Tunnel high-voltage direct-current photovoltaic power generation system diagnosis method and device based on irradiance

Abstract

The application discloses a tunnel high-voltage direct-current photovoltaic power generation system diagnosis method and device based on irradiance, relates to the technical field of tunnel high-voltage direct-current photovoltaic power generation, and collects solar irradiance, solar position, photovoltaic module and installation parameters, environmental correction parameters, voltage and current power of each photovoltaic branch, high-voltage direct-current bus voltage and current and tunnel lighting load power; deviation coefficients are obtained by comparing the current theoretical power generation power with the actual power generation power; open circuit, short circuit, shielding, dust accumulation, attenuation, mismatch and other abnormalities are identified and positioned in combination with the consistency between branches; photovoltaic output, bus state, load demand and power compensation state are jointly analyzed, bus faults, load abnormalities and photovoltaic-load matching states are judged; and abnormal levels, maintenance suggestions and alarms or power compensation are outputted; the application can distinguish normal irradiance fluctuation from real faults, reduces false positives and false negatives, and improves the reliability and operation and maintenance efficiency of the tunnel high-voltage direct-current photovoltaic lighting system.

Description

Technical Field

[0001] This invention belongs to the field of tunnel high voltage direct current photovoltaic power generation technology, and relates to a diagnostic method and device for tunnel high voltage direct current photovoltaic power generation system based on irradiance. Background Technology

[0002] With the development of green transportation, low-carbon energy, and intelligent operation and maintenance technologies, the integration of photovoltaic power generation with tunnel lighting systems has gradually become an important direction for energy-saving renovation of highway tunnels. Tunnel lighting systems typically require long-term continuous operation, especially in entrance, transition, and exit sections, where the lighting load is affected by factors such as external brightness, solar irradiance, weather conditions, traffic flow, and vehicle speed. Traditional tunnel lighting systems mostly use AC mains power and distributed lamp drive methods. The lamps, drive power supplies, and power distribution equipment inside the tunnel are constantly exposed to humid, dusty, vibrating, and temperature-fluctuating environments, which easily leads to problems such as light source attenuation, drive power supply failure, wiring aging, poor contact, and maintenance difficulties.

[0003] To reduce energy consumption for tunnel lighting, existing technologies have incorporated photovoltaic (PV) power generation systems into tunnel lighting supply. Common solutions typically include PV modules, combiner boxes, controllers, batteries, inverters, AC power distribution equipment, and LED lighting loads. These solutions can utilize solar energy resources to some extent, reducing mains power consumption. However, PV power generation is characterized by significant intermittency and fluctuations, with its output power affected by various factors such as solar irradiance, solar altitude angle, module installation angle, ambient temperature, dust accumulation and shading, module aging, and line condition. When using batteries and inverters, the system involves multiple stages including PV DC power generation, energy storage, power conversion, and AC power distribution, resulting in conversion losses, short battery life, high maintenance costs, and numerous potential failure points. When using direct PV power supply with little or no energy storage, the real-time matching between PV output and lighting load becomes even more crucial. If the PV array, DC bus, or lighting load malfunctions, the system needs to promptly identify the fault and determine whether mains power compensation or maintenance is required.

[0004] In recent years, high-voltage direct current (HVDC) power supply technology has begun to be used in LED lighting systems. Compared with the traditional AC power supply plus distributed drive power supply scheme, the HVDC scheme can reduce intermediate conversion links, facilitate the access of photovoltaic DC energy, and improve system energy efficiency through centralized power supply, zoned power distribution, and DC bus power supply. For tunnel lighting scenarios, photovoltaic power generation can be used to power HVDC LED lamps, sensors, and control equipment after DC combiner, step-up, or bus connection. This method is beneficial for reducing inverter losses and the number of distributed power sources in the tunnel, but its operational safety and reliability depend on continuous monitoring of photovoltaic arrays, voltage, current, insulation status, branch anomalies, bus status, and load status.

[0005] Existing photovoltaic (PV) monitoring systems typically determine whether there are anomalies such as open circuits, short circuits, mismatches, shading, hot spots, or decreased power generation efficiency by collecting electrical parameters such as voltage, current, power, and temperature of PV modules or branches. Some systems also combine historical power generation data or meteorological data to assess power generation. However, in tunnel HVDC PV lighting scenarios, PV power generation is not independently connected to the grid but is directly coupled with the tunnel lighting load, smart dimming strategies, grid compensation strategies, and the operating status of the HVDC bus. If the system status is judged solely based on PV output power or voltage and current thresholds, the following problems can easily occur: On cloudy days, when cloud shadows change rapidly, or when the solar altitude angle is low, a decrease in PV output may be a normal change in irradiance but could be misjudged as a module failure; when irradiance is high but power generation is low, it may be caused by dust accumulation, shading, module degradation, poor branch contact, or bus-side anomalies, but simple electrical thresholds are insufficient to distinguish the specific cause; when the dimming power of the lamps changes, the change in PV power may be caused by changes in load demand or by PV-side anomalies, which existing monitoring methods cannot accurately determine.

[0006] Furthermore, traditional tunnel lighting operation and maintenance largely relies on manual inspections, periodic maintenance, and post-fault alarms, making it difficult to promptly detect early potential problems such as minor shading of photovoltaic modules, dust accumulation, branch mismatch, continuous decline in power generation efficiency, abnormal fluctuations in the DC bus, and mismatch between lighting load and photovoltaic output. Especially for mountainous highway tunnels, photovoltaic modules may be located near tunnel entrances, slopes, guardrails, or tunnel management areas, creating complex on-site environments with significant differences in module installation angles and sunlight conditions. Relying solely on power generation data is insufficient to determine whether the system is operating normally. Current technology lacks a diagnostic method that can use solar irradiance as a benchmark to jointly analyze theoretical power generation capacity, actual photovoltaic output, high-voltage DC bus status, and tunnel lighting load status. Summary of the Invention

[0007] The technical solution of this invention is used to solve the problem of how to calculate the theoretical power generation of each photovoltaic branch based on solar irradiance in a tunnel high-voltage direct current photovoltaic power generation system, and to perform joint diagnosis by combining the actual power generation deviation, the consistency of normalized output indicators between branches, the voltage and current of the high-voltage direct current bus, the power of tunnel lighting load, and the power compensation of the mains, so as to accurately distinguish between normal fluctuations in solar irradiance and abnormal power reduction caused by abnormalities in photovoltaic branches, high-voltage direct current bus, or tunnel lighting load, and to achieve anomaly location and operation and maintenance decision-making.

[0008] The present invention solves the above-mentioned technical problems through the following technical solutions: This invention provides a diagnostic method for a tunnel high-voltage direct current photovoltaic power generation system based on irradiance. The system includes a photovoltaic array, a high-voltage direct current bus, a tunnel lighting load, and a mains power compensation module. The photovoltaic array includes N photovoltaic branches. The diagnostic method includes the following steps: S1. Acquire solar irradiance data, solar position parameters, photovoltaic module parameters, installation parameters and environmental correction parameters, and collect the voltage and current of each photovoltaic branch, the voltage and current of the high-voltage DC bus, and the tunnel lighting load power. S2. Based on solar irradiance data, solar position parameters, installation parameters, photovoltaic module parameters, and environmental correction parameters, calculate the theoretical power generation of each photovoltaic branch at the current moment. S3. Calculate the actual power generation of each photovoltaic branch based on the voltage and current of each photovoltaic branch, and calculate the power generation deviation coefficient of each photovoltaic branch based on the theoretical power generation and the actual power generation. S4. Based on the power generation deviation coefficient and the consistency of normalized output indicators among the photovoltaic branches, identify and locate the photovoltaic branches with abnormalities. S5. Perform a joint analysis of the total photovoltaic output power, high-voltage DC bus voltage, tunnel lighting load power, and mains compensation power to determine whether the high-voltage DC bus is in an abnormal state, the tunnel lighting load is in an abnormal state, or the matching status between photovoltaic output and tunnel lighting load. S6. Based on the judgment results of steps S4 and S5, output the anomaly type, anomaly location, anomaly level, and maintenance suggestions, and execute at least one of the following operations: alarm, upload to the operation and maintenance platform, or linkage with the mains power compensation module; before linkage with the mains power compensation module, confirm the busbar safety status.

[0009] Furthermore, step S1 also includes: performing time alignment, outlier removal, missing value imputation, and sliding filtering on the collected data; when the solar irradiance data is lower than the preset lower limit of irradiance, only the running data is recorded and steps S2 to S6 are not executed; when the fluctuation rate of the solar irradiance data exceeds the preset fluctuation threshold, the irradiance data is smoothed by using a moving average or median filter, and a delayed confirmation time is set, triggering diagnosis only after the abnormality has lasted for a preset time.

[0010] Furthermore, the calculation of the theoretical power generation of each photovoltaic branch at the current moment in step S2 includes: Calculate the solar altitude angle and solar azimuth angle based on the date, time, latitude and longitude, and solar position parameters. Combine this with the installation tilt angle and installation azimuth angle of the photovoltaic module to calculate the angle between the incident solar ray and the module normal. The effective irradiance of the receiving surface is determined based on the solar irradiance data acquisition plane; when the data is acquired on the same plane, the measured irradiance is used directly; when the data is acquired on different planes, the incident angle is combined to convert it to the component plane. The theoretical power generation of a single module is calculated based on the effective light-receiving area of ​​the single module, the module conversion efficiency, the irradiance of the effective light-receiving surface, as well as the temperature correction coefficient, the shading correction coefficient, the dust accumulation correction coefficient, and the line loss correction coefficient. Based on the number of series-connected modules and the number of parallel-connected strings in each photovoltaic branch, the theoretical power generation of a single module is converted into the theoretical power generation of each photovoltaic branch; the theoretical power generation corresponds to the current operating mode of the branch; when MPPT is used, the maximum power point reference power is taken, and when MPPT is not used, the healthy reference power corresponding to the current operating voltage is taken.

[0011] Furthermore, the identification and location of the abnormal photovoltaic branch in step S4 includes: Calculate the normalized current value of each photovoltaic branch. and normalized power value ,in Let be the effective irradiance of the i-th photovoltaic branch. Let be the actual power generation of the i-th photovoltaic branch. Let be the theoretical power generation of the i-th photovoltaic branch; Calculate the mean and standard deviation of the normalized output index of each photovoltaic branch. When the normalized output index of a photovoltaic branch deviates from the mean by more than a preset deviation threshold, it is determined that the photovoltaic branch is abnormal. When the voltage of a photovoltaic branch is close to the open circuit voltage and the current is lower than the preset lower current limit, it is judged as an open circuit or open circuit abnormality; when the voltage of a photovoltaic branch is lower than the preset ratio of the average voltage of normal branches and the current fluctuates abnormally, it is judged as a short circuit or wiring abnormality; when the voltage of a photovoltaic branch is within the normal range but the current and power are consistently low, it is judged as partial shading, dust accumulation and pollution, module degradation or branch mismatch. Output the abnormal photovoltaic branch number, abnormal type, and abnormal level.

[0012] Furthermore, the joint analysis described in step S5 includes: When the total output power of photovoltaics is within the normal range but the voltage of the high-voltage DC bus is continuously lower than the lower limit of the bus voltage, it is determined that the high-voltage DC bus, DC line, mains power compensation module or tunnel lighting load side is abnormal. When the total output power of photovoltaics is low and the voltage of the high-voltage DC bus drops synchronously, it is determined that the power supply on the photovoltaic side is insufficient, and the normal irradiance drop and photovoltaic abnormality are further distinguished according to the photovoltaic deviation coefficient. When the high-voltage DC bus voltage is higher than the upper limit of the bus voltage and the tunnel lighting load power decreases, it is determined that the tunnel lighting load is disconnected or the dimming is abnormal.

[0013] Furthermore, the determination of the matching status between photovoltaic output and tunnel lighting load in step S5 includes: Calculate the total output power of photovoltaic power ,in Let N be the actual power generation of the i-th photovoltaic branch, and N be the number of photovoltaic branches. Calculate the effective power supply of photovoltaics Where D(t) is the tunnel lighting load power; Calculate the mains power compensation power ; Calculate the photovoltaic power exceeding the tunnel lighting load. ; When the mains power compensation power When the power output is consistently higher than the compensation power threshold and the power generation deviation coefficient corresponding to the total photovoltaic output power exceeds the deviation threshold, a diagnostic result of abnormal photovoltaic side or insufficient power generation capacity is output. When the photovoltaic power exceeds the tunnel lighting load When the power consumption remains above the waste threshold, output suggestions for optimizing photovoltaic capacity configuration, installation angle, or dimming strategy.

[0014] Furthermore, the anomaly levels described in step S6 are classified as follows: When the power generation deviation coefficient is within the allowable range, the high-voltage DC bus is in normal condition, and the photovoltaic output matches the tunnel lighting load in a normal manner, it is judged as the first level; When the power generation deviation coefficient exceeds the deviation threshold but does not continue to exceed the preset time, it is judged as the second level; When the power generation deviation coefficient continues to exceed the deviation threshold, or the normalized output index deviates from the mean by more than the preset deviation threshold, it is judged as the third level, and maintenance suggestions for cleaning photovoltaic modules or checking obstructions are output. When there is an open circuit, short circuit, abnormal condition of the high voltage DC bus, or abnormal condition of the tunnel lighting load, it is judged as Level 4, and corresponding inspection and maintenance suggestions are output. When there is a risk of loss of voltage on the high-voltage DC bus or power outage of the tunnel lighting load, it is judged as Level 5, and the mains power compensation module is activated to provide compensation power to the high-voltage DC bus, while outputting emergency repair information. The mains power compensation is only activated after there is no short circuit, severe overcurrent or insulation abnormality on the bus, or the relevant faulty branch or bus section has been isolated.

[0015] Furthermore, the maintenance recommendations in step S6 include at least one of the following: cleaning photovoltaic modules, checking for obstructions, checking photovoltaic branch wiring, checking DC bus, checking LED lighting circuits, calibrating sensors, and adjusting mains power compensation strategies.

[0016] The present invention also provides a diagnostic device for a tunnel high-voltage direct current photovoltaic power generation system based on irradiance, comprising: Irradiance sensor, used to collect solar irradiance data; An environmental parameter acquisition module is used to collect at least one of component temperature, ambient temperature, humidity, and wind speed. The photovoltaic branch voltage and current acquisition module is used to acquire the voltage and current of each photovoltaic branch. High-voltage DC bus acquisition module, used to acquire the voltage and current of the high-voltage DC bus; Lighting load acquisition module, used to acquire tunnel lighting load power; A diagnostic controller is connected to an irradiance sensor, an environmental parameter acquisition module, a photovoltaic branch voltage and current acquisition module, a high-voltage DC bus acquisition module, and a lighting load acquisition module, respectively. The diagnostic controller includes a processor and a memory. The memory stores a computer program. When the processor executes the computer program, it implements the diagnostic method according to any one of claims 1 to 8. The alarm module, connected to the diagnostic controller, is used to output an alarm signal when the abnormality level reaches the alarm condition; The communication module, connected to the diagnostic controller, is used to upload diagnostic results to the operation and maintenance platform; It also includes a mains power compensation module, which is connected to the diagnostic controller and the high-voltage DC bus, and is used to provide compensation power to the high-voltage DC bus under the control of the diagnostic controller.

[0017] Furthermore, when the computer program stored in the memory of the diagnostic controller is executed, the diagnostic controller implements the following functional modules: The theoretical power generation calculation module is used to calculate the theoretical power generation of each photovoltaic branch based on solar irradiance data, solar position parameters, installation parameters, photovoltaic module parameters, and environmental correction parameters. The deviation calculation module is used to calculate the power generation deviation coefficient based on the theoretical power generation and the actual power generation. The branch anomaly identification module is used to identify and locate photovoltaic branches with anomalies based on the power generation deviation coefficient and the consistency of normalized output indicators among the photovoltaic branches. The bus status diagnosis module is used to determine whether the high-voltage DC bus status is abnormal based on the high-voltage DC bus voltage, total photovoltaic output power, and tunnel lighting load power. The load matching diagnostic module is used to calculate the effective photovoltaic power supply, the mains power compensation power, and the photovoltaic power exceeding the tunnel lighting load, and to determine the matching status between the photovoltaic output and the tunnel lighting load. The integrated diagnostic decision module uses the output results of the integrated branch anomaly identification module, bus status diagnosis module, and load matching diagnosis module to generate anomaly type, anomaly location, anomaly level, and maintenance suggestions. When the anomaly level reaches the preset alarm conditions, it will trigger the alarm module or the mains power compensation module.

[0018] The beneficial effects of this invention are as follows: (1) Using irradiance as the diagnostic benchmark, it can distinguish between normal weather changes and real system faults, reducing false alarms and missed alarms; (2) By analyzing the deviation of branch-level voltage, current, power and theoretical output, abnormal branches can be located and abnormalities such as open circuit, short circuit, dust accumulation, obstruction, poor contact, and component attenuation can be identified. (3) The photovoltaic side, the high-voltage DC bus side and the lighting load side are jointly diagnosed, which is suitable for photovoltaic direct generation and supply and high-voltage DC LED direct drive tunnel lighting systems; (4) It can calculate the effective photovoltaic power supply, grid power compensation and photovoltaic power exceeding the load, providing a basis for photovoltaic capacity design, dimming strategy optimization and operation and maintenance management; (5) It can output cleaning, maintenance, compensation and emergency repair suggestions according to the level of abnormality, reduce the cost of manual inspection, and improve the reliability and maintainability of the system; (6) Applicable to mountainous highway tunnels, continuous tunnel groups, tunnel entrance photovoltaic arrays, guardrail photovoltaic arrays, and photovoltaic power supply systems in management areas. Attached Figure Description

[0019] Figure 1 This is a flowchart of the diagnostic method for tunnel high-voltage direct current photovoltaic power generation system based on irradiance according to Embodiment 1 of the present invention; Figure 2 This is a structural diagram of the irradiance-based diagnostic device for a tunnel high-voltage direct current photovoltaic power generation system according to Embodiment 2 of the present invention; Figure 3(a) is a diagram of the on-site monitoring interface at 11:38:53 on September 17, 2026, in the example of this invention; Figure 3(b) is a diagram of the on-site monitoring interface at 11:39:45 on September 17, 2026, in the example of this invention; Figure 3(c) is a diagram of the on-site monitoring interface at 11:40:41 on September 17, 2026, in the example of this invention; Figure 3(d) is a screenshot of the on-site monitoring interface at 11:44:43 on September 17, 2026, in the example of this invention; Figure 3(e) is a diagram showing the historical data, energy saving rate, and event alarm interface of the present invention. Figure 4 This is a simulation result diagram of the diagnosis and mains power compensation based on measured data in the example of this invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments: Example 1 like Figure 1 As shown, this embodiment provides a diagnostic method for a tunnel high-voltage direct current photovoltaic power generation system based on irradiance, including the following steps: Step 1: Data Acquisition and Preprocessing Collect solar irradiance data, solar position parameters, photovoltaic module parameters, installation parameters, environmental correction parameters, voltage and current data of each photovoltaic branch, voltage and current data of the high-voltage DC bus, and tunnel lighting load data.

[0022] The diagnostic controller collects real-time solar irradiance data via an irradiance sensor. The component temperature is collected through the environmental parameter acquisition module. Data such as ambient temperature, humidity, and wind speed are collected. The voltage of each photovoltaic branch is acquired via a photovoltaic branch voltage and current acquisition module. Current The high-voltage DC bus voltage is acquired through the high-voltage DC bus acquisition module. and bus current The tunnel lighting load power is collected through the lighting load acquisition module. Lighting voltage, lighting current, and dimming status.

[0023] The diagnostic controller performs time alignment, outlier removal, missing value imputation, and sliding filtering on the above data. Time alignment can be achieved using a unified time scale or interpolation method to ensure that irradiance, branch voltage and current, bus voltage and current, and load power correspond at the same time step. Outlier removal can be performed using the 3σ criterion, median absolute deviation method, or range judgment method. Missing value imputation can be performed using linear interpolation, previous value hold, or historical mean imputation. Sliding filtering can be performed using moving average filtering, median filtering, or low-pass filtering.

[0024] When solar irradiance is below a preset lower limit At this time, the system only records operational data and does not trigger photovoltaic power generation anomaly diagnosis to avoid false alarms at night or under extremely low irradiance conditions. The preset lower limit... The settings can be configured according to on-site calibration, for example, from 30 W / m² to 80 W / m². When solar irradiance fluctuates rapidly, such as when cloud shadows cause short-term large changes in irradiance, the diagnostic controller uses a moving average or median and sets a delay confirmation time. The diagnostic alarm is only triggered after the abnormality has lasted for a preset time, in order to reduce false alarms caused by cloud shadows and sampling noise.

[0025] Step 2: Calculate the theoretical power generation The theoretical power generation of a photovoltaic branch or array at the current moment is calculated based on solar irradiance, solar position, module installation tilt angle, installation azimuth angle, module rated power, conversion efficiency, number of modules, and environmental correction factor.

[0026] (1) Calculate the effective irradiance of the light-receiving surface Calculate the solar altitude angle and solar azimuth angle based on the date, time, latitude, and longitude. Then, combine this with the installation tilt angle and azimuth angle of the photovoltaic module to determine the angle between the incident sunlight and the module normal, which is the solar incidence angle. When the real-time solar irradiance corresponds to a horizontal plane or other reference plane, it is based on the real-time solar irradiance. and the angle of incidence of the sun The effective irradiance of the i-th photovoltaic branch is calculated using the following formula: ;when When the component is not exposed to direct sunlight, it is then set to... When real-time solar irradiance is collected by an irradiance sensor on the same plane as the photovoltaic module, the measured value is directly used as the effective irradiance of the light-receiving surface, and no angle correction is performed.

[0027] (2) Calculate the theoretical power generation of a single component Based on the effective light-receiving area of ​​a single module, the module conversion efficiency, the effective light-receiving surface irradiance, and various correction factors, the theoretical power generation of a single module is calculated as follows: ,in, The effective light-receiving area of ​​a single component. For component conversion efficiency, This is a temperature correction factor. For occlusion correction factor, This is the dust accumulation correction factor. This is the line loss correction factor.

[0028] The temperature correction factor can be calculated based on the module power temperature coefficient and the module temperature, using the following formula: ,in, The power temperature coefficient of the component. Let i be the component temperature of the i-th branch. The standard test temperature is, for example, 25°C. The shading correction factor, dust accumulation correction factor, and line loss correction factor can be determined based on field calibration, historical data, or image recognition results; their values ​​typically range from 0 to 1.

[0029] (3) Calculate the theoretical power generation of photovoltaic branches or photovoltaic arrays based on the series and parallel scale. If the i-th branch includes A series component and If there are several parallel strings, then the theoretical power generation of the i-th branch is: .

[0030] Or it can be expressed as: ,in, Let i be the effective light-receiving area of ​​the i-th branch. Let be the conversion efficiency of the i-th branch component.

[0031] Output the theoretical power generation at the current moment This is used as the benchmark value for subsequent deviation diagnosis. For the entire photovoltaic array, the theoretical total power generation is: When MPPT control is used, the maximum power point reference power at the current irradiance and module temperature is used as the theoretical power generation; when MPPT is not used, the healthy reference power corresponding to the current actual operating voltage is used as the theoretical power generation.

[0032] Step 3: Calculate the actual power generation and deviation. The actual power generation is calculated based on the voltage and current of each photovoltaic branch, and the power generation deviation coefficient is calculated based on the theoretical power generation and the actual power generation.

[0033] The diagnostic controller uses the collected voltage of the i-th photovoltaic branch as a basis. and current Calculate the actual power generation of the i-th photovoltaic branch: Then calculate the power generation deviation coefficient: , in, To prevent small amounts with a denominator of zero, such as 0.001 kW or set according to the system capacity. This indicates the degree to which the actual power generation of the i-th branch deviates from the theoretical power generation. When Greater than the preset deviation threshold And continue for a preset time At that time, it was determined that there was a risk of abnormal power generation in this branch. It can be set according to the on-site calibration, for example, 10%, 15%, 20% or 25%. The interval can be set according to system inertia, such as 1 minute, 5 minutes or 10 minutes.

[0034] The diagnostic controller also calculates the consistency of voltage, current, power, and normalized output parameters across each photovoltaic branch. For example, it calculates the normalized current for each branch: Or calculate the normalized power of each branch: Then, the mean, standard deviation, or coefficient of variation of the normalized index for each branch is calculated. When the normalized index of a branch deviates from the mean by more than a preset range, it is determined that the branch has mismatch, obstruction, dust accumulation, attenuation, or wiring abnormality.

[0035] Step 4: Identify and locate abnormal photovoltaic branches. The diagnostic controller compares the voltage, current, power, and normalized output parameters of each branch to identify the abnormal type of the photovoltaic branch and locate the abnormal branch. The specific judgment logic is shown in Table 1 below.

[0036] Table 1. Judgment Logic Table for Identifying Anomaly Types in Photovoltaic Branches

[0037] When the voltage of a branch is close to the open-circuit voltage while the current is close to zero, it is judged as an open circuit or disconnection abnormality. When the voltage of a branch is significantly lower than that of a normal branch and the current is abnormal, it is judged as a short circuit or wiring abnormality. When the voltage is basically normal but the current and power are consistently low, it is judged as local obstruction, dust accumulation, component degradation, or branch mismatch. The diagnostic controller outputs the abnormal branch number, abnormality type, and abnormality level.

[0038] In one implementation, the diagnostic controller also incorporates historical benchmark data for judgment. For example, it stores the historical average actual power within the same irradiance range, temperature range, and time period, and compares the current actual power with the historical benchmark. If the current actual power is significantly lower than the historical benchmark, and the deviation persists, it is determined to be a long-term anomaly such as component degradation, dust accumulation, or increased contact resistance.

[0039] Step 5: Coupling diagnosis between high-voltage DC bus and tunnel lighting load Collect high voltage DC bus voltage and bus current The condition diagnosis of the high-voltage DC bus is compared with the photovoltaic output power and load demand, including the following situations: When the photovoltaic output is normal but the bus voltage remains low, the problem may be due to an abnormality in the bus, the line, the compensation module, or the load side. For example, this could be due to increased bus contact resistance, excessive DC line voltage drop, a malfunction in the mains compensation module, or a short circuit on the load side.

[0040] When photovoltaic output is low and bus voltage drops simultaneously, it is likely due to insufficient power supply from the photovoltaic side. In this case, the irradiance and theoretical power generation should be considered to determine whether the decrease is due to normal irradiance or an anomaly on the photovoltaic side.

[0041] When the bus voltage rises abnormally while the load power decreases, it is likely due to a load disconnection or a dimming malfunction. For example, the LED lighting circuit may be disconnected, the dimming control may fail, or the load demand may suddenly decrease.

[0042] When the bus voltage fluctuation or ripple exceeds the preset range, it is determined that the problem may be due to poor bus contact, abnormal compensation module, or abnormal filtering circuit.

[0043] Optionally, the diagnostic controller can also collect data on bus insulation status, bus temperature, or the status of protection devices to assist in identifying bus faults.

[0044] The diagnostic controller outputs the bus status based on the above judgments, including bus stability, bus low, bus high, bus fluctuation, or bus abnormality. The bus status diagnostic results and the photovoltaic branch abnormality diagnostic results are used together for comprehensive diagnostic decision-making.

[0045] Step 6: Tunnel lighting load status diagnosis and load matching The diagnostic controller collects the tunnel lighting load power. The system monitors lamp voltage, lamp current, and dimming status. Based on the dimming control command and load requirements, it determines whether the load status is normal. When the lamp power does not match the dimming command, the lamp current is abnormal, or the power of some lamp circuits is abnormal, it outputs a load abnormality or dimming abnormality prompt.

[0046] The diagnostic controller calculates the total photovoltaic output power: ; The effective photovoltaic power supply, the mains power compensation power, and the photovoltaic power exceeding the load are respectively:

[0047]

[0048]

[0049] in, This indicates the effective power supplied by the photovoltaic system to the lighting load at the same time step. This indicates the power that requires mains power compensation; This indicates the portion of photovoltaic output that exceeds load demand.

[0050] when When the voltage continues to rise and the photovoltaic deviation is large, the system outputs a warning indicating photovoltaic-side abnormality or insufficient power generation capacity. When the temperature remains high, the system outputs optimization suggestions for photovoltaic capacity, installation angle, or dimming strategy. and When the matching is good, the system outputs a message indicating that the load is properly matched.

[0051] Step 7: Comprehensive Diagnosis and Decision Making, Alarms and Maintenance The diagnostic controller integrates theoretical power generation deviation, branch consistency, bus stability, load matching status, and historical data to output diagnostic results. These results include the time of the anomaly, the branch number, the anomaly type, the anomaly level, the theoretical power generation, the actual power generation, the deviation coefficient, the bus status, the load status, and maintenance recommendations.

[0052] In one implementation, the fault level can be classified according to the following Table 2.

[0053] Table 2 Fault Level Classification Table

[0054] Maintenance recommendations include cleaning photovoltaic modules, checking for obstructions, inspecting branch wiring, checking DC buses, checking LED lighting circuits, calibrating sensors, or adjusting mains power compensation strategies. When the anomaly level reaches the alarm criteria, the alarm module outputs an audible and visual alarm, and the communication module uploads the diagnostic results to the maintenance platform. The maintenance platform performs historical record recording, status monitoring, report analysis, and maintenance work order management.

[0055] Step 8, Mains Power Compensation Linkage When the anomaly level is high or the photovoltaic power supply is insufficient, the diagnostic controller adjusts the power compensation based on the mains power. A compensation control signal is generated to activate the mains compensation module. The mains compensation module includes mains input and DC compensation output, used to provide compensation power to the high-voltage DC bus, prioritizing the safe power supply to tunnel lighting loads. If the abnormality level reaches the emergency level, the system can forcibly activate mains compensation and simultaneously output a repair work order. Before activating mains compensation, the bus short-circuit, overcurrent, insulation, and protection status are checked; if related faults exist, the faulty branch or bus section is isolated first, and then mains compensation is activated for healthy bus sections that meet the power supply conditions.

[0056] This invention is applicable not only to high-voltage DC photovoltaic lighting systems in single tunnels, but also to continuous tunnel groups, photovoltaic arrays at tunnel entrances, photovoltaic arrays on slopes, photovoltaic arrays on guardrails, and photovoltaic power supply systems in tunnel management areas. For multiple tunnels or multiple photovoltaic arrays, multiple diagnostic controllers can be cascaded or connected to the same operation and maintenance platform via communication modules. The diagnostic controllers can set different diagnostic thresholds and maintenance strategies based on the irradiance conditions, load characteristics, and operating strategies of different tunnels. In another embodiment, the diagnostic controllers can also compare diagnostic results with fault cases in a historical database to generate fault probabilities and maintenance priorities. The operation and maintenance platform can schedule maintenance work orders and spare parts dispatch based on the anomaly level, historical fault frequency, and tunnel traffic flow.

[0057] Example 2 like Figure 2 As shown, this embodiment provides a diagnostic device for a tunnel high-voltage direct current photovoltaic power generation system based on irradiance, which is applied to the tunnel high-voltage direct current photovoltaic power generation system. The system includes a photovoltaic array, an irradiance sensor, an environmental parameter acquisition module, a photovoltaic branch voltage and current acquisition module, a high-voltage direct current bus, a tunnel lighting load, a lighting load acquisition module, a diagnostic controller, an alarm module, a communication module, an operation and maintenance platform, and a mains power compensation module.

[0058] The photovoltaic array comprises multiple photovoltaic branches, such as photovoltaic branch 1, photovoltaic branch 2, ..., photovoltaic branch N. Each photovoltaic branch includes several photovoltaic modules connected in series and / or parallel. The photovoltaic branches are connected to the high-voltage DC bus via a DC combiner and protection device. The high-voltage DC bus supplies power to the tunnel lighting load. The tunnel lighting load includes multiple high-voltage DC LED lamps, such as LED lamp 1, LED lamp 2, ..., LED lamp M. The high-voltage DC bus is also connected to a mains compensation module, which includes mains input and DC compensation output, used to provide compensation power to the high-voltage DC bus when photovoltaic power generation is insufficient or the system is abnormal. The photovoltaic branches can be connected to the high-voltage DC bus via a DC / DC power conditioning module with MPPT function.

[0059] The irradiance sensor is used to collect solar irradiance data near or on the same plane as the photovoltaic array, denoted as The environmental parameter acquisition module includes at least one of a temperature sensor, a humidity sensor, and a wind speed sensor, used to collect environmental parameters such as component temperature, ambient temperature, humidity, and wind speed. The photovoltaic branch voltage and current acquisition module includes a voltage acquisition unit and a current acquisition unit, used to collect the voltage of each photovoltaic branch. Current and power ,in The high-voltage direct current (HVDC) bus acquisition module includes a bus voltage acquisition unit and a bus current acquisition unit, used to acquire HVDC bus voltage. and bus current The lighting load acquisition module includes a voltage acquisition unit, a current acquisition unit, and a power acquisition unit, used to acquire the power of the tunnel lighting load. In addition to data such as the voltage and current of the lamps.

[0060] The diagnostic controller is connected to the irradiance sensor, the environmental parameter acquisition module, the photovoltaic branch voltage and current acquisition module, the mains power compensation module, and the lighting load acquisition module, respectively.

[0061] The diagnostic controller includes a theoretical power generation calculation module, a deviation calculation module, a branch anomaly identification module, a bus status diagnosis module, a load matching diagnosis module, and a comprehensive diagnostic decision module. The diagnostic controller executes the diagnostic method described in Embodiment 1 and outputs diagnostic results.

[0062] The alarm module includes audible and visual alarms and alarm outputs.

[0063] The communication module includes wired and / or wireless communication. The operation and maintenance platform includes at least one of data storage, status monitoring, report analysis, and maintenance management.

[0064] The mains power compensation module performs mains power compensation based on the control signals from the diagnostic controller.

[0065] In one specific embodiment, the irradiance sensor can be a total radiation meter, a photovoltaic reference cell, or an irradiance acquisition device with similar functions. The irradiance sensor is installed near the photovoltaic array, on the same mounting plane, or at a location with similar light-receiving conditions to improve the consistency between the irradiance data and the actual light-receiving conditions of the photovoltaic array. When the irradiance sensor is installed on the same plane as the photovoltaic module, its output is directly used as the irradiance of the module plane, without further angle correction.

[0066] In one specific embodiment, the temperature sensor in the environmental parameter acquisition module can be installed near the back panel or support of the photovoltaic module to collect the module temperature; the humidity sensor and wind speed sensor can be installed near the tunnel entrance or photovoltaic array to assist in judging dust accumulation, condensation, shading and heat dissipation conditions.

[0067] In one specific implementation, the photovoltaic branch voltage and current acquisition module may employ devices such as Hall voltage sensors, Hall current sensors, shunts, isolation amplifiers, and analog-to-digital converters.

[0068] In one specific implementation, the high-voltage DC bus acquisition module may employ a DC voltage transmitter, a DC current sensor, and an isolated sampling circuit.

[0069] In one specific implementation, the lighting load acquisition module may employ a voltage sensor, a current sensor, and a power metering chip.

[0070] In one specific implementation, the diagnostic controller may be a microcontroller, digital signal processor, field-programmable gate array, programmable logic controller, industrial control computer, or edge computing gateway. The diagnostic controller includes a processor, memory, and a communication interface. The memory stores a computer program, and when the processor executes the computer program, it implements the diagnostic method described in Embodiment 1.

[0071] In one specific implementation, the alarm module may employ an audible and visual alarm, a relay output, a dry contact output, or a buzzer.

[0072] In one specific implementation, the communication module may employ RS485 communication, CAN communication, Ethernet communication, fiber optic communication, 4G / 5G communication, LoRa communication, or NB-IoT communication.

[0073] In one specific implementation, the operation and maintenance platform can employ a local server, a cloud server, a monitoring terminal, a database, and a work order management system.

[0074] In one specific implementation, the mains power compensation module can be an AC / DC converter, a DC / DC converter, or a DC compensation power supply, with its input terminal connected to the mains power and its output terminal connected to a high-voltage DC bus or a DC compensation branch.

[0075] Specific calculation examples To verify the above diagnostic methods and devices using actual project data, this example uses typical daily data from July 8, 2026, from "21PCS Single-Sided Photovoltaic Panel Photovoltaic Complementary Data Record 8.5". A total of 120 valid sampling points were selected, with a time range from 06:25:56 to 17:35:02 and an irradiance range from 102 W / m² to 1061 W / m². The maximum power of the two photovoltaic channels were 1687.73 W and 1566.17 W, respectively, and the correlation coefficients between photovoltaic power and irradiance were 0.9928 and 0.9880, respectively. In addition, Figures 3(a) to 3(d) show the on-site monitoring interface at different times on September 17, 2026. The interface synchronously displays operating parameters such as solar irradiance, photovoltaic power ratio, photovoltaic branch voltage, current and power, AC / DC compensation power of the mains power, LED load power, and temperature. Figure 3(e) shows historical energy saving rate, event alarms, historical irradiance data, and photovoltaic panel temperature data, illustrating that the diagnostic device has the data foundation for real-time acquisition, historical query, and anomaly recording. To avoid mislabeling on-site health fluctuations as real faults, this example uses typical daily measured data as a health reference before injecting controlled faults. The health data is calibrated according to the correction relationship between irradiance, temperature, and branch correction coefficients and theoretical power, generating theoretical power benchmarks for the two photovoltaic branches. The effective diagnostic conditions are set as irradiance not less than 300 W / m², power generation deviation threshold set at 20%, and delay confirmation set at 3 consecutive sampling points. From 09:00:56 to 10:55:00 on July 8, 2026, the measured power of the second branch was multiplied by 0.65 to simulate a 35% equivalent power loss due to shading or dust accumulation. At other times, the measured values ​​remained the same as those of the first branch. During the fault injection period, the median deviation coefficient of the second branch was 33.89%. The deviation coefficient of the second branch continuously exceeded the threshold from 09:00:56, and a level 3 warning was issued at the third consecutive sampling point at 09:10:56, identifying it as a candidate fault for partial shading or dust accumulation in the second branch. After 11:00, the controlled loss was removed, and the warning was cleared at 11:10:00 after three consecutive normal sampling points. The diagnostic results are summarized in [link to diagnostic results]. Figure 4 , Figure 4 Figure (a) in the figure shows the irradiance and the power of the two photovoltaic systems. Figure 4 Figure (b) shows the deviation coefficients of the two power generation paths, the 20% diagnostic threshold, and the controlled loss period. According to the load matching method, the measured load power of the second LED path is used as... ,calculate Within the same fault time window, the average value of the mains power compensation command without fault injection was 401.47 W, which increased to 805.29 W after injecting 35% power loss, an average increase of 403.82 W. Figure 4 Figure (c) shows the linkage between the available photovoltaic power, LED load power, and mains compensation power of the second branch. The irradiance, temperature, photovoltaic power, and LED load power in this example are measured data; the 35% power loss is a controlled fault injection and does not represent the actual occurrence of this fault on site.

[0076] Example 3 This embodiment provides an electronic device, including a memory and a processor. The memory stores a computer program that supports the processor in executing the irradiance-based diagnostic method for tunneled high-voltage direct current photovoltaic power generation systems as described in Embodiment 1. The memory can be a high-speed random access memory or a non-volatile memory, such as a disk storage device, flash memory device, or other solid-state storage device. The processor is configured to execute the program stored in the memory. The processor can be a general-purpose central processing unit, a dedicated processor, a microprocessor, or a digital signal processor. The electronic device may also include a communication interface for exchanging data with other computing nodes or storage devices. The communication interface can be a wired interface (such as an Ethernet interface) or a wireless interface. The electronic device may also include input / output interfaces for connecting peripheral devices such as a monitor, keyboard, and mouse, so that users can view the computing status and input control commands.

[0077] Example 4 This embodiment provides a storage medium on which a computer program is stored. The storage medium can be any medium capable of storing program code, including but not limited to: USB flash drive, portable hard drive, read-only memory, random access memory, magnetic disk, optical disk, flash memory card, etc. When the computer program is run by a processor, it executes the steps of the irradiance-based diagnostic method for tunnel high-voltage direct current photovoltaic power generation systems as described in Embodiment 1. The storage medium can be located on a single computing device or distributed across multiple computing devices, such as in a distributed storage system. The program can be loaded onto a single processor for execution or loaded onto multiple processors for parallel execution.

[0078] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A diagnostic method for a tunnel high-voltage direct current photovoltaic power generation system based on irradiance, the system comprising a photovoltaic array, a high-voltage direct current bus, tunnel lighting loads, and a mains power compensation module, wherein the photovoltaic array comprises N photovoltaic branches, characterized in that, The diagnostic method includes the following steps: S1. Acquire solar irradiance data, solar position parameters, photovoltaic module parameters, installation parameters and environmental correction parameters, and collect the voltage and current of each photovoltaic branch, the voltage and current of the high-voltage DC bus, and the tunnel lighting load power. S2. Based on solar irradiance data, solar position parameters, installation parameters, photovoltaic module parameters, and environmental correction parameters, calculate the theoretical power generation of each photovoltaic branch at the current moment. S3. Calculate the actual power generation of each photovoltaic branch based on the voltage and current of each photovoltaic branch, and calculate the power generation deviation coefficient of each photovoltaic branch based on the theoretical power generation and the actual power generation. S4. Based on the power generation deviation coefficient and the consistency of normalized output indicators among photovoltaic branches, identify and locate photovoltaic branches with abnormalities. S5. Perform a joint analysis of the total photovoltaic output power, high-voltage DC bus voltage, tunnel lighting load power, and mains compensation power to determine whether the high-voltage DC bus is in an abnormal state, the tunnel lighting load is in an abnormal state, or the matching status between photovoltaic output and tunnel lighting load. S6. Based on the judgment results of steps S4 and S5, output the anomaly type, anomaly location, anomaly level, and maintenance suggestions, and execute at least one of the following operations: alarm, upload to the operation and maintenance platform, or linkage with the mains power compensation module; and confirm the bus safety status before linkage with the mains power compensation module.

2. The diagnostic method according to claim 1, characterized in that, Step S1 also includes: performing time alignment, outlier removal, missing value imputation, and sliding filtering on the collected data; when the solar irradiance data is lower than the preset lower limit of irradiance, only the running data is recorded and steps S2 to S6 are not executed; when the fluctuation rate of the solar irradiance data exceeds the preset fluctuation threshold, the irradiance data is smoothed by using a moving average or median filter, and a delay confirmation time is set, triggering diagnosis only after the abnormality has lasted for a preset time.

3. The diagnostic method according to claim 1, characterized in that, Step S2, which involves calculating the theoretical power generation of each photovoltaic branch at the current moment, includes: Calculate the solar altitude angle and solar azimuth angle based on the date, time, latitude and longitude, and solar position parameters. Combine this with the installation tilt angle and installation azimuth angle of the photovoltaic module to calculate the angle between the incident solar ray and the module normal. The effective irradiance of the receiving surface is determined based on the solar irradiance data acquisition plane; when the data is acquired on the same plane, the measured irradiance is used directly; when the data is acquired on different planes, the incident angle is combined to convert it to the component plane. The theoretical power generation of a single module is calculated based on the effective light-receiving area of ​​the single module, the module conversion efficiency, the irradiance of the effective light-receiving surface, as well as the temperature correction coefficient, the shading correction coefficient, the dust accumulation correction coefficient, and the line loss correction coefficient. Based on the number of series-connected modules and the number of parallel-connected strings in each photovoltaic branch, the theoretical power generation of a single module is converted into the theoretical power generation of each photovoltaic branch; the theoretical power generation corresponds to the current operating mode of the branch; when MPPT is used, the maximum power point reference power is taken, and when MPPT is not used, the healthy reference power corresponding to the current operating voltage is taken.

4. The diagnostic method according to claim 1, characterized in that, The step S4 of identifying and locating the abnormal photovoltaic branch includes: Calculate the normalized current value of each photovoltaic branch. and normalized power value ,in Let be the effective irradiance of the i-th photovoltaic branch. Let i be the actual power generation of the i-th photovoltaic branch. Let be the theoretical power generation of the i-th photovoltaic branch; Calculate the mean and standard deviation of the normalized output index of each photovoltaic branch. When the normalized output index of a photovoltaic branch deviates from the mean by more than a preset deviation threshold, it is determined that the photovoltaic branch is abnormal. When the voltage of a photovoltaic branch is close to the open circuit voltage and the current is lower than the preset lower current limit, it is judged as an open circuit or open circuit abnormality; when the voltage of a photovoltaic branch is lower than the preset ratio of the average voltage of normal branches and the current fluctuates abnormally, it is judged as a short circuit or wiring abnormality; when the voltage of a photovoltaic branch is within the normal range but the current and power are consistently low, it is judged as partial shading, dust accumulation and pollution, module degradation or branch mismatch. Output the abnormal photovoltaic branch number, abnormal type, and abnormal level.

5. The diagnostic method according to claim 1, characterized in that, The joint analysis described in step S5 includes: When the total output power of photovoltaics is within the normal range but the voltage of the high-voltage DC bus is continuously lower than the lower limit of the bus voltage, it is determined that the high-voltage DC bus, DC line, mains power compensation module or tunnel lighting load side is abnormal. When the total output power of photovoltaics is low and the voltage of the high-voltage DC bus drops synchronously, it is determined that the power supply on the photovoltaic side is insufficient, and the normal irradiance drop and photovoltaic abnormality are further distinguished according to the photovoltaic deviation coefficient. When the high-voltage DC bus voltage is higher than the upper limit of the bus voltage and the tunnel lighting load power decreases, it is determined that the tunnel lighting load is disconnected or the dimming is abnormal.

6. The diagnostic method according to claim 1, characterized in that, Step S5, which involves determining the matching status between photovoltaic output and tunnel lighting load, includes: Calculate the total output power of photovoltaic power ,in Let N be the actual power generation of the i-th photovoltaic branch, and N be the number of photovoltaic branches. Calculate the effective power supply of photovoltaics Where D(t) is the tunnel lighting load power; Calculate the mains power compensation power ; Calculate the photovoltaic power exceeding the tunnel lighting load. ; When the mains power compensation power When the power output is consistently higher than the compensation power threshold and the power generation deviation coefficient corresponding to the total photovoltaic output power exceeds the deviation threshold, a diagnostic result of abnormal photovoltaic side or insufficient power generation capacity is output. When the photovoltaic power exceeds the tunnel lighting load When the power consumption remains above the waste threshold, output suggestions for optimizing photovoltaic capacity configuration, installation angle, or dimming strategy.

7. The diagnostic method according to claim 1, characterized in that, The anomaly levels described in step S6 are classified as follows: When the power generation deviation coefficient is within the allowable range, the high-voltage DC bus is in normal condition, and the photovoltaic output matches the tunnel lighting load in a normal manner, it is judged as the first level; When the power generation deviation coefficient exceeds the deviation threshold but does not continue to exceed the preset time, it is judged as the second level; When the power generation deviation coefficient continues to exceed the deviation threshold, or the normalized output index deviates from the mean by more than the preset deviation threshold, it is judged as the third level, and maintenance suggestions for cleaning photovoltaic modules or checking obstructions are output. When there is an open circuit, short circuit, abnormal condition of the high voltage DC bus, or abnormal condition of the tunnel lighting load, it is judged as Level 4, and corresponding inspection and maintenance suggestions are output. When there is a risk of loss of voltage on the high-voltage DC bus or power outage of the tunnel lighting load, it is judged as Level 5, and the mains power compensation module is activated to provide compensation power to the high-voltage DC bus, while outputting emergency repair information. The mains power compensation is only activated after there is no short circuit, severe overcurrent or insulation abnormality on the bus, or the relevant faulty branch or bus section has been isolated.

8. The diagnostic method according to claim 1, characterized in that, The maintenance recommendations in step S6 include at least one of the following: cleaning photovoltaic modules, checking for obstructions, checking photovoltaic branch wiring, checking DC bus, checking LED lighting circuits, calibrating sensors, and adjusting mains power compensation strategies.

9. A diagnostic device for a tunnel high-voltage direct current photovoltaic power generation system based on irradiance, characterized in that, include: Irradiance sensor, used to collect solar irradiance data; An environmental parameter acquisition module is used to collect at least one of component temperature, ambient temperature, humidity, and wind speed. The photovoltaic branch voltage and current acquisition module is used to acquire the voltage and current of each photovoltaic branch. High-voltage DC bus acquisition module, used to acquire the voltage and current of the high-voltage DC bus; Lighting load acquisition module, used to acquire tunnel lighting load power; A diagnostic controller is connected to an irradiance sensor, an environmental parameter acquisition module, a photovoltaic branch voltage and current acquisition module, a high-voltage DC bus acquisition module, and a lighting load acquisition module, respectively. The diagnostic controller includes a processor and a memory. The memory stores a computer program. When the processor executes the computer program, it implements the diagnostic method according to any one of claims 1 to 8. The alarm module, connected to the diagnostic controller, is used to output an alarm signal when the abnormality level reaches the alarm condition; The communication module, connected to the diagnostic controller, is used to upload diagnostic results to the operation and maintenance platform; And a mains power compensation module, which is connected to the diagnostic controller and the high-voltage DC bus, is used to provide compensation power to the high-voltage DC bus under the control of the diagnostic controller.

10. The apparatus according to claim 9, characterized in that, When the computer program stored in the memory of the diagnostic controller is executed, the diagnostic controller implements the following functional modules: The theoretical power generation calculation module is used to calculate the theoretical power generation of each photovoltaic branch based on solar irradiance data, solar position parameters, installation parameters, photovoltaic module parameters, and environmental correction parameters. The deviation calculation module is used to calculate the power generation deviation coefficient based on the theoretical power generation and the actual power generation. The branch anomaly identification module is used to identify and locate photovoltaic branches with anomalies based on the power generation deviation coefficient and the consistency of normalized output indicators among the photovoltaic branches. The bus status diagnosis module is used to determine whether the high-voltage DC bus status is abnormal based on the high-voltage DC bus voltage, total photovoltaic output power, and tunnel lighting load power. The load matching diagnostic module is used to calculate the effective photovoltaic power supply, the mains power compensation power, and the photovoltaic power exceeding the tunnel lighting load, and to determine the matching status between the photovoltaic output and the tunnel lighting load. The integrated diagnostic decision module uses the output results of the integrated branch anomaly identification module, bus status diagnosis module, and load matching diagnosis module to generate anomaly type, anomaly location, anomaly level, and maintenance suggestions. When the anomaly level reaches the preset alarm conditions, it will trigger the alarm module or the mains power compensation module.

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