Sequence impedance measurement method and product based on two-phase broadband harmonic disturbance injection

Abstract

The invention discloses a sequence impedance measurement method and product based on two-phase broadband harmonic disturbance injection, and compared with a traditional three-phase symmetrical disturbance injection measurement method which can only inject broadband positive sequence disturbance or negative sequence disturbance into a to-be-measured system once, the sequence impedance measurement method only needs to inject broadband disturbance into the to-be-measured system once. Broadband positive-sequence disturbance and broadband negative-sequence disturbance can be injected at the same time, the measurement speed is higher, and frequency band setting is more flexible; in addition, the sequence impedance measurement method also adopts an odd-even frequency band grouping injection strategy, so that aliasing of positive and negative sequence disturbance response components and coupling response components can be effectively avoided, and the accuracy and reliability of subsequent sequence impedance measurement are ensured.

Description

Technical Field

[0001] This application belongs to the field of broadband impedance measurement of power electronic converter grid-connected systems, specifically involving a sequence impedance measurement method and product based on two-phase broadband harmonic disturbance injection. Background Technology

[0002] Currently, impedance measurement research on three-phase grid-connected converters in some new energy systems still employs a combination of single-frequency and frequency sweep methods, which results in slow measurement speeds. Therefore, disturbance design is gradually evolving from single-frequency measurement to multi-frequency measurement. On the other hand, most current measurement methods for three-phase grid-connected converters still utilize a three-phase symmetrical disturbance injection approach. This method requires injecting positive-sequence and negative-sequence disturbances into the system under test twice to obtain the measured sequence impedance matrix. However, the three-phase symmetrical disturbance injection method can only inject wideband positive-sequence and negative-sequence disturbances into the system under test at a time, thus affecting the measurement speed. Summary of the Invention

[0003] To overcome the limitations of existing technologies, this application proposes a sequence impedance measurement method and product based on two-phase broadband harmonic disturbance injection. This application only needs to inject a broadband disturbance into the system under test once, and can simultaneously inject broadband positive-sequence disturbance and negative-sequence disturbance, thereby improving the measurement speed and making the frequency band equipment more flexible.

[0004] This application is achieved through the following technical solution:

[0005] A method for measuring sequence impedance based on two-phase broadband harmonic disturbance injection includes:

[0006] The target sequence impedance measurement bandwidth of the system under test is sequentially divided into multiple wideband measurement frequency segments, and the multiple wideband measurement frequency segments are grouped according to the parity of the sequence number. All odd-numbered frequency segments are assigned to the first group, and all even-numbered frequency segments are assigned to the second group.

[0007] Simultaneous injection of phase difference between any two phases of the system under test into the system is given. The positive and negative sequence broadband disturbances of the first set of odd frequency bands are collected, and after the system under test has fully responded, the three-phase voltage and current signals of the system under test are collected at its common coupling point and the effective response in the signals is extracted and stored as the first set of data.

[0008] Simultaneous injection of phase difference between any two phases of the system under test into the system is given. The positive and negative sequence broadband disturbances of the second even frequency band are collected, and after the system under test has fully responded, the three-phase voltage and current signals of the system under test are collected at its common coupling point and the effective response in the signal is extracted and stored as the second set of data.

[0009] Based on the first set of data and the second set of data, the sequence impedance of the three-phase grid-connected AC circuit under the current injected disturbance frequency band is calculated;

[0010] Determine whether the sequence impedance measurement of the entire measurement bandwidth has been completed. If yes, output the sequence impedance measurement result of the three-phase grid-connected converter; otherwise, return to the step of simultaneously injecting a phase difference of 0.5% into any two phases of the system under test. The steps for positive and negative sequence broadband disturbances in the first odd-frequency segment are repeated, along with the two-phase asymmetric odd-even segment positive and negative sequence grouping injection broadband disturbances and sequence impedance calculations.

[0011] In some embodiments, the step of sequentially dividing the target sequence impedance measurement bandwidth of the system under test into multiple wideband measurement frequency segments includes:

[0012] The target sequence impedance measurement bandwidth is sequentially divided into k wideband measurement frequency segments with a bandwidth less than twice the fundamental frequency, namely the first frequency segment, the second frequency segment, and so on. The kth frequency band;

[0013] The frequency segments with odd numbers in the k frequency segments are assigned to the first group, and the frequency segments with even numbers in the k frequency segments are assigned to the second group; where k is an integer greater than or equal to 2.

[0014] In some embodiments, the step of sequentially dividing the target sequence impedance measurement bandwidth of the system under test into multiple wideband measurement frequency segments includes:

[0015] The frequency range of 0 to 50 Hz is divided into the first frequency band. The remaining frequency bands are then divided into equal frequency intervals of 100 Hz, i.e., 50 to 150 Hz is the second frequency band, and so on, with (100×k-150) to (100×k-50) Hz being the kth frequency band.

[0016] In some embodiments, the currently injected perturbation frequency band comprises an odd-numbered frequency band and an even-numbered frequency band, and the currently injected perturbation signal consists of the currently injected odd-numbered frequency band perturbation injection signal and the currently injected even-numbered frequency band perturbation injection signal, as expressed as:

[0017] ;

[0018] in, Indicates the currently injected disturbance signal; u p_odd (t), u p_even (t) represents the perturbation injection in the odd-frequency segment and the perturbation injection in the even-frequency segment, respectively.

[0019] In some implementations, the odd-frequency segment disturbance injection signal is represented as:

[0020] ;

[0021] The even-frequency band disturbance injection signal is represented as follows:

[0022] ;

[0023] Where r is the modulation ratio of the multi-sine signal; f0 is the lower limit of the frequency band; N odd The total number of frequencies injected into odd-numbered segments; It is the sum of the number of frequencies in the k-th frequency segment and the odd-numbered segments preceding it; It is the sum of the number of frequencies in the (k-2)th frequency segment and the odd-numbered segments preceding it; The frequency interval of the k-th frequency segment; N represents the phase of the disturbance signal. even The total number of frequencies injected into even-numbered segments; It is the sum of the number of frequencies in the k-th frequency segment and the even-numbered segments preceding it; It is the sum of the number of frequencies in the (k-2)th frequency segment and the even-numbered segments before it.

[0024] In some implementations, the perturbation signal phase is used to ensure that the phase difference between any two phases of the perturbation signal injected into the system under test is . .

[0025] In some implementations, the formula for calculating the sequence impedance of the three-phase grid-connected AC circuit is:

[0026] ;

[0027] ;

[0028] in, Z is the positive and negative sequence impedance matrix of the grid-connected converter. pp Z pn Z np Z nn These are the four elements of the impedance matrix, where Z pp With Z nn For positive-sequence impedance and negative-sequence impedance, Z pn With Z np V is the coupling impedance between positive and negative sequences; V and I are the voltage and current components at the output port of the grid-connected converter, respectively; V p1 (f p V p2 (f p -2f1) are the first group of frequencies f p The positive sequence voltage component and frequency f p -2f1 negative sequence voltage coupling component; I p1 (f p), I p2 (f p -2f1) are the first group of frequencies f p The positive sequence current component and frequency f p -2f1 negative sequence current coupling component; V n1 (f p V n2 (f p -2f1) are the second group of frequencies f p The positive-sequence coupling component and the frequency f p -2f1 negative sequence voltage component; I n1 (f p ), I n2 (f p -2f1) are the second group of frequencies f p The positive sequence current coupling component with frequency f p -2f1 negative sequence current component.

[0029] Secondly, this application proposes a sequence impedance measurement device based on two-phase broadband harmonic disturbance injection, comprising:

[0030] The grouping unit is configured to: sequentially divide the target sequence impedance measurement bandwidth of the system under test into multiple wideband measurement frequency segments, and group the multiple wideband measurement frequency segments according to the parity of the sequence number, assigning all odd-numbered frequency segments to the first group and all even-numbered frequency segments to the second group;

[0031] The injection measurement unit is configured to simultaneously inject a phase difference of into any two phases of the system under test. The first set of odd-frequency bands is subjected to positive and negative sequence broadband perturbations. After the system under test (SUT) has fully responded, the three-phase voltage and current signals of the SUT are collected at its common coupling point, and the effective response is extracted and stored as the first set of data. A phase difference of is simultaneously injected into any two phases of the SUT. The positive and negative sequence broadband disturbances of the second even frequency band are collected, and after the system under test has fully responded, the three-phase voltage and current signals of the system under test are collected at its common coupling point and the effective response in the signal is extracted and stored as the second set of data.

[0032] The calculation unit is configured to calculate the sequence impedance of the three-phase grid-connected AC circuit under the current injected disturbance frequency band based on the first set of data and the second set of data.

[0033] In addition, the loop unit is configured to: determine whether the sequence impedance measurement of the entire measurement bandwidth has been completed; if so, output the sequence impedance measurement result of the three-phase grid-connected converter; otherwise, return to the injection measurement unit to repeat the two-phase asymmetric odd-even segment positive and negative sequence grouping injection broadband disturbance and sequence impedance calculation.

[0034] Thirdly, this application proposes an electronic device including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement any of the above-described embodiments of the sequence impedance measurement method.

[0035] Fourthly, this application proposes a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the above-described embodiments of the sequence impedance measurement method.

[0036] This application proposes a sequence impedance measurement method based on two-phase broadband harmonic disturbance injection. Compared with the traditional three-phase symmetrical disturbance injection measurement method, which can only inject broadband positive-sequence or negative-sequence disturbances into the system under test at one time, the sequence impedance measurement method of this application only needs to inject broadband disturbances into the system under test once, and can inject broadband positive-sequence and negative-sequence disturbances simultaneously. The measurement speed is faster and the frequency band setting is more flexible. In addition, the sequence impedance measurement method of this application also adopts an odd and even frequency band grouping injection strategy, which can effectively avoid the aliasing of positive and negative sequence disturbance response components and coupling response components, and ensure the accuracy and reliability of subsequent sequence impedance measurements.

[0037] Accordingly, the impedance measurement device, electronic device and computer-readable storage medium based on two-phase broadband harmonic disturbance injection proposed in this application also have the same technical effects as described above. Attached Figure Description

[0038] The accompanying drawings, which are included to provide a further understanding of the embodiments of this application and form part of this application, do not constitute a limitation on the embodiments of this application. In the drawings:

[0039] Figure 1 This is a flowchart of the sequence impedance measurement method proposed in the embodiments of this application;

[0040] Figure 2 This is a typical main circuit topology and control block diagram of a new energy grid-connected converter system;

[0041] Figure 3 A schematic diagram of two-phase AB disturbance injection;

[0042] Figure 4 Frequency interval step size A schematic diagram of the odd-even segment positive and negative order grouping injection strategy at 10Hz;

[0043] Figure 5 This is a block diagram illustrating the principle of the sequence impedance measurement device proposed in the embodiments of this application.

[0044] Figure 6 This is a schematic diagram of the sequence impedance measurement system architecture proposed in the embodiments of this application;

[0045] Figure 7 This is a schematic diagram of the electronic device proposed in the embodiments of this application;

[0046] Figure 8 This is a schematic diagram of a computer-readable storage medium proposed in an embodiment of this application;

[0047] Figure reference numerals and corresponding component names:

[0048] 200-Sequence impedance measuring device, 201-Grouping unit, 202-Injection measuring unit, 203-Calculation unit, 204-Circulation unit, 300-Sequence impedance measuring system, 301-Input device, 302-Output device, 303-Processor A, 304-Memory A, 400-Electronic device, 410-Memory B, 420-Processor B, 411-Computer program A, 500-Computer readable storage medium, 511-Computer program B. Detailed Implementation

[0049] In the following, the terms “comprising” or “may include” as used in the various embodiments of this application indicate the presence of a function, operation, or element of the invention and do not limit the addition of one or more functions, operations, or elements. Furthermore, as used in the various embodiments of this application, the terms “comprising,” “having,” and their cognates are intended only to indicate a specific feature, number, step, operation, element, component, or combination of the foregoing and should not be construed as primarily excluding the presence of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing, or adding one or more combinations of the foregoing.

[0050] In various embodiments of this application, the expression "or" or "at least one of A and / or B" includes any combination or all combinations of the words listed simultaneously. For example, the expression "A or B" or "at least one of A and / or B" may include A, may include B, or may include both A and B.

[0051] The terms used in the various embodiments of this application (such as "first," "second," etc.) may modify various constituent elements in the various embodiments, but do not limit the corresponding constituent elements. For example, the above terms do not limit the order and / or importance of the elements. The above terms are only used for the purpose of distinguishing one element from other elements. For example, a first user device and a second user device refer to different user devices, although both are user devices. For example, without departing from the scope of the various embodiments of this application, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0052] It should be noted that if a description is made of "connecting" one component to another, then the first component can be directly connected to the second component, and a third component can be "connected" between the first and second components. Conversely, when a component is "directly connected" to another component, it can be understood that there is no third component between the first and second components.

[0053] The terminology used in the various embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the various embodiments of this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of this application pertain. The terms (such as those defined in a generally used dictionary) are to be interpreted as having the same meaning as in the context of the relevant technical field and are not to be interpreted as having an idealized or overly formal meaning, unless clearly defined in the various embodiments of this application.

[0054] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this application are only for explaining this application and are not intended to limit this application.

[0055] To address the issue of slow impedance measurement speed in current three-phase grid-connected converters of new energy systems, this application proposes a sequence impedance measurement method based on two-phase wideband harmonic disturbance injection.

[0056] like Figure 1 As shown, the sequence impedance measurement method proposed in this application includes the following steps:

[0057] Step 1: Divide the target sequence impedance measurement bandwidth of the system under test into multiple wideband measurement frequency segments in sequence, and group the multiple wideband measurement frequency segments according to the parity of the sequence number. Assign all odd frequency segments to the first group and all even frequency segments to the second group.

[0058] Step 2: Simultaneously inject a phase difference of into any two phases of the system under test. The positive and negative sequence broadband disturbances of the first odd frequency band are collected, and after the system under test has fully responded, the three-phase voltage and current signals of the system under test are collected at its common coupling point and the effective response in the signal is extracted and stored as the first set of data.

[0059] Step 3: Simultaneously inject a phase difference of into any two phases of the system under test. The positive and negative sequence broadband disturbances in the second even frequency band are collected, and after the system under test has fully responded, the three-phase voltage and current signals of the system under test are collected at its common coupling point and the effective response in the signal is extracted and stored as the second set of data.

[0060] Step 4: Calculate the sequence impedance of the three-phase grid-connected converter under the current injected disturbance frequency band based on the first set of data and the second set of data.

[0061] Step 5: Determine whether the sequence impedance measurement of the entire measurement bandwidth has been completed. If yes, output the sequence impedance measurement result of the three-phase grid-connected converter. Otherwise, return to step 2 to perform positive and negative sequence broadband disturbances in the next frequency segment to repeat the two-phase asymmetric odd and even segment positive and negative sequence grouping injection broadband disturbances and sequence impedance calculations.

[0062] Figure 2 This diagram illustrates a typical main circuit topology and control block diagram of a new energy grid-connected converter. Figure 2 It can be seen that by acquiring the three-phase voltage signals of phases ABC at the point of common coupling (PPC) and inputting them into the phase-locked loop (PLL), the phase angle required for the dq transformation can be obtained. The three-phase current signal is collected to obtain the control loop input current i. d i q The remaining i in the figure dref i qref These are the reference currents along the d-axis and q-axis in a synchronously rotating coordinate system, respectively; K d K represents the feedforward decoupling gain coefficient. f Voltage feedforward coefficient; H i (s) is the current loop function, H i (s)=(K p_I +K i_I / s) / s,K p_I and K i_I These are the proportional and integral parameters of the current loop PI controller, respectively; Q1~Q6 are the switching signals of each IGBT in the new energy grid-connected converter.

[0063] Due to the nonlinear components and asymmetric structure of the control system of the new energy grid-connected converter, there is a significant frequency coupling phenomenon. Specifically, when a frequency f is applied at the grid connection point... p When the positive sequence voltage is disturbed, in addition to the same frequency point f p In addition to generating the corresponding positive sequence current response component, it will also produce a response at another frequency point f. p -2f1 generates a negative sequence current coupling response component, where f1 is the fundamental frequency, i.e., 50Hz. According to the conversion relationship between the positive and negative sequence components shown in equation (1), the frequency of the positive sequence component is f. p When, it is equivalent to a frequency of -f p Negative order components:

[0064] (1)

[0065] Among them, X p (s) and X n (s) represent the positive and negative order components, respectively; superscript This represents performing a conjugate operation. Therefore, when f p When <2f1, the frequency is f p The negative-sequence current-coupled response component of -2f1 is equivalent to the frequency 2f1-f p The conjugate of the positive-sequence current-coupled response component.

[0066] The sequence impedance of grid-connected converters for new energy sources exhibits multiple-input multiple-output (MIMO) characteristics, and the accurate acquisition of its frequency-coupled impedance matrix is ​​a crucial foundation for ensuring the stability analysis of the grid-connected system. The positive and negative sequence frequency-coupled impedance characteristics can be mathematically characterized by the following analytical expression:

[0067] (2)

[0068] in,

[0069] (3)

[0070] in, Z represents the positive and negative sequence impedance matrix of the grid-connected converter for new energy sources. pp Z pn Z np Z nn These are the four elements of the impedance matrix, where Z pp With Z nn For positive-sequence impedance and negative-sequence impedance, Z pn With Z np V is the coupling impedance between positive and negative sequences; V and I are the voltage and current components at the output port of the new energy grid-connected converter, respectively; V p1 (f p V p2 (f p -2f1) are the first group of frequencies f p The positive sequence voltage component and frequency f p -2f1 negative sequence voltage coupling component; I p1 (f p ), I p2 (f p -2f1) are the first group of frequencies f p The positive sequence current component and frequency f p -2f1 negative sequence current coupling component; V n1 (f p V n2 (fp -2f1) are the second group of frequencies f p The positive-sequence coupling component and the frequency f p -2f1 negative sequence voltage component; I n1 (f p ), I n2 (f p -2f1) are the second group of frequencies f p The positive sequence current coupling component with frequency f p -2f1 is the negative sequence current component. Simultaneously, it must be ensured that the first and second sets of disturbance signals are linearly independent.

[0071] During the measurement process, the three-phase voltage and current responses of phases A, B, and C at the point of common coupling (PCC) of the grid-connected converter are generally directly acquired. Therefore, after acquiring the three-phase voltage and current responses, it is still necessary to separate the positive and negative sequences of the acquired disturbance signals using the symmetrical component method. The calculation formula is as follows:

[0072] (4)

[0073] in, These are the separated positive-order components; The negative-order components are separated; For the separated zero-order components; , and It is the collected three-phase response (voltage or current) of ABC. The rotation factor, i.e. .

[0074] Considering that obtaining the positive and negative sequence impedance matrices of a grid-connected converter requires injecting positive and negative sequence disturbances into the system under test, this application proposes a two-phase asymmetric disturbance injection method. Specifically, it involves arbitrarily selecting two phases in the three-phase system under test and injecting disturbance signals with equal amplitudes and a 180° phase difference in series. For example, a voltage disturbance signal of V1∠0 is injected in series into phase A, and a voltage disturbance signal of V1∠180° is injected in series into phase B. The disturbance injection is as follows: Figure 3 As shown, substituting the voltage disturbances of phases A and B into equation (4) yields the positive-sequence, negative-sequence, and zero-sequence components of phase A at this time:

[0075] (5)

[0076] As can be seen from equation (5), the amplitude of the zero-sequence component, which has no effect on the measurement of the positive and negative sequence impedance matrix, is 0, while the amplitudes of the injected positive and negative sequence disturbance components are equal, which meets the initial requirement of injecting positive and negative sequence disturbances into the system under test.

[0077] Analysis of the frequency coupling phenomenon in the converter shows that simultaneously injecting positive and negative sequence disturbance signals f into the grid-connected converter under test... p Afterwards, the resulting coupled response component is |f p ±2f1 |. When the injected wideband positive and negative sequence perturbation bandwidth is greater than 2f1, i.e. f max -f min >2f1, the frequency band is [f min -2f1,f max The positive-sequence perturbation coupled response components of [-2f1] and [f min +2f1, f max The negative-order perturbation coupling response component of +2f1] will interact with the frequency band [f min f max The effective responses of the system under test overlap, which will inevitably affect the subsequent accurate extraction of the positive and negative sequence response components and their coupled response components. This will lead to errors in the calculation of the positive and negative sequence impedance matrix and affect the measurement results of the broadband impedance.

[0078] To eliminate the aliasing effect of positive and negative sequence responses and positive and negative sequence coupling responses, the selection of the broadband signal for disturbance injection is crucial. This application's embodiment utilizes the controllable amplitude and frequency band characteristics of multiple sinusoidal signals to achieve a rapid measurement strategy for the broadband sequence impedance of grid-connected converters, while also offering the advantage of controllable measurement frequency bands. The multiple sinusoidal signal is a typical multi-frequency signal with controllable bilateral frequency bands and adjustable values ​​at each frequency point; its mathematical expression is:

[0079] (6)

[0080] Where r is the modulation ratio of the multi-sine signal; f0 is the lower limit of the frequency band; N0 is the number of frequencies; The frequency interval step size, i.e., the upper limit of the frequency band, is... Multi-sine signals have the characteristics of uniform and controllable spectral energy, with harmonic components only present at the set frequencies and zero at other unset frequencies. Therefore, this embodiment uses a multi-sine signal device to generate a modulated wave signal with broadband harmonic disturbances.

[0081] Furthermore, based on the above analysis of the interference mechanism of positive and negative sequence perturbation injection coupling response, in order to avoid the aliasing of coupling response and effective response, the injected broadband positive and negative sequence perturbation signal can be sequentially divided into multiple frequency segments with a bandwidth less than 2f1. For example, 0~50Hz can be divided into the first frequency segment, and the remaining frequency segments can be further divided with equal frequency intervals of 100Hz, i.e., 50~150Hz is the second segment, 150~250Hz is the third segment, and so on. When k≥2, the kth segment is (100×k-150)~(100×k-50)Hz.

[0082] Based on the above segmentation method, a positive-negative sequence grouping injection strategy suitable for resisting frequency coupling between positive and negative sequences is proposed, avoiding the aliasing phenomenon of coupled frequency responses. Specifically, the multiple perturbation frequency segments are grouped according to the parity of their sequence numbers, i.e., all odd-numbered frequency segments are assigned to the first group, and all even-numbered frequency segments are assigned to the second group. Then, voltage perturbation signals of these two groups of frequencies are injected sequentially (i.e., according to the first group of odd-numbered frequency segments + the second group of even-numbered frequency segments; the first group of odd-numbered frequency segments + the second group of even-numbered frequency segments; and so on, until the perturbation injection of all frequency segments is completed). The mathematical expression of the injected perturbation signal is:

[0083] (7)

[0084] Among them, u p_odd (t), u p_even (t) represent disturbance injection in odd-frequency segments and even-frequency segments, respectively. The mathematical expression for the disturbance injection signal in odd-frequency segments is:

[0085] (8)

[0086] Where, N odd The total number of frequencies injected into odd-numbered segments; It is the sum of the number of frequencies in the k-th frequency segment and the odd-numbered segments preceding it; It is the sum of the number of frequencies in the (k-2)th frequency segment and the number of odd-numbered segments before it. For example, when k=3, This represents the number of frequencies in the first frequency band. This is the starting frequency of the k-th frequency segment; The frequency interval of the k-th frequency segment; The phase of the disturbance signal is specifically designed to ensure that the phase difference between the disturbance signal injected into phase A and phase B, as described in the embodiments of this application, is [missing information]. ,Right now .

[0087] The mathematical expression for the even-numbered segment perturbation injection signal is:

[0088] (9)

[0089] Where, N even The total number of frequencies injected into even-numbered segments; It is the sum of the number of frequencies in the k-th frequency segment and the even-numbered segments preceding it; It is the sum of the number of frequencies in the (k-2)th frequency segment and the even-numbered segments preceding it. For example, when k=2, .

[0090] Following the above strategy, we obtain Figure 4 The frequency interval step shown The odd-even segment positive-negative order grouping injection strategy is adopted at 10Hz, where Figure 4 (a) represents the disturbance response spectrum for the first set of odd-numbered frequency bands. Of particular note is the positive-sequence disturbance frequency f within the first frequency band. p All are less than 2f1, so the coupling response component should be the frequency 2f1 - f. p The positive-sequence perturbation coupled response component is shown in the figure, with the coupling relationship represented by the orange line. In the remaining frequency range, the purple and green circles represent the positive-sequence and negative-sequence perturbation response components, respectively, distributed in all odd-numbered frequency ranges; the purple triangles and green rectangles represent the positive-sequence and negative-sequence perturbation coupled response components, respectively, distributed in even-numbered frequency ranges. It can be seen that the positive and negative-sequence perturbation response components and the coupled response components are distributed in an alternating pattern of odd and even frequencies, with no frequency overlap between them. Figure 4 (b) shows the disturbance response spectrum for the second set of even-numbered frequency segments. The second frequency segment in the figure contains some positive-sequence disturbance frequencies f. p It is less than 2f1. The coupling relationship of this frequency band is also shown by the orange line in the figure. In the other frequency bands, the positive and negative sequence disturbance response components are distributed in the even frequency bands, and the coupling response components are distributed in the odd frequency bands. There is no mutual interference between the two.

[0091] It is worth noting that, as can be seen from equations (2) and (3), measuring the positive and negative sequence impedance matrix of a grid-connected converter requires two sets of linearly independent voltage and current responses, one set being a frequency of f. p One group is the positive-order perturbation, and the other group is the frequency |f|. p The negative sequence disturbance is -2f1|, and the frequency difference between these two sets of disturbances is exactly 2f1. Therefore, when using the above-mentioned odd-even segment positive and negative sequence grouping injection strategy, the extracted positive and negative sequence disturbance voltage and current response data and positive and negative sequence coupling voltage and current response data are exactly interleaved and distributed in different frequency segments. Thus, it can be seen that the above-mentioned two-phase asymmetric odd-even segment positive and negative sequence grouping injection strategy proposed in this application embodiment can effectively avoid the aliasing of positive and negative sequence disturbance response components and coupling response components, ensuring the accuracy and reliability of subsequent sequence impedance measurements.

[0092] Based on the same technical concept described above, this application also proposes a sequence impedance measurement device based on two-phase broadband harmonic disturbance injection, such as... Figure 5 As shown, the sequence impedance measuring device 200 includes:

[0093] Grouping unit 201 is configured to: sequentially divide the target sequence impedance measurement bandwidth of the system under test into multiple wideband measurement frequency segments, and group these wideband measurement frequency segments according to the parity of their sequence numbers, assigning all odd-numbered frequency segments to the first group and all even-numbered frequency segments to the second group. The specific implementation method is as described in the sequence impedance measurement method above and will not be repeated here.

[0094] The injection measurement unit 202 is configured to simultaneously inject a phase difference of into any two phases of the system under test. The first set of odd-frequency bands contains positive and negative sequence broadband disturbances. After the system under test (SUT) has fully responded, the three-phase voltage and current signals of the SUT are acquired at its common coupling point, and the effective response is extracted and stored as the first set of data. A phase difference of is simultaneously injected into any two phases of the SUT. The second set of even-frequency band positive and negative sequence broadband disturbances are injected, and after the system under test has fully responded, the three-phase voltage and current signals of the system under test are collected at its common coupling point, and the effective response is extracted and stored as the second set of data; that is, two-phase asymmetrical odd and even segment positive and negative sequence grouping broadband disturbances are injected. The specific process is as described in the above sequence impedance measurement method, and will not be elaborated further here.

[0095] The calculation unit 203 is configured to calculate the sequence impedance of the three-phase grid-connected converter under the current injected disturbance frequency band based on the first set of data and the second set of data. The specific calculation method is as described in the sequence impedance measurement method above, and will not be repeated here.

[0096] In addition, the loop unit 204 is configured to: determine whether the sequence impedance measurement of the entire measurement bandwidth has been completed; if so, output the sequence impedance measurement result of the three-phase grid-connected converter; otherwise, return to the injection measurement unit 202 to repeat the two-phase asymmetric odd and even segment positive and negative sequence grouping injection of broadband disturbance and sequence impedance calculation.

[0097] Based on the same technical concept described above, this application also proposes a sequence impedance measurement system based on two-phase broadband harmonic disturbance injection, such as... Figure 6 As shown, the sequence impedance measurement system 300 proposed in this application includes:

[0098] The system comprises an input device 301, an output device 302, a processor A303, and a memory A304; wherein the number of processors A303 and memory A304 can be one or more. Figure 6 The following description uses a processor A303 and a memory A304 as an example. The input device 301, output device 302, processor A303, and memory A304 can be connected via a bus or other means. Figure 6 Taking the example of a connection between China and Israel via a bus.

[0099] Specifically, by calling the operation instructions stored in memory A304, processor A303 executes the following steps:

[0100] The target sequence impedance measurement bandwidth of the system under test is sequentially divided into multiple wideband measurement frequency segments, and the multiple wideband measurement frequency segments are grouped according to the parity of the sequence number. All odd-numbered frequency segments are assigned to the first group, and all even-numbered frequency segments are assigned to the second group.

[0101] Simultaneous injection of phase difference between any two phases of the system under test into the system is given. The positive and negative sequence broadband disturbances of the first odd frequency band are collected, and after the system under test has fully responded, the three-phase voltage and current signals of the system under test are collected at its common coupling point and the effective response in the signal is extracted and stored as the first set of data.

[0102] Simultaneous injection of phase difference between any two phases of the system under test into the system is given. The positive and negative sequence broadband disturbances in the second even frequency band are collected, and after the system under test has fully responded, the three-phase voltage and current signals of the system under test are collected at its common coupling point and the effective response in the signal is extracted and stored as the second set of data.

[0103] Based on the first set of data and the second set of data, the sequence impedance of the three-phase grid-connected converter under the current injected disturbance frequency band is calculated;

[0104] Determine whether the sequence impedance measurement of the entire measurement bandwidth has been completed. If yes, output the sequence impedance measurement result of the three-phase grid-connected converter; otherwise, return to the step of simultaneously injecting a phase difference of 0.5% into any two phases of the system under test. The steps for positive and negative sequence broadband disturbances in the first odd-frequency segment are repeated, along with the two-phase asymmetric odd-even segment positive and negative sequence grouping injection broadband disturbances and sequence impedance calculations.

[0105] Optionally, by calling the operation instructions stored in memory A304, processor A303 is also used to execute any of the embodiments in the corresponding examples of the above-described sequence impedance measurement method.

[0106] Based on the same technical concept described above, this application also proposes an electronic device, such as... Figure 7 As shown, the electronic device 400 includes: a memory B410, a processor B420, and a computer program A411 stored in the memory B410 and executable on the processor B420. When the processor B420 executes the computer program A411, it performs the following steps:

[0107] The target sequence impedance measurement bandwidth of the system under test is sequentially divided into multiple wideband measurement frequency segments, and the multiple wideband measurement frequency segments are grouped according to the parity of the sequence number. All odd-numbered frequency segments are assigned to the first group, and all even-numbered frequency segments are assigned to the second group.

[0108] Simultaneous injection of phase difference between any two phases of the system under test into the system is given. The positive and negative sequence broadband disturbances of the first odd frequency band are collected, and after the system under test has fully responded, the three-phase voltage and current signals of the system under test are collected at its common coupling point and the effective response in the signal is extracted and stored as the first set of data.

[0109] Simultaneous injection of phase difference between any two phases of the system under test into the system is given. The positive and negative sequence broadband disturbances in the second even frequency band are collected, and after the system under test has fully responded, the three-phase voltage and current signals of the system under test are collected at its common coupling point and the effective response in the signal is extracted and stored as the second set of data.

[0110] Based on the first set of data and the second set of data, the sequence impedance of the three-phase grid-connected converter under the current injected disturbance frequency band is calculated;

[0111] Determine whether the sequence impedance measurement of the entire measurement bandwidth has been completed. If yes, output the sequence impedance measurement result of the three-phase grid-connected converter; otherwise, return to the step of simultaneously injecting a phase difference of 0.5% into any two phases of the system under test. The steps for positive and negative sequence broadband disturbances in the first odd-frequency segment are repeated, along with the two-phase asymmetric odd-even segment positive and negative sequence grouping injection broadband disturbances and sequence impedance calculations.

[0112] Optionally, when processor B420 executes computer program A411, it can implement any of the embodiments in the corresponding examples of the above-described sequence impedance measurement method.

[0113] It should be noted that the electronic device proposed in this application embodiment is a device used to implement the above-described sequence impedance measurement method. Therefore, based on the above-described sequence impedance measurement method proposed in this application embodiment, those skilled in the art can understand the specific implementation method and various variations of the electronic device in this application embodiment. Therefore, how the electronic device specifically implements the above-described sequence impedance measurement method will not be described in detail here. Any electronic device used by those skilled in the art to implement the above-described sequence impedance measurement method falls within the scope of protection of this application.

[0114] Based on the same technical concept described above, embodiments of this application also propose a computer-readable storage medium, such as... Figure 8 As shown, the computer-readable storage medium 500 stores a computer program B511, which, when executed by a processor, performs the following steps:

[0115] The target sequence impedance measurement bandwidth of the system under test is sequentially divided into multiple wideband measurement frequency segments, and the multiple wideband measurement frequency segments are grouped according to the parity of the sequence number. All odd-numbered frequency segments are assigned to the first group, and all even-numbered frequency segments are assigned to the second group.

[0116] Simultaneous injection of phase difference between any two phases of the system under test into the system is given. The positive and negative sequence broadband disturbances of the first odd frequency band are collected, and after the system under test has fully responded, the three-phase voltage and current signals of the system under test are collected at its common coupling point and the effective response in the signal is extracted and stored as the first set of data.

[0117] Simultaneous injection of phase difference between any two phases of the system under test into the system is given. The positive and negative sequence broadband disturbances in the second even frequency band are collected, and after the system under test has fully responded, the three-phase voltage and current signals of the system under test are collected at its common coupling point and the effective response in the signal is extracted and stored as the second set of data.

[0118] Based on the first set of data and the second set of data, the sequence impedance of the three-phase grid-connected converter under the current injected disturbance frequency band is calculated;

[0119] Determine whether the sequence impedance measurement of the entire measurement bandwidth has been completed. If yes, output the sequence impedance measurement result of the three-phase grid-connected converter; otherwise, return to the step of simultaneously injecting a phase difference of 0.5% into any two phases of the system under test. The steps for positive and negative sequence broadband disturbances in the first odd-frequency segment are repeated, along with the two-phase asymmetric odd-even segment positive and negative sequence grouping injection broadband disturbances and sequence impedance calculations.

[0120] Optionally, when the computer program B511 is executed by the processor, it can implement any of the embodiments corresponding to the above-described sequence impedance measurement method.

[0121] It should be noted that the descriptions of each embodiment in the above embodiments have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0122] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0123] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0124] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0125] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0126] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above description is only a specific embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for measuring sequence impedance based on two-phase broadband harmonic disturbance injection, characterized in that, include: The target sequence impedance measurement bandwidth of the system under test is sequentially divided into multiple wideband measurement frequency segments, and the multiple wideband measurement frequency segments are grouped according to the parity of the sequence number. All odd-numbered frequency segments are assigned to the first group, and all even-numbered frequency segments are assigned to the second group. Simultaneous injection of phase difference between any two phases of the system under test into the system is given. The positive and negative sequence broadband disturbances of the first set of odd frequency bands are collected, and after the system under test has fully responded, the three-phase voltage and current signals of the system under test are collected at its common coupling point and the effective response in the signals is extracted and stored as the first set of data. Simultaneous injection of phase difference between any two phases of the system under test into the system is given. The positive and negative sequence broadband disturbances of the second even frequency band are collected, and after the system under test has fully responded, the three-phase voltage and current signals of the system under test are collected at its common coupling point and the effective response in the signal is extracted and stored as the second set of data. Based on the first set of data and the second set of data, the sequence impedance of the three-phase grid-connected AC circuit under the current injected disturbance frequency band is calculated; Determine whether the sequence impedance measurement of the entire measurement bandwidth has been completed. If yes, output the sequence impedance measurement result of the three-phase grid-connected converter; otherwise, return to the step of simultaneously injecting a phase difference of 0.5% into any two phases of the system under test. The steps for positive and negative sequence broadband disturbances in the first odd-frequency segment are repeated, along with the two-phase asymmetric odd-even segment positive and negative sequence grouping injection broadband disturbances and sequence impedance calculations.

2. The sequence impedance measurement method based on two-phase broadband harmonic disturbance injection according to claim 1, characterized in that, The method of sequentially dividing the target sequence impedance measurement bandwidth of the system under test into multiple wideband measurement frequency segments includes: The target sequence impedance measurement bandwidth is sequentially divided into k wideband measurement frequency segments with a bandwidth less than twice the fundamental frequency, namely the first frequency segment, the second frequency segment, and so on. The kth frequency band; The frequency segments with odd numbers in the k frequency segments are assigned to the first group, and the frequency segments with even numbers in the k frequency segments are assigned to the second group; where k is an integer greater than or equal to 2.

3. The sequence impedance measurement method based on two-phase broadband harmonic disturbance injection according to claim 2, characterized in that, The method of sequentially dividing the target sequence impedance measurement bandwidth of the system under test into multiple wideband measurement frequency segments includes: The frequency range of 0 to 50 Hz is divided into the first frequency band. The remaining frequency bands are then divided into equal frequency intervals of 100 Hz, i.e., 50 to 150 Hz is the second frequency band, and so on, with (100×k-150) to (100×k-50) Hz being the kth frequency band.

4. A method for measuring sequence impedance based on two-phase broadband harmonic disturbance injection according to any one of claims 1-3, characterized in that, The currently injected perturbation frequency band comprises the currently injected odd-numbered frequency band and even-numbered frequency band, and the currently injected perturbation signal consists of the currently injected odd-numbered frequency band perturbation injection signal and the currently injected even-numbered frequency band perturbation injection signal, expressed as: ； in, Indicates the currently injected disturbance signal; u p_odd (t), u p_even (t) represents the perturbation injection in the odd-frequency segment and the perturbation injection in the even-frequency segment, respectively.

5. The sequence impedance measurement method based on two-phase broadband harmonic disturbance injection according to claim 4, characterized in that, The odd-frequency frequency segment disturbance injection signal is represented as follows: ； The even-frequency band disturbance injection signal is represented as follows: ； Where r is the modulation ratio of the multi-sine signal; f0 is the lower limit of the frequency band; N odd The total number of frequencies injected into odd-numbered segments; It is the sum of the number of frequencies in the k-th frequency segment and the odd-numbered segments preceding it; It is the sum of the number of frequencies in the (k-2)th frequency segment and the odd-numbered segments preceding it; The frequency interval of the k-th frequency segment; N represents the phase of the disturbance signal. even The total number of frequencies injected into even-numbered segments; It is the sum of the number of frequencies in the k-th frequency segment and the even-numbered segments preceding it; It is the sum of the number of frequencies in the (k-2)th frequency segment and the even-numbered segments before it.

6. The method for measuring sequence impedance based on two-phase broadband harmonic disturbance injection according to claim 5, characterized in that, The disturbance signal phase is used to ensure that the phase difference between any two phases of the disturbance signal injected into the system under test is . .

7. The sequence impedance measurement method based on two-phase broadband harmonic disturbance injection according to claim 4, characterized in that, The formula for calculating the sequence impedance of the three-phase grid-connected AC circuit is as follows: ； ； in, Z is the positive and negative sequence impedance matrix of the grid-connected converter. pp Z pn Z np Z nn These are the four elements of the impedance matrix, where Z pp With Z nn For positive-sequence impedance and negative-sequence impedance, Z pn With Z np V is the coupling impedance between positive and negative sequences; V and I are the voltage and current components at the output port of the grid-connected converter, respectively; V p1 (f p V p2 (f p -2f1) are the first group of frequencies f p The positive sequence voltage component and frequency f p -2f1 negative sequence voltage coupling component; I p1 (f p ), I p2 (f p -2f1) are the first group of frequencies f p The positive sequence current component and frequency f p -2f1 negative sequence current coupling component; V n1 (f p V n2 (f p -2f1) are the second group of frequencies f p The positive-sequence coupling component and the frequency f p -2f1 negative sequence voltage component; I n1 (f p ), I n2 (f p -2f1) are the second group of frequencies f p The positive sequence current coupling component with frequency f p -2f1 negative sequence current component.

8. A sequence impedance measurement device based on two-phase broadband harmonic disturbance injection, characterized in that, include: The grouping unit is configured to: sequentially divide the target sequence impedance measurement bandwidth of the system under test into multiple wideband measurement frequency segments, and group the multiple wideband measurement frequency segments according to the parity of the sequence number, assigning all odd-numbered frequency segments to the first group and all even-numbered frequency segments to the second group; The injection measurement unit is configured to simultaneously inject a phase difference of into any two phases of the system under test. The first set of odd-frequency bands is subjected to positive and negative sequence broadband perturbations. After the system under test (SUT) has fully responded, the three-phase voltage and current signals of the SUT are collected at its common coupling point, and the effective response is extracted and stored as the first set of data. A phase difference of is simultaneously injected into any two phases of the SUT. The positive and negative sequence broadband disturbances of the second even frequency band are collected, and after the system under test has fully responded, the three-phase voltage and current signals of the system under test are collected at its common coupling point and the effective response in the signal is extracted and stored as the second set of data. The calculation unit is configured to calculate the sequence impedance of the three-phase grid-connected AC circuit under the current injected disturbance frequency band based on the first set of data and the second set of data. In addition, the loop unit is configured to: determine whether the sequence impedance measurement of the entire measurement bandwidth has been completed; if so, output the sequence impedance measurement result of the three-phase grid-connected converter; otherwise, return to the injection measurement unit to repeat the two-phase asymmetric odd-even segment positive and negative sequence grouping injection broadband disturbance and sequence impedance calculation.

9. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the sequence impedance measurement method according to any one of claims 1-7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the sequence impedance measurement method according to any one of claims 1-7.

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