A method and device for protecting inverter from resonance with power grid

Abstract

The present invention provides a method and device for protecting the resonance between an inverter and a power grid, the method comprising: real-time acquisition of the inductor current of the inverter; extraction of corresponding characteristic information based on the inductor current; judging whether an abnormality occurs based on the extracted characteristic information and a preset threshold; and reporting error information if an abnormality occurs. By means of the above method, the speed of protecting the inverter can be accelerated and the reliability of the inverter can be improved.

Description

Technical Field

[0001] The present invention relates to the field of new energy technology, and in particular to a method and device for protecting resonance between an inverter and a power grid. Background Art

[0002] During the R&D and testing phases, new photovoltaic inverters need to be adjusted to appropriate control parameters and tested for various extreme working conditions. In the early stages of R&D, due to the imperfect protection values ​​and protection functions, when adjusting the inverter control parameters and testing various extreme working conditions, the inverter is prone to resonance with the power grid or power grid simulator, causing damage to the machine.

[0003] When the inverter resonates with the grid, it will affect the grid power equipment. In severe cases, it will cause the grid switch to trip, affecting the normal power environment. When the inverter resonates with the grid simulator, it will reduce the service life of the grid simulator. If the grid simulator is not protected in time, the grid simulator will be damaged. If a slight resonance begins to occur between the inverter and the grid, it is difficult to capture the fault information manually because the resonance period is short and the resonance signal is not obvious. Summary of the invention

[0004] The present invention provides a method and device for protecting resonance between an inverter and a power grid, which solves the technical problem in the prior art that it is difficult to quickly capture resonance.

[0005] The technical solution of the present invention is to provide a protection method for inverter and power grid resonance, comprising:

[0006] Real-time acquisition of the inverter's inductor current;

[0007] Extracting corresponding characteristic information based on the inductor current;

[0008] Determine whether an abnormality occurs based on the extracted feature information and a preset threshold;

[0009] If an exception occurs, an error message will be reported.

[0010] In an optional manner, the extracting corresponding characteristic information based on the inductor current includes:

[0011] Performing spectrum analysis on the collected inductor current;

[0012] Corresponding feature information is extracted based on the analysis results.

[0013] In an optional manner, performing spectrum analysis on the collected inductor current includes:

[0014] Performing window processing on the collected inductor current;

[0015] The Fourier transform algorithm is used to perform spectrum analysis on the windowed inductor current to obtain the corresponding current spectrum.

[0016] In an optional manner, the current spectrum includes at least: fundamental current, second harmonic current, and third harmonic current, and the extracting corresponding feature information based on the analysis result includes:

[0017] Calculate the harmonic current change rate of each harmonic current respectively;

[0018] Calculate the sum of the energy values ​​of each harmonic current; or

[0019] The extracting corresponding feature information based on the analysis result includes:

[0020] Calculate the sum of the energy values ​​of each harmonic current;

[0021] Calculate the harmonic current change rate of each harmonic current respectively.

[0022] In an optional manner, before performing spectrum analysis on the collected inductor current, the method further includes:

[0023] The collected inductor current is filtered.

[0024] In an optional manner, the determining whether an abnormality occurs based on the extracted feature information and a preset threshold value includes:

[0025] comparing the sum of the energy values ​​with an energy threshold and comparing the harmonic current change rate with a change rate threshold;

[0026] If the sum of the energies is greater than the energy threshold and / or the harmonic current change rate is greater than the change rate threshold, it is determined to be abnormal.

[0027] In an optional manner, the sum of the energy values ​​is less than the LC resonant frequency of the inverter, and less than or equal to half of the sum of the harmonic energy values ​​of the switching frequency of the inverter.

[0028] The present invention also provides a protection device for inverter and power grid resonance, the device comprising:

[0029] A collection module, used for collecting the inductor current of the inverter;

[0030] An extraction module, used for extracting corresponding characteristic information based on the inductor current;

[0031] Judgment module: judges whether an abnormality occurs based on the extracted feature information and preset thresholds;

[0032] Execution module, used to report error information if an exception occurs.

[0033] The present invention also provides a computing device, comprising: a processor, a memory, a communication interface and a communication bus, wherein the processor, the memory and the communication interface communicate with each other via the communication bus;

[0034] The memory is used to store at least one executable instruction, and the executable instruction enables the processor to execute the steps of the protection method for the resonance between the inverter and the power grid.

[0035] The present invention also provides a computer storage medium, wherein the storage medium stores at least one executable instruction, and the executable instruction enables a processor to execute the steps of the protection method for the resonance between the inverter and the power grid.

[0036] Compared with the prior art, the present invention has the following beneficial effects: real-time acquisition and detection of the inductor current, judging whether an abnormality occurs based on the characteristic information of the acquired inductor current, and timely capturing fault information, which can speed up the protection of the inverter and improve the reliability of the inverter to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. The drawings described below are only drawings corresponding to some embodiments of the present invention.

[0038] Figure 1 A schematic diagram of a flow chart of a method for protecting resonance between an inverter and a power grid provided by an embodiment of the present invention is shown;

[0039] Figure 2 A schematic diagram of the structure of a protection device for inverter and power grid resonance provided by an embodiment of the present invention is shown;

[0040] Figure 3 A schematic diagram of the structure of a computing device provided by an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0042] The directional terms mentioned in the present invention, such as "up", "down", "front", "back", "left", "right", "inside", "outside", "side", "top" and "bottom", are only for reference to the orientation of the drawings. The directional terms used are used to illustrate and understand the present invention, but not to limit the present invention.

[0043] The terms "first", "second", etc. in the present invention are used for descriptive purposes only and should not be understood as indicating or implying relative importance, and should not be used as a limitation on the order of precedence.

[0044] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] See also Figure 1 The preferred embodiment of the present invention provides a flow chart of a method for protecting an inverter from resonance with a power grid, the method comprising:

[0046] Step S1, collecting the inductor current of the inverter in real time;

[0047] Specifically, the method of this embodiment is applied to a new inverter (preferably a photovoltaic inverter) which is in the research and development stage or the testing stage. First, the inductor current of the inverter is collected in real time. The collection method can preferably adopt the existing technology, which will not be repeated here. The current collected is the current of the inductor in the inverter circuit, or the current of the sensor, which is not limited here. In a preferred embodiment of this embodiment, it can be real-time collection and then real-time monitoring, or periodic collection and monitoring.

[0048] Step S2, extracting corresponding characteristic information based on the inductor current;

[0049] Specifically, characteristic information of the inductor current is extracted, and the characteristic information may include energy value, current harmonic content, etc.

[0050] Step S3: judging whether an abnormality occurs based on the extracted feature information and a preset threshold;

[0051] Specifically, the extracted feature information is compared with the corresponding preset thresholds to determine whether an abnormality occurs. For example, when the value corresponding to the feature information is greater than the corresponding preset threshold, it can be considered abnormal; if it is not greater than the corresponding preset threshold, it is considered normal.

[0052] Step S4: if an exception occurs, report the error information;

[0053] Specifically, if it is determined that an abnormality occurs, the output current is promptly controlled, the AC relay is turned off, and error information is reported. The error information may include the current time point, abnormal data, etc., which is not limited here.

[0054] In the embodiment of the present invention, the inductor current is collected and detected in real time, and whether an abnormality occurs is determined based on the characteristic information of the collected inductor current. Fault information is captured in time, which can speed up the protection of the inverter and improve the reliability of the inverter to a certain extent.

[0055] In an optional manner of this embodiment, before step S1, the following steps may also be included:

[0056] Set preset thresholds;

[0057] Specifically, a preset threshold of response is set for each sub-information of the characteristic information. Specifically, the characteristic information at least includes: the content and energy of each harmonic current, each harmonic current includes: fundamental wave, second harmonic, third harmonic, N-1 harmonic, N harmonic, N is preferably 50, wherein the frequency of the fundamental wave is 50HZ, the frequency of the second harmonic is 100HZ, and the frequency of the 50th harmonic is 2500HZ. Further, the preset threshold is generally one times its value in steady state (i.e., close to the steady-state reference value). Due to different field environments, the harmonic current is also different. It can be considered that the inverter first calculates the harmonic current data for a period of time when working on site as the steady-state reference value.

[0058] In an optional manner of this embodiment, step S2 specifically includes:

[0059] Performing spectrum analysis on the collected inductor current;

[0060] Specifically, the collected inductor current is first windowed, and then the inductor current after the windowing is subjected to spectrum analysis. Preferably, a Fourier transform algorithm is used to perform spectrum analysis to obtain a corresponding current spectrum. In another variation, other algorithms may also be used to perform spectrum analysis, which is not limited here.

[0061] Extract corresponding feature information based on the analysis results;

[0062] Specifically, the analysis result is the current spectrum and corresponding data, for example: the current spectrum includes: fundamental current, second harmonic current, third harmonic current, and 50th harmonic current. The corresponding characteristic information is extracted from the current spectrum, including: the harmonic content and energy value of each harmonic current, such as the harmonic content and energy value of the fundamental current.

[0063] Furthermore, the extraction process may include:

[0064] Calculate the harmonic current change rate of each harmonic current respectively;

[0065] Specifically, the harmonic current change rates of the fundamental current, the second harmonic current, the third harmonic current, and the 50th harmonic current are calculated respectively. For example, the corresponding harmonic current change rates are calculated based on the harmonic current contents of the fundamental current, the second harmonic current, the third harmonic current, and the 50th harmonic current, that is, the change rate of the corresponding harmonic current is calculated according to the difference in harmonic content of the harmonic currents collected twice adjacently; preferably, the calculation formula used is: Among them, P In Indicates the harmonic change rate of the harmonic current In. is the harmonic content of the harmonic current In at time T2, is the harmonic content of the harmonic current In at time T1, W In Indicates the steady-state value corresponding to the harmonic current In.

[0066] In another preferred embodiment of the present invention, since the same harmonic current In can be collected multiple times, the average value can be calculated in the following manner: First, based on the formula Calculate the average harmonic content of each harmonic current In, where Indicates the average value of the harmonic content of the harmonic current In, represents the harmonic content of the harmonic current In collected for the i-th time, and C represents the number of collections. After obtaining the average value of the harmonic content of each harmonic current, according to the formula Calculate the harmonic change rate of the harmonic current In, where L represents the number of acquisitions, represents the harmonic content of the harmonic current In collected for the i-th time, W In Indicates the steady-state value corresponding to the harmonic current In, W In It represents the steady-state value corresponding to the harmonic current In. The current harmonic change rate calculated in this way is more accurate and scientific.

[0067] Calculate the sum of the energy values ​​of each harmonic current;

[0068] Specifically, the harmonic energy value of each harmonic current is added to obtain the corresponding energy sum value.

[0069] According to the formula Calculate the value of power and, where E m Represents the energy value of the mth harmonic current, where 0≤m≤50.

[0070] In a preferred solution of this embodiment, the sum of the energy values ​​meets a preset condition, which is: less than the frequency of the LC resonance of the inverter, and less than or equal to half of the sum of the harmonic energy values ​​of the switching frequency of the inverter.

[0071] In an embodiment of the present invention, the harmonic current change rate of each harmonic current can be calculated first, and then the sum of the energy values ​​of each harmonic current can be calculated, or the sum of the energy values ​​of each harmonic current can be calculated first, and then the harmonic current change rate of each harmonic current can be calculated, or both can be calculated simultaneously, and there is no limitation on this here.

[0072] In an optional manner of this embodiment, before performing spectrum analysis on the collected inductor current, the method further includes:

[0073] Filtering the collected inductor current;

[0074] Specifically, the collected inductor current is first filtered to facilitate subsequent spectrum analysis, which can improve the accuracy and efficiency of the analysis. The existing filtering method can be used for processing, and this is not limited here.

[0075] In an optional manner of this embodiment, step S3 specifically includes:

[0076] comparing the sum of the energy values ​​with an energy threshold and comparing the harmonic current change rate with a change rate threshold;

[0077] Specifically, since the preset threshold is set, the calculated sum of the energy values ​​is compared with the corresponding energy value threshold, and the current change rate is compared with the change rate threshold. If the sum of the energy is greater than the energy threshold and / or the harmonic current change rate is greater than the change rate threshold, it is judged to be abnormal, that is, any situation that satisfies the corresponding threshold can be considered abnormal, and then go to step S4. If the sum of the energy is not greater than the energy threshold and the harmonic current change rate is not greater than the change rate threshold, it is considered to be a normal working state, and go to step S1 to continue collecting the inductor current.

[0078] In the embodiment of the present invention, the inductor current is collected and detected in real time, and whether an abnormality occurs is determined based on the characteristic information of the collected inductor current. Fault information is captured in time, which can speed up the protection of the inverter and improve the reliability of the inverter to a certain extent.

[0079] Secondly, filtering the inductor current before analyzing it can eliminate some influencing factors, improve the accuracy of the analysis, and improve the reliability of the protection.

[0080] Based on the above embodiments, the present invention also proposes a protection device for inverter and power grid resonance, such as Figure 2FIG. 2 shows a schematic diagram of the structure of a protection device for inverter and power grid resonance according to an embodiment of the present invention. The protection device comprises: a collection module 201, an extraction module 202 connected to the collection module 201, a judgment module 203 connected to the extraction module 202, and an execution module 204 connected to the judgment module 203, wherein:

[0081] The acquisition module 201 is used to acquire the inductor current of the inverter in real time;

[0082] Specifically, the method of this embodiment is applied to a new inverter (preferably a photovoltaic inverter) which is in the research and development stage or the testing stage. First, the inductor current of the inverter is collected in real time. The collection method can preferably adopt the existing technology, which will not be repeated here. The current collected is the current of the inductor in the inverter circuit, or the current of the sensor, which is not limited here. In a preferred embodiment of this embodiment, it can be real-time collection and then real-time monitoring, or periodic collection and monitoring.

[0083] An extraction module 202, configured to extract corresponding characteristic information based on the inductor current;

[0084] Specifically, characteristic information of the inductor current is extracted, and the characteristic information may include energy value, current harmonic content, etc.

[0085] A judgment module 203 is used to judge whether an abnormality occurs based on the extracted feature information and a preset threshold;

[0086] Specifically, the extracted feature information is compared with the corresponding preset thresholds to determine whether an abnormality occurs. For example, when the value corresponding to the feature information is greater than the corresponding preset threshold, it can be considered abnormal; if it is not greater than the corresponding preset threshold, it is considered normal.

[0087] Execution module 204, used for reporting error information if an exception occurs;

[0088] Specifically, if it is determined that an abnormality occurs, the output current is promptly controlled, the AC relay is turned off, and error information is reported. The error information may include the current time point, abnormal data, etc., which is not limited here.

[0089] In the embodiment of the present invention, the inductor current is collected and detected in real time, and whether an abnormality occurs is determined based on the characteristic information of the collected inductor current. Fault information is captured in time, which can speed up the protection of the inverter and improve the reliability of the inverter to a certain extent.

[0090] In an optional manner, the extraction module 202 is specifically used for:

[0091] Performing spectrum analysis on the collected inductor current;

[0092] Corresponding feature information is extracted based on the analysis results.

[0093] In an optional manner, the extraction module 202 is specifically used for:

[0094] Performing window processing on the collected inductor current;

[0095] The Fourier transform algorithm is used to perform spectrum analysis on the windowed inductor current to obtain the corresponding current spectrum.

[0096] In an optional manner, the current spectrum includes at least: fundamental current, second harmonic current, and third harmonic current, and the extraction module 202 is specifically used for:

[0097] Calculate the harmonic current change rate of each harmonic current respectively;

[0098] Calculate the sum of the energy values ​​of each harmonic current; or

[0099] The extracting corresponding feature information based on the analysis result includes:

[0100] Calculate the sum of the energy values ​​of each harmonic current;

[0101] Calculate the harmonic current change rate of each harmonic current respectively.

[0102] In an optional manner, the extraction module 202 is further used for:

[0103] The collected inductor current is filtered.

[0104] In an optional manner, the judging module 203 is specifically configured to:

[0105] comparing the sum of the energy values ​​with an energy threshold and comparing the harmonic current change rate with a change rate threshold;

[0106] If the sum of the energies is greater than the energy threshold and / or the harmonic current change rate is greater than the change rate threshold, it is determined to be abnormal.

[0107] In an optional manner, the sum of the energy values ​​is less than the LC resonant frequency of the inverter, and less than or equal to half of the sum of the harmonic energy values ​​of the switching frequency of the inverter.

[0108] In the present invention, the inductor current is collected and detected in real time, and whether an abnormality occurs is determined based on the characteristic information of the collected inductor current. Fault information is captured in time, which can speed up the protection of the inverter and improve the reliability of the inverter to a certain extent.

[0109] Secondly, filtering the inductor current before analyzing it can eliminate some influencing factors, improve the accuracy of the analysis, and improve the reliability of the protection.

[0110] An embodiment of the present invention provides a non-volatile computer storage medium, wherein the computer storage medium stores at least one executable instruction, and the computer executable instruction can execute the protection method for inverter and power grid resonance in any of the above method embodiments.

[0111] The executable instructions may be specifically used to cause the processor to perform the following operations:

[0112] Real-time acquisition of the inverter's inductor current;

[0113] Extracting corresponding characteristic information based on the inductor current;

[0114] Determine whether an abnormality occurs based on the extracted feature information and a preset threshold;

[0115] If an exception occurs, an error message will be reported.

[0116] In an optional manner, the executable instruction causes the processor to perform the following operations:

[0117] Performing spectrum analysis on the collected inductor current;

[0118] Corresponding feature information is extracted based on the analysis results.

[0119] In an optional manner, the executable instruction causes the processor to perform the following operations:

[0120] Performing window processing on the collected inductor current;

[0121] The Fourier transform algorithm is used to perform spectrum analysis on the windowed inductor current to obtain the corresponding current spectrum.

[0122] In an optional manner, the current spectrum includes at least: fundamental current, second harmonic current, and third harmonic current, and the executable instruction enables the processor to perform the following operations:

[0123] Calculate the harmonic current change rate of each harmonic current respectively;

[0124] Calculate the sum of the energy values ​​of each harmonic current; or

[0125] The extracting corresponding feature information based on the analysis result includes:

[0126] Calculate the sum of the energy values ​​of each harmonic current;

[0127] Calculate the harmonic current change rate of each harmonic current respectively.

[0128] In an optional manner, the executable instruction causes the processor to perform the following operations:

[0129] The collected inductor current is filtered.

[0130] In an optional manner, the executable instruction causes the processor to perform the following operations:

[0131] comparing the sum of the energy values ​​with an energy threshold and comparing the harmonic current change rate with a change rate threshold;

[0132] If the sum of the energies is greater than the energy threshold and / or the harmonic current change rate is greater than the change rate threshold, it is determined to be abnormal.

[0133] In an optional manner, the sum of the energy values ​​is less than the LC resonant frequency of the inverter, and less than or equal to half of the sum of the harmonic energy values ​​of the switching frequency of the inverter.

[0134] In the present invention, the inductor current is collected and detected in real time, and whether an abnormality occurs is determined based on the characteristic information of the collected inductor current. Fault information is captured in time, which can speed up the protection of the inverter and improve the reliability of the inverter to a certain extent.

[0135] Secondly, filtering the inductor current before analyzing it can eliminate some influencing factors, improve the accuracy of the analysis, and improve the reliability of the protection.

[0136] Figure 3 A schematic diagram of the structure of a computing device provided by an embodiment of the present invention is shown, and the specific embodiment of the present invention does not limit the specific implementation of the device.

[0137] like Figure 3 As shown, the computing device may include: a processor (processor) 302 , a communication interface (Communications Interface) 304 , a memory (memory) 306 , and a communication bus 308 .

[0138] The processor 302, the communication interface 304, and the memory 306 communicate with each other via the communication bus 308. The communication interface 304 is used to communicate with other devices such as a client or other server network elements. The processor 302 is used to execute the program 310, which can specifically execute the relevant steps in the above-mentioned inverter and power grid resonance protection method embodiment.

[0139] Specifically, the program 310 may include program codes, which include computer operation instructions.

[0140] The processor 302 may be a central processing unit (CPU), or an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present invention. The one or more processors included in the device may be processors of the same type, such as one or more CPUs; or may be processors of different types, such as one or more CPUs and one or more ASICs.

[0141] The memory 306 is used to store the program 310. The memory 306 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0142] The program 310 may be specifically configured to enable the processor 302 to perform the following operations:

[0143] Performing spectrum analysis on the collected inductor current;

[0144] Corresponding feature information is extracted based on the analysis results.

[0145] In an optional manner, the program 310 may be specifically configured to enable the processor 302 to perform the following operations:

[0146] Performing window processing on the collected inductor current;

[0147] The Fourier transform algorithm is used to perform spectrum analysis on the windowed inductor current to obtain the corresponding current spectrum.

[0148] In an optional manner, the current spectrum includes at least: fundamental current, second harmonic current, and third harmonic current. The program 310 may be specifically used to enable the processor 302 to perform the following operations:

[0149] Calculate the harmonic current change rate of each harmonic current respectively;

[0150] Calculate the sum of the energy values ​​of each harmonic current; or

[0151] The extracting corresponding feature information based on the analysis result includes:

[0152] Calculate the sum of the energy values ​​of each harmonic current;

[0153] Calculate the harmonic current change rate of each harmonic current respectively.

[0154] In an optional manner, the program 310 may be specifically configured to enable the processor 302 to perform the following operations:

[0155] The collected inductor current is filtered.

[0156] In an optional manner, the program 310 may be specifically configured to enable the processor 302 to perform the following operations:

[0157] comparing the sum of the energy values ​​with an energy threshold and comparing the harmonic current change rate with a change rate threshold;

[0158] If the sum of the energies is greater than the energy threshold and / or the harmonic current change rate is greater than the change rate threshold, it is determined to be abnormal.

[0159] In an optional manner, the sum of the energy values ​​is less than the LC resonant frequency of the inverter, and less than or equal to half of the sum of the harmonic energy values ​​of the switching frequency of the inverter.

[0160] In the present invention, the inductor current is collected and detected in real time, and whether an abnormality occurs is determined based on the characteristic information of the collected inductor current. Fault information is captured in time, which can speed up the protection of the inverter and improve the reliability of the inverter to a certain extent.

[0161] Secondly, filtering the inductor current before analyzing it can eliminate some influencing factors, improve the accuracy of the analysis, and improve the reliability of the protection.

[0162] In summary, although the present invention has been disclosed as above in terms of preferred embodiments, the above preferred embodiments are not intended to limit the present invention. A person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined in the claims.

Claims

1. A method for protecting an inverter from resonance with a power grid, characterized in that: The method comprises: Real-time acquisition of the inverter's inductor current; The collected inductor current is subjected to windowing processing; a spectrum analysis is performed on the windowed inductor current using a Fourier transform algorithm to obtain a corresponding current spectrum; the current spectrum includes at least: a fundamental current, a second harmonic current, and a third harmonic current; and corresponding feature information is extracted based on the analysis result, including: calculating the harmonic current change rate of each harmonic current respectively; and calculating the sum of the energy values ​​of each harmonic current; Determine whether an abnormality occurs based on the extracted feature information and a preset threshold; If an exception occurs, an error message will be reported.

2. The protection method according to claim 1, characterized in that: Before performing spectrum analysis on the collected inductor current, the method further includes: The collected inductor current is filtered.

3. The protection method according to claim 1, characterized in that: The determining whether an abnormality occurs based on the extracted feature information and a preset threshold value includes: comparing the sum of the energy values ​​with an energy threshold and comparing the harmonic current change rate with a change rate threshold; If the sum of the energies is greater than the energy threshold and / or the harmonic current change rate is greater than the change rate threshold, it is determined to be abnormal.

4. A protection device for inverter and power grid resonance, characterized in that: include: A collection module, used for collecting the inductor current of the inverter; An extraction module performs windowing processing on the collected inductor current; The Fourier transform algorithm is used to perform spectrum analysis on the windowed inductor current to obtain the corresponding current spectrum; The current spectrum includes at least: fundamental current, second harmonic current, and third harmonic current. The corresponding characteristic information is extracted based on the analysis result, including: calculating the harmonic current change rate of each harmonic current respectively; calculating the sum of the energy values ​​of each harmonic current; A judgment module, which judges whether an abnormality occurs based on the extracted feature information and a preset threshold; Execution module, used to report error information if an exception occurs.

5. A computing device, characterized in that: include: A processor, a memory, a communication interface and a communication bus, wherein the processor, the memory and the communication interface communicate with each other via the communication bus; The memory is used to store at least one executable instruction, and the executable instruction enables the processor to execute the steps of the inverter and grid resonance protection method according to any one of claims 1 to 3.

6. A computer storage medium, characterized in that: The storage medium stores at least one executable instruction, and the executable instruction enables the processor to execute the steps of the inverter and grid resonance protection method according to any one of claims 1 to 3.

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