Online measurement method and system for broadband impedance of power grid and inverter

Abstract

The invention discloses an online measurement method and system for broadband impedance of a power grid and an inverter. The method comprises the following steps: acquiring a first parameter of a target system, and injecting a first disturbance signal into the target system; acquiring a second stable parameter of the target system after the first disturbance signal is injected, and injecting a second disturbance signal into the target system; and acquiring a third stable parameter of the target system after the second disturbance signal is injected, and calculating impedance according to the second stable parameter and the third stable parameter. The broadband impedance characteristics of the new energy power electronic equipment and the power grid can be rapidly and accurately measured through a multi-sine disturbance injection method, and accurate measurement of the impedance of the power grid is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of renewable energy power generation, and in particular to an online measurement method and system for broadband impedance of a power grid and an inverter. Background Art

[0002] The large-scale access of new energy equipment to weak AC power grids brings a lot of uncertainty and randomness to the power grid, and the system operation mode becomes more complicated. A large number of power electronic interface converters are connected to the weak power grid, making the power grid highly power-electronic, prone to "source-load interaction" oscillation problems, and the system stability deteriorates. Among the many stability analysis methods, the impedance analysis method has become a commonly used stability analysis method because of its clear physical concepts, high degree of visualization, and strong research expansibility. This method regards the new energy power generation equipment and the power grid impedance as two subsystems cascaded, and uses the impedance ratio for stability analysis.

[0003] The key to the impedance analysis method is to obtain the impedance characteristics of new energy power generation equipment and AC power grid. The impedance characteristics of new energy power generation equipment can be obtained through analytical impedance modeling, but since the control parameters and control structure of actual new energy power generation equipment are in black / gray box, it is impossible to establish an effective impedance model; the impedance of the power grid cannot be obtained from reality. Therefore, it is necessary to use actual impedance measurement to obtain the impedance characteristics of the power grid and the impedance characteristics of new energy power generation equipment.

[0004] At present, impedance measurement is divided into active measurement and passive measurement according to whether disturbance is injected into the power grid. Passive impedance measurement is gradually replaced by active measurement due to its low measurement accuracy. For active measurement methods, existing literature has proposed series voltage disturbance injection method and parallel current disturbance injection method. In actual new energy grid-connected systems, since the impedance of the power grid is often smaller than the impedance of new energy equipment, when series voltage disturbance injection is used, the disturbance voltage output on the power grid side is small and easily interfered by noise, and it is impossible to achieve accurate measurement of the impedance of the power grid; when parallel current disturbance injection is used, it is impossible to achieve accurate measurement of the impedance of new energy power generation equipment. There are few methods for simultaneous measurement of power grids and new energy power generation equipment. In addition, for the selection of disturbance injection signals, existing literature has proposed random binary sequences, maximum length binary sequences, single sinusoidal signals, etc., but these signals have defects in efficiency, accuracy, and controllability. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above existing problems, the present invention is proposed.

[0007] Therefore, the present invention provides a method and system for online measurement of broadband impedance of a power grid and an inverter, which can solve the problems mentioned in the background technology.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0009] In a first aspect, the present invention provides a method for online measurement of broadband impedance of a power grid and an inverter, comprising:

[0010] Acquiring a first parameter of a target system and injecting a first disturbance signal into the target system;

[0011] Acquire a second stable parameter of the target system after the first disturbance signal is injected, and inject a second disturbance signal into the target system;

[0012] Acquire a third stable parameter of the target system after injecting the second disturbance signal;

[0013] The impedance is calculated according to the second stable parameter and the third stable parameter.

[0014] As a preferred solution of the method for online measurement of broadband impedance of power grid and inverter according to the present invention, the step of obtaining the first parameter of the target system and injecting the first disturbance signal into the target system comprises:

[0015] Calculate the first harmonic content of the target system according to the first parameter;

[0016] establishing a first constraint condition based on the first harmonic content;

[0017] A first disturbance signal and a second disturbance signal are established according to the first constraint condition.

[0018] As a preferred solution of the method for online measurement of broadband impedance of power grid and inverter described in the present invention, the first disturbance signal and the second disturbance signal include:

[0019] The first disturbance signal and the second disturbance signal both include a plurality of superimposed sinusoidal signals with different frequencies.

[0020] As a preferred solution of the method for online measurement of broadband impedance of power grid and inverter described in the present invention, the second stability parameter includes:

[0021] A first voltage signal and a first current signal at a plurality of different frequencies corresponding to the first disturbance signal;

[0022] The first voltage signal includes an output voltage signal of the target system when it is stable after the first disturbance signal is injected and a voltage signal of the terminal to be measured;

[0023] The first current signal includes a current signal of a terminal to be measured.

[0024] As a preferred solution of the method for online measurement of broadband impedance of power grid and inverter described in the present invention, the third stability parameter includes:

[0025] A second voltage signal and a second current signal at a plurality of different frequencies corresponding to the second disturbance signal;

[0026] The second voltage signal includes an output voltage signal of the target system when it is stable after the second disturbance signal is injected and a voltage signal of the terminal to be measured;

[0027] The second current signal includes a current signal of a terminal to be measured.

[0028] As a preferred solution of the method for online measurement of broadband impedance of power grid and inverter described in the present invention, the first constraint condition at least includes peak constraints on the first disturbance signal and the second disturbance signal.

[0029] As a preferred solution of the method for online measurement of broadband impedance of power grid and inverter described in the present invention, the first disturbance signal and the second disturbance signal further include:

[0030] The first disturbance signal is a positive-sequence multi-sinusoidal signal;

[0031] The second disturbance signal is a negative-sequence multi-sinusoidal signal.

[0032] In a second aspect, the present invention provides a system for online measurement of broadband impedance of a power grid and an inverter, comprising:

[0033] A first disturbance module, used for acquiring a first parameter of a target system and injecting a first disturbance signal into the target system;

[0034] A second disturbance module, used for acquiring a second stable parameter of the target system after the first disturbance signal is injected, and injecting the second disturbance signal into the target system;

[0035] A parameter acquisition module, used for acquiring a third stable parameter of the target system after the second disturbance signal is injected;

[0036] A calculation module is used to calculate impedance according to the second stability parameter and the third stability parameter.

[0037] 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.

[0038] 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.

[0039] Compared with the prior art, the invention has the following beneficial effects: the invention proposes an online measurement method and system for broadband impedance of power grid and inverter, obtains the first parameter of the target system, and injects the first disturbance signal into the target system; obtains the second stable parameter of the target system after the first disturbance signal is injected, and injects the second disturbance signal into the target system; obtains the third stable parameter of the target system after the second disturbance signal is injected, and calculates the impedance according to the second stable parameter and the third stable parameter. The method of multi-sinusoidal disturbance injection can quickly and accurately measure the broadband impedance characteristics of new energy power electronic equipment and power grids, and realize accurate measurement of power grid impedance. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] 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:

[0041] Figure 1 A method flow chart of an online measurement method and system for broadband impedance of a power grid and an inverter provided by an embodiment of the present invention;

[0042] Figure 2 A structural diagram of a new energy grid-connected system impedance measurement system of a method and system for online measurement of broadband impedance of a power grid and an inverter provided by an embodiment of the present invention;

[0043] Figure 3 A schematic diagram of the positive and negative sequence output impedance characteristics of a new energy power generation equipment and a power grid and its simulation measurement results of a method and system for online measurement of wide-band impedance of a power grid and inverter provided by an embodiment of the present invention, a) is the positive and negative sequence measurement result of the impedance of the new energy inverter, and b) is the positive and negative sequence measurement result of the impedance of the power grid. DETAILED DESCRIPTION

[0044] 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.

[0045] Example 1

[0046] Reference Figure 1-Figure 3 , which is the first embodiment of the present invention, provides a method and system for online measurement of broadband impedance of a power grid and an inverter, comprising:

[0047] There are some technical problems in the existing related technologies, such as insufficient measurement accuracy and the inability to accurately measure the impedance characteristics of the power grid and new energy power generation equipment at the same time.

[0048] 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 online measurement method of broadband impedance of the power grid and inverter.

[0049] Figure 1 A method flow chart of an online measurement method and system for broadband impedance of a power grid and an inverter is shown, comprising:

[0050] S101, obtaining a first parameter of a target system, and injecting a first disturbance signal into the target system;

[0051] In an embodiment of the present application, obtaining a first parameter of a target system and injecting a first disturbance signal into the target system includes:

[0052] Calculate the first harmonic content of the target system according to the first parameter;

[0053] Establishing a first constraint condition based on the first harmonic content;

[0054] A first disturbance signal and a second disturbance signal are established according to the first constraint condition.

[0055] In an optional embodiment, the first parameter is obtained in order to determine the constraint conditions of the first disturbance signal and the second disturbance signal, so it is sufficient to ensure that the first harmonic content of the target system can be obtained from the first parameter;

[0056] In an optional embodiment, the first parameter may include information such as the rated power, rated voltage, and rated current of the target system. It may also be the voltage and current on the new energy system when no disturbance voltage is injected. The harmonic content of the target system in normal working state can be calculated through this information, and then the parameters of the disturbance signal can be determined.

[0057] In an optional embodiment, the first parameter may be acquired through a sensor, or through a measurement module inside a control system, or from an external device through a communication interface. For example, a current sensor and a voltage sensor may be used to monitor the current and voltage of the target system in real time to obtain the first parameter.

[0058] In the embodiment of the present application, the voltage V0 and the current I0 on the new energy system are collected by using sensors when no disturbance voltage is injected;

[0059] In an optional embodiment, the Fourier transform method can be used to obtain the first harmonic content through the voltage and current on the new energy system. Fourier transform is a mathematical transformation used to convert a signal from the time domain to the frequency domain, so that the frequency components of the signal can be analyzed. Through Fourier transform, the harmonic content of the target system under normal working conditions can be obtained, and then the parameters of the disturbance signal can be determined.

[0060] In an optional embodiment, the first harmonic content can also be obtained in other ways. For example, a fast Fourier transform (FFT) algorithm can be used to improve the calculation efficiency. The FFT algorithm is an algorithm for quickly calculating the discrete Fourier transform (DFT) and its inverse transform, which can significantly reduce the amount of calculation, thereby speeding up the harmonic analysis.

[0061] In the embodiment of the present application, the first harmonic content of the system is obtained by FFT analysis;

[0062] In an optional embodiment, the first constraint condition may include a peak value constraint on the first disturbance signal and the second disturbance signal. The peak value constraint can ensure that the injected disturbance signal does not have an excessive impact on the target system, thereby ensuring the stable operation of the system. For example, the peak value constraint can be set to not exceed a certain proportion of the rated voltage or current of the target system, such as 10%.

[0063] In an optional embodiment, the first constraint condition may include other constraints besides the peak value, such as frequency range, duration, etc. These constraints help to ensure the applicability of the disturbance signal and the accuracy of the measurement, and relevant technicians can design the first-level constraint conditions according to actual needs.

[0064] In the embodiment of the present application, the first constraint condition at least includes peak constraints on the first disturbance signal and the second disturbance signal.

[0065] In the embodiment of the present application, according to the first harmonic content, multiple frequencies f are selected in the range of 10 to 2000 Hz to construct a multi-sinusoidal signal. The specific multi-sinusoidal signal function X(t) is:

[0066]

[0067] Among them, A i 、f i and Corresponding to the amplitude, frequency and phase of the i-th sinusoidal wave component.

[0068] In an optional embodiment, in order to prevent the multi-sinusoidal signal injected into the system from affecting the grid-connected system, the peak value of the multi-sinusoidal signal cannot be too large, and the amplitude A i It should not exceed 3% of the system voltage amplitude (i.e. the first constraint condition). The peak value of the multi-sinusoidal signal can be controlled by optimizing the phase. The specific method is as follows:

[0069]

[0070] It should be noted that obtaining the first parameter of the target system and injecting the first disturbance signal into the target system can ensure that the injected disturbance signal effectively measures the impedance characteristics of the target system without destroying the stability of the system. By precisely controlling the parameters of the injected signal, the accuracy and efficiency of the measurement can be improved, while avoiding unnecessary interference to the power grid and new energy power generation equipment.

[0071] S102, acquiring a second stable parameter of the target system after the first disturbance signal is injected, and injecting a second disturbance signal into the target system;

[0072] In the embodiment of the present application, the second stability parameter includes:

[0073] A first voltage signal and a first current signal at a plurality of different frequencies corresponding to the first disturbance signal;

[0074] The first voltage signal includes an output voltage signal of the target system when it is stable after the first disturbance signal is injected and a voltage signal of the terminal to be measured;

[0075] The first current signal includes a current signal of the end to be measured.

[0076] In an optional embodiment, the number of sine waves of different frequencies injected into the first disturbance signal can be designed according to the actual needs of the technicians. For example, a multi-sinusoidal signal formed by superimposing a fixed number of sine waves can be set to form the first disturbance signal;

[0077] In an optional embodiment, the number of sine waves of different frequencies injected into the second disturbance signal can be designed according to the actual needs of the technicians. For example, a multi-sinusoidal signal formed by superimposing a fixed number of sine waves can be set to form the second disturbance signal;

[0078] In an optional embodiment, the number and frequency of the sine waves may also be dynamically adjusted according to the characteristics of the target system. For example, if the target system is more sensitive to disturbances within a certain frequency range, the number of sine waves within the frequency range may be increased to improve the measurement accuracy.

[0079] In the embodiment of the present application, the first disturbance signal and the second disturbance signal further include:

[0080] The first disturbance signal is a positive-sequence multi-sinusoidal signal;

[0081] The second disturbance signal is a negative-sequence multi-sinusoidal signal.

[0082] In the embodiment of the present application, a new energy system is injected with n frequencies f i (i=0,1,2,,,n) The positive-sequence multi-sinusoidal signal V is formed by superposition of positive-sequence sinusoidal wave sequences pa1 、V pb1 、V pc1 After the system runs stably, collect the disturbance output voltage signal V pa1 , the voltage signal V at the output port of the new energy power generation equipment to be tested a1 and the current signal I a1 , extract frequency f i The voltage signal V pa1i 、V a1i and the current signal I a1i .

[0083] In an optional embodiment, the collection of the disturbance output voltage signal, the voltage signal and the current signal of the output port of the tested renewable energy power generation equipment side can be completed by using a dedicated data acquisition card. The data acquisition card can synchronously collect multiple signals and has a high sampling rate and precision, ensuring the accuracy and real-time performance of signal acquisition.

[0084] In an optional embodiment, the collection of the disturbance output voltage signal, the voltage signal and the current signal of the output port of the tested new energy power generation equipment side can also be achieved by setting a sensor or a dedicated signal processing module. The signal processing module can perform pre-processing such as filtering and amplification on the collected signal to improve the signal quality and ensure the accuracy of subsequent analysis.

[0085] In an optional embodiment, the extraction frequency is f i The voltage signal and the current signal may be obtained by using digital signal processing technology, such as extracting the signal component of a specific frequency by a bandpass filter, and then performing synchronous sampling and analysis, which is not limited in this application.

[0086] It should be noted that obtaining the second stable parameters of the target system after the first disturbance signal is injected, and injecting the second disturbance signal into the target system can further ensure the stability and accuracy of the measurement process. By obtaining the stable parameters after the first disturbance signal is injected, the impact of the first disturbance signal on the system can be evaluated, thereby providing the necessary reference for injecting the second disturbance signal. After injecting the second disturbance signal, obtaining the stable parameters of the system again can ensure that the response of the system under different disturbance conditions is accurately recorded, providing reliable data for subsequent impedance calculations.

[0087] S103, obtaining a third stable parameter of the target system after the second disturbance signal is injected;

[0088] In the embodiment of the present application, the third stability parameter includes:

[0089] A second voltage signal and a second current signal at a plurality of different frequencies corresponding to the second disturbance signal;

[0090] The second voltage signal includes an output voltage signal when the target system is stable after the second disturbance signal is injected and a voltage signal of the terminal to be measured;

[0091] The second current signal includes a current signal of the end to be measured.

[0092] In the embodiment of the present application, a new energy system is injected with n frequencies f i (i=0,1,2,,,n) Negative sequence multi-sinusoidal signal V formed by superposition of negative sequence sine wave sequence pa2 、V pb2 、V pc2 After the system runs stably, collect the disturbance output voltage signal V pa2 , the voltage signal V at the output port of the new energy power generation equipment to be tested a2 and the current signal I a2 , extract frequency f i The voltage signal V pa2i 、V a2i and the current signal I a2i .

[0093] In an optional embodiment, the collection of the disturbance output voltage signal, the voltage signal and the current signal of the output port of the tested renewable energy power generation equipment side can be completed by using a dedicated data acquisition card. The data acquisition card can synchronously collect multiple signals and has a high sampling rate and precision, ensuring the accuracy and real-time performance of signal acquisition.

[0094] In an optional embodiment, the collection of the disturbance output voltage signal, the voltage signal and the current signal of the output port of the tested new energy power generation equipment side can also be achieved by setting a sensor or a dedicated signal processing module. The signal processing module can perform pre-processing such as filtering and amplification on the collected signal to improve the signal quality and ensure the accuracy of subsequent analysis.

[0095] In an optional embodiment, the extraction frequency is f i The voltage signal and the current signal may be obtained by using digital signal processing technology, such as extracting the signal component of a specific frequency by a bandpass filter, and then performing synchronous sampling and analysis, which is not limited in this application.

[0096] In the embodiment of the present application, the first disturbance signal and the second disturbance signal include:

[0097] The first disturbance signal and the second disturbance signal both include a plurality of superimposed sinusoidal signals with different frequencies.

[0098] In the embodiment of the present application, the first disturbance signal and the second disturbance signal further include:

[0099] The first disturbance signal is a positive-sequence multi-sinusoidal signal;

[0100] The second disturbance signal is a negative-sequence multi-sinusoidal signal.

[0101] It should be noted that obtaining the third stable parameter of the target system after injecting the second disturbance signal can provide the response data of the system under different disturbance conditions, which is crucial for accurately calculating the impedance characteristics of the target system. By analyzing the third stable parameter, the voltage and current changes of the system under the action of the second disturbance signal can be obtained, and then the impedance characteristics of the system can be analyzed. This measurement method can ensure accurate measurement of the impedance of the power grid and inverter within a wide frequency band, thereby providing a reliable basis for the stable operation of the power grid and the performance evaluation of new energy power generation equipment.

[0102] S104, calculating impedance according to the second stable parameter and the third stable parameter.

[0103] In an optional embodiment, the impedance can be calculated according to the second stable parameter and the third stable parameter in different ways. For example, a frequency domain-based impedance measurement method can be used, which calculates the impedance by analyzing the phase difference and amplitude ratio of the voltage and current at a specific frequency. This method can provide more accurate impedance measurement results, especially in the analysis of broadband characteristics of power grids and inverters.

[0104] In an optional embodiment, the nonlinear characteristics of the system can also be considered when calculating the impedance. Since there are nonlinear elements in the actual power grid and inverter system, such as power electronic equipment, the influence of these nonlinear factors needs to be considered when calculating the impedance. By introducing a nonlinear model, the impedance characteristics of the system under different working conditions can be simulated more accurately.

[0105] In an optional embodiment, the step of calculating the impedance may further include filtering the measured data to eliminate the influence of noise and interference. The filtering process may use a low-pass, high-pass, band-pass or band-stop filter, and the appropriate filter type and parameters are selected according to the characteristics of the signal to ensure the accuracy of the impedance calculation.

[0106] In an optional embodiment, the step of calculating the impedance further includes calibrating the measurement data. Since the sensor and the data acquisition device may have certain measurement errors, these errors need to be calibrated to ensure the accuracy of the impedance calculation results. The calibration process can be performed using a standard resistor or a reference device with known impedance.

[0107] In the embodiment of the present application, the impedance of the new energy power generation equipment is obtained by its own disturbance voltage and response disturbance current, and the grid impedance can be calculated by the disturbance output voltage and the response voltage of the equipment to be tested through the voltage division principle in the circuit principle. The impedance calculation method considering the noise and harmonics on the system is adopted, and the specific formula is:

[0108]

[0109] Among them, Z p , Z n is the positive sequence and negative sequence impedance of the renewable energy power generation equipment; Z gp , Z gn is the positive and negative sequence impedance of the power grid; ΔV a1i , ΔV a2i , ΔV pa1 , ΔV pa2 is the voltage difference before and after the voltage disturbance is injected; ΔI a1i , ΔI a2i is the difference between the current before and after the voltage disturbance is injected.

[0110] It should be noted that the injected disturbance voltage will be divided into the grid impedance side and the grid-connected inverter impedance side. Since the grid-connected inverter impedance is much larger than the grid impedance, the disturbance voltage on the grid-connected inverter side is larger than that on the grid side. The disturbance voltage on the grid side is too small. In some frequency ranges, the signal-to-noise ratio of the small disturbance signal is low, and the accuracy of the grid impedance measurement cannot be guaranteed. Therefore, the difference between the injected disturbance voltage and the disturbance voltage on the grid-connected inverter side is used to calculate the disturbance on the grid side.

[0111] In an optional embodiment, it can be set as follows Figure 2 The system structure diagram of the impedance measurement of the new energy grid-connected system is shown in Figure 1. The impedance measurement system of the new energy grid-connected equipment includes a power grid, a disturbance injection source, and a connected new energy grid-connected inverter. The disturbance injection source injects a small disturbance voltage into the system, responds with a small disturbance current, and collects voltage and current to calculate impedance.

[0112] In summary, the present invention proposes an online measurement method for broadband impedance of power grid and inverter, which obtains the first parameter of the target system and injects the first disturbance signal into the target system; obtains the second stable parameter of the target system after the first disturbance signal is injected, and injects the second disturbance signal into the target system; obtains the third stable parameter of the target system after the second disturbance signal is injected, and calculates the impedance according to the second stable parameter and the third stable parameter. The method of multi-sinusoidal disturbance injection can quickly and accurately measure the broadband impedance characteristics of new energy power electronic equipment and power grids, and realizes accurate measurement of power grid impedance.

[0113] Example 2

[0114] This embodiment also provides a power grid and inverter broadband impedance online measurement system, including:

[0115] A first disturbance module, used for acquiring a first parameter of a target system and injecting a first disturbance signal into the target system;

[0116] A second disturbance module, used for acquiring a second stable parameter of the target system after the first disturbance signal is injected, and injecting the second disturbance signal into the target system;

[0117] A parameter acquisition module, used for acquiring a third stable parameter of the target system after the second disturbance signal is injected;

[0118] The calculation module is used to calculate the impedance according to the second stability parameter and the third stability parameter.

[0119] 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.

[0120] This embodiment also provides a computer device, which can be a terminal. The computer device 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 implemented through WIFI, an operator network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a method for online measurement of broadband impedance of a power grid and an inverter 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 housing of the computer device, or an external keyboard, touchpad or mouse, etc.

[0121] This embodiment further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0122] Acquiring a first parameter of a target system and injecting a first disturbance signal into the target system;

[0123] Acquire a second stable parameter of the target system after the first disturbance signal is injected, and inject a second disturbance signal into the target system;

[0124] Acquire a third stable parameter of the target system after injecting the second disturbance signal;

[0125] The impedance is calculated according to the second stable parameter and the third stable parameter.

[0126] Example 3

[0127] Reference Figure 2-3 , which is an embodiment of the present invention, provides a method and system for online measurement of broadband impedance of a power grid and an inverter. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through experiments.

[0128] Figure 2 The figure shows a feasible system structure diagram of the impedance measurement of the renewable energy grid-connected system in the present application. The renewable energy grid-connected equipment impedance measurement system includes a power grid, a disturbance injection source, and a connected renewable energy grid-connected inverter. The disturbance injection source injects a small disturbance voltage into the system, responds with a small disturbance current, and collects the voltage and current to calculate the impedance.

[0129] Figure 3The positive and negative sequence output impedance characteristics of the new energy power generation equipment and the power grid and the simulation measurement results thereof are shown in FIG. p , Z n are the positive and negative sequence output impedances of the power electronic equipment respectively; Z gp , Z gn The solid line represents the simulation of the theoretical impedance model, the circle represents the impedance result of the traditional impedance measurement method, and the triangle represents the impedance result of the impedance measurement method of the present invention. It can be seen from the figure that when the grid impedance is measured by the grid impedance measurement method of the present invention, the measurement accuracy of the low frequency band is improved.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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. A method for online measurement of broadband impedance of a power grid and an inverter, characterized in that: include: Acquiring a first parameter of a target system and injecting a first disturbance signal into the target system; Acquire a second stable parameter of the target system after the first disturbance signal is injected, and inject a second disturbance signal into the target system; Acquire a third stable parameter of the target system after injecting the second disturbance signal; The impedance is calculated according to the second stable parameter and the third stable parameter.

2. The method for online measurement of broadband impedance of a power grid and an inverter according to claim 1, characterized in that: The acquiring a first parameter of the target system and injecting a first disturbance signal into the target system comprises: Calculate the first harmonic content of the target system according to the first parameter; establishing a first constraint condition based on the first harmonic content; A first disturbance signal and a second disturbance signal are established according to the first constraint condition.

3. The method for online measurement of broadband impedance of a power grid and an inverter according to claim 2, characterized in that: The first disturbance signal and the second disturbance signal include: The first disturbance signal and the second disturbance signal both include a plurality of superimposed sinusoidal signals with different frequencies.

4. The method for online measurement of broadband impedance of a power grid and an inverter according to claim 3, characterized in that: The second stability parameter includes: A first voltage signal and a first current signal at a plurality of different frequencies corresponding to the first disturbance signal; The first voltage signal includes an output voltage signal of the target system when it is stable after the first disturbance signal is injected and a voltage signal of the terminal to be measured; The first current signal includes a current signal of a terminal to be measured.

5. The method for online measurement of broadband impedance of power grid and inverter according to claim 4, characterized in that: The third stability parameter includes: A second voltage signal and a second current signal at a plurality of different frequencies corresponding to the second disturbance signal; The second voltage signal includes an output voltage signal of the target system when it is stable after the second disturbance signal is injected and a voltage signal of the terminal to be measured; The second current signal includes a current signal of a terminal to be measured.

6. The method for online measurement of broadband impedance of a power grid and an inverter according to claim 5, characterized in that: The first constraint condition includes at least peak constraints on the first disturbance signal and the second disturbance signal.

7. The method for online measurement of broadband impedance of a power grid and an inverter according to claim 6, characterized in that: The first disturbance signal and the second disturbance signal further include: The first disturbance signal is a positive-sequence multi-sinusoidal signal; The second disturbance signal is a negative-sequence multi-sinusoidal signal.

8. A broadband impedance online measurement system for power grids and inverters, characterized in that: include: A first disturbance module, used for acquiring a first parameter of a target system and injecting a first disturbance signal into the target system; A second disturbance module, used for acquiring a second stable parameter of the target system after the first disturbance signal is injected, and injecting the second disturbance signal into the target system; A parameter acquisition module, used for acquiring a third stable parameter of the target system after the second disturbance signal is injected; A calculation module is used to calculate impedance according to the second stability parameter and the third stability parameter.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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