Efficient grid-connected inverter frequency coupling admittance measurement method and system

Abstract

The invention discloses an efficient grid-connected inverter frequency coupling admittance measurement method and system. The method comprises the following steps: injecting a first disturbance signal into a target inverter grid-connected system; obtaining a first stable parameter of an inverter port after the first disturbance signal is injected, and injecting a second disturbance signal to the target inverter grid-connected system; obtaining a second stable parameter of the inverter port after the second disturbance signal is injected; and obtaining the frequency coupling admittance of the inverter according to the first stable parameter and the second stable parameter. Through parameter configuration of a multi-sine injection signal, an inverter port signal is accurately measured by using a broadband measurement method based on Taylor Fourier transform, and efficient and accurate measurement of inverter frequency coupling admittance in multiple scenes can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of inverter grid-connected technology, and in particular to an efficient frequency-coupled admittance measurement method and system for a grid-connected inverter. Background Art

[0002] In recent years, as the penetration rate of renewable energy in the power grid continues to increase, the system damping has decreased, resulting in a series of broadband oscillation problems that have occurred frequently, seriously affecting the safe and stable operation of the power grid. How to analyze the stability of renewable energy grid-connected systems has always been a research hotspot at home and abroad. The analysis method based on impedance / admittance characteristics has the advantages of clear physical concepts and simple stability criteria, and is a common system stability analysis method. The key to the impedance analysis method is how to accurately obtain the impedance / admittance characteristics of the renewable energy side.

[0003] When the control method and parameters of the new energy unit are known, the accurate impedance analytical model can be directly obtained through impedance modeling. However, considering that the control method and parameters of the actual new energy device are usually black / gray box, impedance measurement is a common method to obtain impedance characteristics. The principle of impedance measurement is to first inject a disturbance signal into the port of the new energy device, then measure the change characteristics of the port voltage and current phasor through the measurement algorithm, and finally calculate the corresponding impedance characteristics.

[0004] The main factors affecting the impedance measurement results are disturbance injection and phasor extraction by the measurement algorithm. Among them, the types of disturbance injection signals are divided into single sinusoidal signals, multi-sinusoidal signals, and binary sequence signals. Among these methods, multi-sinusoidal signal injection has good flexibility, low interference, and high efficiency, and has good applicability. However, the multi-sinusoidal signal injection method requires the reasonable selection of signal frequency, amplitude, and phase angle. In terms of measurement methods, Fourier transform (fast Fourier transform, FFT) and its improved method are commonly used phasor extraction methods, but this method will cause spectrum leakage under non-rated frequency operation conditions of the power grid, resulting in low measurement accuracy, which in turn affects the impedance / admittance measurement results. It can be seen that efficient and accurate admittance measurement plays an important supporting role in realizing power system stability analysis. Summary of the invention

[0005] In view of the above existing problems, the present invention is proposed.

[0006] Therefore, the present invention provides an efficient method and system for measuring frequency-coupled admittance of a grid-connected inverter, which can solve the problems mentioned in the background technology.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] In a first aspect, the present invention provides an efficient method for measuring the frequency-coupled admittance of a grid-connected inverter, comprising: injecting a first disturbance signal into a target inverter grid-connected system; obtaining a first stable parameter of the inverter port after the first disturbance signal is injected, and injecting a second disturbance signal into the target inverter grid-connected system; obtaining a second stable parameter of the inverter port after the second disturbance signal is injected; and obtaining the inverter frequency-coupled admittance according to the first stable parameter and the second stable parameter.

[0009] As a preferred solution of the efficient grid-connected inverter frequency coupling admittance measurement method of the present invention, wherein: the first disturbance signal includes a voltage signal injected with a random disturbance signal;

[0010] The random disturbance signal includes selecting a number of frequency points within the target frequency range;

[0011] configuring a first sinusoidal signal based on the plurality of frequency points;

[0012] The first sinusoidal signal is injected into the voltage signal as a random disturbance signal.

[0013] As a preferred solution of the efficient grid-connected inverter frequency coupling admittance measurement method described in the present invention, wherein: the step of obtaining the first stable parameter of the inverter port after injecting the first disturbance signal and injecting the second disturbance signal into the target inverter grid-connected system includes:

[0014] The first stable parameter includes a first voltage phasor and a first current phasor at a first frequency and a second frequency;

[0015] The second disturbance signal is a negative-sequence disturbance signal having a second frequency.

[0016] As a preferred solution of the efficient grid-connected inverter frequency coupling admittance measurement method described in the present invention, wherein: the step of obtaining the second stable parameter of the inverter port after injecting the second disturbance signal includes:

[0017] The second stable parameter includes a second voltage phasor and a second current phasor at a first frequency and a second frequency.

[0018] As a preferred solution of the efficient grid-connected inverter frequency coupling admittance measurement method of the present invention, wherein: the first frequency and the second frequency include:

[0019] The second frequency is obtained according to the first frequency and the fundamental frequency;

[0020] The first frequency is a frequency for obtaining the inverter frequency coupling admittance.

[0021] As a preferred solution of the efficient grid-connected inverter frequency coupling admittance measurement method of the present invention, wherein: the injecting of the first disturbance signal into the target inverter grid-connected system comprises:

[0022] Preset the first constraint condition;

[0023] constraining the first disturbance signal according to the first constraint condition;

[0024] A first disturbance signal satisfying a first constraint condition is injected into the target inverter grid-connected system.

[0025] As a preferred solution of the efficient grid-connected inverter frequency coupling admittance measurement method described in the present invention, it also includes: the first stability parameter and the second stability parameter are both calculated by a first wideband measurement strategy based on Taylor Fourier transform.

[0026] In a second aspect, the present invention provides an efficient grid-connected inverter frequency coupling admittance measurement system, comprising:

[0027] A first signal injection module, used for injecting a first disturbance signal into a target inverter grid-connected system;

[0028] A second signal injection module, used for acquiring a first stable parameter of the inverter port after the first disturbance signal is injected, and injecting a second disturbance signal into the target inverter grid-connected system;

[0029] A parameter acquisition module, used for acquiring a second stable parameter of the inverter port after injecting a second disturbance signal;

[0030] A calculation module is used to obtain the inverter frequency coupling admittance according to the first stability parameter and the second stability parameter.

[0031] In a third aspect, the present invention provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above-mentioned method when executing the computer program.

[0032] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of the method described above when executed by a processor.

[0033] Compared with the prior art, the present invention has the following beneficial effects: the present invention proposes an efficient grid-connected inverter frequency coupling admittance measurement method and system, injects a first disturbance signal into the target inverter grid-connected system; obtains the first stable parameter of the inverter port after the first disturbance signal is injected, and injects a second disturbance signal into the target inverter grid-connected system; obtains the second stable parameter of the inverter port after the second disturbance signal is injected; and obtains the inverter frequency coupling admittance according to the first stable parameter and the second stable parameter. By configuring the parameters of the multi-sine injection signal and using a wideband measurement method based on Taylor Fourier transform to accurately measure the inverter port signal, efficient and accurate measurement of the inverter frequency coupling admittance in multiple scenarios can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0035] Figure 1 A method flow chart of an efficient frequency-coupled admittance measurement method and system for a grid-connected inverter provided by an embodiment of the present invention;

[0036] Figure 2 A schematic diagram of a frequency-coupled admittance measurement method and system for a grid-connected inverter based on serial injection of multiple sinusoidal disturbance voltages is provided as an efficient method and system for measuring frequency-coupled admittance of a grid-connected inverter according to an embodiment of the present invention;

[0037] Figure 3 A schematic diagram of a Taylor Fourier transform-based broadband measurement method of an efficient grid-connected inverter frequency-coupled admittance measurement method and system provided by an embodiment of the present invention;

[0038] Figure 4 A comparison diagram of the admittance measurement results of two methods when the grid frequency is 50 Hz for an efficient grid-connected inverter frequency-coupled admittance measurement method and system provided by an embodiment of the present invention;

[0039] Figure 5 An embodiment of the present invention provides an efficient method for measuring frequency-coupled admittance of a grid-connected inverter and a comparison diagram of the admittance measurement results of the two methods when the grid frequency of the system has a frequency offset. DETAILED DESCRIPTION

[0040] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0041] Example 1

[0042] Reference Figure 1-Figure 5 , which is the first embodiment of the present invention, and which provides an efficient grid-connected inverter frequency coupling admittance measurement method and system, comprising:

[0043] There are some technical problems in the existing related technologies, such as low measurement accuracy, complex measurement process, and difficulty in adapting to changes in power grid frequency.

[0044] The present application provides a method that can effectively solve the above-mentioned problems. Next, multiple embodiments will be combined to explain in detail how to implement the efficient grid-connected inverter frequency coupling admittance measurement method;

[0045] Figure 1 A method flow chart of an efficient grid-connected inverter frequency coupling admittance measurement method and system is shown, including:

[0046] S101, injecting a first disturbance signal into a target inverter grid-connected system;

[0047] In an embodiment of the present application, the first disturbance signal includes a voltage signal injected with a random disturbance signal;

[0048] The random disturbance signal includes selecting several frequency points within the target frequency range;

[0049] Configure a first sinusoidal signal based on a plurality of frequency points;

[0050] The first sinusoidal signal is injected into the voltage signal as a random disturbance signal.

[0051] In an optional embodiment, the random disturbance signal may be Gaussian white noise to ensure the randomness and uniformity of the injected signal, thereby improving the measurement accuracy.

[0052] In an optional embodiment, the random disturbance signal may also be a pseudo-random binary sequence with a specific frequency bandwidth to further optimize the signal characteristics during the measurement process.

[0053] In an optional embodiment, the random disturbance signal may also be a multi-sinusoidal signal or a signal in other forms to adapt to different measurement requirements and scenarios.

[0054] In the embodiment of the present application, multiple sinusoidal signals are selected as random disturbance signals to be injected into the target inverter grid-connected system, specifically:

[0055] Select multiple frequency points f in the range of 10 to 2000 Hz to form a multi-sinusoidal signal frequency vector F p , and determine the amplitude and phase of each frequency to complete the parameter configuration of the multi-sine injection signal. The parameter configuration of the multi-sine injection signal includes the configuration of frequency, amplitude and phase, specifically:

[0056] Multi-sinusoidal signal x s (t) The model is as follows:

[0057]

[0058] Where M is the number of sine waves, a m 、f m and The amplitude, frequency and phase of the mth sinusoidal component correspond to t, and time is t. In order to ensure that the injected multi-sinusoidal signal does not have a significant impact on the grid-connected system, it is necessary to reasonably select the amplitude, frequency and phase.

[0059] In an embodiment of the present application, injecting a first disturbance signal into a target inverter grid-connected system includes:

[0060] Preset the first constraint condition;

[0061] constraining the first disturbance signal according to a first constraint condition;

[0062] A first disturbance signal satisfying a first constraint condition is injected into the target inverter grid-connected system.

[0063] In an optional embodiment, because it is necessary to consider the impact of the disturbance signal on the target inverter grid-connected system, the preset first constraint condition may include the amplitude limit, frequency range and injection duration of the disturbance signal, so as to ensure that the injected disturbance signal can effectively trigger the system response and obtain the required measurement data without interfering with the normal operation of the inverter.

[0064] In the embodiment of the present application, the present application requires that each sine wave amplitude a m Not more than 5% of the rated voltage; frequency f m It should be ensured that each sine wave does not affect each other, that is, the frequency vector F p There is no frequency difference of 2f n Or about 2f n Two values ​​​​of symmetry; phase The sine wave peak is optimized by the following optimization formula:

[0065]

[0066] In an optional embodiment, relevant technicians may adopt other first constraints. For example, in practical applications, the operating status of the inverter and the real-time conditions of the power grid may be considered to dynamically adjust the first constraint to adapt to different measurement environments and requirements.

[0067] It should be noted that injecting the first disturbance signal into the target inverter grid-connected system can effectively trigger the response of the inverter grid-connected system, thereby obtaining the stable parameters of the inverter port under the action of the disturbance signal. These parameters are the basis for the subsequent calculation of the inverter frequency coupling admittance. Therefore, the injected disturbance signal must be able to ensure the accuracy and stability of the system response.

[0068] S102, obtaining a first stable parameter of the inverter port after the first disturbance signal is injected, and injecting a second disturbance signal into the target inverter grid-connected system;

[0069] In an embodiment of the present application, obtaining a first stable parameter of an inverter port after injecting a first disturbance signal, and injecting a second disturbance signal into a target inverter grid-connected system includes:

[0070] The first stable parameter includes a first voltage phasor and a first current phasor at a first frequency and a second frequency;

[0071] The second disturbance signal is a negative-sequence disturbance signal having a second frequency.

[0072] In an optional embodiment, the first stable parameter is a relevant parameter that stabilizes after the target inverter grid-connected system is injected with the first disturbance signal. The first stable parameter is generally selected to correctly reflect the typical system parameters after the system has stabilized, for example, it can be the three-phase voltage and three-phase current of the inverter side port, and it can also be the DC side voltage, AC side current, etc. The measurement of these parameters is crucial for the subsequent admittance calculation, because they can provide the response characteristics of the inverter under a specific disturbance.

[0073] In an optional embodiment, because the ultimate goal is to obtain the target point frequency coupling admittance, it is necessary to process the acquired current or voltage value again to obtain the first stable parameter related to the frequency;

[0074] In an optional embodiment, the reprocessing can be performed by a wideband measurement method of Taylor Fourier transform, or by a narrowband measurement method of Fourier transform, or by other suitable signal processing methods to ensure the accuracy and reliability of the measurement results.

[0075] In an optional embodiment, the second disturbance signal is similar to the first disturbance signal and also needs to be constrained by the first constraint condition, but other standard constraint conditions may be used here or no constraint condition may be used;

[0076] In an optional embodiment, when the second disturbance signal does not use a constraint condition, the second disturbance signal is a negative-sequence disturbance signal having a second frequency, and at this time, the design criteria of the first disturbance signal and the second disturbance signal are the same;

[0077] In the embodiment of the present application, the first stability parameter includes the first voltage phasor and the first current phasor at the first frequency and the second frequency, that is, after the grid-connected system is stable, the three-phase voltage and the three-phase current of the inverter side port are extracted, and the frequency F in the extracted signal is calculated by a wide-band measurement method based on Taylor Fourier transform. p and F o The voltage phasor V p ′、V o ′ and current phasor I′ p , I′ o ;

[0078] In the embodiment of the present application, the configured multi-sinusoidal signal is injected into the series as a disturbance voltage. Figure 2 In the grid-connected inverter system shown in the figure, v pa 、v pb and v pc is the series injected disturbance voltage, v a 、v b and v c is the voltage to be extracted from the output port, i a 、i b and i c The output port is used to extract the current. After the system is stable, the three-phase voltage and current on the inverter side are extracted. Figure 3 The broadband measurement method based on Taylor Fourier transform calculates the frequency F in the extracted signal p and F o The voltage phasor V p ′、V o ′ and current phasor I′ p , I′ o ;

[0079] In an optional embodiment, the second injection frequency in the grid-connected system is F o =F p -2f n Negative sequence disturbance, where f n is the fundamental frequency of the power grid;

[0080] In an optional embodiment, relevant technicians can set a specific disturbance signal frequency according to actual needs, and this application does not limit it;

[0081] It should be noted that obtaining the first stable parameter of the inverter port after injecting the first disturbance signal and injecting the second disturbance signal into the target inverter grid-connected system can further ensure the stability of the inverter grid-connected system and the accuracy of the measurement. By injecting the second disturbance signal, the response characteristics of the inverter under different disturbances can be obtained, thereby providing more comprehensive and accurate data support for calculating the inverter frequency coupling admittance.

[0082] S103, obtaining a second stable parameter of the inverter port after injecting the second disturbance signal;

[0083] In an optional embodiment, the second stability parameter is the same as the first stability parameter, and both are obtained for the selected stability parameter;

[0084] In an optional embodiment, the second stability parameter may be different from the first stability parameter, but this will cause a subsequent frequency coupling admittance solution process to change, and relevant technical personnel need to set it according to actual conditions.

[0085] In the embodiment of the present application, the second stability parameter is the same as the first stability parameter, and both selected are voltage phasors and current phasors calculated by a wide-band measurement method based on Taylor Fourier transform;

[0086] In the embodiment of the present application, obtaining the second stable parameter of the inverter port after the second disturbance signal is injected includes: the second stable parameter includes a second voltage phasor and a second current phasor at the first frequency and the second frequency.

[0087] In the embodiment of the present application, the frequency F in the second extracted signal is calculated by a broadband measurement method based on Taylor Fourier transform. p and F o The voltage phasor V p ″、V o ″ and current phasor I′ p ′、I o ″;

[0088] In the embodiment of the present application, the first frequency and the second frequency include:

[0089] The second frequency is obtained according to the first frequency and the fundamental frequency;

[0090] The first frequency is the inverter frequency coupling admittance obtaining frequency.

[0091] In an optional embodiment, the first frequency and the second frequency are not limited in the present application, but the first frequency and the second frequency should be frequencies related to the fundamental frequency to ensure the accuracy and relevance of the measurement results.

[0092] In an optional embodiment, the first frequency is generally designed for the target inverter frequency coupling admittance, and is generally the same as the frequency of the point to be measured. The first frequency is the frequency for obtaining the inverter frequency coupling admittance.

[0093] In the embodiment of the present application, the first stable parameter and the second stable parameter are both calculated by a first wideband measurement strategy based on Taylor Fourier transform.

[0094] In an optional embodiment, the first broadband measurement strategy may be designed by different methods, for example, a narrowband measurement method based on Fourier transform, or other suitable signal processing techniques, to ensure the accuracy and reliability of the measurement results.

[0095] In an optional embodiment, the first broadband measurement strategy can also be optimized based on other signal processing technologies, such as using an adaptive filter to improve the signal-to-noise ratio of the signal, or using a machine learning algorithm to classify and extract features from the signal, thereby further improving the accuracy and efficiency of the measurement.

[0096] In the embodiment of the present application, the voltage phasor and the current phasor calculated by the wideband measurement method based on Taylor Fourier transform can be further used to calculate the frequency coupling admittance of the inverter.

[0097] In an optional embodiment, the first broadband measurement strategy is a broadband measurement method based on Taylor Fourier transform, and the specific steps may be as follows:

[0098] For the sampling sequence y containing multiple frequency components extracted on the inverter side m [n] can be expressed as

[0099]

[0100] Where n is a sequence, n = [-L, -L+1, ..., L-1, L], T s is the sampling interval, A k 、f k and θ k are the amplitude, frequency and phase of the kth frequency component in the signal respectively. m The phasor form of [n] is

[0101]

[0102] In the formula, p k[n] is the phasor of the kth frequency component, and its expression is:

[0103]

[0104] In an alternative embodiment, p k [n] can be approximated by the I-order Taylor series as:

[0105]

[0106] y m Each phase of [n] can be expanded and expressed in matrix form as:

[0107] Y=TP

[0108] Where T is the Taylor Fourier basis vector, P is the column vector composed of the derivatives of each order of the phasor and its conjugate, and the expressions of T and P are:

[0109]

[0110] T=[T1,…,T k ,…,T K ]

[0111] In an alternative embodiment, the basis vector T k Expands to:

[0112]

[0113] By using the least squares method, the phasor result can be solved:

[0114]

[0115] In an optional embodiment, the phasor After that, the amplitude, phase angle and frequency results of each component can be obtained by the formula

[0116]

[0117] In the formula, is the magnitude, phase angle, and frequency of the kth component to be solved.

[0118] In an optional embodiment, the solved result is substituted into the phasor result in the second stable parameter and the first stable parameter, and the frequency coupling admittance can be solved.

[0119] In an optional embodiment, the first broadband measurement strategy can be expressed as:

[0120] ①According to the multi-sinusoidal signal frequency F p Determine the initial frequency value of the Taylor Fourier basis vector;

[0121] ② Given length L, sampling interval T s and order I, construct the sampling sequence y m [n] and Taylor Fourier basis vectors T;

[0122] ③ Solve the column vector by the least squares method

[0123] ④According to Solve for the frequency estimate;

[0124] ⑤ Determine whether the result meets the iteration termination condition. If not, return to step ② to recalculate the basic phasor T. If it meets the condition, the iteration ends.

[0125] ⑥Output F p Corresponding to the amplitude and phase angle of all frequency components.

[0126] It should be noted that obtaining the second stable parameter of the inverter port after injecting the second disturbance signal can provide more accurate and comprehensive data support for the calculation of the inverter frequency-coupled admittance. By obtaining the second stable parameter, it can be ensured that the response characteristics of the inverter under different disturbance conditions are accurately captured, thereby providing a more stable and reliable parameter basis for the subsequent admittance calculation.

[0127] S104: Obtain inverter frequency coupling admittance according to the first stability parameter and the second stability parameter.

[0128] In an optional embodiment, the frequency coupling admittance calculation formula can be used to calculate the grid-connected inverter at the frequency F p The frequency coupling admittance is:

[0129]

[0130] Where Y 11 , Y 12 , Y 21 and Y 22 The four elements form a frequency-coupled admittance matrix. After the matrix is ​​obtained, the admittance measurement of the grid-connected inverter is completed;

[0131] In an alternative embodiment, it is possible to establish Figure 3 The first broadband measurement strategy shown, when the disturbance signal frequency, iteration threshold and iteration maximum value 201 are given, it is necessary to construct the signal time coefficient and calculate p(t) according to the time coefficient and frequency, 202; solve the polynomial coefficient matrix H by the least squares method, 203; calculate the frequency offset Δfm, and correct the frequency fm (k+1) =fm (k)+Δfm, 204; judgment condition 205: judge whether one of the following two conditions is met: maximum frequency offset ≤∈, number of iterations ≥K, 205; if any of the above conditions is met, output the amplitude and phase angle corresponding to the disturbance frequency 207; output the final result, including the amplitude and phase angle corresponding to the disturbance frequency. Otherwise, return to step 206 to continue iteration. Figure 3 The design idea is the same as the first broadband measurement strategy design idea mentioned above, except Figure 3 More details, no limitation here.

[0132] In summary, the present invention proposes an efficient grid-connected inverter frequency coupling admittance measurement method, injecting a first disturbance signal into the target inverter grid-connected system; obtaining a first stable parameter of the inverter port after the first disturbance signal is injected, and injecting a second disturbance signal into the target inverter grid-connected system; obtaining a second stable parameter of the inverter port after the second disturbance signal is injected; and obtaining the inverter frequency coupling admittance according to the first stable parameter and the second stable parameter. By configuring the parameters of the multi-sine injection signal and using a wideband measurement method based on Taylor Fourier transform to accurately measure the inverter port signal, efficient and accurate measurement of the inverter frequency coupling admittance in multiple scenarios can be achieved.

[0133] Example 2

[0134] Reference Figure 4-Figure 5 , which is an embodiment of the present invention, provides an efficient frequency-coupled admittance measurement method and system for a grid-connected inverter. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through experiments.

[0135] In order to verify the effectiveness of the proposed frequency-coupled admittance efficient measurement method for grid-connected inverters, the proposed method is simulated and tested through the inverter admittance measurement platform built by Simulink, and the measurement results are compared with the results of FFT. In the simulation, 27 frequencies [10, 12, 14, 17, 22, 27, 33, 39, 64, 71, 80, 107, 138, 158, 193, 240, 287, 349, 425, 518, 631, 769, 936, 1141, 1389, 1693, 2000] are taken as the multi-sinusoidal signal frequency F p When the grid frequency is 50Hz, the inverter frequency coupling admittance measurement results of the proposed method are as follows: Figure 4 shown.

[0136] Depend on Figure 4 It can be seen that both the FFT method and the proposed wideband measurement method based on Taylor Fourier transform can accurately measure the inverter frequency coupling admittance at the rated frequency.

[0137] To further verify the measurement accuracy of the two methods when the grid frequency is offset, the grid frequency is 49.9Hz and 50.1Hz, and the admittance measurement results are as follows: Figure 5 a) and b). Since the FFT method will cause spectrum leakage at non-rated frequencies, Figure 5 The measurement results of this method will have obvious deviations, while the proposed method can effectively solve the problem of frequency offset. The admittance measurement errors of the two methods at various grid frequencies are statistically shown in Table 1. It can be seen that compared with FFT, the proposed method can achieve high-precision measurement of inverter frequency coupling admittance in various grid-connected scenarios.

[0138] Table 1 Admittance measurement errors of the two methods at various grid frequencies

[0139]

[0140] To verify the efficiency of the proposed method, the simulation time of multi-sine simultaneous injection and the simulation time of single-sine injection are statistically shown in Table 2. It can be seen that the multi-sine injection method can reduce a lot of running time compared to the single-sine injection method, and can achieve efficient inverter frequency-coupled admittance measurement.

[0141] Table 2 Simulation time of multiple sinusoidal injection and simulation time of single sinusoidal injection

[0142] Injection method Single sine injection Multi-sine injection time 295.46s 8.98s

[0143] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

[0144] Example 3

[0145] This embodiment provides an efficient grid-connected inverter frequency coupling admittance measurement system, including:

[0146] A first signal injection module, used for injecting a first disturbance signal into a target inverter grid-connected system;

[0147] A second signal injection module, used for acquiring a first stable parameter of the inverter port after the first disturbance signal is injected, and injecting a second disturbance signal into the target inverter grid-connected system;

[0148] A parameter acquisition module, used for acquiring a second stable parameter of the inverter port after injecting a second disturbance signal;

[0149] The calculation module is used to obtain the inverter frequency coupling admittance according to the first stability parameter and the second stability parameter.

[0150] The above-mentioned unit modules may be embedded in or independent of a processor in a computer device in the form of hardware, or may be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to the above-mentioned modules.

[0151] This embodiment also provides an electronic device, which includes a processor, a memory, a communication interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a busbar pressure loss load transfer analysis method is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covered on the display screen, or a key, trackball or touchpad set on the computer device housing, or an external keyboard, touchpad or mouse, etc.

[0152] This embodiment also provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the method proposed in the above embodiment is implemented.

[0153] The storage medium proposed in this embodiment and the method proposed in the above embodiment belong to the same inventive concept. The technical details not fully described in this embodiment can be referred to the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0154] Through the above description of the implementation methods, the technicians in the relevant field can clearly understand that the present invention can be implemented by means of software and necessary general hardware, and of course can also be implemented by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ReadOnly, Memory, ROM), random access memory (RandomAccess Memory, RAM), flash memory (FLASH), hard disk or optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform the methods of various embodiments of the present invention.

[0155] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The scheme in the embodiments of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0156] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0157] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0158] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0159] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0160] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. An efficient method for measuring frequency-coupled admittance of a grid-connected inverter, characterized in that: include: Injecting a first disturbance signal into a target inverter grid-connected system; Acquire a first stable parameter of the inverter port after the first disturbance signal is injected, and inject a second disturbance signal into the target inverter grid-connected system; Acquire a second stable parameter of the inverter port after injecting a second disturbance signal; The inverter frequency coupling admittance is obtained according to the first stability parameter and the second stability parameter.

2. The efficient frequency coupling admittance measurement method for grid-connected inverter according to claim 1, characterized in that: The first disturbance signal comprises a voltage signal injected with a random disturbance signal; The random disturbance signal includes selecting a number of frequency points within the target frequency range; configuring a first sinusoidal signal based on the plurality of frequency points; The first sinusoidal signal is injected into the voltage signal as a random disturbance signal.

3. The efficient frequency coupling admittance measurement method for grid-connected inverter according to claim 2, characterized in that: The step of obtaining a first stable parameter of the inverter port after the first disturbance signal is injected, and injecting a second disturbance signal into the target inverter grid-connected system comprises: The first stable parameter includes a first voltage phasor and a first current phasor at a first frequency and a second frequency; The second disturbance signal is a negative-sequence disturbance signal having a second frequency.

4. The efficient frequency coupling admittance measurement method for grid-connected inverter according to claim 3, characterized in that: The step of obtaining the second stable parameter of the inverter port after the second disturbance signal is injected comprises: The second stable parameter includes a second voltage phasor and a second current phasor at a first frequency and a second frequency.

5. The efficient frequency coupling admittance measurement method for grid-connected inverter according to claim 4, characterized in that: The first frequency and the second frequency include: The second frequency is obtained according to the first frequency and the fundamental frequency; The first frequency is a frequency for obtaining the inverter frequency coupling admittance.

6. The efficient frequency coupling admittance measurement method for grid-connected inverter according to claim 5, characterized in that: The injecting a first disturbance signal into the target inverter grid-connected system comprises: Preset the first constraint condition; constraining the first disturbance signal according to the first constraint condition; A first disturbance signal satisfying a first constraint condition is injected into the target inverter grid-connected system.

7. The efficient frequency coupling admittance measurement method for grid-connected inverter according to claim 6, characterized in that: Also includes: The first stable parameter and the second stable parameter are both calculated by a first wideband measurement strategy based on Taylor Fourier transform.

8. A system using the efficient grid-connected inverter frequency coupling admittance measurement method as claimed in any one of claims 1 to 7, characterized in that: include: A first signal injection module, used for injecting a first disturbance signal into a target inverter grid-connected system; A second signal injection module, used for acquiring a first stable parameter of the inverter port after the first disturbance signal is injected, and injecting a second disturbance signal into the target inverter grid-connected system; A parameter acquisition module, used for acquiring a second stable parameter of the inverter port after injecting a second disturbance signal; A calculation module is used to obtain the inverter frequency coupling admittance according to the first stability parameter and the second stability parameter.

9. An electronic device, comprising: Memory and processor; The memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions. When the computer executable instructions are executed by the processor, the steps of the busbar pressure loss load transfer analysis method described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the steps of the busbar voltage loss load transfer analysis method according to any one of claims 1 to 7.

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