses. Therefore, achieving rapid detection and accurate location of grounding faults in PV arrays is a core technological requirement for ensuring the safe and stable operation of PV systems and improving operation and maintenance efficiency, and it has important practical significance for promoting the high-quality development of the PV industry.

[0003] Currently, various technical solutions have been developed in the field of photovoltaic array grounding fault detection. The mainstream existing technologies mainly fall into two categories: one is the insulation resistance detection method, which monitors the insulation resistance value of the photovoltaic array to ground, and determines a fault when the resistance is lower than a set threshold; the other is impedance analysis-based detection technology, which collects the output impedance parameters of the photovoltaic array, combines them with the impedance model during normal system operation, and identifies and initially locates the fault by comparing differences. While these two methods provide some support for photovoltaic array grounding fault detection, they still have many shortcomings in practical applications that urgently need to be addressed: the insulation resistance detection method has a slow response speed, requires regular manual inspections, and suffers from a significant lag in fault detection, making it difficult to meet the needs of rapid fault handling; the impedance analysis-based detection technology has poor adaptability. The varying number of series-connected components in distributed photovoltaic arrays, the output imbalance caused by shading, and the differences in electrical parameters between components from different manufacturers can significantly reduce the accuracy of the impedance analysis model, leading to high false positive and false negative rates, making it difficult to meet the needs of accurate monitoring and rapid processing. These shortcomings severely restrict the timeliness and effectiveness of photovoltaic array grounding fault handling, necessitating a breakthrough with a new type of detection and location device.

[0004] Therefore, how to develop a photovoltaic array grounding fault detection and location device that is fast-responding, highly adaptable, and accurately positioned to overcome existing technological bottlenecks is an urgent problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide at least one device for rapid detection and location of grounding faults in photovoltaic arrays, which is characterized by rapid response, strong adaptability, and accurate location of grounding faults in photovoltaic arrays.

[0006] To address the aforementioned technical problems, at least one embodiment of this application provides a rapid detection and location device for photovoltaic array grounding faults, comprising: a fault signal acquisition unit, a fault feature extraction unit, a distributed location unit, and a main control unit; The input end of the fault signal acquisition unit is connected to the positive and negative DC bus of the photovoltaic array through the DC bus interface, and to different areas of the photovoltaic array grounding grid through the grounding grid partition interface. It is used to acquire the global operating parameters of the DC bus and different areas of the grounding grid. The output end is connected to the input end of the fault feature extraction unit. The fault feature extraction unit extracts fault features based on the global operating parameters and generates feature values. The main control unit is connected to the fault feature extraction unit at one end and to the distributed positioning unit at the other end, and is used to determine the fault based on the feature value; if a grounding fault is detected, a fault positioning command is sent to the distributed positioning unit; if the fault positioning information is received, the positioning information is sent to the external monitoring equipment. The distributed positioning unit is connected to the beginning and end of each photovoltaic module string and at least two intermediate nodes through the component string multi-node interface. After receiving the fault positioning command, it collects the local operating parameters of the beginning and end of each photovoltaic module string and the intermediate nodes, performs fault positioning based on the local operating parameters, generates the positioning information, and feeds the positioning information back to the main control unit.

[0007] In one embodiment, the fault signal acquisition unit has a built-in channel switching switch and a partition potential detection module; The input terminal of the partition potential detection module is connected to the grounding grid partition interface, and is used to collect the potential of each partition of the grounding grid and send it to the main control unit; The main control unit is also used to calculate the potential difference based on the potential of each zone of the grounding grid, and determine whether there is a high-risk zone with a potential difference exceeding a preset threshold; if so, it determines the access object of the acquisition channel from the high-risk zone, generates the corresponding object switching instruction and sends it to the channel switching switch. The input terminal of the channel switching switch is connected to each independent access terminal of the grounding grid partition interface, and the output terminal is connected to the internal acquisition channel of the fault signal acquisition unit. It is used to receive the object switching command and switch the conduction relationship between the target access terminal of the grounding grid partition interface and the internal acquisition channel according to the object switching command.

[0008] In one embodiment, the signal input terminal of the fault signal acquisition unit has a built-in impedance adjustment chip; The two signal pins of the impedance adjustment chip are respectively connected to the positive conductive core and the negative conductive core of the signal input terminal, and the control pin of the impedance adjustment chip is connected to the main control unit. The main control unit is further configured to calculate the impedance matching deviation value based on the impedance characteristics of the acquired signal and the preset standard value of the output impedance of the photovoltaic array, and generate a corresponding adjustment command, and adjust the programmable gain and / or internal matching resistor network configuration parameters of the impedance adjustment chip according to the adjustment command.

[0009] In one embodiment, the signal input terminal of the fault signal acquisition unit is wrapped with a metal shielding layer. One end of the metal shielding layer is injection molded and fixed to the insulating shell of the input terminal, and the other end is bolted to the common grounding terminal of the grounding grid partition interface to block external electromagnetic interference.

[0010] In one embodiment, the main control unit has a built-in threshold dynamic calibration module; the threshold dynamic calibration module includes a temperature and humidity sensor, a power sensor, and a calibration unit. The output terminals of the temperature and humidity sensor and the power sensor are respectively connected to the input terminal of the calibration unit. The output terminal of the calibration unit is connected to the main control unit, which is used to collect the ambient temperature and humidity and the output power of the photovoltaic array, and dynamically adjust the preset threshold according to the ambient temperature and humidity and the output power of the photovoltaic array.

[0011] In one embodiment, the main control unit is further configured to: if there is no grounding grid partition with a potential difference exceeding the preset threshold, switch access to each grounding grid partition according to a preset polling order, generate a polling object switching instruction, and send it to the channel switching switch.

[0012] In one embodiment, the outer casing of the fault signal acquisition unit has through-holes for heat dissipation.

[0013] In one embodiment, a stainless steel dustproof mesh is embedded in the heat dissipation hole.

[0014] In one embodiment, a copper equipotential bonding terminal is provided at the bottom of the housing of the fault signal acquisition unit; The equipotential bonding terminal is connected to the common grounding terminal of the grounding grid partition interface via a copper braided strip.

[0015] In one embodiment, the length of the copper braided strip is the distance between the equipotential connection terminal and the common grounding terminal of the grounding grid partition interface, plus the sum of the preset elastic connection redundancy length.

[0016] In the photovoltaic array grounding fault rapid detection and location device provided in the embodiments of this application, the fault signal acquisition unit synchronously covers different areas of the DC bus and the grounding grid through dual interfaces, ensuring the comprehensiveness of fault feature information acquisition. The fault feature extraction unit generates standardized feature values ​​based on multi-dimensional global parameters, avoiding the limitations of single impedance parameter analysis affected by factors such as the number of components in series, shading, and differences in manufacturer parameters, significantly reducing the fault false judgment rate and false negative rate. In addition, the distributed positioning unit achieves full-link coverage of the beginning, end and intermediate nodes through the multi-node interface of the component string, and can accurately locate the specific component string and node position where the fault is located after receiving the positioning command. This solves the pain point of the existing technology that can only preliminarily identify the fault area and cannot meet the requirements of precise operation and maintenance, comprehensively improving the timeliness, effectiveness and convenience of photovoltaic array grounding fault handling, and providing effective technical support for the safe and stable operation of photovoltaic systems, the improvement of power generation efficiency and the reduction of operation and maintenance costs. Attached Figure Description

[0017] One or more embodiments are illustrated by way of example with reference to the accompanying drawings, and these illustrative descriptions do not constitute a limitation on the embodiments.

[0018] Figure 1 This is a schematic diagram of the structure of a photovoltaic array grounding fault rapid detection and location device provided in one embodiment of this application. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the various embodiments of this application will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the various embodiments of this application to help readers better understand this application. However, the technical solutions claimed in this application can be implemented even without these technical details and various changes and modifications based on the following embodiments. The division of the various embodiments below is for the convenience of description and should not constitute any limitation on the specific implementation of this application. The various embodiments can be combined with and referenced by each other without contradiction.

[0020] This invention proposes a rapid detection and location device for photovoltaic array grounding faults. The implementation details of the rapid detection and location device for photovoltaic array grounding faults in this embodiment are described below. The following content is only for the convenience of understanding and is not necessary for implementing this solution.

[0021] Example 1: The structure of the photovoltaic array grounding fault rapid detection and location device in this embodiment can be as follows: Figure 1 As shown, it includes: a fault signal acquisition unit, a fault feature extraction unit, a distributed positioning unit, and a main control unit.

[0022] The causes of grounding faults in photovoltaic arrays may come from the DC bus (such as bus insulation damage, cable aging and leakage) or the grounding grid (such as grounding electrode corrosion, poor zone grounding leading to abnormal potential). Currently, traditional monitoring devices only collect signals from a single area, which may lead to missed fault detection.

[0023] In this device, the fault signal acquisition unit establishes physical and electrical connections with the positive and negative DC buses of the photovoltaic array through a dedicated DC bus interface. Simultaneously, it interfaces with multiple independent areas of the photovoltaic array's grounding grid (such as the array edge area, the middle area, and the inverter near-end area) through a grounding grid partition interface. Its core function is to acquire global operating parameters from different areas of the DC bus and grounding grid. Grounding faults are often characterized by abnormal system-level parameters (such as DC bus-to-ground potential shift and excessive potential differences between different areas of the grounding grid). Acquiring only local parameters cannot reflect the full picture of the fault. The fault signal acquisition unit in this device integrates and analyzes global operating parameters, simultaneously covering different areas of the DC bus and grounding grid, avoiding omissions of grounding faults due to blind spots. It is particularly suitable for the complex topology of large photovoltaic arrays (such as MW-level power plants), overcoming the coverage limitations of traditional single-point acquisition (such as only acquiring the bus or a single grounding end), thereby achieving fault identification based on global perception.

[0024] Specifically, the global operating parameters of different areas of the DC bus and grounding grid include: electrical parameters reflecting the main energy transmission backbone of the photovoltaic array, such as the voltage, current, and insulation status of the DC bus; and electrical parameters reflecting the system's grounding safety status, such as the potential and grounding resistance of different areas of the grounding grid. After the fault signal acquisition unit completes the acquisition, it transmits the integrated global operating parameters to the fault feature extraction unit through signal lines, providing raw data support for subsequent fault identification.

[0025] The fault feature extraction unit is connected to the fault signal acquisition unit and is mainly used to extract fault features based on the global operating parameters transmitted by the fault signal acquisition unit, through preset signal processing algorithms and logic. This completes the entire process of raw data preprocessing → fault feature identification → feature quantization and transformation. Specifically, one working process is as follows: First, the raw global operating parameters are preprocessed by filtering, denoising, and normalization to remove environmental interference (such as power frequency noise and instantaneous voltage fluctuations) and data redundancy. Then, features strongly correlated with grounding faults are identified from the preprocessed data, such as the DC bus-to-ground potential offset, the potential difference change rate in different areas of the grounding grid, and the insulation resistance attenuation trend. Finally, these abstract fault features are transformed into quantifiable and calculable feature values, such as the duration of potential difference exceeding the standard, the insulation resistance threshold deviation, and the characteristic frequency amplitude, and these feature values ​​are output to the main control unit. It should be noted that this embodiment does not limit the specific feature processing logic and algorithm of the fault feature extraction unit; the above method is only used as an example. Other methods can refer to the description in this embodiment and will not be elaborated further here.

[0026] The signal input terminal of the main control unit is directly connected to the signal output terminal of the fault feature extraction unit via a shielded cable or fiber optic link. The specific connection method is not limited. It is mainly used to receive the standardized fault feature values ​​output by the feature extraction unit. Its control output terminal establishes a communication connection with the control input terminal of the distributed positioning unit to issue fault location commands and receive feedback information. At the same time, the main control unit is also equipped with an external communication interface for data interaction with external monitoring equipment (such as power plant monitoring platform, operation and maintenance terminal, etc.).

[0027] The main working logic of the main control unit is as follows: First, based on the received fault characteristic values, the validity of the grounding fault is determined by the preset discrimination rules (such as comparison of characteristic values ​​with standard thresholds, characteristic trend analysis, multi-feature fusion judgment, etc.); if the discrimination result is that a grounding fault exists, a standardized fault location command is immediately generated and sent to the distributed location unit; after receiving the accurate fault location information (such as fault component string number, specific node location, etc.) fed back by the distributed location unit, the location information is packaged according to the preset protocol format and transmitted to the external monitoring equipment through the external communication interface to realize the real-time reporting of fault information.

[0028] The distributed positioning unit establishes both physical and electrical connections with the key nodes of each photovoltaic module string in the photovoltaic array through a dedicated multi-node interface for the module string. It not only covers the beginning and end of the module string (energy input / output endpoints), but also includes at least two intermediate nodes (such as the middle section of the module string, the third point, etc.). Each node is bound to the corresponding branch terminal of the interface through an independent shielded cable to ensure the independence and stability of signal transmission.

[0029] Photovoltaic module strings typically consist of dozens of modules connected in series. Intermediate nodes (such as module junction boxes and series connectors) are high-risk areas for grounding faults (e.g., loose wiring, insulation aging, and leakage). Simply collecting parameters from the beginning and end of the string cannot pinpoint the exact location of the fault, and the parameters may even appear normal if the fault is located in the middle. To address this, this device uses multi-node connections covering the beginning, end, and intermediate nodes of the module string to refine the positioning granularity from the entire module string group to a single module string plus a specific node. This completely solves the maintenance and troubleshooting difficulties caused by insufficient positioning accuracy in traditional methods, making it particularly suitable for long-distance, multi-module photovoltaic module strings.

[0030] In addition, the control port of the distributed positioning unit is bidirectionally connected to the control output port of the main control unit, which is used to receive fault location commands issued by the main control unit and to provide feedback on the generated accurate positioning information.

[0031] The main working logic of the distributed positioning unit is as follows: When no positioning command is received, the unit can be set to a low-power standby state; once a fault positioning command is received from the main control unit, local operating parameter acquisition is immediately started. For the beginning, end and middle nodes of each component string, local electrical parameters directly related to the fault, such as voltage, current, insulation resistance, and ground potential, are collected synchronously. The specific parameter types collected are not limited in this embodiment. Then, through a preset positioning algorithm (such as node parameter difference comparison, fault feature matching, path tracing analysis, etc.), the data collected by multiple nodes are analyzed collaboratively to accurately locate the specific component string where the grounding fault is located and the location of the fault node on that component string. Finally, the key information such as the fault component string number, the fault node location, and the fault parameter amplitude are integrated into standardized positioning information and fed back to the main control unit through the communication bus to complete the positioning execution closed loop.

[0032] Based on the above introduction, in the photovoltaic array grounding fault rapid detection and location device provided in this embodiment, the fault signal acquisition unit synchronously covers different areas of the DC bus and the grounding grid through dual interfaces, ensuring the comprehensiveness of fault feature information acquisition. The fault feature extraction unit generates standardized feature values ​​based on multi-dimensional global parameters, avoiding the limitations of single impedance parameter analysis affected by factors such as the number of components in series, shading, and differences in manufacturer parameters, significantly reducing the fault false judgment rate and false negative rate. In addition, the distributed positioning unit achieves full-link coverage of the beginning, end and intermediate nodes through the multi-node interface of the component string, and can accurately locate the specific component string and node position where the fault is located after receiving the positioning command. This solves the pain point of the existing technology, which can only preliminarily identify the fault area and cannot meet the requirements of precise operation and maintenance, comprehensively improving the timeliness, effectiveness and convenience of photovoltaic array grounding fault handling, and providing effective technical support for the safe and stable operation of photovoltaic systems, the improvement of power generation efficiency and the reduction of operation and maintenance costs.

[0033] Example 2: In complex photovoltaic scenarios, the grounding grid is typically divided into multiple independent zones based on array areas and module string clusters. Traditional fault signal acquisition units employ a uniform acquisition mode across the entire area, which can easily lead to efficiency redundancy issues such as untimely signal acquisition in high-fault-risk areas and resource hogging in fault-free areas. To address this, this device further integrates a channel switching switch and a zone potential detection module within the fault signal acquisition unit, forming an intelligent channel scheduling acquisition optimization mechanism based on zone potential sensing.

[0034] Specifically, the fault signal acquisition unit has a built-in channel switching switch and a zone potential detection module.

[0035] The signal input terminal of the zone potential detection module establishes a corresponding connection with each independent access terminal of the grounding grid zone interface to capture the real-time potential signal of each grounding grid zone. Its signal output terminal communicates bidirectionally with the feedback input terminal of the main control unit through the signal line to realize the real-time transmission of potential data.

[0036] The input terminals of the channel switching switch are connected one-to-one with the independent access terminals of the grounding grid partition interface, and the output terminal is directly connected to the internal acquisition channel of the fault signal acquisition unit. The control input terminal of the switch is connected to the control output terminal of the main control unit through the control bus to receive the switching command issued by the main control unit.

[0037] The zone potential detection module continuously collects potential data from each zone of the grounding grid and uploads the raw potential signal to the main control unit in real time. After receiving the data, the main control unit calculates the potential difference between each zone and between the zone and the common grounding terminal using a preset algorithm, compares it with a preset threshold, and determines whether there are high-risk zones with potential differences exceeding the threshold. If a high-risk zone is determined, the main control unit determines the target zone to be collected first based on risk priority, generates a targeted object switching command, and sends it to the channel switching switch. After receiving the command, the channel switching switch quickly switches the internal contact conduction state, so that the independent access terminal of the grounding grid zone interface corresponding to the target high-risk zone forms a conduction loop with the internal acquisition channel of the fault signal acquisition unit, thereby realizing the directional switching of the acquisition channel to the high-risk zone.

[0038] If there are no non-high-risk zones, subsequent data acquisition and scheduling will be executed according to preset logic. This embodiment does not limit the specific preset logic. To ensure that all zones of the grounding grid are periodically acquired, without missing potential early faults or sudden faults that have not reached the threshold, this embodiment further proposes that the main control unit is also used to: if there are no grounding grid zones with potential differences exceeding the preset threshold, switch access to each grounding grid zone according to the preset polling order, generate a polling object switching command, and send it to the channel switching switch. Through polling acquisition, the changing trend of potential data in each zone can be continuously tracked, complementing the high-risk priority acquisition logic, constructing a dual-layer acquisition and scheduling mechanism of key monitoring + comprehensive inspection, providing data support for early fault warning, making the working logic of the fault signal acquisition unit more complete, thereby achieving the goal of all-time, no-blind-spot fault detection. Of course, other preset logics can also be adopted. This embodiment only uses the above as an example for introduction. The device structure and working logic under other preset logics can refer to the introduction of this embodiment, and will not be repeated here.

[0039] In this embodiment, high-risk fault zones are accurately identified through zone potential detection. The channel switching switch directs the target zone and the acquisition channel, so that the acquisition resources focus on the risk area where the potential difference exceeds the threshold. This avoids the dilution or delay in capturing high-risk signals caused by traditional indiscriminate acquisition, and greatly reduces the probability of missing ground fault detection. It is especially suitable for complex scenarios with multiple zones in large photovoltaic arrays.

[0040] Example 3: The output impedance of a photovoltaic array is not a fixed value; it fluctuates dynamically with factors such as the number of modules connected in series, shading, changes in ambient temperature, and the degree of module aging. In contrast, the input impedance of a traditional fault signal acquisition unit is a fixed value. The two are prone to impedance mismatch, which leads to reflection, attenuation, and waveform distortion of the acquired signal during transmission. In particular, weak signals in the early stages of a ground fault (such as microvolt-level leakage current and millivolt-level potential difference) are overwhelmed by distorted signals and noise, resulting in deviations in subsequent feature extraction and fault identification.

[0041] In response to this, based on the above embodiments, this embodiment proposes to further integrate an impedance adjustment chip at the signal input terminal of the fault signal acquisition unit.

[0042] Specifically, the two signal pins of the impedance adjustment chip are electrically connected to the positive and negative conductive cores of the signal input terminal, respectively, and directly connected to the transmission circuit of the acquired signal; the control pin of the chip is connected to the I / O port of the main control unit through a standardized communication link, so as to realize the main control unit's command to the chip and status feedback.

[0043] The main control unit acquires the acquired signals transmitted by the fault signal acquisition unit in real time, extracts the impedance characteristics of the signals, and compares these characteristics with the preset standard value of the photovoltaic array output impedance. The impedance matching deviation between the two is calculated by an algorithm. Based on the magnitude and direction of the deviation, the main control unit generates a targeted impedance adjustment command and sends it to the impedance adjustment chip through the control link. After receiving the command, the impedance adjustment chip dynamically adjusts its programmable gain parameters (to optimize signal amplitude adaptability) and / or the resistance value of its internal matching resistor network (to adjust the input impedance of the acquisition loop), ultimately making the input impedance of the fault signal acquisition unit match the output impedance of the photovoltaic array, thus achieving high-quality transmission of the acquired signals.

[0044] Furthermore, in order to isolate complex electromagnetic interference sources in the photovoltaic array operating environment, such as power frequency electromagnetic radiation generated by power equipment such as inverters and transformers in centralized power plants, and stray electromagnetic fields formed by power grid lines and surrounding electronic equipment in distributed rooftop scenarios, this device adds a metal shielding layer to the outside of the signal input end of the fault signal acquisition unit, forming a triple optimization mechanism of directional acquisition + impedance matching + electromagnetic protection. Specifically, the outside of the signal input end of the fault signal acquisition unit is wrapped with a metal shielding layer. One end of the metal shielding layer is injection molded and fixed to the insulating shell of the input end, and the other end is bolted to the common grounding end of the grounding grid partition interface to block external electromagnetic interference.

[0045] The specific material selection for the metal shielding layer is not limited in this embodiment. For example, materials with low magnetic resistance and high conductivity, such as oxygen-free copper and tin-plated steel plates, can be used.

[0046] The metal shielding layer effectively attenuates various types of external interference, such as power frequency interference, stray electromagnetic radiation, and electrostatic induction, through the dual functions of physical isolation and grounding. Of course, a metal shielding layer can be omitted, and this embodiment does not limit this.

[0047] In this embodiment, the dynamic parameter adjustment of the impedance adjustment chip controls the matching deviation between the input impedance of the acquisition circuit and the output impedance of the photovoltaic array within a reasonable range. This significantly reduces signal reflection, attenuation, and waveform distortion, effectively preventing weak grounding fault signals from being drowned out by noise and significantly improving the sensitivity of fault detection. Moreover, the real-time control mechanism of the main control unit can quickly respond to dynamic changes in the output impedance of the photovoltaic array. Whether it is an increase or decrease in the number of module strings, output imbalance caused by shading, or impedance shift caused by temperature fluctuations or module aging, impedance matching can be achieved by adjusting the chip parameters. This adapts to different scenarios and complex operating conditions, such as centralized power plants, distributed rooftops, and mountainous areas, breaking through the adaptation limitations of traditional fixed impedance design.

[0048] Example 4: Based on the above embodiments, in order to further improve the matching degree between fault discrimination criteria and real-time operating conditions, this embodiment further proposes to build a threshold dynamic calibration module inside the main control unit.

[0049] Specifically, the main control unit has a built-in threshold dynamic calibration module, which consists of three core components: a temperature and humidity sensor, a power sensor, and a calibration unit.

[0050] Among them, the temperature and humidity sensor is used to capture the temperature and humidity data of the device's operating environment; the power sensor is used to collect real-time output power data of the photovoltaic array.

[0051] The signal output terminals of the temperature and humidity sensor and the power sensor are respectively connected to the input terminal of the calibration unit through a standardized signal link, and the real-time data of continuously collected ambient temperature and humidity and photovoltaic array output power are uploaded to the calibration unit according to a preset cycle.

[0052] The signal output terminal of the calibration unit is bidirectionally connected to the threshold storage and control interface of the main control unit. On the one hand, it receives the calibration trigger command issued by the main control unit, and on the other hand, it calculates the normal range of the grounding grid partition potential difference under the current operating conditions through the built-in algorithm, and then generates a calibration threshold that matches the range. The calibration unit sends the calibrated threshold parameters to the main control unit. After receiving the parameters, the main control unit automatically replaces the original preset threshold as a new standard for subsequent grounding grid partition potential difference discrimination and high-risk area identification, thereby realizing the dynamic adaptation of the threshold to the real-time operating conditions.

[0053] The operating conditions of photovoltaic arrays are dynamically affected by the environment and load. High temperature and humidity environments can reduce the insulation performance of the grounding grid, causing the potential difference under normal operating conditions to naturally increase. When operating at low power, the potential difference amplitude corresponding to a grounding fault is significantly lower than that under high power conditions, which can easily lead to misjudging normal conditions as faults or missing minor faults because the potential difference does not reach the threshold. In this embodiment, by real-time acquisition of temperature, humidity and output power and dynamic adjustment of the threshold, the fault discrimination standard is accurately matched with the normal potential difference range under the current operating conditions. This avoids misjudging normal potential differences under high humidity environments as faults and also prevents missing minor faults under low power conditions because the potential difference does not reach the fixed threshold. This ensures that the discrimination accuracy of the device is consistent under all operating conditions, including day and night, seasons, and different loads, and significantly reduces the misjudgment and missed judgment rates.

[0054] Example 5: The fault signal acquisition unit incorporates electronic components such as a channel switching switch, a zone potential detection module, and an impedance adjustment chip. These components continuously generate heat during operation, and since photovoltaic arrays are often deployed in open outdoor environments, high summer temperatures and direct sunlight can cause a rapid increase in the internal temperature of the unit. To further address the heat dissipation requirements for outdoor operation, the fault signal acquisition unit's outer casing features through-hole ventilation holes on its sidewalls. These holes allow for air convection cooling between the unit's internal structure and the external environment.

[0055] A stainless steel dust filter can be embedded in the heat dissipation holes. The dust filter can be tightly fitted to the hole wall using a snap-fit ​​structure or adhesive process, ensuring airflow while preventing external dust and debris from entering the unit, thus providing a dual protection effect of heat dissipation and dust prevention. In this embodiment, the connection method between the dust filter and the outer shell and the heat dissipation hole wall is not limited; only the above method is described as an example, and will not be elaborated further.

[0056] Example 6: The fault signal acquisition unit is exposed to outdoor electromagnetic environments for extended periods, and its casing is prone to accumulating charge due to electromagnetic induction and electrostatic induction. To prevent this charge from affecting internal electronic components, a copper equipotential bonding terminal can be installed at the bottom of the casing. This copper equipotential bonding terminal, made of copper, can be reliably electrically connected to the casing via welding or bolting to ensure that both are at the same potential. The equipotential bonding terminal is connected to the common grounding terminal of the grounding grid interface via a copper braided strip. Both the copper equipotential bonding terminal and the copper braided strip possess low impedance and high conductivity, enabling rapid dissipation of accumulated electrostatic and electromagnetic induction charges on the casing. This precisely aligns the casing potential with the grounding grid potential, preventing charge from damaging internal electronic components or interfering with the acquired signal, significantly improving the operational stability and lifespan of the acquisition unit.

[0057] Copper materials possess excellent conductivity, corrosion resistance, and oxidation resistance, enabling them to withstand outdoor wind, rain, and ultraviolet radiation, preventing increased contact resistance due to material aging. Copper braided straps combine flexibility and strength, adapting to angular deviations during outdoor installations while absorbing stress from wind vibrations and thermal expansion and contraction caused by temperature changes, preventing loosening and breakage issues that can occur with rigid connections and ensuring long-term connection reliability. This embodiment only uses copper braided straps as an example; other materials and connection methods can be described with reference to this embodiment and will not be elaborated further.

[0058] In order to ensure that the two ends are securely fixed to the equipotential bonding terminal and the common grounding terminal by bolts, and to provide the connection structure with a certain elastic deformation space through the redundant length, so as to ensure the continuity and reliability of the electrical connection, the length of the copper braided strip is the distance between the equipotential bonding terminal and the common grounding terminal of the grounding grid partition interface, and the sum of the preset elastic connection redundant length.

[0059] The total length of the copper braided tape consists of two parts. The first is the actual straight-line distance between the copper equipotential connection terminal at the bottom of the fault signal acquisition unit housing and the common grounding terminal of the grounding grid partition interface, ensuring the necessary length for basic connection continuity. The second is the preset elastic connection redundancy length, which is an extra length reserved according to the characteristics of the outdoor environment and the installation scenario. The total length after the two are added together ensures that the copper braided tape is in a slightly relaxed state after connection, rather than being completely taut. In the face of external forces such as wind vibration and minor collisions, the redundancy length gives the copper braided tape a certain elastic buffering capacity. It can absorb external forces through its own deformation, avoid external forces acting directly on the connection end, reduce the risk of connection end detachment and braided tape damage, and adapt to the complex mechanical environment of the outdoors.

[0060] Those skilled in the art will understand that the above embodiments are specific embodiments for implementing this application, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of this application.

Claims

1. A rapid detection and location device for grounding faults in photovoltaic arrays, characterized in that, include: Fault signal acquisition unit, fault feature extraction unit, distributed positioning unit and main control unit; The input end of the fault signal acquisition unit is connected to the positive and negative DC bus of the photovoltaic array through the DC bus interface, and to different areas of the photovoltaic array grounding grid through the grounding grid partition interface. It is used to acquire the global operating parameters of the DC bus and different areas of the grounding grid. The output end is connected to the input end of the fault feature extraction unit. The fault feature extraction unit extracts fault features based on the global operating parameters and generates feature values. The main control unit is connected to the fault feature extraction unit at one end and to the distributed positioning unit at the other end, and is used to determine the fault based on the feature value; if a grounding fault is detected, a fault positioning command is sent to the distributed positioning unit; if the fault positioning information is received, the positioning information is sent to the external monitoring equipment. The distributed positioning unit is connected to the beginning and end of each photovoltaic module string and at least two intermediate nodes through the component string multi-node interface. After receiving the fault positioning command, it collects the local operating parameters of the beginning and end of each photovoltaic module string and the intermediate nodes, performs fault positioning based on the local operating parameters, generates the positioning information, and feeds the positioning information back to the main control unit.

2. The rapid detection and location device for photovoltaic array grounding faults according to claim 1, characterized in that, The fault signal acquisition unit has a built-in channel switching switch and a zone potential detection module. The input terminal of the partition potential detection module is connected to the grounding grid partition interface, and is used to collect the potential of each partition of the grounding grid and send it to the main control unit; The main control unit is also used to calculate the potential difference based on the potential of each zone of the grounding grid, and to determine whether there are high-risk zones with potential differences exceeding a preset threshold. If such an object exists, the access object of the acquisition channel is determined from the high-risk partition, the corresponding object switching instruction is generated and sent to the channel switching switch; The input terminal of the channel switching switch is connected to each independent access terminal of the grounding grid partition interface, and the output terminal is connected to the internal acquisition channel of the fault signal acquisition unit. It is used to receive the object switching command and switch the conduction relationship between the target access terminal of the grounding grid partition interface and the internal acquisition channel according to the object switching command.

3. The rapid detection and location device for photovoltaic array grounding faults according to claim 2, characterized in that, The fault signal acquisition unit has a built-in impedance adjustment chip at its signal input terminal. The two signal pins of the impedance adjustment chip are respectively connected to the positive conductive core and the negative conductive core of the signal input terminal, and the control pin of the impedance adjustment chip is connected to the main control unit. The main control unit is further configured to calculate the impedance matching deviation value based on the impedance characteristics of the acquired signal and the preset standard value of the output impedance of the photovoltaic array, and generate a corresponding adjustment command, and adjust the programmable gain and / or internal matching resistor network configuration parameters of the impedance adjustment chip according to the adjustment command.

4. The rapid detection and location device for photovoltaic array grounding faults according to claim 3, characterized in that, The signal input terminal of the fault signal acquisition unit is wrapped with a metal shielding layer. One end of the metal shielding layer is injection molded to the insulating shell of the input terminal, and the other end is bolted to the common grounding terminal of the grounding grid partition interface to block external electromagnetic interference.

5. The rapid detection and location device for photovoltaic array grounding faults according to claim 2, characterized in that, The main control unit has a built-in threshold dynamic calibration module; the threshold dynamic calibration module includes a temperature and humidity sensor, a power sensor, and a calibration unit. The output terminals of the temperature and humidity sensor and the power sensor are respectively connected to the input terminal of the calibration unit. The output terminal of the calibration unit is connected to the main control unit, which is used to collect the ambient temperature and humidity and the output power of the photovoltaic array, and dynamically adjust the preset threshold according to the ambient temperature and humidity and the output power of the photovoltaic array.

6. The rapid detection and location device for photovoltaic array grounding faults according to claim 2, characterized in that, The main control unit is also used to: if there is no grounding grid partition with a potential difference exceeding the preset threshold, switch access to each grounding grid partition according to a preset polling order, generate a polling object switching instruction and send it to the channel switching switch.

7. The rapid detection and location device for photovoltaic array grounding faults according to claim 1, characterized in that, The fault signal acquisition unit has through-type heat dissipation holes on the side wall of its outer casing.

8. The rapid detection and location device for photovoltaic array grounding faults according to claim 7, characterized in that, Stainless steel dustproof mesh is embedded in the heat dissipation holes.

9. The rapid detection and location device for photovoltaic array grounding faults according to claim 1, characterized in that, The bottom of the casing of the fault signal acquisition unit is provided with a copper equipotential connection terminal. The equipotential bonding terminal is connected to the common grounding terminal of the grounding grid partition interface via a copper braided strip.

10. The rapid detection and location device for photovoltaic array grounding faults according to claim 9, characterized in that, The length of the copper braided strip is the distance between the equipotential connection terminal and the common grounding terminal of the grounding grid partition interface, plus the sum of the preset elastic connection redundancy length.

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