An inverter ISO detection method, device and medium

Abstract

The application relates to the field of inverters, and discloses an inverter ISO detection method, an inverter ISO detection device and a medium. Before inverter self-checking is performed, an input voltage and a bus voltage are acquired; a difference voltage is calculated according to the input voltage and the bus voltage; whether the difference voltage is greater than a minimum grid-connected voltage and less than a threshold voltage is judged; wherein the threshold voltage is calculated according to a rated voltage and the minimum grid-connected voltage; if yes, self-checking is not performed; and if no, self-checking is performed. Compared with the current technology, since impedance and sampling voltage change, the calculated ISO value is greater than the actual value, and the ISO miss report phenomenon is caused. According to the technical scheme, the fluctuation region with the greatest sampling voltage change, i.e. the region greater than the minimum grid-connected voltage and less than the threshold voltage, is divided, whether self-checking is performed is confirmed by judging whether the difference voltage is in the region, and thus the ISO miss report phenomenon caused by the great sampling voltage error during inverter self-checking is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of inverters, and particularly relates to an inverter ISO detection method and device and medium. BACKGROUND

[0002] An inverter is a converter that converts direct current (battery, storage battery) into fixed frequency and fixed voltage or frequency and voltage adjustable alternating current (generally 220V, 50HZ sine or square wave). In common language, an inverter is a device that converts direct current (DC) into alternating current (AC). It is composed of an inverter bridge, control logic and a filter circuit. In order to protect the safety of the inverter, ISO detection is usually required before grid connection.

[0003] Specifically, by sampling and analyzing the voltage before and after the relay in the inverter is closed, it is determined whether the ISO value exceeds the ISO alarm threshold. If it exceeds, an alarm is given. However, in specific implementation, when self-checking, the external input impedance is adjusted to be low after the grid is disconnected and self-checking is performed again. Since the sampling voltage decreases with the bus voltage, the calculated impedance value is larger than the actual external impedance, which further leads to the calculated ISO value being larger than the actual value, resulting in ISO false alarm phenomenon.

[0004] Therefore, how to avoid ISO false alarm during inverter self-checking is a problem to be solved by those skilled in the art. SUMMARY

[0005] The present application provides an inverter ISO detection method, device and medium, which can avoid ISO false alarm during inverter self-checking.

[0006] To solve the above technical problems, the present application provides an inverter ISO detection method, comprising:

[0007] obtaining an input voltage and a bus voltage of an inverter;

[0008] determining the size relationship of the input voltage and the bus voltage;

[0009] determining whether the size relationship of the input voltage and the bus voltage determined conforms to a preset condition;

[0010] if the preset condition is met, self-checking is not performed;

[0011] if the preset condition is not met, self-checking is performed.

[0012] Preferably, the determination of the size relationship of the input voltage and the bus voltage comprises:

[0013] calculating a difference voltage according to the input voltage and the bus voltage; the calculation of the difference voltage is: ΔU = abs(Ubus -U);

[0014] wherein, ΔU is the difference voltage, U bus is the bus voltage, U is the input voltage.

[0015] Preferably, further comprising:

[0016] obtaining a minimum grid-connected voltage and a rated voltage;

[0017] calculating a threshold voltage according to the minimum grid-connected voltage and the rated voltage;

[0018] Further, the determining whether the determined magnitude relationship between the input voltage and the bus voltage meets a preset condition comprises:

[0019] determining whether the difference voltage is greater than the minimum grid-connected voltage and less than the threshold voltage;

[0020] If yes, it is confirmed that the determined magnitude relationship between the input voltage and the bus voltage meets the preset condition, and if no, it is confirmed that the determined magnitude relationship between the input voltage and the bus voltage does not meet the preset condition.

[0021] Preferably, the calculation of the threshold voltage is U0-2*U1.

[0022] wherein, U0 is the rated voltage, and U1 is the minimum grid-connected voltage.

[0023] Preferably, the obtaining of the input voltage of the inverter comprises:

[0024] Further, the calculating of the difference voltage according to the input voltage and the bus voltage comprises:

[0025] confirming that the voltage with the largest voltage value among the obtained input voltages of each input channel connected with the inverter is the input voltage;

[0026] calculating the difference voltage according to the input voltage with the largest voltage value and the bus voltage.

[0027] Preferably, further comprising:

[0028] determining whether the input voltage is greater than the rated voltage;

[0029] If no, modifying the ISO alarm threshold.

[0030] Preferably, the ISO alarm threshold is R, and the modifying of the ISO alarm threshold comprises:

[0031] If U≤(U0-2*U1), setting the ISO alarm threshold as R+2*10.

[0032] If (U0-2*U1) < U ≤ U0, the ISO alarm threshold is set as R+1*10;

[0033] Wherein, U is input voltage, U0 is rated voltage, and U1 is minimum grid-connected voltage.

[0034] To solve the above technical problems, the application further provides an inverter ISO detection device, comprising:

[0035] An acquisition module is configured to acquire input voltage and bus voltage of an inverter.

[0036] A determination module is configured to determine the size relationship between the input voltage and the bus voltage.

[0037] A processing module is configured to determine whether the determined size relationship between the input voltage and the bus voltage meets a preset condition, and if so, not to perform self-checking, and if not, to perform self-checking.

[0038] To solve the above technical problems, the application further provides another inverter ISO detection device, comprising a memory configured to store a computer program.

[0039] A processor is configured to execute the computer program to implement the steps of the inverter ISO detection method as described above.

[0040] To solve the above technical problems, the application further provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the steps of the inverter ISO detection method as described above.

[0041] The inverter ISO detection method provided by the application, before performing self-checking of the inverter, acquires input voltage and bus voltage of the inverter, determines the size relationship between the input voltage and the bus voltage, determines whether the determined size relationship between the input voltage and the bus voltage meets a preset condition, and if so, does not perform self-checking, and if not, performs self-checking. Compared with the current technology, since the impedance and the sampling voltage change, the calculated ISO value is larger than the actual value, causing ISO false negative phenomenon. By using the technical solution, the fluctuation region with the largest sampling voltage change, i.e. the preset condition, is divided, the size relationship between the input voltage and the bus voltage is determined, it is determined whether the size relationship meets the preset condition to confirm whether to perform self-checking, and when the preset condition is met, it is indicated that the sampling voltage fluctuation is large, and at this time, self-checking is not performed, thereby avoiding the ISO false negative phenomenon caused by large sampling voltage error during self-checking of the inverter.

[0042] In addition, the inverter ISO detection device and the medium provided by the present application correspond to the inverter ISO detection method described above, and have the same effects. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present application, the drawings required to be used in the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0044] Figure 1 A flow chart of an inverter ISO detection method provided by an embodiment of the present application;

[0045] Figure 2 A structure diagram of an inverter ISO detection device provided by an embodiment of the present application;

[0046] Figure 3 A structure diagram of another inverter ISO detection device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, but not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0048] The core of the present application is to provide an inverter ISO detection method, device and medium, which is used to avoid ISO false negatives when performing inverter self-checking.

[0049] In order to enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0050] Figure 1 A flow chart of an inverter ISO detection method provided by an embodiment of the present application is shown in FIG. 1, which includes the following steps. Figure 1

[0051] S10: obtaining an input voltage and a bus voltage of an inverter;

[0052] S11: determining the size relationship between the input voltage and the bus voltage;

[0053] S12: judging whether the size relationship between the input voltage and the bus voltage determined in S11 meets a preset condition; if the preset condition is met, no self-checking is performed; if the preset condition is not met, self-checking is performed.​

[0054] Inverter is the heart of a photovoltaic power station, which not only concerns the design, installation and operation of the whole life cycle of the photovoltaic system, although it only accounts for 5% to 10% of the cost of the photovoltaic system, but controls 100% of the power generation of the whole photovoltaic system, and because it is always the "brain" of the photovoltaic system, the self-checking of the inverter is particularly important before grid connection.

[0055] In the current technology, the self-checking of the inverter includes: sampling a first voltage average value in a first preset time before the sampling relay is attracted as a first sampling value; sampling a second voltage average value in a second preset time after the sampling relay is attracted as a second sampling value; calculating an ISO calculation value of the inverter according to the first sampling value and the second sampling value and an external impedance value; judging whether the ISO calculation value is less than an ISO alarm threshold value; and if so, issuing an alarm.

[0056] The specific embodiment samples the voltage of the PV with respect to the ground, samples the average voltage PE1 in the time interval of T1s before the ISO relay is attracted and T1ms, samples the average voltage PE2 in the time interval of T2s after the relay is attracted. The sampled voltage values before and after the relay is attracted are calculated to obtain the external impedance value of the inverter. The external impedance value X=R(PE1-PE2) / PE2, and R is the ISO alarm threshold value of the inverter. The input voltage PV is set to be low voltage, and the external impedance is connected to PV-. It is found by observing the oscilloscope waveform that after the ISO self-check is completed, the bus voltage rises from low voltage to rated voltage, and the sampled voltage also rises with the bus voltage. When the bus voltage is stable at the rated voltage, the sampled voltage also remains stable. If the PV or AC is disconnected at this time, the bus voltage gradually decreases, and the sampled voltage also decreases. Because the impedance X=R(PE1-PE2) / PE2, if the external impedance is changed to a small impedance again to perform the ISO self-check in a short time after the PV or AC is disconnected, the sampled voltage decreases with the bus voltage, which leads to a large error of the value of (PE1-PE2), and the calculated impedance value is larger than the actual external impedance, which causes the ISO false alarm phenomenon. For example, assuming that the ISO threshold value is 200K, the PV-external impedance is 300K, and the ISO self-check is performed, the bus voltage rises to the rated voltage, the PV is disconnected, the resistance is changed to 150K, the PV is connected, and the ISO calculation value is 210K, which is larger than the actual value. At this time, it should be reported that the insulation impedance is too low, but due to the large calculation value, the false alarm occurs. When the PV input is high voltage, the bus voltage is equal to the PV voltage and will not be lifted, and the sampled voltage will not change with the bus voltage, so the sampling is more accurate. When the PV input is low voltage, the bus will be lifted to the rated voltage. It is found by observing the waveform and multiple tests that when the bus voltage decreases from U0-2*U1 to U1, the slope is large and the change is fast, and at this time the sampled voltage also changes fast, so the sampling error is large in this time interval, and therefore the ISO self-check is not performed in this time interval in this embodiment. U0 is the rated voltage, and U1 is the minimum grid-connected voltage. In this embodiment, the judgment is whether the size relationship determined by the input voltage and the bus voltage meets the preset condition, that is, whether the size relationship is in the interval of U0-2*U1 to U1. Specifically, the size relationship of the input voltage and the bus voltage is determined by calculating the difference voltage according to the input voltage and the bus voltage.

[0057] In this embodiment, the calculation of the difference voltage is ΔU=abs(U bus -U);

[0058] Wherein, ΔU is the difference voltage, U bus is the bus voltage, and U is the input voltage.

[0059] In the ISO detection method of the inverter, the minimum grid-connected voltage and the rated voltage also need to be obtained;

[0060] calculating a threshold voltage according to the minimum grid-connected voltage and the rated voltage;

[0061] Further, the determining whether the determined magnitude relationship between the input voltage and the bus voltage meets the preset condition comprises:

[0062] determining whether the difference voltage is greater than the minimum grid-connected voltage and less than the threshold voltage;

[0063] If yes, it is confirmed that the determined magnitude relationship between the input voltage and the bus voltage meets the preset condition, and if no, it is confirmed that the determined magnitude relationship between the input voltage and the bus voltage does not meet the preset condition.

[0064] The calculation of the threshold voltage is: U0-2*U1;

[0065] wherein, U0 is the rated voltage, and U1 is the minimum grid-connected voltage.

[0066] In a specific implementation, the inverter has multiple input channels, in the embodiment, the input voltage of the inverter is obtained by obtaining the input voltages of the input channels connected to the inverter, and further, the calculating the difference voltage according to the input voltage and the bus voltage comprises: confirming the voltage with the maximum voltage value among the obtained input voltages of the input channels connected to the inverter as the input voltage, and calculating the difference voltage according to the input voltage with the maximum voltage value and the bus voltage.

[0067] The inverter ISO detection method provided by the embodiment of the application obtains the input voltage and the bus voltage of the inverter before performing the self-check of the inverter, determines the magnitude relationship between the input voltage and the bus voltage, determines whether the determined magnitude relationship between the input voltage and the bus voltage meets the preset condition, performs the self-check if the preset condition is not met, and does not perform the self-check if the preset condition is met. Compared with the current technology, the ISO calculation value calculated due to the change of impedance and sampling voltage is greater than the actual value, causing the ISO missing report phenomenon. By using the technical solution, the fluctuation region with the maximum sampling voltage change, i.e., the preset condition, is divided, the magnitude relationship between the input voltage and the bus voltage is determined, it is determined whether the magnitude relationship meets the preset condition to confirm whether to perform the self-check, and when the preset condition is met, it is indicated that the sampling voltage fluctuation is large, and the self-check is not performed, thereby avoiding the ISO missing report phenomenon caused by the large sampling voltage error during the self-check of the inverter.

[0068] In a specific implementation, the discharging phenomenon of the bus voltage cannot be avoided, the low-voltage external impedance is connected to PV-, and there is still a certain deviation, therefore, on the basis of the above embodiment, in the embodiment, the following steps are further included:

[0069] determining whether the input voltage is greater than the rated voltage;

[0070] If no, the ISO alarm threshold is modified.

[0071] Specifically, in the case of modifying the ISO alarm threshold, the ISO alarm threshold is R, if U≤(U0-2*U1), the ISO alarm threshold is set to R+2*10. If (U0-2*U1)<U≤U0, the ISO alarm threshold is set to R+1*10. Wherein, U is the input voltage, U0 is the rated voltage, U1 is the minimum grid-connected voltage.

[0072] The embodiment further ensures that the ISO calculation value is not missed when the ISO calculation value is less than the threshold by changing the ISO alarm threshold.

[0073] In the above embodiment, the inverter ISO detection method is described in detail, and the present application also provides an embodiment of an inverter ISO detection device. It should be noted that the embodiments of the device part are described from two angles, one is based on the functional module angle, and the other is based on the hardware angle.

[0074] Figure 2 A structure diagram of an inverter ISO detection device provided by the embodiment of the present application is shown in FIG. 1, which comprises: Figure 2

[0075] The acquisition module 10 is configured to acquire the input voltage and the bus voltage of the inverter.

[0076] The determination module 11 is configured to determine the size relationship between the input voltage and the bus voltage.

[0077] The processing module 12 is configured to judge whether the determined size relationship between the input voltage and the bus voltage meets a preset condition. If the preset condition is met, no self-checking is performed. If the preset condition is not met, self-checking is performed.

[0078] Since the embodiments of the device part correspond to the embodiments of the method part, the embodiments of the device part are described in the description of the embodiments of the method part, which will not be described here.

[0079] ​The inverter ISO detection device provided by the embodiment of the present application obtains the input voltage and bus voltage of the inverter before the inverter self-checking; determines the size relationship between the input voltage and the bus voltage; judges whether the determined size relationship between the input voltage and the bus voltage meets the preset condition; if the preset condition is met, the self-checking is not performed; if the preset condition is not met, the self-checking is performed. Compared with the current technology, the ISO calculation value calculated is larger than the actual value due to the change of impedance and sampling voltage, causing the ISO missing report phenomenon. The present technical solution divides the fluctuation region with the largest sampling voltage change, that is, the preset condition. The size relationship between the input voltage and the bus voltage is determined to judge whether the size relationship meets the preset condition to confirm whether the self-checking is performed. When the preset condition is met, it indicates that the sampling voltage fluctuation is large, and the self-checking is not performed, thereby avoiding the ISO missing report phenomenon caused by the large sampling voltage error during the inverter self-checking.

[0080] Figure 3 The structure diagram of another inverter ISO detection device provided by the embodiment of the present application is shown in FIG. 2, which includes a memory 20 for storing a computer program. Figure 3

[0081] A processor 21 is configured to execute the computer program to implement the steps of the inverter ISO detection method as described in the above embodiment.

[0082] The inverter ISO detection device provided by the embodiment of the present application can include but is not limited to a smart phone, a tablet computer, a notebook computer, a desktop computer, and the like.

[0083] ​The processor 21 may include one or more processing cores, such as a quad-core processor or an octa-core processor. The processor 21 may be implemented using at least one of the following hardware forms: Digital Signal Processor (DSP), Field-Programmable Gate Array (FPGA), or Programmable Logic Array (PLA). The processor 21 may also include a main processor and a coprocessor. The main processor, also known as the Central Processing Unit (CPU), is used to process data in the wake-up state; the coprocessor is a low-power processor used to process data in the standby state. In some embodiments, the processor 21 may integrate a Graphics Processing Unit (GPU), which is responsible for rendering and drawing the content to be displayed on the screen. In some embodiments, the processor 21 may also include an Artificial Intelligence (AI) processor, which is used to handle computational operations related to machine learning.

[0084] The memory 20 may include one or more computer-readable storage media, which may be non-transitory. The memory 20 may also include high-speed random access memory and non-volatile memory, such as one or more disk storage devices or flash memory devices. In this embodiment, the memory 20 is used to store at least the following computer program 201, which, after being loaded and executed by the processor 21, is capable of implementing the relevant steps of the inverter ISO detection method disclosed in any of the foregoing embodiments. In addition, the resources stored in the memory 20 may also include an operating system 202 and data 203, and the storage method may be temporary or permanent storage. The operating system 202 may include Windows, Unix, Linux, etc. The data 203 may include, but is not limited to, differential voltage, threshold voltage, etc.

[0085] In some embodiments, the inverter ISO detection device may further include a display screen 22, an input / output interface 23, a communication interface 24, a power supply 25, and a communication bus 26.

[0086] Those skilled in the art will understand that Figure 3 The structure shown does not constitute a limitation on the inverter ISO detection device and may include more or fewer components than shown.

[0087] The inverter ISO detection device provided by the embodiment of the application comprises a memory and a processor, and the processor can realize the following method when executing the program stored in the memory: obtaining input voltage and bus voltage of an inverter; determining the size relationship of the input voltage and the bus voltage; judging whether the determined size relationship of the input voltage and the bus voltage meets a preset condition; if the preset condition is met, not performing self-checking; and if the preset condition is not met, performing self-checking.

[0088] The inverter ISO detection device provided by the embodiment of the application, before performing self-checking of the inverter, obtains input voltage and bus voltage of the inverter, determines the size relationship of the input voltage and the bus voltage, judges whether the determined size relationship of the input voltage and the bus voltage meets a preset condition, if the preset condition is met, does not perform self-checking, and if the preset condition is not met, performs self-checking. In the current technology, the calculated ISO value is larger than the actual value due to the change of impedance and sampling voltage, causing ISO false negative phenomenon. In the technical solution, the fluctuation region with the largest sampling voltage change, that is, the preset condition, is divided, the size relationship of the input voltage and the bus voltage is determined, it is judged whether the size relationship meets the preset condition to confirm whether to perform self-checking, when the preset condition is met, it is indicated that the sampling voltage fluctuation is large, at this time, self-checking is not performed, thereby avoiding the ISO false negative phenomenon caused by large sampling voltage error during self-checking of the inverter.

[0089] Finally, the application also provides an embodiment corresponding to a computer readable storage medium. The computer readable storage medium stores a computer program, and the computer program is executed by a processor to realize the steps recorded in the above method embodiments.

[0090] It can be understood that if the method in the above embodiment is realized in the form of a software function unit and sold or used as an independent product, it can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the application essentially or the part that contributes to the prior art or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and executes all or part of the steps of the method described in each embodiment of the application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (Read-Only Memory, ROM), a random access memory (Random Access Memory, RAM), a magnetic disk or an optical disk and various program code storage media.

[0091] The computer readable storage medium provided by the embodiment of the application obtains the input voltage and the bus voltage of the inverter before the self-checking of the inverter; determines the size relationship of the input voltage and the bus voltage; judges whether the size relationship of the determined input voltage and bus voltage meets the preset condition; if the preset condition is met, the self-checking is not performed; if the preset condition is not met, the self-checking is performed. In the current technology, the ISO calculation value calculated is larger than the actual value due to the change of impedance and sampling voltage, causing the ISO false negative phenomenon. In the technical solution, the fluctuation region with the largest sampling voltage change, that is, the preset condition, is divided, the size relationship of the input voltage and the bus voltage is determined, it is judged whether the size relationship meets the preset condition to confirm whether the self-checking is performed, when the preset condition is met, it is indicated that the sampling voltage fluctuation is large, at this time, the self-checking is not performed, thereby avoiding the ISO false negative phenomenon caused by the large sampling voltage error during the self-checking of the inverter.

[0092] The inverter ISO detection method, device and medium provided by the application are described in detail above. The embodiments in the specification are described in a progressive manner, and each embodiment mainly describes the difference from other embodiments. The same or similar parts of each embodiment can be referred to. For the device disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the related parts can be referred to the method part. It should be pointed out that for ordinary skilled in the art, without departing from the principle of the application, the application can be improved and modified, and these improvements and modifications also fall within the protection scope of the claims of the application.

[0093] It should be further noted that in the specification, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitation, the element defined by the statement "including a" does not exclude the presence of another identical element in the process, method, article or device including the element.

Claims

1. An inverter ISO detection method, characterized by, The method comprises: acquiring input voltage and bus voltage of the inverter; determining a magnitude relationship between the input voltage and the bus voltage; wherein the determining the magnitude relationship between the input voltage and the bus voltage comprises calculating a difference voltage from the input voltage and the bus voltage; the calculation of the difference voltage is: ; wherein, is the difference voltage, is the bus voltage, is the input voltage; determining whether the determined magnitude relationship between the input voltage and the bus voltage meets a preset condition; wherein the determining whether the determined magnitude relationship between the input voltage and the bus voltage meets the preset condition comprises: determining whether the difference voltage is greater than a minimum grid-connected voltage and less than a threshold voltage; if yes, confirming that the determined magnitude relationship between the input voltage and the bus voltage meets the preset condition, and if no, confirming that the determined magnitude relationship between the input voltage and the bus voltage does not meet the preset condition; the threshold voltage is calculated as ; wherein, is a rated voltage, is the minimum grid-connected voltage; if a preset condition is met, not performing self-checking; if the preset condition is not met, performing self-checking.

2. The method of claim 1, wherein, The input voltage of the inverter is acquired by acquiring input voltage of each input channel connected with the inverter. Further, the calculating difference voltage according to the input voltage and the bus voltage comprises: confirming the voltage with the largest voltage value among the acquired input voltage of each input channel connected with the inverter as input voltage; calculating difference voltage according to the input voltage with the largest voltage value and the bus voltage.

3. The method of claim 1, wherein, Further, the method comprises: judging whether the input voltage is greater than rated voltage; if not, modifying ISO alarm threshold.

4. The method of claim 3, wherein the ISO detection method is characterized by, The ISO alarm threshold is R, and the modifying ISO alarm threshold comprises: If , then set the ISO alert threshold to ; If , then set the ISO alert threshold to ; wherein, is the input voltage, is the nominal voltage, is the minimum grid voltage.

5. An inverter ISO detection apparatus characterized by comprising: The method comprises: an acquiring module, configured to acquire input voltage and bus voltage of the inverter; determining a magnitude relationship between the input voltage and the bus voltage; wherein the determining the magnitude relationship between the input voltage and the bus voltage comprises calculating a difference voltage from the input voltage and the bus voltage; the calculation of the difference voltage is: ; wherein, is the difference voltage, is the bus voltage, is the input voltage; The processing module is configured to determine whether the determined magnitude relationship between the input voltage and the bus voltage meets a preset condition, and if the preset condition is met, the self-check is not performed, and if the preset condition is not met, the self-check is performed. The determination of whether the determined magnitude relationship between the input voltage and the bus voltage meets the preset condition comprises: determining whether the difference voltage is greater than a minimum grid-connected voltage and less than a threshold voltage, and if yes, it is determined that the determined magnitude relationship between the input voltage and the bus voltage meets the preset condition, and if no, it is determined that the determined magnitude relationship between the input voltage and the bus voltage does not meet the preset condition. The threshold voltage is calculated as ; wherein, is a rated voltage, is the minimum grid-connected voltage.

6. An inverter ISO detection apparatus characterized by comprising: a memory, configured to store a computer program; a processor, configured to execute the computer program to realize the inverter ISO detection method according to any one of claims 1 to 4.

7. A computer-readable storage medium, characterized in that, The computer program is stored on the computer readable storage medium, and the computer program is executed by the processor to realize the inverter ISO detection method according to any one of claims 1 to 4.

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