Photovoltaic power generation system diagnosis method, device, diagnosis system and storage medium

Abstract

This invention provides a method, apparatus, control device, and diagnostic system for diagnosing photovoltaic (PV) power generation systems. The method, based on a differential power processing device in the PV power generation system, includes: acquiring a terminal voltage signal and a current signal output in response to a preset excitation voltage signal from the PV panel under test based on a fault diagnosis trigger signal; matching the terminal voltage signal and current signal with a preset diode model of a solar cell to determine the values ​​of various modeled circuit parameters corresponding to the terminal voltage and current signals in the diode model of the preset solar cell; and performing fault diagnosis on the PV panel under test based on the values ​​of these modeled circuit parameters. This invention can avoid the reduction in PV power generation efficiency caused by faults that are difficult to detect in a localized manner over a long period; and it does not require additional device costs.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power generation technology, and in particular to a method, apparatus, control equipment and diagnostic system for photovoltaic power generation systems. Background Technology

[0002] With the energy crisis looming ever closer, new energy sources have become one of the world's main energy sources in the future. As an emerging green energy industry, photovoltaic power generation has gradually gained attention and support from the government.

[0003] However, due to the large number of photovoltaic (PV) panels in a PV power plant, the high failure rate of these panels caused by internal and external factors, and the difficulty in detecting circuit breaks in the collector lines between the PV panels and the combiner box, the photoelectric conversion efficiency of PV power generation gradually decreases, leading to increased operation and maintenance costs and a waste of electrical resources. Adding specialized fault diagnosis devices to PV power plants would significantly increase investment costs. Summary of the Invention

[0004] This invention provides a method, apparatus, control device, and diagnostic system for diagnosing photovoltaic power generation systems, in order to address the problem that photovoltaic panel failures can lead to a decrease in the photoelectric conversion efficiency of photovoltaic power generation, while adding a fault diagnosis device for photovoltaic panels would significantly increase device costs.

[0005] In a first aspect, embodiments of the present invention provide a method for diagnosing a photovoltaic power generation system, based on a differential power processing device in the photovoltaic power generation system, comprising:

[0006] The terminal voltage signal of the photovoltaic panel under test and the current signal output in response to the preset excitation voltage signal are obtained based on the fault diagnosis trigger signal. The terminal voltage signal is the voltage signal output by the photovoltaic panel under test based on the preset excitation voltage signal sent by the differential power processing device.

[0007] The terminal voltage signal and the current signal are matched with the diode model of the preset solar cell to determine the values ​​of each modeled circuit parameter in the diode model of the preset solar cell corresponding to the terminal voltage signal and the current signal.

[0008] Fault diagnosis is performed on the photovoltaic panel under test based on the parameter values ​​of each of the modeled circuits.

[0009] In one possible implementation, the preset excitation voltage signal is used to drive the terminal voltage signal of the photovoltaic panel under test from a minimum voltage level to a maximum voltage level; the maximum voltage level is determined based on the current level of degradation or radiation of the photovoltaic panel under test and the operating point of the grid-connected inverter operably connected to the photovoltaic panel under test.

[0010] In one possible implementation, the diode model of the preset solar cell is a dynamic single-diode model of the solar cell.

[0011] In one possible implementation, the fault diagnosis of the photovoltaic panel under test based on the parameter values ​​of each of the modeled circuits includes:

[0012] Based on the terminal voltage signal and the parameter values ​​of each of the modeled circuits, predict the predicted terminal current signal generated in the diode model of the preset solar cell;

[0013] Fault diagnosis is performed on the photovoltaic panel under test based on the predicted terminal current signal and the current signal.

[0014] In a second aspect, embodiments of the present invention provide a photovoltaic power generation system diagnostic device, based on a differential power processing device in a photovoltaic power generation system, comprising:

[0015] The acquisition module is used to acquire the terminal voltage signal of the photovoltaic panel under test and the current signal output in response to the preset excitation voltage signal based on the fault diagnosis trigger signal. The terminal voltage signal is the voltage signal output by the photovoltaic panel under test based on the preset excitation voltage signal sent by the differential power processing device.

[0016] A matching module is used to match the terminal voltage signal and the current signal with a preset diode model of a solar cell to determine the values ​​of each modeled circuit parameter in the preset diode model corresponding to the terminal voltage signal and the current signal.

[0017] The diagnostic module is used to diagnose faults in the photovoltaic panel under test based on the parameter values ​​of each of the modeled circuits.

[0018] Thirdly, embodiments of the present invention provide a control device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method as described in the first aspect or any possible implementation of the first aspect.

[0019] Fourthly, embodiments of the present invention provide a photovoltaic power generation system diagnostic system, comprising: a differential power processing device and a control device as described in the third aspect above;

[0020] The differential power processing device is connected across at least two photovoltaic panels connected in series. When a fault diagnosis trigger signal is received, it sends a preset excitation voltage signal to at least one of the photovoltaic panels under test based on different non-zero disturbance frequencies, and detects the terminal voltage signal of the photovoltaic panel under test and the current signal output in response to the preset excitation voltage signal.

[0021] In normal mode, where the fault diagnosis trigger signal is not received, maximum power point tracking is performed on at least two photovoltaic panels connected in series.

[0022] In one possible implementation, the differential power processing device includes: a communication module, a drive circuit, a power converter, a sampling module, and a controller;

[0023] The communication module is connected to the driving circuit and the sampling module respectively, and is used to receive the fault diagnosis trigger signal and send the fault diagnosis trigger signal to the driving circuit, as well as to acquire the terminal voltage signal of the photovoltaic panel under test detected by the sampling module and the current signal output in response to the preset excitation voltage signal and send them to the control device.

[0024] The drive circuit is connected to the power converter and the controller respectively, and is used to provide a gating signal to control the switching transistor in the power converter according to the fault diagnosis trigger signal and the control signal output by the controller.

[0025] The power converter is connected across at least two photovoltaic panels connected in series, and is used to send a preset excitation voltage signal to at least one of the photovoltaic panels under test based on different non-zero perturbation frequencies under the control of the gating signal.

[0026] The sampling module is connected to the photovoltaic panel under test and also to the controller. It is used to detect the terminal voltage signal of the photovoltaic panel under test and the current signal output in response to the preset excitation voltage signal and send them to the controller. The controller outputs a control signal based on the difference between the detected terminal voltage signal and the reference voltage signal with a non-zero perturbation frequency. The control signal is used to control the terminal voltage signal of the photovoltaic panel under test to follow the reference voltage signal.

[0027] In one possible implementation, the power converter includes: a first capacitor, a second capacitor, an inductor, a first switching transistor, and a second switching transistor;

[0028] The first capacitor has its first end connected to the first end of the first photovoltaic panel in at least two photovoltaic panels connected in series and the source of the first switching transistor, and its second end connected to the second end of the first photovoltaic panel and the first end of the second capacitor.

[0029] The second capacitor has its first end connected to the first end of the second photovoltaic panel in at least two photovoltaic panels connected in series, and its second end connected to the second end of the second photovoltaic panel and the drain of the second switching transistor, respectively.

[0030] The inductor has a first end connected between the first capacitor and the second capacitor, and a second end connected between the drain of the first switching transistor and the source of the second switching transistor.

[0031] The gates of both the first and second switching transistors are connected to the driving circuit.

[0032] Fifthly, embodiments of the present invention provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the method as described in the first aspect or any possible implementation thereof.

[0033] This invention provides a method, apparatus, control device, and diagnostic system for diagnosing photovoltaic (PV) power generation systems. Based on a differential power processing device in the PV power generation system, it acquires the terminal voltage signal and the current signal output in response to a preset excitation voltage signal of the PV panel under test based on a fault diagnosis trigger signal. The terminal voltage signal is the voltage signal output by the PV panel under test based on the preset excitation voltage signal sent by the differential power processing device. The terminal voltage signal and current signal are matched with a preset diode model of a solar cell to determine the modeled circuit parameter values ​​corresponding to the terminal voltage signal and current signal in the diode model of the preset solar cell. Fault diagnosis is performed on the PV panel under test based on the modeled circuit parameter values. This method can diagnose faults in PV panels within a PV power generation system, avoiding reduced power generation efficiency of the PV power plant due to long-term, difficult-to-detect local fault points. Furthermore, since this invention uses a differential power processing device to send a preset excitation voltage signal, it eliminates the need for additional specialized fault diagnosis devices in the PV power plant, thus reducing device costs. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a flowchart illustrating the implementation of the photovoltaic power generation system diagnostic method provided in this embodiment of the invention;

[0036] Figure 2 This is a schematic diagram of a dynamic single-diode model of a solar cell provided in an embodiment of the present invention;

[0037] Figure 3 This is a schematic diagram of the structure of the photovoltaic power generation system diagnostic device provided in an embodiment of the present invention;

[0038] Figure 4 This is a schematic diagram of the control device provided in an embodiment of the present invention;

[0039] Figure 5 This is a schematic diagram of a power converter provided in an embodiment of the present invention. Detailed Implementation

[0040] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0041] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described below in conjunction with the accompanying drawings.

[0042] See Figure 1 The document illustrates a flowchart of the photovoltaic power generation system diagnostic method provided in an embodiment of the present invention. This method is based on a differential power processing device in a photovoltaic power generation system, and is described in detail below:

[0043] In step 101, the terminal voltage signal of the photovoltaic panel under test and the current signal output in response to the preset excitation voltage signal are obtained based on the fault diagnosis trigger signal.

[0044] Among them, the terminal voltage signal is the voltage signal output by the photovoltaic panel under test based on the preset excitation voltage signal sent by the differential power processing equipment.

[0045] Differential power processing equipment can send a preset excitation voltage signal to the photovoltaic panel under test when triggered by a fault diagnosis trigger signal.

[0046] Optionally, the differential power processing device sends a preset excitation voltage signal to the photovoltaic panel under test (PV panel) to drive the terminal voltage signal of the PV panel under test from a minimum voltage level to a maximum voltage level. The maximum voltage level is determined based on the current level of degradation or radiation of the PV panel under test and the operating point of the grid-connected inverter operatively connected to the PV panel under test.

[0047] Each preset excitation voltage signal can have a duration in the millisecond range.

[0048] In step 102, the terminal voltage signal and current signal are matched with the diode model of the preset solar cell to determine the values ​​of each modeled circuit parameter in the diode model of the preset solar cell corresponding to the terminal voltage signal and current signal.

[0049] Optionally, the diode model of the solar cell is preset to a dynamic single diode model of the solar cell.

[0050] The dynamic single-diode model of the solar cell defines multiple modeled circuit elements and multiple modeled circuit parameters associated with the modeled circuit elements, which are used to determine the corresponding values ​​of the multiple modeled circuit parameters corresponding to the detected terminal voltage signal and output current signal of the photovoltaic panel under test. At least one of the determined values ​​of the multiple modeled circuit parameters represents the value of an inherent parameter indicating the state of the photovoltaic panel under test.

[0051] Among them, such as Figure 2 As shown, the multiple modeled circuit elements defined by the dynamic single diode model of a solar cell may include: a simulated current source that provides simulated current based on simulated incident light, a simulated diode connected in parallel with the simulated current source, a simulated capacitor connected in parallel with the simulated current source, a simulated first resistor connected in parallel with the simulated current source, and a simulated second resistor connected in series with the simulated first resistor and the simulated current source, respectively.

[0052] Among them, several modeled circuit parameters include the current I provided by the simulated current source in the dynamic single diode model. ph The reverse saturation current I in the dynamic single diode model o The thermal voltage V in the dynamic single diode model T In the dynamic single diode model, the resistance R of the first resistor is simulated. sh In the dynamic single diode model, the capacitance C of the simulated capacitor is... sh In the dynamic single diode model, the resistance R of the simulated second resistor is... s Among them, the resistance R sh Indicates the inherent pn junction resistance and capacitance C associated with the photovoltaic panel under test. sh Indicates the inherent pn junction capacitance associated with the photovoltaic panel under test.

[0053] In step 103, fault diagnosis is performed on the photovoltaic panel under test based on the parameter values ​​of each modeled circuit.

[0054] Optionally, fault diagnosis of the photovoltaic panel under test based on the parameter values ​​of each modeled circuit may include:

[0055] Based on the terminal voltage signal and the parameter values ​​of each modeled circuit, the predicted terminal current signal generated in the diode model of the preset solar cell is predicted.

[0056] Fault diagnosis is performed on the photovoltaic panel under test based on the predicted current signal and the current signal.

[0057] In this embodiment, the current predictor can predict the terminal current generated in the dynamic single diode model based on the detected terminal voltage signal of the photovoltaic panel under test and multiple modeled circuit parameter values.

[0058] Based on this, optimization algorithms can be used to determine the objective function values ​​associated with multiple modeled circuit parameter values.

[0059] This invention utilizes a differential power processing device within a photovoltaic (PV) power generation system. Based on a fault diagnosis trigger signal, it acquires the terminal voltage signal of the PV panel under test and the current signal output in response to a preset excitation voltage signal. The terminal voltage signal is the voltage signal output by the PV panel under test based on the preset excitation voltage signal sent by the differential power processing device. The terminal voltage signal and current signal are matched with a preset diode model of a solar cell to determine the corresponding modeled circuit parameter values ​​in the diode model of the preset solar cell. Fault diagnosis is then performed on the PV panel under test based on these modeled circuit parameter values. This method can diagnose faults in PV panels within a PV power generation system, preventing reduced power generation efficiency due to long-term, difficult-to-detect localized fault points. Furthermore, since this invention uses a differential power processing device to send a preset excitation voltage signal, it eliminates the need for additional specialized fault diagnosis equipment in the PV power plant, thus reducing device costs.

[0060] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0061] The following are device embodiments of the present invention. For details not described in detail, please refer to the corresponding method embodiments described above.

[0062] Figure 3 A schematic diagram of the photovoltaic power generation system diagnostic device provided in an embodiment of the present invention is shown. For ease of explanation, only the parts related to the embodiment of the present invention are shown, and are described in detail below:

[0063] like Figure 3 As shown, the photovoltaic power generation system diagnostic device includes: an acquisition module 31, a matching module 32, and a diagnostic module 33.

[0064] The acquisition module 31 is used to acquire the terminal voltage signal of the photovoltaic panel under test and the current signal output in response to the preset excitation voltage signal based on the fault diagnosis trigger signal. The terminal voltage signal is the voltage signal output by the photovoltaic panel under test based on the preset excitation voltage signal sent by the differential power processing device.

[0065] The matching module 32 is used to match the terminal voltage signal and the current signal with the diode model of the preset solar cell to determine the values ​​of each modeled circuit parameter in the diode model of the preset solar cell corresponding to the terminal voltage signal and the current signal.

[0066] The diagnostic module 33 is used to perform fault diagnosis on the photovoltaic panel under test based on the parameter values ​​of each of the modeled circuits.

[0067] This invention utilizes a differential power processing device within a photovoltaic (PV) power generation system. It acquires the terminal voltage signal of the PV panel under test and the current signal output in response to a preset excitation voltage signal based on a fault diagnosis trigger signal. The terminal voltage signal is the voltage output by the PV panel under test based on the preset excitation voltage signal sent by the differential power processing device. The terminal voltage signal and current signal are matched with a preset diode model of a solar cell to determine the corresponding modeled circuit parameter values ​​in the diode model of the preset solar cell. Fault diagnosis is then performed on the PV panel under test based on these modeled circuit parameter values. This method can diagnose faults in PV panels within a PV power generation system, preventing reduced power generation efficiency due to long-term, difficult-to-detect localized faults. Furthermore, since this invention uses a differential power processing device to send a preset excitation voltage signal, it eliminates the need for additional specialized fault diagnosis equipment in the PV power plant, thus reducing device costs.

[0068] In one possible implementation, the preset excitation voltage signal is used to drive the terminal voltage signal of the photovoltaic panel under test from a minimum voltage level to a maximum voltage level; the maximum voltage level is determined based on the current level of degradation or radiation of the photovoltaic panel under test and the operating point of the grid-connected inverter operably connected to the photovoltaic panel under test.

[0069] In one possible implementation, the diode model of the preset solar cell is a dynamic single-diode model of the solar cell.

[0070] In one possible implementation, the diagnostic module 33 is used to predict the predicted terminal current signal generated in the diode model of the preset solar cell based on the terminal voltage signal and the parameter values ​​of each of the modeled circuits.

[0071] Fault diagnosis is performed on the photovoltaic panel under test based on the predicted terminal current signal and the current signal.

[0072] Figure 4 This is a schematic diagram of the control device provided in an embodiment of the present invention. Figure 4As shown, the control device 4 in this embodiment includes a processor 40, a memory 41, and a computer program 42 stored in the memory 41 and executable on the processor 40. When the processor 40 executes the computer program 42, it implements the steps described in the various photovoltaic power generation system diagnostic method embodiments above, for example... Figure 1 Steps 101 to 103 are shown. Alternatively, when processor 40 executes computer program 42, it implements the functions of each module / unit in the above-described device embodiments, for example... Figure 3 The functions of modules / units 31 to 33 shown.

[0073] For example, computer program 42 can be divided into one or more modules / units, one or more of which are stored in memory 41 and executed by processor 40 to complete the present invention. One or more modules / units can be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of computer program 42 in control device 4. For example, computer program 42 can be divided into... Figure 3 Modules / units 31 to 33 are shown.

[0074] Control device 5 can be a computing device such as a desktop computer, laptop, handheld computer, or cloud server. Control device 4 may include, but is not limited to, processor 40 and memory 41. Those skilled in the art will understand that... Figure 4 This is merely an example of control device 4 and does not constitute a limitation on control device 4. It may include more or fewer components than shown, or combine certain components, or different components. For example, the terminal may also include input / output devices, network access devices, buses, etc.

[0075] The processor 40 may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0076] The memory 41 can be an internal storage unit of the control device 4, such as a hard disk or RAM of the control device 4. The memory 41 can also be an external storage device of the control device 4, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the control device 4. Furthermore, the memory 41 can include both internal storage units and external storage devices of the control device 4. The memory 41 is used to store computer programs and other programs and data required by the terminal. The memory 41 can also be used to temporarily store data that has been output or will be output.

[0077] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0078] Optionally, the control device 4 may also include a communication module for communicating with the differential power processing device.

[0079] Optionally, the control device 4 may also include another communication module for transmitting the parameter values ​​of each modeled circuit to a remote memory.

[0080] The communication module in the control device 4 may include a wireless communication module, such as a Zigbee communication module.

[0081] The remote memory is used to store the parameter values ​​of each modeled circuit determined by the control device, and the remote memory may include a server.

[0082] In remote memory, the time series of parameter values ​​for each modeled circuit can be analyzed to determine the predicted state of the photovoltaic panel under test, i.e., the predicted fault diagnosis result.

[0083] As another embodiment of the present invention, the present invention may also include a photovoltaic power generation system diagnostic system, comprising: a differential power processing device and a control device as described in the above embodiments.

[0084] A differential power processing device is connected across at least two photovoltaic panels connected in series. When a fault diagnosis trigger signal is received, it sends a preset excitation voltage signal to at least one of the photovoltaic panels under test based on different non-zero perturbation frequencies, and detects the terminal voltage signal of the photovoltaic panel under test and the current signal output in response to the preset excitation voltage signal.

[0085] In normal mode, where no fault diagnosis trigger signal is received, maximum power point tracking is performed on at least two photovoltaic panels connected in series.

[0086] In this embodiment, the differential power processing device can be understood as a data acquisition device. The differential power processing device can operate in normal mode to perform maximum power point tracking, and in diagnostic mode it can operate as a data acquisition device. Therefore, there is no need to add a professional fault diagnosis device to the photovoltaic power station, which helps to reduce the cost of the device.

[0087] Optionally, the differential power processing device may include: a communication module, a drive circuit, a power converter, a sampling module, and a controller.

[0088] The communication module is connected to the drive circuit and the sampling module respectively. It is used to receive the fault diagnosis trigger signal and send the fault diagnosis trigger signal to the drive circuit, as well as to acquire the terminal voltage signal of the photovoltaic panel under test detected by the sampling module and the current signal output in response to the preset excitation voltage signal and send them to the control device.

[0089] The drive circuit is connected to the power converter and the controller respectively, and is used to provide gating signals to control the switching transistors in the power converter according to the fault diagnosis trigger signal and the control signal output by the controller.

[0090] A power converter is connected across at least two series-connected photovoltaic panels to send a preset excitation voltage signal to at least one of the series-connected photovoltaic panels under test based on different non-zero perturbation frequencies, under the control of a gating signal.

[0091] The sampling module is connected to the photovoltaic panel under test and also to the controller. It is used to detect the terminal voltage signal of the photovoltaic panel under test and the current signal output in response to the preset excitation voltage signal and send them to the controller. The controller outputs a control signal based on the difference between the detected terminal voltage signal and the reference voltage signal with a non-zero perturbation frequency. The control signal is used to control the terminal voltage signal of the photovoltaic panel under test to follow the reference voltage signal.

[0092] In this embodiment, the drive circuit, power converter, and controller can be regarded as connection circuits in a differential power processing device (i.e., data acquisition device). They are arranged on a photovoltaic panel to send a preset excitation voltage signal to at least one of at least two photovoltaic panels connected in series. Each preset excitation voltage signal has its own non-zero perturbation frequency to establish the photovoltaic panel under test during normal operation of the at least two photovoltaic panels connected in series, detect the terminal voltage signal, and output the current signal of the photovoltaic panel under test in response to the preset excitation voltage signal.

[0093] The power converter can be a power converter with two switches. A drive circuit provides gating signals to operate the two switches complementaryly. A controller controls the drive circuit based on the difference between the detected terminal voltage signal of the photovoltaic panel under test and a reference voltage signal with a non-zero perturbation frequency, so that the measured terminal voltage signal of the photovoltaic panel under test follows the reference voltage signal.

[0094] The communication module in the differential power processing device is used to communicate with the control device to receive a trigger signal from the control device, thereby initiating the transmission of a preset excitation voltage signal, and transmitting the detected terminal voltage signal and current signal to the control device for analysis and determination of the state of the photovoltaic panel under test.

[0095] The communication module in the differential power processing device may include a wireless communication module, such as a Zigbee communication module.

[0096] The sampler in the differential power processing device is used to sample the detected terminal voltage signal and output current signal to provide the sampled corresponding signal, and the communication module in the differential power processing device can be used to transmit the sampled corresponding signal to the control device.

[0097] Optionally, the differential power processing device may also include a memory for storing the detected terminal voltage signal and output current signal.

[0098] Optionally, the power converter described above may include a DC-DC converter, which may include a buck-boost converter, and the buck-boost converter may be configured to operate in continuous conduction mode.

[0099] Optional, combined Figure 5 The power converter 50 includes: a first capacitor C1, a second capacitor C2, an inductor L, a first switch S1, and a second switch S2.

[0100] The first capacitor C1 has its first end connected to the first end of the first photovoltaic panel P1 and the source of the first switching transistor S1, which are connected in series. Its second end is connected to the second end of the first photovoltaic panel P1 and the first end of the second capacitor C2.

[0101] The second capacitor C2 has its first end connected to the first end of the second photovoltaic panel P2, which is connected in series with at least two photovoltaic panels, and its second end connected to the second end of the second photovoltaic panel P2 and the drain of the second switching transistor S2.

[0102] The inductor L has its first end connected between the first capacitor C1 and the second capacitor C2, and its second end connected between the drain of the first switching transistor S1 and the source of the second switching transistor S2.

[0103] The gates of the first switch S1 and the second switch S2 are both connected to the driving circuit.

[0104] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0105] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0106] In the embodiments provided by this invention, it should be understood that the disclosed devices / terminals and methods can be implemented in other ways. For example, the device / terminal embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0107] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0108] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0109] If integrated modules / units are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above-described embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various photovoltaic power generation system diagnostic method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0110] 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, and should all be included within the protection scope of the present invention.

Claims

1. A photovoltaic power generation system diagnostic system, characterized in that, include: Differential power processing equipment and control equipment; The differential power processing device is connected across at least two photovoltaic panels connected in series. When a fault diagnosis trigger signal is received, it sends a preset excitation voltage signal to at least one of the photovoltaic panels under test based on different non-zero disturbance frequencies, and detects the terminal voltage signal of the photovoltaic panel under test and the current signal output in response to the preset excitation voltage signal. In the normal mode where the fault diagnosis trigger signal is not received, maximum power point tracking is performed on at least two photovoltaic panels connected in series. The control device is used to acquire the terminal voltage signal of the photovoltaic panel under test and the current signal output in response to the preset excitation voltage signal based on the fault diagnosis trigger signal. The terminal voltage signal is the voltage signal output by the photovoltaic panel under test based on the preset excitation voltage signal sent by the differential power processing device. The terminal voltage signal and the current signal are matched with the diode model of the preset solar cell to determine the values ​​of each modeled circuit parameter in the diode model of the preset solar cell corresponding to the terminal voltage signal and the current signal. Fault diagnosis is performed on the photovoltaic panel under test based on the parameter values ​​of each of the modeled circuits. The differential power processing device includes: a communication module, a drive circuit, a power converter, a sampling module, and a controller; The power converter includes: a first capacitor, a second capacitor, an inductor, a first switching transistor, and a second switching transistor; The first capacitor has its first end connected to the first end of the first photovoltaic panel in at least two photovoltaic panels connected in series and the source of the first switching transistor, and its second end connected to the second end of the first photovoltaic panel and the first end of the second capacitor. The second capacitor has its first end connected to the first end of the second photovoltaic panel in at least two photovoltaic panels connected in series, and its second end connected to the second end of the second photovoltaic panel and the drain of the second switching transistor, respectively. The inductor has a first end connected between the first capacitor and the second capacitor, and a second end connected between the drain of the first switching transistor and the source of the second switching transistor. The gates of both the first and second switching transistors are connected to the driving circuit.

2. The photovoltaic power generation system diagnostic system according to claim 1, characterized in that, The communication module is connected to the driving circuit and the sampling module respectively, and is used to receive the fault diagnosis trigger signal and send the fault diagnosis trigger signal to the driving circuit, as well as to acquire the terminal voltage signal of the photovoltaic panel under test detected by the sampling module and the current signal output in response to the preset excitation voltage signal and send them to the control device. The drive circuit is connected to the power converter and the controller respectively, and is used to provide a gating signal to control the switching transistor in the power converter according to the fault diagnosis trigger signal and the control signal output by the controller. The power converter is connected across at least two photovoltaic panels connected in series, and is used to send a preset excitation voltage signal to at least one of the photovoltaic panels under test based on different non-zero perturbation frequencies under the control of the gating signal. The sampling module is connected to the photovoltaic panel under test and also to the controller. It is used to detect the terminal voltage signal of the photovoltaic panel under test and the current signal output in response to the preset excitation voltage signal and send them to the controller. The controller outputs a control signal based on the difference between the detected terminal voltage signal and the reference voltage signal with a non-zero perturbation frequency. The control signal is used to control the terminal voltage signal of the photovoltaic panel under test to follow the reference voltage signal.

3. A method for diagnosing a photovoltaic power generation system, characterized in that, The method, applied to the photovoltaic power generation system diagnostic system as described in claim 1 or 2, comprises: The terminal voltage signal of the photovoltaic panel under test and the current signal output in response to the preset excitation voltage signal are obtained based on the fault diagnosis trigger signal. The terminal voltage signal is the voltage signal output by the photovoltaic panel under test based on the preset excitation voltage signal sent by the differential power processing device. The terminal voltage signal and the current signal are matched with the diode model of the preset solar cell to determine the values ​​of each modeled circuit parameter in the diode model of the preset solar cell corresponding to the terminal voltage signal and the current signal. Fault diagnosis is performed on the photovoltaic panel under test based on the parameter values ​​of each of the modeled circuits.

4. The photovoltaic power generation system diagnostic method according to claim 3, characterized in that, The preset excitation voltage signal is used to drive the terminal voltage signal of the photovoltaic panel under test from the minimum voltage level to the maximum voltage level; the maximum voltage level is determined based on the current level of degradation or radiation of the photovoltaic panel under test and the operating point of the grid-connected inverter operably connected to the photovoltaic panel under test.

5. The photovoltaic power generation system diagnostic method according to claim 3, characterized in that, The diode model of the preset solar cell is a dynamic single diode model of the solar cell.

6. The photovoltaic power generation system diagnostic method according to any one of claims 3-5, characterized in that, The fault diagnosis of the photovoltaic panel under test based on the parameter values ​​of each of the modeled circuits includes: Based on the terminal voltage signal and the parameter values ​​of each of the modeled circuits, predict the predicted terminal current signal generated in the diode model of the preset solar cell; Fault diagnosis is performed on the photovoltaic panel under test based on the predicted terminal current signal and the current signal.

7. A diagnostic device for a photovoltaic power generation system, characterized in that, The photovoltaic power generation system diagnostic system as described in claim 1 or 2 above includes: The acquisition module is used to acquire the terminal voltage signal of the photovoltaic panel under test and the current signal output in response to the preset excitation voltage signal based on the fault diagnosis trigger signal. The terminal voltage signal is the voltage signal output by the photovoltaic panel under test based on the preset excitation voltage signal sent by the differential power processing device. A matching module is used to match the terminal voltage signal and the current signal with a preset diode model of a solar cell to determine the values ​​of each modeled circuit parameter in the preset diode model corresponding to the terminal voltage signal and the current signal. The diagnostic module is used to diagnose faults in the photovoltaic panel under test based on the parameter values ​​of each of the modeled circuits.

8. A control device, characterized in that, It includes a memory and a processor, the memory being used to store a computer program, and the processor being used to call and run the computer program stored in the memory to perform the method as described in any one of claims 3 to 6.

9. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 3 to 6 above.

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