Device and method for detecting reliable connection of solar module

Abstract

The invention discloses a detection device and a detection method for reliable connection of a solar module. The detection device comprises a type facing a plurality of strings and a type facing a single string. The multi-string-level fault positioning system is used for realizing string-level fault positioning for the types of multiple strings, comprises an MCU (Microprogrammed Control Unit) main control chip, a pulse transformer, a high-frequency small-signal circuit and a sampling conditioning circuit, and adopts a current excitation mode. Component-level fault positioning is achieved for the type of a single string, the device comprises an AC source and a current sensor or a current transformer connected with an MCU2 main control chip, the primary end of the current transformer is connected in series in a photovoltaic string loop, and the secondary end of the current transformer is connected to the input end of a sampling conditioning circuit; and the MCU2 main control chip judges whether the connection of the photovoltaic module circuit is reliable or not. According to the invention, detection of two arc forms of series connection and parallel connection is realized; the detection of a low-impedance value loop is realized, and the influence of direct-current large current on photovoltaic power in the detection process is avoided; and high-granularity fault positioning is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of power system detection, and in particular relates to a solar module reliability connection detection device and detection method. Background Art

[0002] The development of renewable energy has promoted the widespread application of combined photovoltaic and storage systems. The combined photovoltaic and storage system is a system that combines photovoltaic power generation and electrochemical energy storage. It can convert solar energy into electrical energy through the photovoltaic power generation system and store the electrical energy in electrochemical energy storage batteries. This system can provide stable electricity when photovoltaic power generation is not available, such as at night or on cloudy days.

[0003] With the continuous advancement of photovoltaic and electrochemical energy storage technologies, the efficiency and energy density of combined photovoltaic and electrochemical energy storage systems are becoming higher and higher, while the cost is becoming lower and lower.

[0004] During the process of mass installation and large-scale operation of combined photovoltaic and energy storage systems, people have also discovered that since photovoltaic modules are DC power generation devices, when the contact at the line connection is poor, the resistance at that point will increase, and the lost energy will be converted into heat. When the temperature rises rapidly to reach the softening temperature and melting point of the line material, gaps will appear in the local line, and DC arcing will further occur, destroying the insulation and flame retardancy of the material, causing fires in cables and components, and possibly causing thermal runaway of the energy storage battery. In recent years, many major fires have been caused by poor contact at the line connection.

[0005] Based on the above risks, some countries and regions have clearly stated that systems involving photovoltaic power generation need to be equipped with DC arc detection and judgment devices. For example, the US UL 1699B requires the system to have a DC arc detection device (AFCI); China has also issued the national standard GB / T 39750-2021, which is basically close to the requirements of UL 1699B.

[0006] Most of the current detection methods for combined photovoltaic and energy storage systems are aimed at series arcs (arcs caused by component failures, DC line failures, etc.), rather than detecting the reliability of line connections before the arc occurs. There is also little research on parallel arcs (arcs caused by short circuits, grounding, and other faults).

[0007] These traditional detection methods for series arcs currently mainly use current sensors to detect changes in current, and analyze the time domain and frequency domain characteristics of the changing current. This detection is only suitable for detecting series arcs that occur suddenly and abnormally, and can be used to determine whether the line is suddenly broken or the photovoltaic storage system itself has a sudden failure. However, there is a blind spot for the high impedance caused by poor line contact in the photovoltaic storage system at the beginning. Since the arc phenomenon is gradually caused by continuous poor contact, it lacks frequency domain characteristics and is considered to be background noise, and cannot be detected in this way.

[0008] Traditional detection methods have the following problems:

[0009] 1) There are obvious blind spots in the detection, and there is a lack of recognition ability for arcs caused by poor line contact and high impedance that exist from the beginning. In this case, the frequency domain characteristics are not obvious.

[0010] 2) Lack of parallel arc detection capability requires additional voltage sensors to detect voltage changes, resulting in increased costs.

[0011] 3) The existing technology cannot accurately determine the location and type of arc, and cannot locate and repair it well.

[0012] 4) In existing current detection schemes, if the wires connecting solar photovoltaic (PV) are affected by electromagnetic induction, induced current will be generated, which may be mistaken by the arc detection system as a signal of arc fault, resulting in a greater risk of false alarm. Summary of the invention

[0013] In view of this, the present invention proposes a line reliability connection detection device that can detect poor line connection in a photovoltaic storage system and accurately locate the position of the string where the line is poor. It can effectively detect the connection reliability of the solar module line, and at the same time accurately locate the position, without blind spots, and with a fast response speed, effectively preventing arcs and even fires caused by poor connection of solar modules, and improving the troubleshooting efficiency of operation and maintenance personnel. The detection device can be used to solve the safety problem of excessive local impedance due to unreliable wiring, local heating, DC arcing, and fire.

[0014] The first aspect of the present application discloses a solar module reliability connection detection device, which is electrically connected to n photovoltaic strings, and includes an MCU main control chip, n sampling and conditioning circuits, a pulse transformer T1, and an AC source;

[0015] The AC source is used to generate an AC signal. The AC source forms a loop with the primary end of the pulse transformer T1, transmits the current signal to the main circuit, and performs high-frequency small-signal current disturbance on the main circuit. An AC switch K1 is connected in series to the main circuit, and the AC switch K1 receives the control instruction of the MCU main control chip to perform a switching action.

[0016] The primary end of the pulse transformer T1 is connected to the AC source, and the secondary end is connected in series in the n photovoltaic string circuits. The pulse transformer T1 is used to inject the AC signal generated by the AC source into the main circuit of the photovoltaic string;

[0017] The n sampling and conditioning circuits are sequentially connected to the n photovoltaic string main circuits to sample and process the electrical signals of the photovoltaic string main circuits; the two ends of the sampling and conditioning circuit are connected to the positive and negative busbars of the photovoltaic string main circuits, and the sampling resistors in the sampling and conditioning circuits are used to detect the line voltage, transmit the data to the MCU main control chip, and calculate the line impedance;

[0018] The MCU main control chip is connected to the output ends of the n sampling and conditioning circuits, and is used to receive the electrical signals processed by the n sampling and conditioning circuits.

[0019] Further, the sampling and conditioning circuit includes a resistor R1, a resistor R2, a resistor R3, a capacitor C2, an operational amplifier U5A, a resistor R4, a resistor R5, a capacitor C3, a capacitor C4, a resistor R6, a resistor R7, an operational amplifier U5D and a 2.5V power supply, wherein the two ends of the resistor R1 are respectively connected to the two ends of the transformer T2, one end is also connected to one end of the resistor R2, and the other end is also respectively connected to one end of the resistor R3, one end of the capacitor C2, one end of the resistor R4, and the 2.5V power supply; the other end of the resistor R2 is respectively connected to the other end of the resistor R3, the other end of the capacitor C2, the operational amplifier U5D and the 2.5V power supply. The inverting input terminal of the operational amplifier U5A is connected; the inverting input terminal of the operational amplifier U5A is respectively connected to the other end of the resistor R4 and one end of the resistor R5, and the output terminal of the operational amplifier U5A is respectively connected to the other end of the resistor R5 and one end of the capacitor C3; the other end of the capacitor C3 is respectively connected to one end of the capacitor C4 and one end of the resistor R6, and the other end of the capacitor C4 is respectively connected to the inverting input terminal of the operational amplifier U5D and one end of the resistor R7, and the other end of the resistor R7 is connected to a 2.5V power supply; the other end of the resistor R6 is respectively connected to the output terminal and the inverting input terminal of the operational amplifier U5D.

[0020] The second aspect of the present application discloses a method for detecting the reliability connection of a solar module, which is used to detect the reliability of a main circuit of a photovoltaic string, and comprises the following steps:

[0021] S1, MCU main control chip controls the AC switch to close, and controls the AC source to output an AC signal. The AC disturbance signal output by the AC source is injected into the main circuit of the photovoltaic string through the pulse transformer T1;

[0022] S2, the sampling and conditioning circuit samples the power-on signal of the photovoltaic string and performs bandwidth and amplitude conditioning;

[0023] S3, the sampling and conditioning circuit outputs the signal to the MCU main control chip, and the MCU main control chip calculates the pure impedance value R of the photovoltaic string line L , when satisfied:

[0024] R L >>R PV

[0025] Among them, R PV The impedance of photovoltaic power generation; if the wiring of the line is bad, the detection device will execute shutdown, positioning and alarm processing;

[0026] S4. Detect the voltage sampling value of each main circuit and the insulation resistance to ground to determine whether there is a ground short circuit fault and a short circuit fault between lines. If so, the detection device executes shutdown, positioning and alarm processing.

[0027] The third aspect of the present application discloses a solar module reliability connection detection device for connection fault point location, which is used in a single string or a small number of strings photovoltaic system: comprising an AC source, a plurality of sampling and conditioning circuits, and an MCU2 main control chip;

[0028] In each photovoltaic string, m photovoltaic modules are connected in series, and both ends of each photovoltaic module are connected to the input end of the sampling and conditioning circuit respectively, and the output end of the sampling and conditioning circuit is connected to the MCU2 main control chip of the module detection device;

[0029] The AC source is connected to the photovoltaic string and the input end of the sampling and conditioning circuit to generate an AC signal, transmit the current signal to the main circuit, and perform high-frequency small-signal current disturbance on the main circuit;

[0030] The primary end of the current transformer T2 is connected in series in the photovoltaic string circuit, and the secondary end is connected to the input end of the sampling and conditioning circuit;

[0031] The MCU2 main control chip performs frequency domain analysis on the current signal input by the sampling and conditioning circuit, and detects the line impedance based on the voltage sensor to determine whether the connection of the PV module line is reliable.

[0032] Furthermore, the detection device also includes a current transformer T2, the primary end of the current transformer T2 is connected in series to the photovoltaic string, and the secondary end is connected to the input end of the sampling and conditioning circuit to sample the DC current, and the output end of the sampling and conditioning circuit is connected to the MCU2 main control chip.

[0033] Furthermore, the detection device also includes a current sensor I1 for sampling AC and / or DC. The current sensor I1 is connected in series to each of the photovoltaic strings, and the current sensor I1 is also connected to the MCU2 main control chip; the MCU2 main control chip performs frequency domain analysis on the current signal input by the current sensor I1, and detects the line impedance based on the voltage sensor to determine whether the connection of the photovoltaic component line is reliable; the current sensor is also connected to the AC source.

[0034] A fourth aspect of the present application discloses a method for detecting the reliability of a solar module connection. The method detects the reliability of a module connection line of a photovoltaic module, comprising the following steps:

[0035] Step 1: Detection starts, MCU2 main control chip controls the AC source to switch at different frequencies f h To track photovoltaic energy, the current sensor I1 detects the current i1 of the main circuit of the photovoltaic string and the corresponding switch ripple current ΔI; the sampling and conditioning circuits on both sides of each photovoltaic module in the photovoltaic string sample the voltage effective value V at both ends of the photovoltaic module and the corresponding switching frequency f h The ripple voltage ΔV under

[0036] Step 2. The FFT of the MCU2 main control chip resolves the changing power component ΔP:

[0037] ΔP=ΔV*ΔI;

[0038] Step 3. Calculate the impedance R of each photovoltaic module according to the switch ripple current ΔI and ripple voltage ΔV in step 1: R = ΔV / ΔI;

[0039] Step 4. According to step 2 and step 3, determine whether the component connection lines of adjacent photovoltaic components are abnormal. When the impedance R of each photovoltaic component exceeds the impedance setting value, when it is detected that the change power component ΔP exceeds the power component setting value, it is determined that the photovoltaic component connection is abnormal and a DC arc risk has occurred. The setting of the impedance setting value and the power component setting value is adjusted according to different solar panels;

[0040] Step 6: If a DC arc risk occurs, stop the equipment and report the arc fire risk.

[0041] Compared with the prior art, this application has the following beneficial effects:

[0042] 1) The present invention can realize the detection of two types of arcs: series and parallel:

[0043] For series DC arcs caused by poor line contact, active high-frequency small-signal current disturbance is used to determine whether the arc has a high impedance value through FFT analysis;

[0044] For sudden parallel arcs, passive sampling of the loop voltage and detection of insulation resistance to ground are performed to determine whether there are short-circuit faults between lines and short-circuit faults to ground, avoiding the problem that traditional methods cannot detect series arcs and parallel arcs at the same time.

[0045] 2) The present invention uses a high-frequency, low-amplitude AC small current superimposed with a DC current for detection, which can realize the detection of a low-impedance loop and avoid the influence of a large DC current on the photovoltaic during the detection process.

[0046] 3) Each circuit uses a voltage sensing circuit to accurately locate group-level faults. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 An electrical schematic diagram of fault detection for parallel-connected photovoltaic strings provided in one embodiment of the present application;

[0048] Figure 2 An electrical schematic diagram of bad position detection of a photovoltaic storage combined system according to an embodiment of the present application;

[0049] Figure 3 For this application Figure 2 The electrical schematic diagram of the current transformer T2;

[0050] Figure 4 A reliability connection detection flow chart of a detection device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0051] The present invention is further described below in conjunction with the accompanying drawings, but the present invention is not limited in any way. Any changes or substitutions made based on the teachings of the present invention belong to the protection scope of the present invention.

[0052] The present application provides a solar module reliability connection detection device, which injects AC interference signals into n photovoltaic strings or energy storage main circuits, and injects interference signals into photovoltaic module connection lines of photovoltaic string circuits, and analyzes and judges the signals between the main circuits or module connection lines.

[0053] Embodiment 1:

[0054] refer to Figure 1 In one embodiment, the detection device of the present application is used to perform fault judgment on multiple parallel photovoltaic strings, including an MCU main control chip, a sampling and conditioning circuit, a pulse transformer T1, and a high-frequency small signal circuit. The high-frequency small signal circuit includes an AC source and an AC switch K1. The AC source, the AC switch K1, and the primary end of the pulse transformer T1 are connected in series to form a loop. The AC switch K1 performs a switching action under the control instruction of the MCU main control chip; the secondary end of the pulse transformer T1 is connected in series in the main circuit of the photovoltaic string circuit. After the AC switch K1 is closed, the primary end of the pulse transformer T1 outputs an AC signal and injects it into the main circuit of the photovoltaic string through the secondary end. Exemplarily, the photovoltaic modules PV1-PVm and the photovoltaic converter form loop 1 or loop 2, and multiple photovoltaic modules and the energy storage converter are connected in series to form loop n-1 or loop n-2.

[0055] Figure 1As shown, the main circuits of n photovoltaic strings are connected to n sampling and conditioning circuits U1 to Un one by one respectively, and the AC source injects a high-frequency small signal into the main circuit of the photovoltaic and energy storage combined system through the pulse transformer T1. The main circuit of the photovoltaic and energy storage combined system is connected to the input end of the sampling and conditioning circuit between the secondary end of the pulse transformer T1 and the DC / DC circuit, and the output end of the sampling and conditioning circuit is connected to the MCU main control chip. The sampling and conditioning circuit samples the line AC impedance of the main circuit and transmits the data to the MCU main control chip to determine whether the connection of the photovoltaic string line is reliable.

[0056] In this embodiment, step 1): the AC switch K1 is closed, the AC source outputs an AC signal, and the main circuit is energized by the pulse transformer T1 at a frequency of f h The high-frequency small signal current disturbance is sampled and conditioned by the voltage sensor circuit, and the voltage signal is conditioned and sampled by the ADC, and finally sent to the MCU main control chip for FFT analysis.

[0057] Step 2): FFT resolves the high frequency f h The voltage disturbance value of the same frequency corresponding to the AC signal, that is, the AC voltage value, is used to calculate the pure electrical impedance R of the line. L When the pure electrical impedance is high, it is judged that the line has poor wiring. The MCU main control chip executes shutdown, positioning and alarm processing. The detection device informs the DSP or EMS to shut down the inverter and the photovoltaic storage system through communication. At this time, the pure electrical impedance of the line is:

[0058] R L >>R PV

[0059] Among them, R PV is the impedance of the PV string;

[0060] When there is no high-frequency small signal disturbance, when FFT analyzes a large inductive reactance or capacitive reactance value, it is judged that a sudden line contact failure or arc occurs, and the MCU main control chip executes shutdown, positioning and alarm processing;

[0061] Step 3): The MCU detects the insulation resistance of the voltage sampling circuit to the ground, and whether the sampling voltage values ​​of loop 1 and loop n are within the normal range, and determines whether there is a ground short circuit fault and a short circuit fault between lines. If so, the detection device executes shutdown, positioning and alarm processing. The detection device informs the DSP or EMS through communication, the EMS fault light will light up, and the inverter and photovoltaic storage combined system will be shut down at the same time.

[0062] The disclosed detection device is connected to a switch of a high-frequency small signal circuit (AC source). The high-frequency small signal circuit (AC source) generates an AC signal (i.e., a high-frequency small signal). The AC source has a frequency conversion function, and the frequency conversion is 1KHZ-40KHZ. The AC source is connected to an AC switch, and the AC switch is used to control the AC source.

[0063] The high-frequency small signal circuit transmits the current signal to the main circuit through the pulse transformer T1, and performs high-frequency f h Small signal current disturbance, voltage sensor detects line impedance and transmits data to the detection device to detect line AC impedance and determine whether the PV module line connection is reliable.

[0064] refer to Figure 3 The electrical schematic diagram of the main circuit fault judgment shows the detection of a single component. The detection principle of a string composed of multiple components is the same. The two ends of the sampling and conditioning circuit are connected to the positive and negative busbars of the main circuit of the photovoltaic string, and are connected to the main control chip of MCU2. The sampling and conditioning circuit includes resistor R1, resistor R2, resistor R3, capacitor C2, operational amplifier U5A, resistor R4, resistor R5, capacitor C3, capacitor C4, resistor R6, resistor R7, operational amplifier U5D and 2.5V power supply, wherein the two ends of resistor R1 are respectively connected to the two ends of transformer T2, one end is also connected to one end of resistor R2, and the other end is also respectively connected to one end of resistor R3, one end of capacitor C2, one end of resistor R4, and 2.5V power supply; the other end of resistor R2 is respectively connected to the other end of resistor R3, the other end of capacitor C2, operational amplifier U The inverting input terminal of the operational amplifier U5A is respectively connected to the other end of the resistor R4 and one end of the resistor R5, and the output terminal of the operational amplifier U5A is respectively connected to the other end of the resistor R5 and one end of the capacitor C3; the other end of the capacitor C3 is respectively connected to one end of the capacitor C4 and one end of the resistor R6, and the other end of the capacitor C4 is respectively connected to the inverting input terminal of the operational amplifier U5D and one end of the resistor R7, and the other end of the resistor R7 is connected to a 2.5V power supply; the other end of the resistor R6 is respectively connected to the output terminal and the inverting input terminal of the operational amplifier U5D.

[0065] Embodiment 2:

[0066] Figure 2 As shown, the detection device is used to detect whether the component connection lines in the main circuit of the photovoltaic energy storage system are reliable. Figure 2 The figure takes the connection line detection of the photovoltaic string circuit 1 as an example. In the photovoltaic string circuit 1, there are m photovoltaic modules connected in series. The input / output ends of each photovoltaic module are respectively connected to the two input ends of the sampling and conditioning circuit, and the output end of the sampling and conditioning circuit is connected to the MCU2 main control chip.

[0067] exist Figure 2In the application shown, the AC source is connected in series in the photovoltaic string. The series circuit is also provided with a current transformer T2 connected to the sampling and conditioning circuit and a current sensor I1 connected to the MCU2 main control chip. The primary end of the current transformer T2 is connected in series in the photovoltaic string circuit, and the secondary end is connected to the input end of the sampling and conditioning circuit.

[0068] When the AC source injects an AC signal into the photovoltaic string circuit, the current sensor I1 samples the current signal on the circuit and uploads it to the MCU2 main control chip. The current transformer T2 mainly samples the AC component and processes it through the sampling conditioning circuit U 1_0 Complete data processing and transmit it to the MCU2 main control chip; in the photovoltaic string circuit, the two ends of each photovoltaic module are connected to the two input ends of the sampling and conditioning circuit, and the data is transmitted to the MCU2 main control chip after sampling and processing by the sampling and conditioning circuit.

[0069] by Figure 4 As an example, the detection device is used to detect the photovoltaic string circuit 1. The detection steps are as follows: Step 1: At the beginning of the detection, the MCU2 main control chip controls the AC source to generate different frequencies f h Photovoltaic energy tracking (the embodiment can use 20KHZ), the current sensor I1 detects the current i1 and the corresponding photovoltaic string series circuit switch ripple current ΔI; the sampling conditioning circuit U 1_1 、u 1_2 , U 1_m Sample the voltage RMS values ​​and corresponding switching frequency f at PV1, PV2, and PVm respectively h The voltage ripples ΔV1, ΔV2, ΔVm-1, ΔVm under.

[0070] Step 2: The MCU2 main control chip uses the FFT algorithm to parse out the 500HZ-100KHZ variable power component ΔP, ΔP = ΔI * ΔV;

[0071] Step 3: Calculate the component connection impedance of adjacent PV modules based on the switching ripple current ΔI and ripple voltage in step 1: R1 = ΔV1 / ΔI, R2 = ΔV2 / ΔI, Rm-1 = ΔVm-1 / ΔI, Rm = ΔVm / ΔI, R1 is the PV1 connection impedance, R2 is the PV2 connection impedance, Rm-1 is the PVm-1 impedance, and Rm is the PVm connection impedance.

[0072] Step 4: Determine whether the connection lines of the PV modules are reliable according to steps 2 and 3. When the impedances R1, R2, Rm-1, and Rm exceed the set value R, and when it is detected that ΔP exceeds the set value P, it is determined that the solar module connection is abnormal and a DC arc risk has occurred. The settings of R and P can be different and can be adjusted according to different solar modules.

[0073] Step 6: If a DC arc risk occurs, it is necessary to stop the equipment and report the arc fire risk.

[0074] In this application, the MCU2 main control chip and the MCU main control chip realize shutdown by controlling the opening and closing of the power supply. For faults such as ground short circuit faults, short circuit faults between lines, and poor wiring of the line, the detection device can accurately locate and alarm through the alarm circuit. The alarm circuit is a prior art in this field. The alarm circuit alarms by sound, light, electricity, etc., and this application will not repeat them. Exemplarily, the MCU2 main control chip is BQ79616, bq455A, and the MCU main control chip can be model TMS320F280039, STM32 series.

[0075] 1) The present invention can realize the detection of two types of arcs: series and parallel:

[0076] For series DC arcs caused by poor line contact, active high-frequency small-signal current disturbance is used to determine whether the arc has a high impedance value through FFT analysis;

[0077] For sudden parallel arcs, passive sampling of the loop voltage and detection of insulation resistance to ground are performed to determine whether there are short-circuit faults between lines and short-circuit faults to ground, which solves the problem that traditional methods cannot detect series arcs and parallel arcs at the same time.

[0078] 2) The present invention uses a high-frequency, low-amplitude AC small current superimposed with a DC current for detection, which can realize the detection of a low-impedance loop and avoid the influence of a large DC current on the photovoltaic during the detection process.

[0079] 3) Each circuit uses a voltage sensing circuit to accurately locate group-level faults.

[0080] As used herein, the word "preferred" is intended to be used as an example, instance, or illustration. Any aspect or design described herein as "preferred" is not necessarily to be construed as being more advantageous than other aspects or designs. On the contrary, the use of the word "preferred" is intended to present concepts in a specific way. The term "or" as used in this application is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless otherwise specified or clear from the context, "X uses A or B" means any one of the naturally included permutations. That is, if X uses A; X uses B; or X uses both A and B, then "X uses A or B" is satisfied in any of the foregoing examples.

[0081] Moreover, although the present disclosure has been shown and described with respect to one or implementations, those skilled in the art will think of equivalent variations and modifications based on the reading and understanding of this specification and the accompanying drawings. The present disclosure includes all such modifications and variations, and is limited only by the scope of the appended claims. In particular, with respect to the various functions performed by the above-mentioned components (such as elements, etc.), the terms used to describe such components are intended to correspond to any component (unless otherwise indicated) that performs the specified function of the component (such as it is functionally equivalent), even if the structure is not equivalent to the disclosed structure of the function in the exemplary implementation of the present disclosure shown herein. In addition, although the specific features of the present disclosure have been disclosed with respect to only one of several implementations, such features can be combined with one or other features of other implementations that may be desired and advantageous for a given or specific application. Moreover, insofar as the terms "including", "having", "containing" or their variations are used in specific embodiments or claims, such terms are intended to be included in a manner similar to the term "comprising".

[0082] The functional units in the embodiments of the present invention may be integrated into a processing module, or each unit may exist physically separately, or multiple or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium. The above-mentioned storage medium may be a read-only memory, a disk or an optical disk, etc. The above-mentioned devices or systems may execute the storage method in the corresponding method embodiment.

[0083] To sum up, the above embodiment is an implementation mode of the present invention, but the implementation mode of the present invention is not limited by the embodiment. Any other changes, modifications, substitutions, combinations, and simplifications that deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A solar module reliability connection detection device, the detection device is electrically connected to n photovoltaic strings, characterized in that: The detection device includes an MCU main control chip, n sampling and conditioning circuits, a pulse transformer T1, and an AC source; The AC source is used to generate an AC signal. The AC source forms a loop with the primary end of the pulse transformer T1, transmits the current signal to the main circuit, and performs high-frequency small-signal current disturbance on the main circuit. An AC switch K1 is connected in series to the main circuit, and the AC switch K1 receives the control instruction of the MCU main control chip to perform a switching action. The primary end of the pulse transformer T1 is connected to the AC source, and the secondary end is connected in series in the n photovoltaic string circuits. The pulse transformer T1 is used to inject the AC signal generated by the AC source into the main circuit of the photovoltaic string; The n sampling and conditioning circuits are sequentially connected to the n photovoltaic string main circuits to sample and process the electrical signals of the photovoltaic string main circuits; the two ends of the sampling and conditioning circuit are connected to the positive and negative busbars of the photovoltaic string main circuits, and the sampling resistors in the sampling and conditioning circuits are used to detect the line voltage, transmit the data to the MCU main control chip, and calculate the line impedance; The MCU main control chip is connected to the output ends of the n sampling and conditioning circuits, and is used to receive the electrical signals processed by the n sampling and conditioning circuits.

2. The solar module reliability connection detection device according to claim 1, characterized in that: The sampling and conditioning circuit includes a resistor R1, a resistor R2, a resistor R3, a capacitor C2, an operational amplifier U5A, a resistor R4, a resistor R5, a capacitor C3, a capacitor C4, a resistor R6, a resistor R7, an operational amplifier U5D and a 2.5V power supply, wherein the two ends of the resistor R1 are respectively connected to the two ends of the transformer T2, one end is also connected to one end of the resistor R2, and the other end is also respectively connected to one end of the resistor R3, one end of the capacitor C2, one end of the resistor R4, and the 2.5V power supply; the other end of the resistor R2 is respectively connected to the other end of the resistor R3, the other end of the capacitor C2, the operational amplifier U5D, and the 2.5V power supply. The inverting input terminal of the operational amplifier U5A is connected to the other end of the resistor R4 and one end of the resistor R5, and the output terminal of the operational amplifier U5A is connected to the other end of the resistor R5 and one end of the capacitor C3; the other end of the capacitor C3 is connected to one end of the capacitor C4 and one end of the resistor R6, and the other end of the capacitor C4 is connected to the inverting input terminal of the operational amplifier U5D and one end of the resistor R7, and the other end of the resistor R7 is connected to a 2.5V power supply; the other end of the resistor R6 is connected to the output terminal and the inverting input terminal of the operational amplifier U5D.

3. A solar module reliability connection detection method using the solar module reliability connection detection device according to any one of claims 1-2, the detection method is used to detect the reliability of the main circuit of a photovoltaic string, characterized in that: The following steps are involved: S1, MCU main control chip controls the AC switch to close, and controls the AC source to output an AC signal. The AC disturbance signal output by the AC source is injected into the main circuit of the photovoltaic string through the pulse transformer T1; S2, the sampling and conditioning circuit samples the power-on signal of the photovoltaic string and performs bandwidth and amplitude conditioning; S3, the sampling and conditioning circuit outputs the signal to the MCU main control chip, and the MCU main control chip calculates the pure impedance value R of the photovoltaic string line L , when satisfied: R L >>R PV Among them, R PV The impedance of photovoltaic power generation; if the wiring of the line is bad, the detection device will execute shutdown, positioning and alarm processing; S4. Detect the voltage sampling value of each main circuit and the insulation resistance to ground to determine whether there is a ground short circuit fault and a short circuit fault between lines. If so, the detection device executes shutdown, positioning and alarm processing.

4. A solar module reliability connection detection device for locating connection fault points, used in a single string or a small number of strings photovoltaic system, characterized by: Including AC source, multiple sampling and conditioning circuits, and MCU2 main control chip; In each photovoltaic string, m photovoltaic modules are connected in series, and both ends of each photovoltaic module are respectively connected to the input end of the sampling and conditioning circuit, and the output end of the sampling and conditioning circuit is connected to the MCU2 main control chip of the module detection device; The AC source is connected to the photovoltaic string and the input end of the sampling and conditioning circuit to generate an AC signal, transmit the current signal to the main circuit, and perform high-frequency small-signal current disturbance on the main circuit; The primary end of the current transformer T2 is connected in series in the photovoltaic string circuit, and the secondary end is connected to the input end of the sampling and conditioning circuit; The MCU2 main control chip performs frequency domain analysis on the current signal input by the sampling and conditioning circuit, and detects the line impedance based on the voltage sensor to determine whether the connection of the PV module line is reliable.

5. The solar module reliability connection detection device for locating connection fault points according to claim 4 is characterized in that: The detection device also includes a current transformer T2, the primary end of which is connected in series to the photovoltaic string, and the secondary end is connected to the input end of the sampling and conditioning circuit to sample the DC current, and the output end of the sampling and conditioning circuit is connected to the MCU2 main control chip.

6. The solar module reliability connection detection device for connection fault point location according to claim 4, characterized in that: The detection device also includes a current sensor I1 for sampling AC and / or DC. The current sensor I1 is connected in series to each photovoltaic string and is also connected to the MCU2 main control chip. The MCU2 main control chip performs frequency domain analysis on the current signal input by the current sensor I1, and detects the line impedance based on the voltage sensor to determine whether the connection of the photovoltaic component line is reliable. The current sensor is also connected to the AC source.

7. A solar module reliability connection detection method using the solar module reliability connection detection device for connection fault point location according to any one of claims 4 to 6, wherein the detection method detects the reliability of the module connection line of the photovoltaic module, characterized in that: The following steps are involved: Step 1: Detection starts, MCU2 main control chip controls the AC source to switch at different frequencies f h To track photovoltaic energy, the current sensor I1 detects the current i1 of the main circuit of the photovoltaic string and the corresponding switch ripple current ΔI; the sampling and conditioning circuits on both sides of each photovoltaic module in the photovoltaic string sample the voltage effective value V at both ends of the photovoltaic module and the corresponding switching frequency f h The ripple voltage ΔV under Step 2. The FFT of the MCU2 main control chip resolves the changing power component ΔP: ΔP=ΔV*ΔI; Step 3. Calculate the impedance R of each photovoltaic module according to the switch ripple current ΔI and ripple voltage ΔV in step 1: R = ΔV / ΔI; Step 4. According to step 2 and step 3, determine whether the component connection lines of adjacent photovoltaic components are abnormal. When the impedance R of each photovoltaic component exceeds the impedance setting value, when it is detected that the change power component ΔP exceeds the power component setting value, it is determined that the photovoltaic component connection is abnormal and a DC arc risk has occurred. The setting of the impedance setting value and the power component setting value is adjusted according to different solar panels; Step 5: If a DC arc risk occurs, stop the equipment and report the arc fire risk.

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