Method for recognizing AC faults in inverters and solar power generation systems

Abstract

This application provides a method for recognizing AC faults in an inverter and a photovoltaic power system, in which a controller records waveforms for a certain parameter of a photovoltaic power system, and uploads the recorded waveforms to an external device, and the external device with high data storage and processing capabilities stores and processes the waveforms, thereby realizing accurate recognition of the faults on the AC side of the inverter. The operator can view the detailed waveforms from the external device, which greatly improves the monitoring accuracy of the system. The external device can make full use of the advantages of storage capacity, big data, and computing power to analyze the waveforms and generate control commands to adjust the operation of the inverter, making the control more accurate, and cooperating with the local in real time and quickly to control and achieve better system performance.

Description

Technical Field

[0001] This application claims the priority of a Chinese patent application filed with the China National Intellectual Property Administration on July 20, 2021, with an application number of 202110819893.2 and an invention title of "Method for Recognizing AC Faults of an Inverter and a Photovoltaic Power Generation System", and all its contents are incorporated herein by reference.

[0002] This application relates to the technical field of power electronics, and particularly to a method for recognizing AC faults of an inverter and a photovoltaic power generation system.

Background Art

[0003] Generally, a power grid needs to be connected to the AC side of a solar power generation inverter. When a device fails, a specific fault type is determined based on the characteristics of key parameters during the fault. For example, when the grid voltage exceeds a threshold, it is determined as an overvoltage fault, and when the current exceeds a threshold, it is determined as an overcurrent fault, so that the solar power generation inverter can respond appropriately.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Therefore, a system solution is needed to ensure that accurate fault recognition for the AC side of a solar power generation inverter can be achieved.

[0005] This application provides a method for recognizing AC faults of an inverter and a photovoltaic power generation system to achieve accurate recognition of faults on the AC side of the inverter.

Means for Solving the Problems

[0006] To achieve the above object, embodiments of the present invention provide the following technical solutions. The first aspect of the present invention provides a method for recognizing AC faults of a photovoltaic power generation system. The controller of the solar power generation system performs a step of recording waveforms for predetermined parameters of the solar power generation system, wherein the predetermined parameters include AC parameters of the inverter in the solar power generation system. The controller includes the step of uploading the recorded waveform to an external device, The external device includes the step of recognizing an AC fault in the photovoltaic power generation system by displaying and / or analyzing the waveform.

[0007] Preferably, the controller of the photovoltaic power generation system performs the step of recording waveforms for predetermined parameters of the photovoltaic power generation system, The controller performs the step of determining whether a recording trigger signal has been generated, When the recording trigger signal is generated, the controller performs a waveform recording for the predetermined parameters, the steps include:

[0008] Preferably, the controller determines whether a recording trigger signal has been generated. The controller takes the step of determining whether it has received the recording trigger signal from an external source, or The controller includes the step of determining whether the recording trigger signal has been generated internally.

[0009] Preferably, if the recording trigger signal originates from an external source, it specifically originates from the external device.

[0010] Preferably, if the recording trigger signal originates from within the controller, specifically, the controller's internal timing module generates the recording trigger signal when the timer reaches a set time.

[0011] Preferably, if the recording trigger signal originates from within the controller, specifically, the controller generates the recording trigger signal when it recognizes that the inverter has failed.

[0012] Preferably, an AC power grid or AC load is connected to the AC-side power port of the inverter, and the AC parameters include at least one of AC voltage, AC current, and leakage current.

[0013] Preferably, the predetermined parameter further includes at least one of DC voltage, DC current, and DC power.

[0014] Preferably, if the inverter is grounded, the predetermined parameter further includes at least one of the ground common-mode voltage and ground isolation resistance.

[0015] Preferably, if the photovoltaic power generation system is provided with a sensor located outside the inverter, the predetermined parameter further includes at least one of the following: entry point voltage, entry point current, load access point voltage, load access point current, external device current, external ambient temperature, and illuminance.

[0016] Preferably, when the controller performs waveform recording for the predetermined parameter, the recording frequency is at least twice the characteristic frequency of the predetermined parameter, and / or the recording period is at least the waveform period of the predetermined parameter.

[0017] Preferably, the step of the external device performing analysis on the waveform is: The step includes the external device performing a time-domain or frequency-domain analysis on the waveform.

[0018] Preferably, the reference data used by the external device when performing analysis on the waveform includes at least one of the following: standard waveform data stored on the cloud server, other waveforms uploaded by the inverter, waveform data historically uploaded by the inverter, and waveform data uploaded by other inverters.

[0019] Preferably, after the external device analyzes the waveform, The method further includes a step in which the external device issues a command to the controller based on the analysis result to adjust the state of the inverter.

[0020] Preferably, the command includes any one of startup, stop, and adjustment of operation parameters.

[0021] Preferably, after the step of uploading the waveform recorded by the controller to the external device is executed at least twice, the external device executes the step of displaying and / or analyzing the waveform.

[0022] Preferably, before the controller of the solar power generation system records the waveform for the predetermined parameters of the solar power generation system, The external device further includes a step of issuing a command to the controller once to set the state of the inverter.

[0023] Preferably, after adjusting the state of the inverter, the controller of the solar power generation system repeatedly executes the step of recording the waveform for the predetermined parameters of the solar power generation system.

[0024] Preferably, the external device is a remote server, a cloud server, or a mobile device.

[0025] The second aspect of the present invention further provides an inverter, including a main circuit and a controller, A solar power generation array of the solar power generation system is directly or indirectly connected to a power port on the DC side of the main circuit, and an AC power grid or an AC load is connected to a power port on the AC side of the main circuit. The main circuit is controlled by the controller. The controller is communicatively connected to an external device and executes each step executed by the controller of the solar power generation system in the method for recognizing an AC fault of the solar power generation system according to any one paragraph of the first aspect above.

[0026] Preferably, the controller further adjusts the state of the inverter based on commands issued by the external device.

[0027] Preferably, the controller and the external device are connected by wired communication, wireless communication, or power carrier communication.

[0028] Preferably, the main circuit is a DC-AC converter, or a DC-AC converter and at least one DC-DC converter preceding it. [Effects of the Invention]

[0029] According to the AC fault recognition method for a photovoltaic power generation system provided by the present invention, the controller records waveforms for predetermined parameters of the photovoltaic power generation system, uploads the recorded waveforms to an external device, and the external device, which has high data storage and processing capabilities, performs storage and subsequent processing operations on these waveforms, thereby achieving accurate recognition of faults on the AC side of the inverter.

[0030] To more clearly illustrate the embodiments of this application or the technical concepts in the prior art, the following is a brief introduction of the necessary drawings describing the embodiments or the prior art. The drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on the structures shown in these drawings, provided they do not perform the necessary work to demonstrate inventiveness. [Brief explanation of the drawing]

[0031] [Figure 1] This is a flowchart illustrating a method for recognizing AC faults in a solar power generation system provided in an embodiment of the present invention. [Figure 2] This is a schematic diagram of waveform recording provided by an embodiment of the present invention. [Figure 3] This is a schematic diagram of data monitoring in a conventional system provided by an embodiment of the present invention. [Figure 4]These are four other flowcharts illustrating a method for recognizing AC faults in a photovoltaic power generation system provided in an embodiment of the present invention. [Figure 5] These are four other flowcharts illustrating a method for recognizing AC faults in a photovoltaic power generation system provided in an embodiment of the present invention. [Figure 6] These are four other flowcharts illustrating a method for recognizing AC faults in a photovoltaic power generation system provided in an embodiment of the present invention. [Figure 7] These are four other flowcharts illustrating a method for recognizing AC faults in a photovoltaic power generation system provided in an embodiment of the present invention. [Figure 8] This is a schematic diagram of an application scenario for an inverter provided by an embodiment of the present invention. [Modes for carrying out the invention]

[0032] The following describes the technical aspects of embodiments of the present invention clearly and completely by combining drawings of embodiments of the present invention, and the embodiments described are not all embodiments but only a selection of embodiments of the present invention. All other embodiments obtained based on embodiments of the present invention, provided that a person skilled in the art does not perform work worthy of inventive step, are all within the scope of protection of the present invention.

[0033] In this application, the terms “include,” “incorporate,” or any other variation thereof are intended to include non-exclusive inclusion, thereby meaning that a process, method, article, or apparatus containing a set of elements includes not only those elements but also other elements not explicitly listed, or even elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element limited by the phrase “includes one XX” does not preclude a process, method, article, or apparatus containing that element from having other identical elements.

[0034] This invention provides a method for recognizing AC faults in a solar power generation system to improve the accuracy of recognition and determination of waveform characteristics.

[0035] The inverter includes a main circuit and a controller. The structure and configuration of the main circuit can be determined according to the specific application environment; it may include only a DC-AC conversion circuit, or at least one DC-DC conversion circuit may be provided before the DC-AC conversion circuit. The internal and external parameters of the inverter are transmitted to the controller via appropriate detection equipment, and the controller can achieve accurate control of the main circuit when monitoring the appropriate parameters.

[0036] The controller communicates with an external device, which may be a remote server, cloud server, or mobile device. Generally, the external device is the master machine, and the controller is the slave machine. The external device remotely sends commands to the controller to control the start, stop, and operation of the inverter and to obtain the inverter's operating parameters. The communication method between the controller and the external device may be wired, such as RS485, CAN, Ethernet, or USB; or wireless, such as WiFi, Bluetooth®, Zigbee®, LoRa®, NB-IoT, or optical communication; or even PLC power carrier communication. All of these fall within the scope of protection of this application.

[0037] Referring to Figure 1, the method for recognizing an AC fault in the solar power generation system includes the following steps: S101: The controller of the solar power generation system records waveforms for predetermined parameters of the solar power generation system.

[0038] Generally, the inverter is equipped with multiple detection devices inside or outside to detect electrical parameters such as voltage, current, and power, or external environmental parameters such as temperature and irradiance. These detection devices output their detection results to a controller, which then performs waveform recording for one or more of the corresponding predetermined parameters.

[0039] In practical applications, the predetermined parameters include at least one of the AC parameters of an inverter in a photovoltaic power generation system, such as AC voltage, AC current, and leakage current. Continuous waveform recording of AC voltage and AC current allows for the analysis of relevant characteristics of the AC power grid or AC load, such as voltage harmonics, current harmonics, DC component of voltage, DC component of current, AC active power, AC reactive power, AC apparent power, power factor, AC resistance, and stability. Continuous waveform recording of leakage current allows for tracking the insulation and safety status of the system.

[0040] In the process by which the controller records waveforms for predetermined parameters, the frequency and duration of the recording should be determined according to the specific application environment. In actual applications, in order to ensure the fidelity of the waveform recording, the frequency of the waveform recording should be at least twice the characteristic frequency of the predetermined parameter, satisfying Shannon's theorem for signal sampling. That is, key information can only be collected when the acquisition frequency is greater than twice the characteristic frequency. For example, when recording a 50Hz AC voltage waveform from the AC power port of the inverter, the frequency of the waveform recording should be 100Hz or higher, meaning that more than 100 voltage points are recorded every second. Also, if the frequency of the waveform recording is constant, the longer the waveform recording period, the more points are collected, and the better the integrity of the waveform. The waveform recording period should preferably be greater than or equal to the period of the original waveform of the predetermined parameter. For example, if recording a 50Hz AC voltage waveform from an AC power port with a period of 20ms, the waveform recording length should preferably be 20ms or longer. Furthermore, multiple consecutive waveform periods, such as 10 waveform periods, may be recorded to demonstrate the periodicity of the waveform. Of course, the longer the recorded waveform period, the larger the amount of data to be recorded, stored, and transmitted, which increases the demands on the system hardware, and there may be trade-offs in actual applications. Figure 2 is a schematic diagram for recording a 50Hz (period 20ms) sinusoidal voltage waveform (e.g., a power grid voltage waveform), recording the waveform according to a period of 50us, and recording 400 points for each period.

[0041] S102: The controller uploads the recorded waveform to an external device.

[0042] The controller uploads the recorded waveform to an external device using an appropriate communication method, and the selection of such communication method should be determined according to the specific application environment; all such methods fall within the scope of protection of this application.

[0043] S103: External equipment enables the recognition of AC faults in the solar power generation system by displaying and / or analyzing waveforms.

[0044] In practical applications, the inverter determines the specific type of failure based on the characteristics of key parameters at the time of failure. For example, if the power grid voltage exceeds a threshold, it determines that it is an overvoltage fault; if the current exceeds a threshold, it determines that it is an overcurrent fault. Furthermore, the inverter proactively detects characteristics of the AC power grid, such as the power grid voltage range, power grid resistance, and power grid harmonics, and adjusts its own relevant operating parameters in a timely manner to adapt as closely as possible to the characteristics of the AC power grid.

[0045] However, whether it is fault detection or dynamic adjustment of operating parameters, if both are performed based on the inverter's local control unit (i.e., the controller mentioned above), the accuracy of recognition and determination is limited because both its data storage capacity and processing capacity are finite.

[0046] Therefore, by steps S102 and S103, these operations are entrusted to an external device, which displays the waveform transmitted by the inverter through its own display interface or a connected display terminal. In this case, the function it performs is equivalent to a remote oscilloscope. Furthermore, the external device can also analyze the waveform and output the results of the waveform analysis.

[0047] Specifically, the waveform analysis method used may be a time-domain or frequency-domain feature analysis of the current waveform. This analysis may include analyzing the waveform's harmonics, DC components, amplitude values, and system stability.

[0048] In actual applications, the reference data used by external devices to analyze waveforms includes at least one of the following: standard waveform data stored on a cloud server, other waveforms uploaded by the inverter, waveform data historically uploaded by the inverter, and waveform data uploaded by other inverters.

[0049] The waveform analysis methods used are as follows: the current waveform is compared with standard waveform data stored in an external device, and the analysis results are obtained and output. Alternatively, the current waveform (e.g., AC voltage waveform) and other waveform data uploaded by the inverter (e.g., current waveform) are comprehensively analyzed, and the analysis results are obtained and output. Alternatively, the current waveform and waveform data historically uploaded by the inverter are comprehensively analyzed, and the analysis results are obtained and output. Alternatively, the current waveform and waveform data uploaded by other inverters are comprehensively analyzed, and the analysis results are obtained and output.

[0050] According to the AC fault recognition method for a solar power generation system provided in this embodiment, an external device with high data storage and processing capabilities performs storage and subsequent processing operations on these waveforms to achieve accurate recognition of faults on the AC side of the inverter.

[0051] Here, the waveform recording described in this embodiment differs from data monitoring in conventional systems. Conventional systems generally monitor data at the minute level, and as shown in Figure 3, they can only monitor AC voltage at the minute level, so they cannot display real-time waveforms and can only display the waveform contour of the effective voltage value Vrms. In this embodiment, by recording the waveforms of fine segments of the inverter, external equipment can perform subsequent detailed analysis and display, significantly improving the accuracy of system monitoring.

[0052] Based on Figure 1, the AC fault recognition method provided by another embodiment of the present invention, as shown in Figure 4, specifically includes the following steps in step S101: S201: The controller determines whether a recording trigger signal has been generated.

[0053] The specific process is as follows: the controller determines whether it has received an external recording trigger signal, or whether an internal recording trigger signal has been generated. That is, the recording trigger signal may originate from an external source or an internal source, and this can be determined according to the specific application environment, in which case it falls within the scope of protection of this application.

[0054] One suitable implementation solution is for the recording trigger signal to be an external trigger signal. For example, an external device, such as an operating interface for a remote server / cloud server, a program on a mobile device, or the operation of an external key, can send the recording trigger signal to the inverter and trigger the inverter to perform waveform recording.

[0055] As another preferred implementation solution, the recording trigger signal is triggered by an internal timing mechanism of the inverter, and when the timer of the internal timing module of the inverter's controller reaches a set time, the controller generates the recording trigger signal and triggers the controller to perform the waveform recording operation. For example, the inverter triggers waveform recording once every hour, thus considering the real-time nature of waveform recording while avoiding the occupation of excessive memory and communication channel resources.

[0056] Another preferred implementation solution is to generate a recording trigger signal when the inverter detects a fault, and the controller performs a waveform recording operation when it detects the inverter fault. For example, in the event of a power grid overvoltage fault, the controller is triggered to record the power grid voltage. This ensures accurate recording of the waveform at the time of the fault while avoiding the excessive use of memory and communication channel resources by continuously recording the waveform.

[0057] The above are merely some specific examples and are not limited thereto. The specific process by which the controller determines whether a recording trigger signal has been generated may be modified according to the actual situation, and any such modification falls within the scope of protection of this application.

[0058] If a recording trigger signal is generated, step S102 is executed.

[0059] S102: The controller records waveforms for predetermined parameters.

[0060] The process and requirements for recording this information should be referred to in previous examples, and no further explanation will be provided here.

[0061] Regardless of the structure of the inverter's main circuit, in practical applications, the inverter generally has two power ports: a DC power port and an AC power port. The AC power port is connected to an AC power grid or an AC load, and the DC power port is directly connected to a photovoltaic array, or indirectly connected to a photovoltaic array via a DC-DC converter. Depending on the specific environment, a combiner box may be added to the DC upstream stage, all of which fall within the scope of protection of this application.

[0062] Furthermore, the inverter is further equipped with appropriate detection equipment for detecting the electrical parameters of the corresponding power ports, and the inverter's controller performs continuous and high-speed waveform recording of these electrical parameters by corresponding steps of the above method and transmits the recorded waveforms to an external device via communication. Specifically, the inverter's controller detects whether a recording trigger signal is present, and if so, performs continuous waveform recording for a first time period duration for at least one of the electrical parameters from the corresponding power ports. For example, if the presence of a recording trigger signal is detected, continuous waveform recording of the voltage of the AC power port is immediately initiated.

[0063] In practical applications, the predetermined parameters include the electrical parameters of the AC-side power port, as well as at least one of the electrical parameters of the DC-side power port, such as DC voltage, DC current, and DC power. Continuous waveform recording of DC voltage and DC current allows for the analysis of relevant characteristics of the DC power source or DC load, such as DC power and voltage / current stability.

[0064] In practical applications, the inverter may also have a ground terminal, in which case the predetermined parameter may be an electrical parameter of the ground, specifically including at least one of the ground common-mode voltage and ground isolation resistance. Continuous waveform recording of the ground common-mode voltage and ground isolation resistance allows for the detection of the system's insulation and safety status.

[0065] Furthermore, the inverter may be further equipped with external sensors, in which case the predetermined parameters may be external electrical parameters, specifically including at least one of the following: entry point voltage, entry point current, load access point voltage, load access point current, external ambient temperature, and illuminance. In practical applications, an external current sensor may measure the entry point current and / or the current of an external third-party device; an external temperature sensor may measure the external ambient temperature and convert it into an electrical parameter signal, which may be transmitted to the controller; and an external illumination sensor may measure illuminance and convert it into an electrical signal, which may be transmitted to the controller. Continuous waveform recording of the external electrical parameters can track changes in external related equipment or the external environment.

[0066] The above are merely some specific examples of the specified parameters, and in actual applications, the application is not limited to these; any parameter to be analyzed or demonstrated may be used, and all of these fall within the scope of protection of this application.

[0067] Based on the above embodiment, in the AC fault recognition method provided by another embodiment of the present invention, after the external device completes waveform analysis, it generates a control command to control the operation of the inverter, and in this case, the function realized corresponds to a remote CPU central processing unit / processor.

[0068] That is, as shown in Figure 5 (exhibited based on Figure 1), after step S103, the method for recognizing the AC fault further includes the following steps: S104: The external device sends commands to the controller based on the analysis results to adjust the inverter status.

[0069] The instruction includes one of the following: starting, stopping, or adjusting operating parameters.

[0070] Based on the waveform analysis results, the external equipment issues further commands to the inverter. For example, if the analysis reveals that parameters such as AC current harmonics / DC components / leakage current are large, it issues a command to adjust the inverter's operating parameters to reduce current harmonics / DC components / leakage current; if the analysis reveals that the solar power DC voltage has deviated far from the historical maximum power point, it issues a command to adjust the inverter's operating parameters to track the maximum power point; if the analysis reveals that the stability of the AC power grid is low, it issues a command to adjust the inverter's operating parameters to reduce the impact on the AC power grid, for example, by reducing the output of active power or strengthening the AC power grid's support capacity, for example, by increasing the output of capacitive reactive power; and if the analysis reveals that a potential fault exists in the system, for example, that ground isolation is persistently degrading, it issues a command to adjust the inverter's operating parameters in advance to optimize system operation, eliminate the potential fault or prevent the fault from escalating, and enter a protective state beforehand.

[0071] In practical applications, adjusting the operating parameters of an inverter includes, but is not limited to, adjustments to control loop parameters, duty cycle, target voltage, target current, and target power.

[0072] External devices such as remote servers or cloud servers generally possess large memory capacity, big data capabilities, and computing power that the inverter's local control unit lacks. Therefore, in the AC fault detection method for the solar power generation system provided in this embodiment, using external devices such as remote servers or cloud servers to analyze waveforms and obtain control commands provides more accurate control performance than the local control unit. The remote server or cloud server interacts with the local control unit via communication, and although the speed is relatively slow, it complements and cooperates with the real-time and rapid control of the inverter's local control unit, significantly improving the system's performance.

[0073] Furthermore, when adjusting the inverter's operating state or parameters, external devices such as remote servers or cloud servers make decisions based on waveforms recorded multiple times to operate the system where the inverter is located in an optimal state. For example, based on the waveforms recorded and uploaded by the inverter in the morning, noon, and evening, an overall decision is made, and then the optimal operating state or parameters are provided, or different operating states or parameters are provided for different times, so that the inverter's operating status is optimized for each time period. That is, the process of steps S101 to S102 may be executed multiple times before executing step S103, in which case, refer to Figure 6 for a flowchart of the AC fault recognition method.

[0074] External devices such as remote servers or cloud servers may proactively issue commands, first adjusting the inverter's operating state or operating parameters, then causing the inverter to record and upload the waveform after the adjustment of the operating state or operating parameters. The external devices such as remote servers or cloud servers then provide the final optimal operating state or operating parameters based on the waveform analysis. For example, for a grid-connected inverter, the cloud server first issues a command to control the inverter to operate in a low-power state and to record and upload the output voltage waveform. Then, the cloud server issues another command to control the inverter to operate in a high-power state and to record and upload the output voltage waveform. Based on a comparative analysis of the output voltage waveforms before and after, the cloud server determines the strength of the power grid connected to the inverter and calculates the optimal operating parameters for the stability of the inverter and system, such as adjusting to appropriate proportional-integral control parameters, increasing / decreasing the degree of voltage feedforward control, or increasing / decreasing the magnitude of the enabled or disabled output. That is, before executing step S101, there may be a step S100, in which the external device issues a command to the controller once to set the inverter state. After executing step S104, the process may be repeated back to step S101, and steps S101 to S104 may be executed multiple times. The specific number of times should be determined according to the application environment. In this case, refer to Figure 7 for a flowchart of the AC fault recognition method.

[0075] In actual applications, the AC fault recognition methods shown in Figures 6 and 7 may be combined with other applications and determined according to the specific application environment, and all of these fall within the scope of protection of this application.

[0076] Another embodiment of the present invention further provides an inverter, referring to Figure 7, which specifically includes a main circuit 101 and a controller 102. The DC power port of the main circuit 101 is directly or indirectly connected to the solar power array of the solar power generation system, and the AC power port of the main circuit 101 is connected to the AC power grid or AC load. The main circuit 101 is controlled by the controller 102. The controller 102 communicates with the external device 200 and performs steps S101 and S102 of the method for recognizing AC faults in a solar power generation system described in any one of the above embodiments. For the specific process and principle of this method, please refer to the above embodiments, and no further explanation will be given here.

[0077] The external device 200 displays the waveform transmitted by the inverter through its own display interface or a connected display terminal.

[0078] Preferably, the controller 102 further adjusts the state of the inverter based on commands issued by an external device.

[0079] In actual applications, communication between the controller 102 and external devices is achieved through wired communication, wireless communication, or power carrier communication.

[0080] Furthermore, the structure of the main circuit 101 is a DC-AC conversion circuit, or a DC-AC conversion circuit and at least one DC-DC conversion circuit preceding it.

[0081] Regarding other structures and installations of the inverter, prior art may be referenced, and the AC fault recognition method may be realized in cooperation with the external device 200, all of which fall within the scope of protection of this application.

[0082] Each embodiment in this specification is described in a progressive manner, and similar or identical parts between embodiments may be referenced to one another. Each embodiment primarily describes the differences from the other embodiments. In particular, since systems or system embodiments are fundamentally similar to method embodiments, their description is simple, and relevant parts may be referenced to the descriptions of the method embodiments. The systems and system embodiments described above are merely schematic, and the units described as individual components may or may not be physically separate, and 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. Based on actual needs, some or all of these units can be selected to achieve the objectives of the technical proposal of this embodiment. A person skilled in the art can understand and implement it without performing work commensurate with inventive step.

[0083] As will be further noted to those skilled in the art, each exemplary unit and algorithmic step described in combination with the embodiments disclosed herein is implemented by electronic hardware, computer software, or a combination of both. To clearly illustrate the compatibility between hardware and software, the configurations and steps of each example are generally described in the above description according to their function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical proposal. Those skilled in the art may implement the described functions using different methods for each specific application, but such implementations do not exceed the scope of the invention.

[0084] As described above for the disclosed embodiments, features described in each embodiment herein may be substituted or combined with each other so that those skilled in the art can realize or use the present invention. Various modifications to these embodiments are obvious to those skilled in the art, and the general principles defined herein can be realized in other embodiments without departing from the spirit or scope of the invention. Accordingly, the present invention is not limited to these embodiments herein and fits the broadest scope that is consistent with the principles and novel features disclosed herein.

Claims

1. A method for recognizing AC faults in a solar power generation system, The controller of the solar power generation system performs a step of recording waveforms for predetermined parameters of the solar power generation system, wherein the predetermined parameters include AC parameters of the inverter in the solar power generation system. The controller includes the step of uploading the recorded waveform to an external device, The external device includes the step of recognizing an AC fault in the photovoltaic power generation system by displaying and / or analyzing the waveform, The controller of the solar power generation system performs the step of recording waveforms for predetermined parameters of the solar power generation system, The controller performs the step of determining whether a recording trigger signal has been generated, When the recording trigger signal is generated, the controller includes the step of performing waveform recording for the predetermined parameters, The controller determines whether a recording trigger signal has been generated. The controller includes the step of determining whether it has received the recording trigger signal from an external source, A method for recognizing AC faults in a solar power generation system, characterized in that, if the recording trigger signal originates from an external source, the recording trigger signal originates from the external device.

2. The step of determining whether a recording trigger signal has occurred in the controller further includes: The method for recognizing an AC fault in a solar power generation system according to claim 1, characterized in that the controller includes a step of determining whether the recording trigger signal has occurred internally.

3. The method for recognizing an AC fault in a solar power generation system according to claim 2, characterized in that, if the recording trigger signal originates from within the controller, the internal timing module of the controller generates the recording trigger signal when the timer reaches a set time.

4. The method for recognizing an AC fault in a solar power generation system according to claim 2, characterized in that, if the recording trigger signal originates from within the controller, the controller generates the recording trigger signal when it recognizes that the inverter has failed.

5. The method for recognizing an AC fault in a photovoltaic power generation system according to claim 1, characterized in that an AC power grid or an AC load is connected to the AC-side power port of the inverter, and the AC parameter includes at least one of AC voltage, AC current, and leakage current.

6. The method for recognizing an AC fault in a photovoltaic power generation system according to claim 1, characterized in that the predetermined parameter further includes at least one of DC voltage, DC current, and DC power.

7. The method for recognizing an AC fault in a photovoltaic power generation system according to claim 1, characterized in that when the inverter is grounded, the predetermined parameter further includes at least one of the ground common-mode voltage and ground insulation resistance.

8. The method for recognizing an AC fault in a solar power generation system according to claim 1, characterized in that, if the solar power generation system is provided with a sensor located outside the inverter, the predetermined parameter further includes at least one of the following: voltage at the entry point, current at the entry point, voltage at the load access point, current at the load access point, current of an external device, external ambient temperature, and illuminance.

9. The method for recognizing an AC fault in a photovoltaic power generation system according to claim 1, characterized in that when the controller performs waveform recording for the predetermined parameter, the frequency of the recording is at least twice the characteristic frequency of the predetermined parameter, and / or the duration of the recording is at least the waveform period of the predetermined parameter.

10. The step in which the external device performs analysis on the waveform is, A method for recognizing an AC fault in a photovoltaic power generation system according to any one of claims 1 to 9, characterized in that the external device performs a time-domain or frequency-domain analysis on the waveform.

11. The method for recognizing AC faults in a solar power generation system according to any one of claims 1 to 9, characterized in that the reference data used by the external device to analyze the waveform includes at least one of the following: standard waveform data stored on a cloud server, other waveforms uploaded by the inverter, waveform data historically uploaded by the inverter, and waveform data uploaded by other inverters.

12. After the external device performs an analysis on the waveform, A method for recognizing an AC fault in a solar power generation system according to any one of claims 1 to 9, further comprising the step of the external device issuing a command to the controller based on the analysis results to adjust the state of the inverter.

13. The method for recognizing an AC fault in a photovoltaic power generation system according to claim 12, characterized in that the command includes one of starting, stopping, and adjusting operating parameters.

14. A method for recognizing an AC fault in a photovoltaic power generation system according to any one of claims 1 to 9, characterized in that the controller performs the step of uploading the waveform it has recorded to an external device at least twice, and the external device then performs the step of displaying and / or analyzing the waveform.

15. Before the controller of the solar power generation system performs waveform recording for predetermined parameters of the solar power generation system, The method for recognizing an AC fault in a solar power generation system according to claim 12, further comprising the step of the external device issuing a command once to the controller to set the state of the inverter.

16. The method for recognizing an AC fault in a solar power generation system according to claim 15, characterized in that, after adjusting the state of the inverter, the controller of the solar power generation system repeatedly performs the step of recording waveforms for predetermined parameters of the solar power generation system.

17. The method for recognizing an AC fault in a solar power generation system according to any one of claims 1 to 9, characterized in that the external device is a remote server, a cloud server, or a mobile device.

18. An inverter, including a main circuit and a controller, The DC power port of the main circuit is directly or indirectly connected to the solar power array of a solar power generation system, and the AC power port of the main circuit is connected to an AC power grid or an AC load. The main circuit is controlled by the controller. The inverter is characterized in that the controller communicates with an external device and performs each step performed by the controller of the solar power generation system in the method for recognizing an AC fault in the solar power generation system described in any one of claims 1 to 9.

19. The inverter according to claim 18, further characterized in that the controller adjusts the state of the inverter based on a command issued by the external device.

20. The inverter according to claim 18, characterized in that communication connection between the controller and the external device is achieved by wired communication, wireless communication, or power carrier communication.

21. The inverter according to claim 18, characterized in that the main circuit is a DC-AC conversion circuit, or a DC-AC conversion circuit and at least one DC-DC conversion circuit preceding it.

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