Inverter impedance measurement method, device, terminal equipment and storage medium

Abstract

The present application is applicable to the field of impedance measurement technology, and provides an inverter impedance measurement method, device, terminal equipment and storage medium. The method includes: obtaining a disturbance voltage frequency domain signal and a response current frequency domain signal when a disturbance voltage of a first disturbance frequency is injected into the inverter; obtaining a disturbance voltage frequency domain signal and a response current frequency domain signal when a disturbance voltage of a second disturbance frequency is injected into the inverter; determining a first disturbance voltage signal and a first response current signal, as well as a second disturbance voltage signal and a second response current signal according to the above-mentioned disturbance voltage frequency domain signal and the response current frequency domain signal; determining a first impedance of the first disturbance frequency and a second impedance of the second disturbance frequency according to the above-mentioned disturbance voltage signal and the response current signal; determining the impedance of a preset frequency according to the first impedance and the second impedance. The present application can improve the accuracy of the inverter impedance measurement, and thereby improve the accuracy of the subsequent dynamic characteristic analysis of the inverter.

Description

Technical Field

[0001] The present application relates to the technical field of impedance measurement, and in particular to an inverter impedance measurement method, device, terminal equipment and storage medium. Background Art

[0002] Power electronic devices such as inverters have the advantages of flexibility and controllability, which can significantly enhance the regulation and control capabilities of the power system. A large number of new equipment are connected to the power transmission and distribution network through power electronic devices, and the degree of power electronics in the power grid is constantly improving.

[0003] However, the dynamic characteristics of power electronic equipment are complex and highly nonlinear, which brings severe challenges to the transient stability analysis of power electronic power systems. Therefore, it is very important to study the dynamic characteristics of power electronic equipment in the power grid. Port impedance can comprehensively characterize the dynamic characteristics of power electronic equipment such as inverters, and the impedance results can be used to analyze the dynamic characteristics of inverters.

[0004] Existing impedance measurement methods usually apply disturbances to the inverter port and directly use the measurement results corresponding to the sweep frequency points as the impedance results. However, due to the high uncertainty of the power system, the impedance results obtained by the above method have low accuracy, which in turn reduces the accuracy of subsequent dynamic characteristics analysis of the inverter. Summary of the invention

[0005] In view of this, the embodiments of the present application provide an inverter impedance measurement method, apparatus, terminal device and storage medium to solve the technical problem that the existing inverter impedance measurement method has low measurement accuracy, thereby reducing the accuracy of subsequent dynamic characteristics analysis of the inverter.

[0006] In a first aspect, an embodiment of the present application provides an inverter impedance measurement method, comprising: obtaining a first disturbance voltage frequency domain signal and a first response current frequency domain signal when a disturbance voltage of a first disturbance frequency is injected into the inverter; obtaining a second disturbance voltage frequency domain signal and a second response current frequency domain signal when a disturbance voltage of a second disturbance frequency is injected into the inverter; determining the first disturbance voltage signal and the first response current signal according to the first disturbance voltage frequency domain signal and the first response current frequency domain signal; determining the second disturbance voltage signal and the second response current signal according to the second disturbance voltage frequency domain signal and the second response current frequency domain signal; the first disturbance frequency and the second disturbance frequency are frequencies on both sides of a preset frequency; determining the first impedance of the first disturbance frequency according to the first disturbance voltage signal and the first response current signal, and determining the second impedance of the second disturbance frequency according to the second disturbance voltage signal and the second response current signal; determining the impedance of the preset frequency according to the first impedance and the second impedance.

[0007] In a possible implementation of the first aspect, a first disturbance voltage frequency domain signal and a first response current frequency domain signal are obtained when a disturbance voltage of a first disturbance frequency is injected into the inverter; a second disturbance voltage frequency domain signal and a second response current frequency domain signal are obtained when a disturbance voltage of a second disturbance frequency is injected into the inverter, including: obtaining a first disturbance voltage time domain signal and a first response current time domain signal when a disturbance voltage of a first disturbance frequency is injected into the inverter; obtaining a second disturbance voltage time domain signal and a second response current time domain signal when a disturbance voltage of a second disturbance frequency is injected into the inverter; performing discrete Fourier transform on the first disturbance voltage time domain signal and the first response current time domain signal, respectively, to obtain a first disturbance voltage frequency domain signal and a first response current frequency domain signal; performing discrete Fourier transform on the second disturbance voltage time domain signal and the second response current time domain signal, respectively, to obtain a second disturbance voltage frequency domain signal and a second response current frequency domain signal.

[0008] In a possible implementation of the first aspect, the disturbance voltage is a three-phase disturbance voltage; a first disturbance voltage time domain signal and a first response current time domain signal are obtained when a disturbance voltage of a first disturbance frequency is injected into the inverter; a second disturbance voltage time domain signal and a second response current time domain signal are obtained when a disturbance voltage of a second disturbance frequency is injected into the inverter, including: according to a preset sampling frequency, a first three-phase disturbance voltage time domain signal and a first three-phase response current time domain signal are obtained when a disturbance voltage of a first disturbance frequency is injected into the inverter; according to a preset sampling frequency, a second disturbance voltage time domain signal and a second response current time domain signal are obtained when a disturbance voltage of a second disturbance frequency is injected into the inverter A second three-phase disturbance voltage time domain signal and a second three-phase response current time domain signal when the disturbance voltage has two disturbance frequencies; performing abc / αβ coordinate transformation on the first three-phase disturbance voltage time domain signal and the first three-phase response current time domain signal respectively, to obtain a first disturbance voltage time domain signal after coordinate transformation and a first response current time domain signal after coordinate transformation; performing abc / αβ coordinate transformation on the second three-phase disturbance voltage time domain signal and the second three-phase response current time domain signal respectively, to obtain a second disturbance voltage time domain signal after coordinate transformation and a second response current time domain signal after coordinate transformation;

[0009] Correspondingly, the first disturbance voltage time domain signal and the first response current time domain signal are discrete Fourier transformed respectively to obtain the first disturbance voltage frequency domain signal and the first response current frequency domain signal; the second disturbance voltage time domain signal and the second response current time domain signal are discrete Fourier transformed respectively to obtain the second disturbance voltage frequency domain signal and the second response current frequency domain signal, including: discrete Fourier transforming the first disturbance voltage time domain signal after coordinate transformation and the first response current time domain signal after coordinate transformation respectively to obtain the first disturbance voltage frequency domain signal and the first response current frequency domain signal; discrete Fourier transforming the second disturbance voltage time domain signal after coordinate transformation and the second response current time domain signal after coordinate transformation respectively to obtain the second disturbance voltage frequency domain signal and the second response current frequency domain signal.

[0010] In a possible implementation of the first aspect, a first disturbance voltage signal and a first response current signal are determined according to a first disturbance voltage frequency domain signal and a first response current frequency domain signal; and a second disturbance voltage signal and a second response current signal are determined according to a second disturbance voltage frequency domain signal and a second response current frequency domain signal, including: performing signal extraction on the first disturbance voltage frequency domain signal and the first response current frequency domain signal, respectively, to determine the first disturbance voltage signal and the first response current signal of the first disturbance frequency; performing signal extraction on the second disturbance voltage frequency domain signal and the second response current frequency domain signal, respectively, to determine the second disturbance voltage signal and the second response current signal of the second disturbance frequency.

[0011] In a possible implementation manner of the first aspect, determining the impedance of the preset frequency according to the first impedance and the second impedance includes: calculating the mean of the first impedance and the second impedance to determine the impedance of the preset frequency.

[0012] In a possible implementation of the first aspect, the inverter impedance measurement method also includes: taking multiple equally spaced target frequencies in a preset frequency sweep interval as preset frequencies in turn, executing the above-mentioned impedance determination step for the preset frequencies, and obtaining the impedance of each equally spaced target frequency in the preset frequency sweep interval; for each equally spaced target frequency in the preset frequency sweep interval, determining the adjacent first frequency and second frequency of the target frequency in the preset frequency sweep interval; determining a first change slope according to the impedance of the disturbance frequency of the first frequency and the impedance of the disturbance frequency of the target frequency; determining a second change slope according to the impedance of the disturbance frequency of the second frequency and the impedance of the disturbance frequency of the target frequency; and judging whether the absolute value of the difference between the first change slope and the second change slope is greater than a preset threshold, and if so, correcting the impedance of the target frequency.

[0013] In a possible implementation of the first aspect, when the absolute value of the difference between the first change slope and the second change slope is greater than a preset threshold, the impedance of the target frequency is corrected, including: determining the corrected impedance of the target frequency according to the value of the intersection of the straight line corresponding to the first change slope and the straight line corresponding to the second change slope.

[0014] In a second aspect, an embodiment of the present application provides an inverter impedance measurement device, comprising:

[0015] The acquisition module is used to acquire a first disturbance voltage frequency domain signal and a first response current frequency domain signal when a disturbance voltage with a first disturbance frequency is injected into the inverter; and to acquire a second disturbance voltage frequency domain signal and a second response current frequency domain signal when a disturbance voltage with a second disturbance frequency is injected into the inverter.

[0016] The first determination module is used to determine the first disturbance voltage signal and the first response current signal according to the first disturbance voltage frequency domain signal and the first response current frequency domain signal; determine the second disturbance voltage signal and the second response current signal according to the second disturbance voltage frequency domain signal and the second response current frequency domain signal; the first disturbance frequency and the second disturbance frequency are frequencies on both sides of the preset frequency.

[0017] The second determination module is used to determine the first impedance of the first disturbance frequency according to the first disturbance voltage signal and the first response current signal, and to determine the second impedance of the second disturbance frequency according to the second disturbance voltage signal and the second response current signal.

[0018] The third determination module is used to determine the impedance of a preset frequency according to the first impedance and the second impedance.

[0019] In a third aspect, an embodiment of the present application provides a terminal device, including a memory and a processor, wherein the memory stores a computer program that can be executed on the processor, and when the processor executes the computer program, the inverter impedance measurement method as described in any one of the first aspects is implemented.

[0020] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the inverter impedance measurement method as described in any one of the first aspects is implemented.

[0021] In a fifth aspect, an embodiment of the present application provides a computer program product. When the computer program product is run on a terminal device, the terminal device executes the inverter impedance measurement method described in any one of the above-mentioned first aspects.

[0022] It can be understood that the beneficial effects of the second to fifth aspects mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here.

[0023] The inverter impedance measurement method, device, terminal device and storage medium provided in the embodiments of the present application obtain a first disturbance voltage frequency domain signal and a first response current frequency domain signal when a disturbance voltage of a first disturbance frequency is injected into the inverter, and a second disturbance voltage frequency domain signal and a second response current frequency domain signal when a disturbance voltage of a second disturbance frequency is injected into the inverter, determine the first disturbance voltage signal and the first response current signal according to the above-mentioned disturbance voltage frequency domain signal and the response current frequency domain signal, and determine the second disturbance voltage signal and the second response current signal, wherein the first disturbance frequency and the second disturbance frequency are frequencies on both sides of a preset frequency, determine the first impedance of the first disturbance frequency according to the above-mentioned disturbance voltage signal and the response current signal, and determine the second impedance of the second disturbance frequency, determine the impedance of the preset frequency according to the first impedance and the second impedance, calculate the average of the impedance of the disturbance frequency on both sides of the preset frequency and use the average as the impedance of the preset frequency, so as to improve the accuracy of the impedance of the preset frequency, that is, to improve the accuracy of the inverter impedance measurement, thereby improving the accuracy of the subsequent dynamic characteristics analysis of the inverter.

[0024] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0026] Figure 1 It is a flow chart of an inverter impedance measurement method provided by an embodiment of the present application;

[0027] Figure 2 is a circuit connection diagram of an inverter and a disturbance voltage source provided in an embodiment of the present application;

[0028] Figure 3 is a flow chart of an inverter impedance measurement method provided by another embodiment of the present application;

[0029] Figure 4 is a flow chart of an inverter impedance measurement method provided in yet another embodiment of the present application;

[0030] Figure 5 is a flow chart of an inverter impedance measurement method provided by another embodiment of the present application;

[0031] Figure 6It is a Bode plot comparing the calculated impedance value and the theoretical impedance value obtained by using the existing inverter impedance measurement method;

[0032] Figure 7 It is a schematic diagram of the absolute value of the gain relative error between the calculated impedance value and the theoretical impedance value obtained by using the existing inverter impedance measurement method;

[0033] Figure 8 It is a schematic diagram of the absolute value of the relative phase error between the calculated impedance value and the theoretical impedance value obtained by using the existing inverter impedance measurement method;

[0034] Fig. 9 is a Bode diagram comparing the calculated impedance value and the theoretical impedance value obtained by using the inverter impedance measurement method provided by the embodiment of the present application;

[0035] Fig.10 is a schematic diagram of the absolute value of the relative gain error between the calculated impedance value and the theoretical impedance value obtained by using the inverter impedance measurement method provided by the embodiment of the present application;

[0036] Fig.11 is a schematic diagram of the absolute value of the relative phase error between the calculated impedance value and the theoretical impedance value obtained by using the inverter impedance measurement method provided by the embodiment of the present application;

[0037] Fig.12 is a structural schematic diagram of an inverter impedance measurement device provided in an embodiment of the present application;

[0038] Fig.13 It is a structural diagram of a terminal device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0039] The present application is described more clearly below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the effects of the present application, but are not intended to limit the present application in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present application. These all fall within the scope of protection of the present application.

[0040] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0041] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0042] In the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0043] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0044] In addition, the “plurality” mentioned in the embodiments of the present application should be interpreted as two or more.

[0045] Power electronic devices such as inverters have the advantages of flexibility and control, which can significantly enhance the control capability of the power system. A large number of new devices are connected to the power transmission and distribution network through power electronic devices, and the degree of power electronics in the power grid is constantly improving. However, the dynamic characteristics of power electronic devices are complex and highly nonlinear, which brings severe challenges to the transient stability analysis of power electronic power systems. Problems such as power system oscillation caused by grid connection are gradually emerging. Therefore, it is very important to study the dynamic characteristics of power electronic devices in the power grid.

[0046] Port impedance can comprehensively characterize the dynamic characteristics of power electronic equipment such as inverters, and the impedance results can be used to analyze the dynamic characteristics of inverters. Existing impedance measurement methods usually apply disturbances to the inverter ports and directly use the measurement results corresponding to the frequency sweep points as impedance results. However, due to the high uncertainty of the power system, the impedance results obtained by the above methods are of low accuracy, which in turn reduces the accuracy of subsequent analysis of the dynamic characteristics of the inverter.

[0047] Based on the above problems, the inventors have discovered through research that the accuracy of the inverter impedance measurement can be improved by injecting a disturbance voltage into the inverter, measuring the impedance of the disturbance frequency on both sides of the preset frequency, and calculating the average of the above impedance as the impedance of the preset frequency. It is also possible to further determine whether the impedance of the preset frequency needs to be corrected, and correct the impedance of the preset frequency when correction is required, thereby further ensuring the reliability of the inverter impedance measurement results.

[0048] That is to say, in the inverter impedance measurement method provided in the embodiment of the present application, a first disturbance voltage frequency domain signal and a first response current frequency domain signal are obtained when a disturbance voltage of a first disturbance frequency is injected into the inverter, and a second disturbance voltage frequency domain signal and a second response current frequency domain signal are obtained when a disturbance voltage of a second disturbance frequency is injected into the inverter. The first disturbance voltage signal and the first response current signal are determined according to the above-mentioned disturbance voltage frequency domain signal and the response current frequency domain signal, and the second disturbance voltage signal and the second response current signal are determined, wherein the first disturbance frequency and the second disturbance frequency are frequencies on both sides of the preset frequency, and the first impedance of the first disturbance frequency is determined according to the above-mentioned disturbance voltage signal and the response current signal, and the second impedance of the second disturbance frequency is determined, and the impedance of the preset frequency is determined according to the first impedance and the second impedance. By calculating the mean of the impedance of the disturbance frequencies on both sides of the preset frequency and using the mean as the impedance of the preset frequency, the accuracy of the impedance of the preset frequency can be improved, that is, the accuracy of the inverter impedance measurement can be improved, thereby improving the accuracy of the subsequent dynamic characteristics analysis of the inverter.

[0049] Figure 1 FIG. 1 is a flow chart of an inverter impedance measurement method provided by an embodiment of the present application. Figure 1 As shown, the method in the embodiment of the present application may include:

[0050] Step 101, obtaining a first disturbance voltage frequency domain signal and a first response current frequency domain signal when a disturbance voltage with a first disturbance frequency is injected into the inverter, and obtaining a second disturbance voltage frequency domain signal and a second response current frequency domain signal when a disturbance voltage with a second disturbance frequency is injected into the inverter.

[0051] Figure 2 Schematic diagram of the circuit connection between the inverter and the disturbance voltage source provided by an embodiment of the present application. Figure 2 As shown, the inverter is a three-phase inverter, which is the inverter to be measured. When the impedance of the inverter is measured, the inverter is in an offline state and connected to an offline test voltage source, which is a three-phase voltage source for powering the inverter. A disturbance voltage source is connected in series between the inverter and the offline test voltage source, and the disturbance voltage source is a three-phase disturbance voltage source, which is used to provide the inverter with disturbance voltages of different frequencies within a preset sweep frequency interval, and the disturbance voltage is a three-phase disturbance voltage.

[0052] Optionally, the first disturbance frequency and the second disturbance frequency are frequencies on both sides of the preset frequency. Wherein, the preset frequency is a plurality of equally spaced frequencies in a preset frequency sweep interval. In the embodiment of the present application, the impedance of the plurality of preset frequencies is measured, that is, the impedance of the inverter at the preset frequency is measured. The first disturbance frequency and the second disturbance frequency are the frequencies on both sides of the preset frequency, respectively. For example, the preset frequency sweep interval can be set to the mid-frequency band [500Hz, 5000Hz], then the preset frequencies in the preset frequency sweep interval can be set to 500Hz, 600Hz, 700Hz, ..., 4900Hz, 5000Hz, a total of 46 preset frequencies, and the first disturbance frequency and the second disturbance frequency of each preset frequency can be set to the frequency of the preset frequency ±10Hz. For example, if the preset frequency is 600Hz, the first disturbance frequency corresponding to the preset frequency is 590Hz, and the second disturbance frequency is 610Hz, that is, there are 92 disturbance frequencies corresponding to 46 preset frequencies.

[0053] It should be noted that the above-mentioned preset frequency sweep interval, preset frequency, and the corresponding values ​​of the first disturbance frequency and the second disturbance frequency can be set according to specific circumstances and are not specifically limited here.

[0054] In some embodiments, see Figure 3 In step 101, the following may be specifically included:

[0055] Step 1011, obtaining a first disturbance voltage time domain signal and a first response current time domain signal when a disturbance voltage with a first disturbance frequency is injected into the inverter, and obtaining a second disturbance voltage time domain signal and a second response current time domain signal when a disturbance voltage with a second disturbance frequency is injected into the inverter.

[0056] Optionally, to ensure the stability of the acquired time domain signal, the corresponding time domain signal is acquired in the last disturbance cycle of the injected disturbance voltage. Specifically, when a disturbance voltage of a first disturbance frequency is injected into the inverter, the first disturbance voltage time domain signal and the first response current time domain signal of the last disturbance cycle under the disturbance voltage are acquired. When a disturbance voltage of a second disturbance frequency is injected into the inverter, the second disturbance voltage time domain signal and the second response current time domain signal of the last disturbance cycle under the disturbance voltage are acquired.

[0057] Step 1012, performing discrete Fourier transform on the first disturbance voltage time domain signal and the first response current time domain signal respectively to obtain a first disturbance voltage frequency domain signal and a first response current frequency domain signal, and performing discrete Fourier transform on the second disturbance voltage time domain signal and the second response current time domain signal respectively to obtain a second disturbance voltage frequency domain signal and a second response current frequency domain signal.

[0058] Optionally, the acquired time domain signal includes a signal corresponding to the fundamental frequency and a signal corresponding to the disturbance frequency. Therefore, it is necessary to perform discrete Fourier transform on the above time domain signal to obtain the corresponding frequency domain signal, and then extract the signal corresponding to the disturbance frequency from the frequency domain signal.

[0059] Specifically, the first disturbance voltage time domain signal is discretely transformed to obtain a first disturbance voltage frequency domain signal, and the first response current time domain signal is discretely transformed to obtain a first response current frequency domain signal. The second disturbance voltage time domain signal is discretely transformed to obtain a second disturbance voltage frequency domain signal, and the second response current time domain signal is discretely transformed to obtain a second response current frequency domain signal.

[0060] In a possible implementation, step 1011 may specifically include:

[0061] Step S1, according to a preset sampling frequency, obtaining a first three-phase disturbance voltage time domain signal and a first three-phase response current time domain signal when a disturbance voltage with a first disturbance frequency is injected into the inverter.

[0062] Step S2: acquiring, according to a preset sampling frequency, a second three-phase disturbance voltage time domain signal and a second three-phase response current time domain signal when a disturbance voltage with a second disturbance frequency is injected into the inverter.

[0063] Step S3, performing abc / αβ coordinate transformation on the first three-phase disturbance voltage time domain signal and the first three-phase response current time domain signal respectively to obtain a first disturbance voltage time domain signal after coordinate transformation and a first response current time domain signal after coordinate transformation.

[0064] Step S4, performing abc / αβ coordinate transformation on the second three-phase disturbance voltage time domain signal and the second three-phase response current time domain signal respectively to obtain a second disturbance voltage time domain signal after coordinate transformation and a second response current time domain signal after coordinate transformation.

[0065] Wherein, the corresponding time domain signal is obtained according to the preset sampling frequency, and the obtained time domain signal is a discrete signal. The preset sampling frequency can be set according to the specific situation. For example, the time domain signal can be obtained with a sampling interval of 5 Hz.

[0066] Optionally, the disturbance voltage is a three-phase disturbance voltage, and the first disturbance voltage time domain signal obtained when the disturbance voltage of the first disturbance frequency is injected into the inverter includes the first three-phase disturbance voltage time domain signal, and the first response current time domain signal obtained includes the first three-phase response current time domain signal. The second disturbance voltage time domain signal obtained when the disturbance voltage of the second disturbance frequency is injected into the inverter includes the second three-phase disturbance voltage time domain signal, and the second response current time domain signal obtained includes the second three-phase response current time domain signal.

[0067] Exemplarily, the three-phase disturbance voltage time domain signal can be expressed as:

[0068]

[0069] The three-phase response current time domain signal can be expressed as:

[0070]

[0071] Among them, u a 、u b and u c is the three-phase disturbance voltage time domain signal, i a 、i b and i c is the three-phase response current time domain signal, V amp is the amplitude of the disturbance voltage, for example, the amplitude of the disturbance voltage can be 10V, I amp is the amplitude of the response current, and f is the disturbance frequency.

[0072] The three-phase disturbance voltage time domain signal is transformed into abc / αβ coordinates to obtain the disturbance voltage time domain signal after coordinate transformation, which can be specifically expressed as:

[0073]

[0074] The three-phase response current time domain signal is subjected to abc / αβ coordinate transformation to obtain the response current time domain signal after coordinate transformation, which can be specifically expressed as:

[0075]

[0076] In the formula, u α and u β is the value of the three-phase disturbance voltage time domain signal in the αβ stationary coordinate system, u α +ju β is the disturbance voltage time domain signal after coordinate transformation. α and i β is the value of the three-phase response current time domain signal in the αβ stationary coordinate system, i α +ji β is the response current time domain signal after coordinate transformation.

[0077] Specifically, according to the above abc / αβ coordinate transformation formula, the first three-phase disturbance voltage time domain signal is subjected to abc / αβ coordinate transformation to obtain the first disturbance voltage time domain signal after coordinate transformation, and the first three-phase response current time domain signal is subjected to abc / αβ coordinate transformation to obtain the first response current time domain signal after coordinate transformation. The second three-phase disturbance voltage time domain signal is subjected to abc / αβ coordinate transformation to obtain the second disturbance voltage time domain signal after coordinate transformation, and the second three-phase response current time domain signal is subjected to abc / αβ coordinate transformation to obtain the second response current time domain signal after coordinate transformation.

[0078] Accordingly, step 1012 may specifically include:

[0079] Step S11, performing discrete Fourier transform on the first disturbance voltage time domain signal after coordinate transformation and the first response current time domain signal after coordinate transformation respectively to obtain a first disturbance voltage frequency domain signal and a first response current frequency domain signal.

[0080] Step S12, performing discrete Fourier transform on the second disturbance voltage time domain signal after coordinate transformation and the second response current time domain signal after coordinate transformation, respectively, to obtain a second disturbance voltage frequency domain signal and a second response current frequency domain signal.

[0081] Exemplarily, a discrete Fourier transform is performed on the time domain signal after the coordinate transformation to obtain a frequency domain signal, which can be specifically expressed as:

[0082]

[0083] Wherein, x(n) is the time domain signal after coordinate transformation, which is a discrete signal, where n represents the nth discrete point, N is the length of the time domain signal after coordinate transformation, and X(k) is the frequency domain signal, which is also a discrete signal, where k represents the kth discrete point.

[0084] Specifically, according to the above discrete Fourier transform formula, the first disturbance voltage time domain signal after coordinate transformation is discrete Fourier transformed to obtain the first disturbance voltage frequency domain signal, and the first response current time domain signal after coordinate transformation is discrete Fourier transformed to obtain the first response current frequency domain signal. The second disturbance voltage time domain signal after coordinate transformation is discrete Fourier transformed to obtain the second disturbance voltage frequency domain signal, and the second response current time domain signal after coordinate transformation is discrete Fourier transformed to obtain the second response current frequency domain signal.

[0085] Step 102: determine a first disturbance voltage signal and a first response current signal according to the first disturbance voltage frequency domain signal and the first response current frequency domain signal, and determine a second disturbance voltage signal and a second response current signal according to the second disturbance voltage frequency domain signal and the second response current frequency domain signal.

[0086] In a possible implementation, in step 102, see Figure 4 , which may include:

[0087] Step 1021 : extract the first disturbance voltage frequency domain signal and the first response current frequency domain signal respectively to determine the first disturbance voltage signal and the first response current signal of the first disturbance frequency.

[0088] Step 1022: extract the second disturbance voltage frequency domain signal and the second response current frequency domain signal respectively to determine the second disturbance voltage signal and the second response current signal of the second disturbance frequency.

[0089] Optionally, a signal corresponding to the disturbance frequency is extracted from the frequency domain signal. Specifically, a signal extraction is performed on the first disturbance voltage frequency domain signal to determine the first disturbance voltage signal of the first disturbance frequency, and a signal extraction is performed on the first response current frequency domain signal to determine the first response current signal of the first disturbance frequency. A signal extraction is performed on the second disturbance voltage frequency domain signal to determine the second disturbance voltage signal of the second disturbance frequency, and a signal extraction is performed on the second response current frequency domain signal to determine the second response current signal of the second disturbance frequency.

[0090] Step 103: determining a first impedance at a first disturbance frequency according to the first disturbance voltage signal and the first response current signal, and determining a second impedance at a second disturbance frequency according to the second disturbance voltage signal and the second response current signal.

[0091] Optionally, the impedance calculation formula is:

[0092]

[0093] In the formula, f 0,1 is the first disturbance frequency, f 0,2 is the second disturbance frequency, Z(f 0,1 ) is the first impedance, Z(f 0,2 ) is the second impedance, PerRI(f 0,1 ) is the first disturbance voltage signal, ResRI(f 0,1 ) is the first response current signal, PerRI(f 0,2 ) is the second disturbance voltage signal, ResRI(f 0,2 ) is the second response current signal.

[0094] Step 104: Determine an impedance of a preset frequency according to the first impedance and the second impedance.

[0095] In a possible implementation, step 104 may specifically include: calculating the mean of the first impedance and the second impedance to determine the impedance of the preset frequency.

[0096] Alternatively, the impedance at a preset frequency can be expressed as:

[0097]

[0098] In the formula, f 0 is the preset frequency, Z(f 0 ) is the impedance at the preset frequency.

[0099] It should be noted that, according to the preset frequencies within the preset frequency scanning interval, the first disturbance frequency and the second disturbance frequency of each preset frequency are determined, disturbance voltages of different frequencies are injected into the inverter according to the above disturbance frequencies, and steps 101 to 104 are repeated to determine the impedance of each preset frequency within the preset frequency scanning interval, so as to analyze the dynamic characteristics of the inverter according to the above multiple preset frequencies and the impedances of the preset frequencies.

[0100] By calculating the impedance of the first disturbance frequency and the second disturbance frequency on both sides of the preset frequency, and calculating the average of the impedance of the first disturbance frequency and the impedance of the second disturbance frequency, and using the average as the impedance of the preset frequency, the accuracy of the impedance of the preset frequency can be improved, that is, the accuracy of the inverter impedance measurement can be improved, thereby improving the accuracy of the subsequent dynamic characteristics analysis of the inverter.

[0101] In a possible implementation manner, in order to further improve the accuracy of the impedance of the preset frequency, it is also possible to determine whether the calculated impedance of the preset frequency needs to be corrected, and to correct the impedance of the preset frequency when correction is required, see Figure 5 The inverter impedance measurement method provided in the embodiment of the present application may further include:

[0102] Step 105: taking a plurality of equally spaced target frequencies in the preset frequency sweep interval as preset frequencies in sequence, executing the above-mentioned step of determining the impedance of the preset frequencies, and obtaining the impedance of each equally spaced target frequency in the preset frequency sweep interval.

[0103] Specifically, a plurality of equally spaced target frequencies in a preset frequency sweep interval are sequentially used as preset frequencies, a first disturbance frequency and a second disturbance frequency of the preset frequencies are determined, disturbance voltages of different frequencies are injected into the inverter according to the above disturbance frequencies, and steps 101 to 104 are executed to obtain the impedances of each equally spaced target frequency in the preset frequency sweep interval.

[0104] The specific implementation process and principle of step 105 in this embodiment can be found in the above-mentioned embodiment and will not be described again here.

[0105] Step 106: for each equally spaced target frequency within the preset frequency sweep interval, determine the adjacent first frequency and second frequency of the target frequency within the preset frequency sweep interval; determine the first change slope according to the impedance of the disturbance frequency of the first frequency and the impedance of the disturbance frequency of the target frequency; determine the second change slope according to the impedance of the disturbance frequency of the second frequency and the impedance of the disturbance frequency of the target frequency; determine whether the absolute value of the difference between the first change slope and the second change slope is greater than a preset threshold, and if so, correct the impedance of the target frequency.

[0106] It should be noted that the adjacent first frequency and second frequency of the target frequency in the preset frequency scanning interval are respectively the other two target frequencies adjacent to the target frequency in the preset frequency scanning interval. For example, when the preset frequency scanning interval is set to the mid-frequency band [500Hz, 5000Hz], the target frequency is 700Hz, then the adjacent first frequency and second frequency of the target frequency in the preset frequency scanning interval are 600Hz and 800Hz respectively.

[0107] Exemplarily, specifically, the first change slope is determined according to the impedance of the second disturbance frequency of the first frequency and the impedance of the first disturbance frequency of the target frequency, and the second change slope is determined according to the impedance of the first disturbance frequency of the second frequency and the impedance of the second disturbance frequency of the target frequency.

[0108] The calculation formula of the change slope can be expressed as:

[0109]

[0110] In the formula, k 1 is the first change slope, k 2 is the second change slope, Z(f 3,1 ) is the target frequency f 3 The first disturbance frequency f 3,1 The impedance, Z(f 3,2 ) is the second disturbance frequency f of the target frequency 3,2 The impedance, Z(f 1,2 ) is the second disturbance frequency f of the first frequency 1,2 The impedance, Z(f 2,1 ) is the first disturbance frequency f of the second frequency 2,1 impedance.

[0111] Judgment|k 2 -k 1 |Is it greater than a preset threshold, where the preset threshold can be 2e -5 , if |k 2 -k 1 |Greater than the preset threshold 2e -5 , then there may be a pole at this time, and the impedance of the target frequency needs to be corrected.

[0112] A simple example is that when the preset sweep frequency interval is set to the mid-frequency band [500Hz, 5000Hz], the target frequency is 700Hz, then the adjacent first frequency and second frequency of the target frequency in the preset sweep frequency interval are 600Hz and 800Hz respectively, the first disturbance frequency of the first frequency is 590Hz, and the second disturbance frequency is 610Hz, the first disturbance frequency of the second frequency is 790Hz, and the second disturbance frequency is 810Hz, the first disturbance frequency of the target frequency is 690Hz, and the second disturbance frequency is 710Hz.

[0113] It should be noted that if the target frequency is an end point of a preset frequency sweep interval, the impedance of the target frequency may not be corrected.

[0114] Optionally, in step 106, when the absolute value of the difference between the first change slope and the second change slope is greater than a preset threshold, the step of correcting the impedance of the target frequency can specifically include: determining the corrected impedance of the target frequency according to the value of the intersection of the straight line corresponding to the first change slope and the straight line corresponding to the second change slope.

[0115] Exemplarily, the straight line corresponding to the first change slope and the straight line corresponding to the second change slope can be respectively expressed as:

[0116]

[0117] The value of the intersection of the straight line corresponding to the first change slope and the straight line corresponding to the second change slope is calculated as the corrected impedance of the target frequency, that is, as the final impedance of the target frequency:

[0118]

[0119] In the formula, |Z(f 3 )| is the target frequency f 3 The final impedance, i.e. the target frequency f 3 The corrected impedance.

[0120] By determining the adjacent first frequency and second frequency of the target frequency within a preset frequency sweep interval, and determining the first change slope according to the impedance of the second disturbance frequency of the first frequency and the impedance of the first disturbance frequency of the target frequency, and determining the second change slope according to the impedance of the first disturbance frequency of the second frequency and the impedance of the second disturbance frequency of the target frequency, judging whether the impedance of the target frequency needs to be corrected according to the above-mentioned change slopes, and correcting the impedance of the target frequency when correction is required, the reliability of the results of the inverter impedance measurement can be further guaranteed.

[0121] An inverter impedance measurement method provided in an embodiment of the present application comprises: obtaining a first disturbance voltage frequency domain signal and a first response current frequency domain signal when a disturbance voltage of a first disturbance frequency is injected into the inverter, and a second disturbance voltage frequency domain signal and a second response current frequency domain signal when a disturbance voltage of a second disturbance frequency is injected into the inverter, determining a first disturbance voltage signal and a first response current signal according to the above-mentioned disturbance voltage frequency domain signal and the response current frequency domain signal, and determining a second disturbance voltage signal and a second response current signal, wherein the first disturbance frequency and the second disturbance frequency are frequencies on both sides of a preset frequency, determining a first impedance of the first disturbance frequency according to the above-mentioned disturbance voltage signal and the response current signal, and determining a second impedance of the second disturbance frequency, determining an impedance of the preset frequency according to the first impedance and the second impedance, performing mean calculation on the impedance of the disturbance frequencies on both sides of the preset frequency and using the mean as the impedance of the preset frequency, so as to improve the accuracy of the impedance of the preset frequency, that is, to improve the accuracy of the inverter impedance measurement, and thereby to improve the accuracy of the subsequent dynamic characteristic analysis of the inverter.

[0122] It is judged whether the obtained impedance of the preset frequency needs to be corrected, and the impedance of the preset frequency is corrected when correction is needed, so as to further ensure the reliability of the result of the inverter impedance measurement.

[0123] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0124] Below, in order to verify the accuracy and effectiveness of the inverter impedance measurement method provided in the embodiment of the present application, an inverter impedance test model is built in a Matlab platform or a Simulink platform to calculate the theoretical value of the impedance at a preset frequency, which is called the theoretical impedance value, and the impedance at the preset frequency obtained according to the inverter impedance measurement method is called the calculated impedance value, wherein the above-mentioned inverter impedance measurement method may include the inverter impedance measurement method provided in the embodiment of the present application, and the Matlab platform is used to compare and analyze the above-mentioned theoretical impedance value and the calculated impedance value.

[0125] Figure 6 This is a Bode plot comparing the calculated impedance value and the theoretical impedance value obtained by using the existing inverter impedance measurement method, see Figure 6 , the curve represents the theoretical impedance value, and the discrete asterisk points represent the calculated impedance value. Figure 7 is a schematic diagram of the absolute value of the relative gain error between the calculated impedance value and the theoretical impedance value obtained by using the existing inverter impedance measurement method, see Figure 7 , the calculated gain mean absolute percentage error is 3.57%. Figure 8is a schematic diagram of the absolute value of the relative phase error between the calculated impedance value and the theoretical impedance value obtained by using the existing inverter impedance measurement method, see Figure 8 The calculated phase average absolute percentage error is 1.65%. From the above results, it can be concluded that the accuracy of the calculated impedance value obtained by the existing inverter impedance measurement method is not high, and as the preset frequency increases, the error of the calculated impedance value gradually increases.

[0126] Fig. 9 is a Bode diagram comparing the calculated impedance value and the theoretical impedance value obtained by the inverter impedance measurement method provided in the embodiment of the present application, see Fig. 9 , the curve represents the theoretical impedance value, and the discrete asterisk points represent the calculated impedance value. Fig.10 Schematic diagram of the absolute value of the relative gain error between the calculated impedance value and the theoretical impedance value obtained by the inverter impedance measurement method provided in the embodiment of the present application, see Fig.10 , the calculated gain mean absolute percentage error is 3.19%. Fig.11 Schematic diagram of the absolute value of the relative phase error between the calculated impedance value and the theoretical impedance value obtained by the inverter impedance measurement method provided in the embodiment of the present application, see Fig.11 The calculated phase average absolute percentage error is 0.85%. From the above results, it can be concluded that the accuracy of the calculated impedance value obtained by the inverter impedance measurement method provided in the embodiment of the present application is high, the error is effectively reduced, and the accuracy and reliability of the inverter impedance measurement are improved.

[0127] Fig.12 Schematic diagram of the structure of an inverter impedance measurement device provided by an embodiment of the present application. Fig.12 As shown, the inverter impedance measurement device provided in this embodiment may include: an acquisition module 201 , a first determination module 202 , a second determination module 203 and a third determination module 204 .

[0128] Among them, the acquisition module 201 is used to obtain a first disturbance voltage frequency domain signal and a first response current frequency domain signal when a disturbance voltage with a first disturbance frequency is injected into the inverter; and to obtain a second disturbance voltage frequency domain signal and a second response current frequency domain signal when a disturbance voltage with a second disturbance frequency is injected into the inverter.

[0129] The first determination module 202 is used to determine the first disturbance voltage signal and the first response current signal according to the first disturbance voltage frequency domain signal and the first response current frequency domain signal; determine the second disturbance voltage signal and the second response current signal according to the second disturbance voltage frequency domain signal and the second response current frequency domain signal; the first disturbance frequency and the second disturbance frequency are frequencies on both sides of the preset frequency.

[0130] The second determination module 203 is used to determine a first impedance of a first disturbance frequency according to the first disturbance voltage signal and the first response current signal, and to determine a second impedance of a second disturbance frequency according to the second disturbance voltage signal and the second response current signal.

[0131] The third determination module 204 is configured to determine the impedance of a preset frequency according to the first impedance and the second impedance.

[0132] Optionally, the acquisition module 201 is specifically used to: acquire a first disturbance voltage time domain signal and a first response current time domain signal when a disturbance voltage with a first disturbance frequency is injected into the inverter; acquire a second disturbance voltage time domain signal and a second response current time domain signal when a disturbance voltage with a second disturbance frequency is injected into the inverter; perform discrete Fourier transform on the first disturbance voltage time domain signal and the first response current time domain signal, respectively, to obtain a first disturbance voltage frequency domain signal and a first response current frequency domain signal; perform discrete Fourier transform on the second disturbance voltage time domain signal and the second response current time domain signal, respectively, to obtain a second disturbance voltage frequency domain signal and a second response current frequency domain signal.

[0133] Optionally, the disturbance voltage is a three-phase disturbance voltage, and the acquisition module 201 is also specifically used to: according to a preset sampling frequency, obtain a first three-phase disturbance voltage time domain signal and a first three-phase response current time domain signal when a disturbance voltage of a first disturbance frequency is injected into the inverter; according to a preset sampling frequency, obtain a second three-phase disturbance voltage time domain signal and a second three-phase response current time domain signal when a disturbance voltage of a second disturbance frequency is injected into the inverter; perform abc / αβ coordinate transformation on the first three-phase disturbance voltage time domain signal and the first three-phase response current time domain signal respectively, to obtain the first disturbance voltage time domain signal after coordinate transformation and the first response current time domain signal after coordinate transformation; perform abc / αβ coordinate transformation on the second three-phase disturbance voltage time domain signal and the second three-phase response current time domain signal respectively, to obtain the second disturbance voltage time domain signal after coordinate transformation and the second response current time domain signal after coordinate transformation;

[0134] The first disturbance voltage time domain signal after coordinate transformation and the first response current time domain signal after coordinate transformation are respectively subjected to discrete Fourier transformation to obtain a first disturbance voltage frequency domain signal and a first response current frequency domain signal; the second disturbance voltage time domain signal after coordinate transformation and the second response current time domain signal after coordinate transformation are respectively subjected to discrete Fourier transformation to obtain a second disturbance voltage frequency domain signal and a second response current frequency domain signal.

[0135] Optionally, the first determination module 202 is specifically used to: perform signal extraction on the first disturbance voltage frequency domain signal and the first response current frequency domain signal, respectively, to determine the first disturbance voltage signal and the first response current signal of the first disturbance frequency; perform signal extraction on the second disturbance voltage frequency domain signal and the second response current frequency domain signal, respectively, to determine the second disturbance voltage signal and the second response current signal of the second disturbance frequency.

[0136] Optionally, the third determination module 204 is specifically used to: calculate the average of the first impedance and the second impedance to determine the impedance of the preset frequency.

[0137] Optionally, the third determination module 204 is also specifically used to: take multiple equally spaced target frequencies in the preset frequency sweep interval as preset frequencies in turn, execute the above-mentioned step of determining the impedance of the preset frequencies, and obtain the impedance of each equally spaced target frequency in the preset frequency sweep interval; for each equally spaced target frequency in the preset frequency sweep interval, determine the adjacent first frequency and second frequency of the target frequency in the preset frequency sweep interval; determine a first change slope according to the impedance of the disturbance frequency of the first frequency and the impedance of the disturbance frequency of the target frequency; determine a second change slope according to the impedance of the disturbance frequency of the second frequency and the impedance of the disturbance frequency of the target frequency; determine whether the absolute value of the difference between the first change slope and the second change slope is greater than a preset threshold, and if so, correct the impedance of the target frequency.

[0138] Optionally, the third determination module 204 is further specifically configured to determine the corrected impedance of the target frequency according to a value of an intersection of a straight line corresponding to the first change slope and a straight line corresponding to the second change slope.

[0139] It should be noted that the information interaction, execution process, etc. between the above-mentioned devices / units are based on the same concept as the method embodiment of the present application. Their specific functions and technical effects can be found in the method embodiment part and will not be repeated here.

[0140] Fig.13 Schematic diagram of the structure of a terminal device provided by an embodiment of the present application. Fig.13 As shown, the terminal device 300 of this embodiment includes: a processor 310 and a memory 320, wherein the memory 320 stores a computer program 321 that can be run on the processor 310. When the processor 310 executes the computer program 321, the steps in any of the above method embodiments are implemented, for example Figure 1 Alternatively, when the processor 310 executes the computer program 321, the functions of each module in the above-mentioned device embodiments are implemented, for example Fig.12 The functions of modules 201 to 204 are shown.

[0141] Exemplarily, the computer program 321 may be divided into one or more modules / units, one or more modules / units are stored in the memory 320, and are executed by the processor 310 to complete the present application. The one or more modules / units may be a series of computer program instruction segments capable of completing specific functions, and the instruction segments are used to describe the execution process of the computer program 321 in the terminal device 300.

[0142] Those skilled in the art will understand that Fig.13 It is only an example of a terminal device and does not constitute a limitation on the terminal device. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components, such as input and output devices, network access devices, buses, etc.

[0143] The processor 310 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may be any conventional processor, etc.

[0144] The memory 320 may be an internal storage unit of the terminal device, such as a hard disk or memory of the terminal device, or an external storage device of the terminal device, such as a plug-in hard disk, a smart memory card (SmartMedia Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. equipped on the terminal device. The above-mentioned memory 320 may also include both an internal storage unit of the terminal device and an external storage device. The above-mentioned memory 320 is used to store computer programs and other programs and data required by the terminal device. The memory 320 may also be used to temporarily store data that has been output or is to be output.

[0145] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0146] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0147] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0148] In the embodiments provided by the present invention, it should be understood that the disclosed devices / terminal equipment and methods can be implemented in other ways. For example, the device / terminal equipment embodiments described above are only schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0149] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0150] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0151] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electrical carrier signal, telecommunication signal and software distribution medium, etc.

[0152] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A method for measuring inverter impedance, characterized in that: include: Acquire a first disturbance voltage frequency domain signal and a first response current frequency domain signal when a disturbance voltage with a first disturbance frequency is injected into the inverter; Acquire a second disturbance voltage frequency domain signal and a second response current frequency domain signal when a disturbance voltage with a second disturbance frequency is injected into the inverter; Determine a first disturbance voltage signal and a first response current signal according to the first disturbance voltage frequency domain signal and the first response current frequency domain signal; Determining a second disturbance voltage signal and a second response current signal according to the second disturbance voltage frequency domain signal and the second response current frequency domain signal; the first disturbance frequency and the second disturbance frequency are frequencies on both sides of a preset frequency; Determine a first impedance of a first disturbance frequency according to the first disturbance voltage signal and the first response current signal, determine a second impedance of a second disturbance frequency according to the second disturbance voltage signal and the second response current signal; determine an impedance of the preset frequency according to the first impedance and the second impedance; Wherein, determining the impedance of the preset frequency according to the first impedance and the second impedance includes: calculating the mean of the first impedance and the second impedance to determine the impedance of the preset frequency; The method further comprises: Taking a plurality of equally spaced target frequencies in a preset frequency sweep interval as the preset frequency in sequence, executing the above-mentioned step of determining the impedance of the preset frequency to obtain the impedance of each equally spaced target frequency in the preset frequency sweep interval; For each equally spaced target frequency within the preset frequency sweep interval, determine the adjacent first frequency and second frequency of the target frequency within the preset frequency sweep interval; determine a first change slope according to the impedance of the disturbance frequency of the first frequency and the impedance of the disturbance frequency of the target frequency; determine a second change slope according to the impedance of the disturbance frequency of the second frequency and the impedance of the disturbance frequency of the target frequency; determine whether the absolute value of the difference between the first change slope and the second change slope is greater than a preset threshold, and if so, correct the impedance of the target frequency; When the absolute value of the difference between the first change slope and the second change slope is greater than a preset threshold, the impedance of the target frequency is corrected, including: determining the corrected impedance of the target frequency according to the value of the intersection of the straight line corresponding to the first change slope and the straight line corresponding to the second change slope.

2. The inverter impedance measurement method according to claim 1, characterized in that: The acquiring is a first disturbance voltage frequency domain signal and a first response current frequency domain signal when a disturbance voltage having a first disturbance frequency is injected into the inverter; Acquiring a second disturbance voltage frequency domain signal and a second response current frequency domain signal when a disturbance voltage having a second disturbance frequency is injected into the inverter, comprising: Acquire a first disturbance voltage time domain signal and a first response current time domain signal when a disturbance voltage with a first disturbance frequency is injected into the inverter; Acquire a second disturbance voltage time domain signal and a second response current time domain signal when a disturbance voltage with a second disturbance frequency is injected into the inverter; The first disturbance voltage time domain signal and the first response current time domain signal are discrete Fourier transformed respectively to obtain a first disturbance voltage frequency domain signal and a first response current frequency domain signal; the second disturbance voltage time domain signal and the second response current time domain signal are discrete Fourier transformed respectively to obtain a second disturbance voltage frequency domain signal and a second response current frequency domain signal.

3. The inverter impedance measurement method according to claim 2, characterized in that: The disturbance voltage is a three-phase disturbance voltage; The acquiring is a first disturbance voltage time domain signal and a first response current time domain signal when a disturbance voltage having a first disturbance frequency is injected into the inverter; Acquiring a second disturbance voltage time domain signal and a second response current time domain signal when a disturbance voltage having a second disturbance frequency is injected into the inverter, comprising: According to a preset sampling frequency, a first three-phase disturbance voltage time domain signal and a first three-phase response current time domain signal are obtained when a disturbance voltage with a first disturbance frequency is injected into the inverter; According to a preset sampling frequency, obtaining a second three-phase disturbance voltage time domain signal and a second three-phase response current time domain signal when a disturbance voltage with a second disturbance frequency is injected into the inverter; The first three-phase disturbance voltage time domain signal and the first three-phase response current time domain signal are respectively subjected to abc / Coordinate transformation to obtain a first disturbance voltage time domain signal after coordinate transformation and a first response current time domain signal after coordinate transformation; The second three-phase disturbance voltage time domain signal and the second three-phase response current time domain signal are respectively subjected to abc / Coordinate transformation to obtain a second disturbance voltage time domain signal after coordinate transformation and a second response current time domain signal after coordinate transformation; Correspondingly, the first disturbance voltage time domain signal and the first response current time domain signal are subjected to discrete Fourier transform respectively to obtain a first disturbance voltage frequency domain signal and a first response current frequency domain signal; the second disturbance voltage time domain signal and the second response current time domain signal are subjected to discrete Fourier transform respectively to obtain a second disturbance voltage frequency domain signal and a second response current frequency domain signal, including: Performing discrete Fourier transform on the first disturbance voltage time domain signal after coordinate transformation and the first response current time domain signal after coordinate transformation respectively to obtain a first disturbance voltage frequency domain signal and a first response current frequency domain signal; Discrete Fourier transform is performed on the second disturbance voltage time domain signal after the coordinate transformation and the second response current time domain signal after the coordinate transformation respectively to obtain a second disturbance voltage frequency domain signal and a second response current frequency domain signal.

4. The inverter impedance measurement method according to claim 1, characterized in that: Determining a first disturbance voltage signal and a first response current signal according to the first disturbance voltage frequency domain signal and the first response current frequency domain signal; Determining a second disturbance voltage signal and a second response current signal according to the second disturbance voltage frequency domain signal and the second response current frequency domain signal comprises: Performing signal extraction on the first disturbance voltage frequency domain signal and the first response current frequency domain signal respectively to determine a first disturbance voltage signal and a first response current signal of a first disturbance frequency; Signal extraction is performed on the second disturbance voltage frequency domain signal and the second response current frequency domain signal respectively to determine a second disturbance voltage signal and a second response current signal of a second disturbance frequency.

5. An inverter impedance measuring device, characterized in that: include: An acquisition module, used for acquiring a first disturbance voltage frequency domain signal and a first response current frequency domain signal when a disturbance voltage with a first disturbance frequency is injected into the inverter; Acquire a second disturbance voltage frequency domain signal and a second response current frequency domain signal when a disturbance voltage with a second disturbance frequency is injected into the inverter; A first determination module, configured to determine a first disturbance voltage signal and a first response current signal according to the first disturbance voltage frequency domain signal and the first response current frequency domain signal; Determine a second disturbance voltage signal and a second response current signal according to the second disturbance voltage frequency domain signal and the second response current frequency domain signal; The first disturbance frequency and the second disturbance frequency are frequencies on both sides of the preset frequency; a second determination module, configured to determine a first impedance of a first disturbance frequency according to the first disturbance voltage signal and the first response current signal, and to determine a second impedance of a second disturbance frequency according to the second disturbance voltage signal and the second response current signal; A third determination module, configured to determine the impedance of the preset frequency according to the first impedance and the second impedance; The third determination module is further used to calculate the mean of the first impedance and the second impedance to determine the impedance of the preset frequency; and taking a plurality of equally spaced target frequencies in a preset frequency sweep interval as the preset frequency in sequence, executing the above-mentioned step of determining the impedance of the preset frequency to obtain the impedance of each equally spaced target frequency in the preset frequency sweep interval; For each equally spaced target frequency within the preset frequency sweep interval, determine the adjacent first frequency and second frequency of the target frequency within the preset frequency sweep interval; determine a first change slope according to the impedance of the disturbance frequency of the first frequency and the impedance of the disturbance frequency of the target frequency; determine a second change slope according to the impedance of the disturbance frequency of the second frequency and the impedance of the disturbance frequency of the target frequency; determine whether the absolute value of the difference between the first change slope and the second change slope is greater than a preset threshold, and if so, correct the impedance of the target frequency; And according to the value of the intersection of the straight line corresponding to the first change slope and the straight line corresponding to the second change slope, the corrected impedance of the target frequency is determined.

6. A terminal device, comprising a memory and a processor, wherein the memory stores a computer program that can be run on the processor, characterized in that: When the processor executes the computer program, the inverter impedance measurement method according to any one of claims 1 to 4 is implemented.

7. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the inverter impedance measurement method according to any one of claims 1 to 4 is implemented.

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