Impedance detection method, device, equipment and medium for network construction type power equipment

Abstract

The embodiment of the invention relates to the field of power system stability analysis, and provides an impedance detection method, device, equipment and medium for network construction type power equipment, and the method comprises the steps: obtaining operation data required by the network construction type power equipment when the network construction type power equipment operates at a grid-connected point; obtaining an injection current source under the corresponding scanning frequency according to the operation data and the target scanning frequency; acquiring voltage data and current data of the network construction type power equipment after the first injection current source and the second injection current source are injected; and according to the voltage data and the current data, obtaining an impedance frequency response characteristic value of the network construction type power equipment. The impedance frequency response characteristic of the network construction type power equipment is obtained through the frequency sweeping method based on signal injection, the method is suitable for the network construction type power equipment, the accurate impedance frequency response characteristic of the network construction type power equipment can be accurately obtained, and the accuracy of evaluating the broadband oscillation risk is guaranteed.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of power system stability analysis, and in particular, to an impedance detection method for network-forming power equipment, an impedance detection device for network-forming power equipment, a corresponding electronic device, and a corresponding computer-readable storage medium. Background Art

[0002] In the context of a new power system, with the wide access of large-scale power equipment such as new energy, Voltage Source Converter High Voltage Direct Current (VSC-HVDC for short), and Flexible Alternating Current Transmission Systems (FACTS for short), the dynamic characteristics of the power system will change significantly. Although the access of these devices can improve the flexibility and controllability of the system, it also brings new challenges, especially the problem of broadband oscillation.

[0003] Broadband oscillation refers to the unstable phenomenon that occurs in the power system within a relatively wide frequency range due to the fast response characteristics of power equipment, which may trigger system oscillation or even collapse.

[0004] The frequency-domain analysis method based on impedance modeling (referred to as the impedance method for short) is a common method for analyzing broadband oscillation problems. The key lies in obtaining the frequency response characteristics of the grid-connected impedance of power equipment. According to different control strategies, power equipment can be divided into grid-following and network-forming types. In the related technologies for obtaining the impedance frequency response characteristics of power equipment, the frequency sweeping method used is not applicable to network-forming power equipment, resulting in errors in the obtained frequency response characteristics and unable to ensure the accuracy of the results. Summary of the Invention

[0005] The embodiments of the present application provide an impedance detection method, device, equipment, and medium for network-forming power equipment, which can accurately obtain the accurate impedance frequency response characteristics of network-forming power equipment and ensure the accuracy of evaluating the risk of broadband oscillation.

[0006] In one aspect, the embodiments of the present application provide an impedance detection method for network-forming power equipment, and the method includes:

[0007] Obtain the operating data required for the network-forming power equipment to operate at the grid connection point;

[0008] Based on the operating data and the target scanning frequency, an injection current source at the corresponding scanning frequency is obtained; the injection current source includes a first injection current source at the fundamental frequency and at least one second injection current source at at least one target scanning frequency;

[0009] Obtain the voltage data and current data of the network-forming power equipment after injecting the first injection current source and the second injection current source;

[0010] Based on the voltage data and the current data, obtain the impedance frequency response characteristic value of the network-forming power equipment.

[0011] In some embodiments of the present application, the obtaining of the injection current source at the corresponding scanning frequency according to the operating data and the target scanning frequency includes:

[0012] Obtain the fundamental frequency, and based on the operating data and the fundamental frequency, obtain the first injection current source of the network-forming power equipment at the fundamental frequency;

[0013] Determine a frequency sequence including at least one target scanning frequency;

[0014] Based on the operating data and at least one target scanning frequency, respectively obtain each second injection current source of the network-forming power equipment at each target scanning frequency in the frequency sequence.

[0015] In some embodiments of the present application, the operating data includes the active power absorption value, the reactive power absorption value, and the voltage amplitude; the obtaining of the first injection current source of the network-forming power equipment at the fundamental frequency according to the operating data and the fundamental frequency includes:

[0016] Use the active power absorption value, the reactive power absorption value, and the voltage amplitude to calculate and obtain a change signal quantity;

[0017] Perform signal processing on the change signal quantity through a band-pass filter with a center frequency of the fundamental frequency to obtain the first injection current source of the network-forming power equipment at the fundamental frequency.

[0018] In some embodiments of the present application, the determining of the frequency sequence including at least one target scanning frequency includes:

[0019] Obtain the frequency interval of the frequency sequence to be injected and the frequency range required for frequency scanning; the frequency range is used to determine the frequency scanning coefficient;

[0020] Use the fundamental frequency, the frequency interval, and the frequency scanning coefficient to generate a frequency sequence including at least one target scanning frequency.

[0021] In some embodiments of the present application, the operating data includes active power absorption value, reactive power absorption value, and voltage amplitude; the obtaining of each second injection current source of the network-forming power equipment at each target scanning frequency in the frequency sequence according to the operating data and at least one target scanning frequency includes:

[0022] Obtain the injection quantity proportionality coefficient and injection time period at each target scanning frequency;

[0023] Using the active power absorption value, the reactive power absorption value, the voltage amplitude, as well as each target scanning frequency, the injection quantity proportionality coefficient and injection time period at each target scanning frequency, calculate each second injection current source at different injection time periods for each target scanning frequency.

[0024] In some embodiments of the present application, the obtaining of the voltage data and current data of the network-forming power equipment after injecting the first injection current source and the second injection current source includes:

[0025] Obtain a pre-constructed electromagnetic transient simulation model; the electromagnetic transient simulation model stores three-phase voltage data and three-phase current data at the same injection time period under different frequencies;

[0026] Through the electromagnetic transient simulation model, use the first injection current source and the second injection current source for simulation to obtain the three-phase voltage data and three-phase current data after injecting the first injection current source and the second injection current source.

[0027] In some embodiments of the present application, the voltage data includes three-phase voltage data, and the current data includes three-phase current data; the obtaining of the impedance frequency response characteristic value of the network-forming power equipment according to the voltage data and the current data includes:

[0028] Perform frequency domain analysis on the three-phase voltage data and the three-phase current data to obtain a frequency domain analysis result; the frequency domain analysis result includes the amplitude and phase corresponding to different target scanning frequencies;

[0029] Using the amplitude and phase corresponding to different target scanning frequencies, calculate the impedance frequency response characteristic value of the network-forming power equipment at different target scanning frequencies.

[0030] On the other hand, an impedance detection device for a network-forming power equipment provided by an embodiment of the present application includes:

[0031] An operating data acquisition module, configured to acquire the operating data required for the network-forming power equipment to operate at the grid connection point;

[0032] An injection current source calculation module, configured to obtain an injection current source at a corresponding scan frequency according to the operation data and a target scan frequency; the injection current source includes a first injection current source at a fundamental frequency and at least one second injection current source at at least one target scan frequency;

[0033] A current source injection module, configured to obtain voltage data and current data of the network-forming power equipment after injecting the first injection current source and the second injection current source;

[0034] An impedance frequency response module, configured to obtain an impedance frequency response characteristic value of the network-forming power equipment according to the voltage data and the current data.

[0035] In some embodiments of the present application, the injection current source calculation module includes:

[0036] An injection current source calculation sub-module, configured to obtain a fundamental frequency, and according to the operation data and the fundamental frequency, obtain a first injection current source of the network-forming power equipment at the fundamental frequency; determine a frequency sequence including at least one target scan frequency; according to the operation data and at least one target scan frequency, respectively obtain each second injection current source of the network-forming power equipment at each target scan frequency in the frequency sequence.

[0037] In some embodiments of the present application, the operation data includes an active power absorption value, a reactive power absorption value, and a voltage amplitude; the injection current source calculation sub-module includes:

[0038] A first injection current source calculation unit, configured to calculate a variation signal quantity by using the active power absorption value, the reactive power absorption value, and the voltage amplitude; perform signal processing on the variation signal quantity through a band-pass filter with a center frequency of the fundamental frequency to obtain a first injection current source of the network-forming power equipment at the fundamental frequency.

[0039] In some embodiments of the present application, the injection current source calculation sub-module includes:

[0040] A frequency sequence generation unit, configured to obtain a frequency interval of a frequency sequence to be injected, and a frequency range required for frequency scanning; the frequency range is used to determine a frequency scanning coefficient; generate a frequency sequence including at least one target scan frequency by using the fundamental frequency, the frequency interval, and the frequency scanning coefficient.

[0041] In some embodiments of the present application, the operation data includes an active power absorption value, a reactive power absorption value, and a voltage amplitude; the injection current source calculation sub-module includes:

[0042] A second injection current source calculation unit, configured to obtain injection quantity proportion coefficients and injection time periods at respective target scanning frequencies; calculate respective second injection current sources at different injection time periods for respective target scanning frequencies by using the active power absorption value, the reactive power absorption value, the voltage amplitude, as well as respective target scanning frequencies, injection quantity proportion coefficients at respective target scanning frequencies, and injection time periods.

[0043] In some embodiments of the present application, the current source injection module includes:

[0044] A simulation sub-module, configured to obtain a pre-constructed electromagnetic transient simulation model; the electromagnetic transient simulation model stores three-phase voltage data and three-phase current data at the same injection time period under different frequencies; perform simulation by using the first injection current source and the second injection current source through the electromagnetic transient simulation model to obtain three-phase voltage data and three-phase current data after injecting the first injection current source and the second injection current source.

[0045] In some embodiments of the present application, the voltage data includes three-phase voltage data, and the current data includes three-phase current data; the impedance frequency response module includes:

[0046] An impedance frequency response sub-module, configured to perform frequency domain analysis on the three-phase voltage data and the three-phase current data to obtain a frequency domain analysis result; the frequency domain analysis result includes amplitudes and phases corresponding to different target scanning frequencies; calculate impedance frequency response characteristic values of the network-forming power equipment at different target scanning frequencies by using the amplitudes and phases corresponding to different target scanning frequencies.

[0047] In another aspect, an embodiment of the present application further provides an electronic device, including: a processor, a memory, and a computer program stored on the memory and capable of running on the processor, where when the computer program is executed by the processor, it implements the impedance detection method of the network-forming power equipment according to any one of the above.

[0048] In another aspect, an embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the impedance detection method of the network-forming power equipment according to any one of the above.

[0049] In another aspect, an embodiment of the present application further provides a computer program product including instructions, which when running on a computer, causes the computer to execute the impedance detection method of the network-forming power equipment described in the above aspects.

[0050] The impedance detection method, device, equipment and storage medium for network-forming power equipment provided by the embodiments of the present application obtain the operating data required when the network-forming power equipment operates at the grid connection point, and obtain the injection current source at the corresponding scanning frequency according to the operating data and the target scanning frequency. The injection current source may include a first injection current source at the fundamental frequency and at least one second injection current source at at least one target scanning frequency. At this time, the voltage data and current data of the network-forming power equipment after injecting the foregoing first injection current source and second injection current source can be obtained, and then the impedance frequency response characteristic value of the network-forming power equipment can be obtained according to the voltage data and current data. By obtaining the impedance frequency response characteristic of the network-forming power equipment through a frequency-sweeping method based on signal injection, it is applicable to the network-forming power equipment, can accurately obtain the accurate impedance frequency response characteristic of the network-forming power equipment, and ensure the accuracy of evaluating the wide-frequency oscillation risk. Description of the Drawings

[0051] Figure 1 is a flowchart of the steps of an impedance detection method for a network-forming power equipment according to an embodiment of the present application;

[0052] Figure 2 is a schematic diagram of obtaining the impedance frequency response characteristic of the network-forming power equipment provided by the embodiment of the present application;

[0053] Figure 3 is a structural block diagram of an impedance detection device for a network-forming power equipment according to an embodiment of the present application;

[0054] Figure 4 is a structural block diagram of an electronic device provided by the embodiment of the present application;

[0055] Figure 5 is a structural block diagram of a computer-readable storage medium provided by the embodiment of the present application. Detailed Embodiments

[0056] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0057] In the context of a new power system, the problem of wide-frequency oscillation has become an important factor affecting system stability.

[0058] The impedance method is a commonly used method for analyzing broadband oscillation problems. The key to the impedance method lies in obtaining the frequency response characteristics of the grid-connected impedance of power equipment. The impedance frequency response characteristics reflect the impedance changes of power equipment under different frequency signals, usually manifested as amplitude-frequency characteristics and phase-frequency characteristics. By analyzing the impedance characteristics of power equipment at different frequencies, it is possible to determine whether the equipment is prone to resonance or instability with the power grid at a specific frequency, which is the basis for evaluating the broadband oscillation risk of the grid-forming power equipment system.

[0059] The embodiment of the present application obtains the impedance frequency response characteristics of grid-forming power equipment through a frequency-sweeping method based on signal injection. It is applicable to grid-forming power equipment and can accurately obtain the accurate impedance frequency response characteristics of grid-forming power equipment, ensuring the accuracy of the evaluation of broadband oscillation risk.

[0060] Referring to Figure 1 , a flowchart of the steps of an impedance detection method for a grid-forming power equipment provided by an embodiment of the present application is shown, which may specifically include the following steps:

[0061] Step S101, obtain the operating data required for the grid-forming power equipment to operate at the grid connection point;

[0062] In the embodiment of the present application, in order to ensure the accuracy of the evaluation of broadband oscillation risk, there is a need to obtain the impedance frequency response characteristic values of grid-forming power equipment. For the acquisition of impedance frequency response characteristic values, it depends on injecting a current source into the grid-forming power equipment, that is, it can be realized through the method of injecting a current source for testing and analysis.

[0063] In some embodiments of the present application, the operating data of the grid connection point of the grid-forming power equipment can be obtained. These operating data can provide basic information and reference conditions for subsequent impedance analysis. For example, the determination of the injected current source depends on the foregoing operating data.

[0064] Optionally, the grid-forming power equipment can be an electronic device such as a energy storage converter, a virtual synchronous machine, etc.; the obtained operating data can include the active power absorption value, the reactive power absorption value, the voltage amplitude, etc., and the embodiment of the present application does not limit this.

[0065] In practical applications, the operating data required for operation at the grid connection point can be determined by the system power flow of the power system, that is, it can be obtained from the system power flow calculation results of the power system. These data are not only used to determine the working state of the equipment and design the injected current source, but also provide accurate input information for impedance calculation. Specifically, the operating data such as the active power absorption value, the reactive power absorption value, and the voltage amplitude can be determined by the voltage and current at the fundamental frequency.

[0066] It should be noted that after the injection current source at the fundamental frequency is determined, the values of the aforementioned operating data will not change with the subsequent changes in the voltage data and current data measured after the injection current source.

[0067] Step S102: Obtain the injection current source at the corresponding scanning frequency according to the operating data and the target scanning frequency.

[0068] Based on the signal injection frequency sweep method, it is specifically manifested as injecting a small-amplitude current signal of a specific frequency into the grid-connected point of the grid-forming power equipment, and then measuring the responses of the voltage and current of the grid-forming power equipment after the injection current source, so as to calculate the impedance characteristics of the equipment.

[0069] In some embodiments of the present application, the injected current source may include a first injection current source at the fundamental frequency and at least one second injection current source at at least one target scanning frequency. The determination of the injection current source depends on the operating data and the target scanning frequency and fundamental frequency to be injected.

[0070] In the embodiments of the present application, injecting a three-phase current source can be used to test and analyze the dynamic characteristics of the system, that is, the designed injection current source is a three-phase current source. The influence of the operating data on the design of the injection current source can be manifested as the first injection current source at the fundamental frequency being determined based on the operating data and the fundamental frequency, and the second injection current source at the target scanning frequency being determined based on the operating data and at least one target scanning frequency.

[0071] Specifically, the fundamental frequency can be obtained, and the first injection current source of the grid-forming power equipment at the fundamental frequency can be calculated according to the operating data and the fundamental frequency.

[0072] Optionally, the operating data required for the operation of the grid-connected point may include the active power absorption value P0, the inductive reactive power absorption value Q0, and the line voltage effective value (i.e., voltage amplitude) V0. Assuming the fundamental frequency is f0, at this time, the first injection current source at the fundamental frequency f0 can be calculated based on the active power absorption value P0, the inductive reactive power absorption value Q0, the line voltage effective value V0, and the fundamental frequency f0.

[0073] First, the active power absorption value P0, the inductive reactive power absorption value Q0, and the line voltage effective value V0 can be used to calculate a variable signal quantity. The calculated variable signal quantity is used as an intermediate variable, and then, with this intermediate variable as the input, the variable signal quantity is processed by a band-pass filter with a center frequency of the fundamental frequency f0 to obtain the first injection current source of the grid-forming power equipment at the fundamental frequency f0.

[0074] Exemplarily, assume the variable signal quantity is I ga1、 I gb1, I gc1 , the calculation formula of the variation signal quantity can be shown as follows:

[0075]

[0076] Then, the calculated intermediate variable I ga1、 I gb1 , I gc1 are respectively processed through band-pass filters with the center frequency of the fundamental frequency f0 for signal processing, and the first injection current sources I ga , I gb , I gc are obtained after processing. Among them, the calculated intermediate variable, that is, the variation signal quantity, is actually three signal quantities that vary with time; the signal processing performed by the band-pass filter mainly refers to filtering through a band-pass filter characterized by a function.

[0077] It should be noted that the recommended type of the band-pass filter can be a second-order band-pass filter, and the transfer function expression used by the second-order band-pass filter during signal processing can be shown as follows:

[0078]

[0079] Among them, can refer to the damping ratio of the band-pass filter, and the recommended value can be 0.05; s can represent the Laplace operator, that is, the complex frequency. For the specifically used band-pass filter, it can also be other filters, and in this regard, the embodiments of the present application do not impose limitations.

[0080] In some embodiments of the present application, for the determination of the second injection current source at the target scanning frequency, a frequency sequence including at least one target scanning frequency can be determined, and then according to the operation data and at least one target scanning frequency, each second injection current source of the network-forming power equipment at each target scanning frequency in the frequency sequence can be obtained respectively.

[0081] Specifically, the frequency sequence is determined based on the frequency interval of the frequency to be injected and the frequency range of the actual required frequency sweep. The scanning frequency is any value in the frequency sequence, that is, any value can be obtained from the generated frequency sequence as the target scanning frequency.

[0082] Among them, the frequency range of the required frequency sweep can be used to determine the frequency sweep coefficient. The frequency interval of the frequency sequence to be injected and the frequency range of the required frequency sweep can be obtained, and then by using the fundamental frequency, the frequency interval, and the frequency sweep coefficient, a frequency sequence including at least one target scanning frequency is generated.

[0083] Exemplarily, assume that the frequency interval of the frequency sequence to be injected is Δf (Δf > 0), and the frequency sweep coefficient determined based on the frequency range to be scanned is N (N is a positive integer). Then, the frequency sequence to be injected can be: [f0 - NΔf, f0 - (N - 1)Δf, f0 - (N - 2)Δf, ..., f0 - 2Δf, f0 - Δf, f0 + Δf, f0 + 2Δf, ..., f0 + (N - 2)Δf, f0 + (N - 1)Δf, f0 + NΔf]. It should be noted that the recommended value of the frequency interval Δf can be 1 Hz, and the specific determination method of the frequency sweep coefficient is not limited in the embodiments of the present application.

[0084] After obtaining the frequency sequence including at least one target scan frequency, the respective second injection current sources at each target scan frequency can be calculated.

[0085] In some embodiments of the present application, the injection amount proportionality coefficient and the injection time period at each target scan frequency can be obtained, and then the respective second injection current sources at each target scan frequency under different injection time periods can be calculated by using the active power absorption value, the reactive power absorption value, and the voltage amplitude, as well as each target scan frequency, the injection amount proportionality coefficient at each target scan frequency, and the injection time period.

[0086] Optionally, the injection amount proportionality coefficient can be used to control the ratio of the amplitude of the second injection current source to the fundamental current, where the fundamental current refers to the first injection current source calculated at the above fundamental frequency. For example, when the injection amount proportionality coefficient is 0.1, it can be stated that the amplitude of the second injection current source is 10% of the fundamental current. Different target scan frequencies can have different injection amount proportionality coefficients, so as to achieve independent control of the current injection of different frequency components. A larger injection amount proportionality coefficient will result in stronger current injection, and the influence of the injection current on the system is greater, while a smaller injection amount proportionality coefficient will control the influence of the injection current on the system to be smaller. The recommended value can be 0.02, and the embodiments of the present application do not limit this.

[0087] Optionally, the injection time period can be used to define the action range of the second injection current source in time. For example, it can be defined in which time periods the second injection current source is effective. Further, a dynamic current injection strategy can be achieved by setting different injection time periods.

[0088] In a preferred embodiment, the adjustment of the injection amount proportionality coefficient and the injection time period can affect the design of the second injection current source, so as to meet different test or operation requirements. As an example, at a certain frequency, setting a larger injection amount proportionality coefficient and a shorter injection time period can simulate a short-term strong interference; as another example, at another frequency, setting a smaller injection amount proportionality coefficient and a longer injection time period can simulate a long-term weak interference. The embodiments of the present application do not limit this.

[0089] Exemplarily, for the second injection current source at the corresponding scanning frequency f j the calculation expression thereof can be as follows:

[0090]

[0091] wherein, I ja , I jb , I jc can be the second injection current sources at the corresponding scanning frequency f j respectively; k j is the injection amount proportionality coefficient; t is the injection time period; f j respectively take [f0 - NΔf, f0 - (N - 1)Δf, f0 - (N - 2)Δf, ..., f0 - 2Δf, f0 - Δf, f0 + Δf, f0 + 2Δf, ..., f0 + (N - 2)Δf, f0 + (N - 1)Δf, f0 + NΔf].

[0092] Step S103, obtain the voltage data and current data of the network-forming power equipment after injecting the first injection current source and the second injection current source;

[0093] The system response after injecting the injection current source can be used to evaluate the performance of the network-forming power equipment. For example, after injecting the injection current source, the injection current source is usually used to introduce a specific current signal into the power system to test the dynamic response characteristics of the equipment under current disturbance.

[0094] In some embodiments of the present application, after calculating the first injection current source of the network-forming power equipment at the fundamental frequency and at least one second injection current source at at least one target scanning frequency according to the operation data required when the network-forming power equipment operates at the grid connection point, the foregoing obtained injection current sources can be injected into the network-forming power equipment, and then the voltage data and current data of the equipment after injecting the foregoing injection current sources can be obtained. Among them, the designed injection current source is a three-phase current source, the voltage data obtained based on the three-phase current source can be three-phase voltage data, and the current data obtained thereby can be three-phase current data, so as to perform frequency domain analysis based on the time domain waveforms and frequency domain spectra of the three-phase voltage and three-phase current.

[0095] Optionally, the acquisition of three-phase voltage and three-phase current can be implemented based on a pre-constructed electromagnetic transient simulation model.

[0096] The electromagnetic transient simulation model can be constructed based on the topology of the power system. Specifically, it can be based on Figure 2 the schematic diagram for obtaining the impedance frequency response characteristics of the network-forming power equipment shown in the electromagnetic transient simulation software to build a circuit diagram. The electromagnetic transient simulation software can be, for example, PSCAD (Power Systems Computer Aided Design), EMTDC (Electromagnetic Transients including DC), etc. Among them, P0, Q0, and V0 respectively represent the active power absorption value, inductive reactive power absorption value, and line voltage effective value at the connection point of the power equipment; φ represents the phase information generated by the control system of the network-forming power equipment based on the internal frequency; f0 represents the fundamental frequency; I ga (f0), I gb (f0), I gc (f0) represent the injection current sources at the frequency f0; f j represents the scanning frequency (f j ≠f0), I ja (f j ), I jb (f j ), I jc (f j ) represent the injection current sources at the frequency f j ; V a , V b , V c and I a , I b , I c represent the three-phase voltage and three-phase current measured after the injection current source.

[0097] Specifically, a pre-constructed electromagnetic transient simulation model can be obtained. The obtained electromagnetic transient simulation model stores three-phase voltage data and three-phase current data at the same injection time period at different frequencies. At this time, the electromagnetic transient simulation model can be used to perform simulation with an injection current source to obtain the three-phase voltage data and three-phase current data after injecting the aforementioned injection current source.

[0098] In practical applications, the three-phase voltages V a , V b , V c and the three-phase currents I a , I b , Ic It is mainly obtained by numerical simulation after building a simulation model according to the Figure 2 structure, that is, its value can be obtained through the measurement and data storage modules of the simulation software. Specifically, after building an electromagnetic transient simulation model, a first injection current source at the fundamental frequency and at least one second injection current source at the target sweep frequency can be injected respectively, f j Take [f0 - NΔf, f0 - (N - 1)Δf, f0 - (N - 2)Δf, ..., f0 - 2Δf, f0 - Δf, f0 + Δf, f0 + 2Δf, ..., f0 + (N - 2)Δf, f0 + (N - 1)Δf, f0 + NΔf] respectively. After the power system is stable, the phase voltage and current of the power equipment obtained by the simulation can be stored and recorded respectively through the data storage module, that is, for each f j frequency, the three-phase voltages V a , V b , V c and the three-phase currents I a , I b , I c .

[0099] For the convenience of expression, the frequency sequence f j can be expressed by using and . and can be combined into the above frequency sequence f j . Specifically, let:

[0100]

[0101]

[0102] where k is a positive integer in the range. As can be seen from the above, N can be determined according to the actual required frequency range of the frequency sweep. represents the positive frequency part [f0 + Δf, f0 + 2Δf, ..., f0 + (N - 2)Δf, f0 + (N - 1)Δf, f0 + NΔf] in the frequency sequence, represents the negative frequency part [f0 - NΔf, f0 - (N - 1)Δf, f0 - (N - 2)Δf, ..., f0 - 2Δf, f0 - Δf] in the frequency sequence.

[0103] Exemplarily, under the injection of the f j (k) frequency, the three-phase voltages V a , V b , Vc and three-phase current I a , I b , I c are denoted as V a (k), V b (k), V c (k) and I a (k), I b (k), I c (k); Under the injection of the frequency f j (-k), the three-phase voltages V a , V b , V c stored in the data storage module and the three-phase current I a , I b , I c are denoted as V a (-k), V b (-k), V c (-k) and I a (-k), I b (-k), I c (-k). Each time a target scanning frequency f j is injected, whether it is a positive frequency or a negative frequency, a set of three-phase voltages V a , V b , V c and the three-phase current I a , I b , I c can be obtained through numerical simulation. For the convenience of expression, V a (k), V b (k), V c (k) and I a (k), I b (k), I c (k) indicates that the simulation data is stored by injecting a positive frequency, that is ; V a (-k), V b (-k), V c (-k) and I a (-k), I b (-k), I c (-k) indicates that the simulation data is stored by injecting a negative frequency, that is ; In this way, the results of positive frequency injection and negative frequency injection are distinguished in symbols.

[0104] It should be noted that according to Figure 2The constructed electromagnetic transient simulation model can be reused in terms of its model structure. For different power electronic devices, new power electronic devices can be replaced on the original model structure. For the differences in the active power absorption value P0, inductive reactive power absorption value Q0, line voltage effective value V0, and phase information generated based on the internal frequency at the connection point of the power equipment, it can be achieved by modifying the specific values of the injected current sources on the basis of the original model. The calculated values can be realized by adopting the relevant formulas provided in the embodiments of the present application, and the embodiments of the present application do not limit this.

[0105] Step S104: Obtain the impedance frequency response characteristic values of the network-forming power equipment according to the voltage data and current data.

[0106] The injected current source can introduce specific current signals into the power system and test the dynamic response characteristics of the equipment under current disturbances. Specifically, it can be manifested as obtaining the three-phase voltage and three-phase current of the equipment after injecting the current source, and performing frequency-domain analysis on the three-phase voltage data and three-phase current data, so as to evaluate and obtain the impedance frequency response characteristics of the network-forming power equipment at different target scanning frequencies based on the frequency-domain analysis results.

[0107] Specifically, the frequency-domain analysis results can include the amplitude and phase corresponding to different target scanning frequencies. The amplitude and phase corresponding to different target scanning frequencies can be used to calculate the impedance frequency response characteristic values of the network-forming power equipment at different target scanning frequencies, and then accurately obtain the accurate impedance frequency response characteristics of the network-forming power equipment, ensuring the accuracy of the assessment of the wide-frequency oscillation risk.

[0108] In practical applications, the frequency-domain analysis performed can be fast Fourier transform analysis (Fast Fourier Transform, abbreviated as FFT), that is, FFT analysis can be performed on all stored V a and I a data, and the obtained frequency-domain analysis results can be FFT analysis results.

[0109] Usually, in the Fourier transform, the frequency is symmetric, and the positive and negative frequencies represent different rotation directions. In the frequency-domain analysis, the positive and negative frequencies together constitute the complete spectrum information.

[0110] Exemplarily, assuming that in the FFT analysis result of V a (k), the amplitude and phase corresponding to the frequency are A V1 (k) and θ V1 (k), the amplitude and phase corresponding to the frequency are A V2 (k) and θ V2 (k), the amplitude and phase corresponding to the frequency are AV3 (k) and θ V3 (k); in V a In the FFT analysis result of (-k), The amplitude and phase corresponding to the frequency are A V4 (k) and θ V4 (k), The amplitude and phase corresponding to the frequency are A V5 (k) and θ V5 (k), The amplitude and phase corresponding to the frequency are A V6 (k) and θ V6 (k). And, in I a In the FFT analysis result of (k), The amplitude and phase corresponding to the frequency are A I1 (k) and θ I1 (k); in I a In the FFT analysis result of (-k), The amplitude and phase corresponding to the frequency are A I2 (k) and θ I2 (k).

[0111] According to the above FFT analysis results of V a (k), V a (-k), I a (k), I a (-k), calculate the frequency response characteristic values of the impedance of the network-forming power equipment. Exemplarily, at f j (k)= This positive frequency part, f j (-k)= This negative frequency part, calculate the frequency response characteristics of the impedance of the network-forming power equipment respectively.

[0112] As an example, when f j (k) , that is >0 and >0, it means that the phase sequence of the three-phase voltage and current at the frequencies of f j (k) and f j (-k) is positive sequence. In this case, the frequency response characteristics of the impedance of the network-forming power equipment calculated can be:

[0113]

[0114]

[0115] As another example, when f j (k) , that is > 0 and < 0, it indicates that the j phase sequence of the three - phase voltage and current at f j (k) frequency is positive - sequence, while the

[0116]

[0117]

[0118] where Z(k) represents the impedance value of the grid - forming power electronic device at f j (k) frequency, reflecting the impedance characteristic of the device to positive disturbances; Z( - k) represents the impedance value of the grid - forming power electronic device at f j ( - k) frequency, characterizing the response of the device to reverse disturbances; k is a positive integer within the range. As can be seen from the above, N can be determined according to the actually required frequency range of the swept frequency.

[0119] It should be noted that the positive - frequency part f j (k) of the frequency sequence does not have a situation less than zero; and in the impedance frequency response characteristic of the power device, f j ( - k)=0 belongs to a singular point, and the situation where f j ( - k) is equal to 0 will be avoided in advance in the selection of the frequency sequence. The embodiments of the present application do not limit this. j

[0120] In the embodiments of the present application, by obtaining the operating data required for the grid - forming power device during operation at the connection point, according to the operating data and the target scanning frequency, an injection current source at the corresponding scanning frequency is obtained. The injection current source may include a first injection current source at the fundamental frequency and at least one second injection current source at at least one target scanning frequency. At this time, the voltage data and current data of the grid - forming power device after injecting the foregoing injection current source can be obtained, and then according to the voltage data and current data, the impedance frequency response characteristic value of the grid - forming power device is obtained. Obtaining the impedance frequency response characteristic of the grid - forming power device through the swept - frequency method based on signal injection is applicable to the grid - forming power device, can accurately obtain the accurate impedance frequency response characteristic of the grid - forming power device, and ensure the accuracy of evaluating the broadband oscillation risk.

[0121] It should be noted that for method embodiments, for the sake of simple description, they are all expressed as a series of action combinations. However, those skilled in the art should know that the embodiments of the present application are not limited by the described action sequences, because according to the embodiments of the present application, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily essential for the embodiments of the present application.

[0122] Referring to Figure 3 , a structural block diagram of an impedance detection device for a network-constructing power device provided by an embodiment of the present application is shown, which may specifically include the following modules:

[0123] An operating data acquisition module 301, configured to acquire the operating data required for the network-constructing power device to operate at the grid connection point;

[0124] An injection current source calculation module 302, configured to obtain an injection current source at a corresponding scanning frequency according to the operating data and a target scanning frequency; the injection current source includes a first injection current source at the fundamental frequency and at least one second injection current source at at least one target scanning frequency;

[0125] A current source injection module 303, configured to acquire voltage data and current data of the network-constructing power device after injecting the first injection current source and the second injection current source;

[0126] An impedance frequency response module 304, configured to obtain an impedance frequency response characteristic value of the network-constructing power device according to the voltage data and the current data.

[0127] In some embodiments of the present application, the injection current source calculation module 302 may include the following sub-modules:

[0128] An injection current source calculation sub-module, configured to acquire the fundamental frequency, and according to the operating data and the fundamental frequency, obtain the first injection current source of the network-constructing power device at the fundamental frequency; determine a frequency sequence including at least one target scanning frequency; and according to the operating data and at least one target scanning frequency, respectively obtain each second injection current source of the network-constructing power device at each target scanning frequency in the frequency sequence.

[0129] In some embodiments of the present application, the operating data includes an active power absorption value, a reactive power absorption value, and a voltage amplitude; the injection current source calculation sub-module may include the following units:

[0130] The first injection current source calculation unit is configured to calculate a variation signal quantity by using the active power absorption value, the reactive power absorption value, and the voltage amplitude; perform signal processing on the variation signal quantity through a band-pass filter with a center frequency of the fundamental frequency to obtain the first injection current source of the network-forming power equipment at the fundamental frequency.

[0131] In some embodiments of the present application, the injection current source calculation sub-module may include the following units:

[0132] The frequency sequence generation unit is configured to obtain the frequency interval of the frequency sequence to be injected, as well as the frequency range to be swept; the frequency range is used to determine the sweep coefficient; generate a frequency sequence including at least one target scanning frequency by using the fundamental frequency, the frequency interval, and the sweep coefficient.

[0133] In some embodiments of the present application, the operating data includes the active power absorption value, the reactive power absorption value, and the voltage amplitude; the injection current source calculation sub-module may include the following units:

[0134] The second injection current source calculation unit is configured to obtain the injection quantity proportionality coefficient and the injection time period at each target scanning frequency; calculate the second injection current sources at different injection time periods for each target scanning frequency by using the active power absorption value, the reactive power absorption value, and the voltage amplitude, as well as each target scanning frequency, the injection quantity proportionality coefficient, and the injection time period at each target scanning frequency.

[0135] In some embodiments of the present application, the current source injection module 303 may include the following sub-modules:

[0136] The simulation sub-module is configured to obtain a pre-constructed electromagnetic transient simulation model; the electromagnetic transient simulation model stores three-phase voltage data and three-phase current data at the same injection time period at different frequencies; perform simulation through the electromagnetic transient simulation model by using the first injection current source and the second injection current source to obtain the three-phase voltage data and the three-phase current data after injecting the first injection current source and the second injection current source.

[0137] In some embodiments of the present application, the voltage data includes three-phase voltage data, and the current data includes three-phase current data; the impedance frequency response module 304 may include the following sub-modules:

[0138] The impedance frequency response sub-module is configured to perform frequency-domain analysis on the three-phase voltage data and the three-phase current data to obtain a frequency-domain analysis result; the frequency-domain analysis result includes the amplitude and phase corresponding to different target scanning frequencies; calculate the impedance frequency response characteristic values of the network-forming power equipment at different target scanning frequencies by using the amplitude and phase corresponding to different target scanning frequencies.

[0139] In an embodiment of the present application, by obtaining the operating data required for the grid-forming power equipment when operating at the grid connection point, and according to the operating data and the target scanning frequency, an injection current source at the corresponding scanning frequency is obtained. The injection current source may include a first injection current source at the fundamental frequency and at least one second injection current source at at least one target scanning frequency. At this time, the voltage data and current data of the grid-forming power equipment after injecting the aforementioned injection current source can be obtained, and then, based on the voltage data and current data, the impedance frequency response characteristic value of the grid-forming power equipment can be obtained. Obtaining the impedance frequency response characteristic of the grid-forming power equipment through the signal injection-based frequency scanning method is applicable to the grid-forming power equipment and can accurately obtain the accurate impedance frequency response characteristic of the grid-forming power equipment, ensuring the accuracy of evaluating the broadband oscillation risk.

[0140] For the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple. For the relevant parts, refer to the partial description of the method embodiment.

[0141] An embodiment of the present application further provides an electronic device. Refer to Figure 4 , the provided electronic device 400 includes a memory 410, a processor 420, and a computer program 411 stored on the memory 410 and capable of running on the processor 420. When the computer program 411 is executed by the processor, it implements each process of the impedance detection method embodiment of the above-mentioned grid-forming power equipment, and can achieve the same technical effect. To avoid repetition, it will not be elaborated here.

[0142] An embodiment of the present application further provides a computer-readable storage medium. Refer to Figure 5 , the provided computer-readable storage medium 500 stores a computer program 411. When the computer program 411 is executed by the processor, it implements each process of the impedance detection method embodiment of the above-mentioned grid-forming power equipment, and can achieve the same technical effect. To avoid repetition, it will not be elaborated here.

[0143] Each embodiment in this specification is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other.

[0144] It should be noted that the terms "first", "second", etc. in the description, claims and the above-mentioned drawings of the embodiments of the present application are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments described here can be implemented in an order other than that illustrated or described here. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or modules does not necessarily have to be limited to those steps or modules clearly listed, but may include other steps or modules not clearly listed or inherent to these processes, methods, products or devices. The division of modules in the embodiments of the present application is only a logical division, and there may be other division methods in actual implementation. For example, multiple modules can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed coupling or direct coupling or communication connection between each other can be through some interfaces, and the indirect coupling or communication connection between modules can be electrical or other similar forms, which are not limited in the embodiments of the present application. And the modules or sub-modules described as separate components may or may not be physically separated, may or may not be physical modules, or may be distributed to multiple circuit modules. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of the embodiments of the present application.

[0145] In the above embodiments, the descriptions of the respective embodiments have their own emphases. For the parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0146] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the systems, devices and modules described above can refer to the corresponding processes in the foregoing method embodiments, and will not be elaborated here.

[0147] In several embodiments provided by the embodiments of the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of the modules is only a logical function division, and there may be other division methods in actual implementation. For example, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection between each other can be through some interfaces, and the indirect coupling or communication connection of the devices or modules can be electrical, mechanical or other forms.

[0148] The module described as a separation component may or may not be physically separated. The component shown as a module may or may not be a physical module, that is, it may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0149] In addition, in each embodiment of this application, each functional module can be integrated in a processing module, or each module can exist physically alone, or two or more modules can be integrated in one module. The above integrated module can be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium.

[0150] In the above embodiment, it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product.

[0151] The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions described in the embodiments of this application are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from a website, computer, server, or data center to another website, computer, server, or data center by wire (such as coaxial cable, optical fiber, Digital Subscriber Line (DSL)) or wirelessly (such as infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that a computer can store or a data storage device such as a server or data center that includes one or more integrated available media. The available medium can be a magnetic medium (for example, a floppy disk, a hard disk, a magnetic tape), an optical medium (for example, a DVD), or a semiconductor medium (for example, a Solid State Disk (SSD)), etc.

[0152] Embodiments of the present application are described with reference to the flowcharts and / or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing terminal devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing terminal devices generate a means for implementing the functions specified in one process Figure 1 one process or multiple processes and / or blocks Figure 1 or a means for implementing the functions specified in multiple blocks.

[0153] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing terminal device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including an instruction means that implements the functions specified in one process Figure 1 one process or multiple processes and / or blocks Figure 1 or multiple blocks; these computer program instructions can also be loaded onto a computer or other programmable data processing terminal device, such that a series of operation steps are executed on the computer or other programmable terminal device to generate a computer-implemented process, so that the instructions executed on the computer or other programmable terminal device provide steps for implementing the functions specified in one process Figure 1 one process or multiple processes and / or blocks Figure 1 or multiple blocks.

[0154] Although the preferred embodiments of the embodiments of the present application have been described, those skilled in the art can make additional changes and modifications to these embodiments once they learn the basic creative concepts. Therefore, the appended claims are intended to be construed to include the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present application.

[0155] Finally, it should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in the present application are all information and data that have been authorized by the user or fully authorized by all parties. And the collection, use, and processing of relevant data need to comply with the relevant laws, regulations, and standards of relevant countries and regions, and corresponding operation entrances are provided for users to choose to authorize or refuse.

[0156] The above has introduced the technical solutions provided by the embodiments of the present application in detail. Specific examples are used in the embodiments of the present application to elaborate on the principles and implementation manners of the embodiments of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the embodiments of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the embodiments of the present application, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation on the embodiments of the present application.

Claims

1. A method for detecting impedance of a grid-type power device, characterized in that: The method comprises: Acquiring the operating data required by the grid-connected power equipment when operating at the grid connection point; According to the operation data and the target scanning frequency, an injection current source at a corresponding scanning frequency is obtained; the injection current source comprises a first injection current source at a fundamental frequency and at least one second injection current source at at least one target scanning frequency; Acquire voltage data and current data of the grid-forming power equipment after the first injection current source and the second injection current source are injected; The impedance frequency response characteristic value of the grid-type power equipment is obtained according to the voltage data and the current data.

2. The method according to claim 1, characterized in that The step of obtaining an injection current source at a corresponding scanning frequency according to the operation data and the target scanning frequency comprises: Acquire a fundamental frequency, and obtain a first injection current source of the grid-forming power equipment at the fundamental frequency according to the operation data and the fundamental frequency; determining a frequency sequence including at least one target scanning frequency; According to the operation data and at least one target scanning frequency, respective second injection current sources of the grid-forming power equipment at respective target scanning frequencies in the frequency sequence are obtained respectively.

3. The method according to claim 2, characterized in that The operation data includes an active power absorption value, a reactive power absorption value and a voltage amplitude; and obtaining a first injection current source of the grid-forming power equipment at the fundamental frequency according to the operation data and the fundamental frequency includes: The active power absorption value, the reactive power absorption value and the voltage amplitude are used to calculate the change signal amount; The changed signal quantity is processed by a bandpass filter whose center frequency is the fundamental frequency to obtain a first injection current source of the grid-forming power equipment at the fundamental frequency.

4. The method according to claim 2, characterized in that: The determining of a frequency sequence including at least one target scanning frequency comprises: Obtaining the frequency interval of the frequency sequence to be injected and the frequency range required for the frequency sweep; the frequency range is used to determine the frequency sweep coefficient; The fundamental frequency, the frequency interval and the frequency sweep coefficient are used to generate a frequency sequence including at least one target sweep frequency.

5. The method according to claim 2, characterized in that: The operation data includes an active power absorption value, a reactive power absorption value and a voltage amplitude; and obtaining, according to the operation data and at least one target scanning frequency, each second injection current source of the grid-forming power equipment at each target scanning frequency in the frequency sequence, respectively includes: Obtaining the injection volume proportional coefficient and injection time period at each target scanning frequency; The active power absorption value, the reactive power absorption value and the voltage amplitude, as well as each target scanning frequency, the injection amount proportional coefficient and the injection time period at each target scanning frequency are used to calculate each second injection current source at each target scanning frequency in different injection time periods.

6. The method according to any one of claims 1 to 5, characterized in that: The obtaining of voltage data and current data of the grid-type power equipment after the first injection current source and the second injection current source are injected includes: Acquire a pre-constructed electromagnetic transient simulation model; the electromagnetic transient simulation model stores three-phase voltage data and three-phase current data of the same injection time period at different frequencies; The electromagnetic transient simulation model is used to perform simulation using the first injection current source and the second injection current source to obtain three-phase voltage data and three-phase current data after the first injection current source and the second injection current source are injected.

7. The method according to claim 1, characterized in that The voltage data includes three-phase voltage data, and the current data includes three-phase current data; and obtaining the impedance frequency response characteristic value of the grid-type power equipment according to the voltage data and the current data includes: Performing frequency domain analysis on the three-phase voltage data and the three-phase current data to obtain frequency domain analysis results; the frequency domain analysis results include amplitudes and phases corresponding to different target scanning frequencies; The impedance frequency response characteristic value of the grid-forming power equipment at different target scanning frequencies is calculated by using the amplitude and phase corresponding to different target scanning frequencies.

8. An impedance detection device for a grid-type power device, characterized in that: The device comprises: An operation data acquisition module, used to acquire the operation data required by the grid-connected power equipment when it is operating at the grid connection point; An injection current source calculation module, used to obtain an injection current source at a corresponding scanning frequency according to the operation data and the target scanning frequency; the injection current source includes a first injection current source at a fundamental frequency and at least one second injection current source at at least one target scanning frequency; A current source injection module, used to obtain voltage data and current data of the grid-forming power device after the first injection current source and the second injection current source are injected; The impedance frequency response module is used to obtain the impedance frequency response characteristic value of the grid-forming power equipment according to the voltage data and the current data.

9. An electronic device, characterized in that: include: A processor, a memory, and a computer program stored in the memory and capable of running on the processor, wherein when the computer program is executed by the processor, the impedance detection method for a grid-type power device as claimed in any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the impedance detection method for a grid-type power device as claimed in any one of claims 1 to 7 is implemented.

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