Online reverse impedance modeling method and device suitable for distribution network distributed power supply

Abstract

The application relates to an online reverse impedance modeling method and device suitable for distributed power supply of a power distribution network, wherein the method comprises the following steps: generating voltage disturbance signals of each frequency component with a synchronous time scale based on a signal generating source, and injecting the voltage disturbance signals into a grid-connected point of a power distribution network to-be-tested; synchronously collecting current voltage signals and current current signals of the grid-connected point, and inputting the current voltage signals and the current current signals into preset filters respectively; outputting voltage signals and current signals of interest; and calculating phasor information of each frequency component in the voltage signals and the current signals of interest respectively, so as to calculate impedance of the power distribution network to-be-tested under each frequency component online, and obtain an online impedance model of the power distribution network to-be-tested by impedance fitting. Therefore, the technical problem that in the prior art, due to the complex structure of power electronic equipment, time-varying operation mode and parameters, and the difficulty in obtaining the control structure and basic parameters, it is difficult to obtain the impedance model of the power electronic equipment through practical analysis or theoretical derivation is solved.

Description

Technical Field

[0001] This application relates to the field of power system analysis technology, and in particular to an online reverse impedance modeling method and apparatus suitable for distributed generation in distribution networks. Background Technology

[0002] Compared to traditional distribution networks, new distribution networks feature a large number of distributed renewable energy sources with low inertia levels and distributed power sources interacting across multiple time scales. To facilitate flexible control, these distributed power sources extensively utilize power electronic devices. As the level of power electronics in distribution networks continues to increase, various homogeneous / heterogeneous power electronic devices dynamically intertwine, leading to oscillation problems dominated by these devices.

[0003] To address the aforementioned issues, impedance models offer certain advantages in handling large-scale distributed renewable energy systems. Therefore, constructing impedance models for power electronic devices is fundamental for analyzing the power electronics-dominated oscillation process in distribution networks and ensuring the safe and stable operation of these networks.

[0004] However, in related technologies, there is a problem that it is difficult to establish an accurate mathematical model for power electronic equipment. There are two main reasons: (1) The control structure of power electronic equipment is complex, and its operation mode and parameters are time-varying, making it difficult to derive an analytical impedance model; (2) In actual systems, due to the protection of trade secrets, manufacturers are unwilling to provide detailed structure and parameters of the power electronic equipment control system, and it is usually difficult to directly construct the impedance model of power electronic equipment through theoretical derivation.

[0005] In summary, the impedance model of power electronic equipment is difficult to obtain through practical analysis or theoretical derivation in related technologies, and needs to be improved. Summary of the Invention

[0006] This application provides an online reverse impedance modeling method and apparatus suitable for distributed generation in power distribution networks, in order to solve the technical problem in related technologies that the impedance model of power electronic equipment is difficult to obtain through practical analysis or theoretical derivation due to the complex structure, time-varying operation mode and parameters of power electronic equipment, and the difficulty in obtaining the control structure and basic parameters.

[0007] The first aspect of this application provides an online reverse impedance modeling method suitable for distributed generation in a distribution network, comprising the following steps: generating a voltage disturbance signal with time-labeled components containing different frequency components based on a signal source, and setting the voltage disturbance signal at time t. start Injected into the grid connection points of each device under test in the distribution network, continuing until time t. endAccording to a preset sampling rate, the current voltage signal and current current signal of the grid connection point are collected starting at time t1 and continue until time t2, and the current voltage signal and current current signal are time-stamped; the current voltage signal and current current signal are respectively input to a preset filter, and the voltage signal and current signal of interest are output, and the phasors with different frequency components with time stamps in the voltage signal and current signal of interest are calculated respectively; and the impedance of the device under test at each frequency component is calculated using the phasors with different frequency components with time stamps in the voltage signal and current signal of interest, so as to obtain the impedance model of the device under test by online fitting of the impedance.

[0008] Optionally, in one embodiment of this application, injecting the voltage disturbance signal into the grid connection point of the distribution network device under test includes: obtaining the number of distribution network devices under test; when the number of distribution network devices under test is at least two, timing the voltage disturbance signals of the at least two distribution network devices under test based on a clock signal, and controlling the at least two distribution network devices under test to simultaneously inject the timing-stamped voltage disturbance signals into the distribution network.

[0009] Optionally, in one embodiment of this application, the calculation formula for the disturbance signal is:

[0010]

[0011] Among them, f ci f si Let u be the coupling frequency of the i-th group at the perturbation injection point. ci u si These are the disturbance amplitudes, These are the phases.

[0012] Optionally, in one embodiment of this application, the formula for constructing the preset filter is:

[0013]

[0014] Among them, H p This is a bandpass filter unit.

[0015] Optionally, in one embodiment of this application, the impedance model is:

[0016]

[0017] Where Z is the impedance sequence, a0,…,a n b0,…,b n For the polynomial coefficients, s = jω, where j is the imaginary unit, ω is the angular frequency, and f is the injected frequency value.

[0018] A second aspect of this application provides an online reverse impedance modeling device suitable for distributed generation in a distribution network, comprising: an injection module for generating a time-labeled voltage disturbance signal containing different frequency components based on a signal source, and for injecting the voltage disturbance signal at time t. start Injected into the grid connection points of each device under test in the distribution network, continuing until time t. end The system includes: a data acquisition module for acquiring the current voltage and current signals of the grid connection point at time t1 according to a preset sampling rate, continuing until time t2, and adding time stamps to the current voltage and current signals; a calculation module for inputting the current voltage and current signals into preset filters, outputting the voltage and current signals of interest, and calculating the time-stamped phasors containing different frequency components in the voltage and current signals of interest; and a modeling module for using the time-stamped phasors containing different frequency components in the voltage and current signals of interest to calculate the impedance of the device under test at each frequency component, so as to obtain the impedance model of the device under test by online fitting of the impedance.

[0019] Optionally, in one embodiment of this application, the injection module includes: an acquisition unit, configured to acquire the number of devices under test in the distribution network; and an injection unit, configured to, when the number of devices under test in the distribution network is at least two, time-stamp the voltage disturbance signals of the at least two devices under test based on a clock signal, and control the at least two devices under test to simultaneously inject the time-stamped voltage disturbance signals into the distribution network.

[0020] Optionally, in one embodiment of this application, the calculation formula for the disturbance signal is:

[0021]

[0022] Among them, f ci f si Let u be the coupling frequency of the i-th group at the perturbation injection point. ci u si These are the disturbance amplitudes, These are the phases.

[0023] Optionally, in one embodiment of this application, the formula for constructing the preset filter is:

[0024]

[0025] Among them, H p This is a bandpass filter unit.

[0026] Optionally, in one embodiment of this application, the impedance model is:

[0027]

[0028] Where Z is the impedance sequence, a0,…,a n b0,…,b n For the polynomial coefficients, s = jω, where j is the imaginary unit, ω is the angular frequency, and f is the injected frequency value.

[0029] A third aspect of this application provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the online reverse impedance modeling method for distributed power sources in distribution networks as described in the above embodiments.

[0030] A fourth aspect of this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described online reverse impedance modeling method for distributed generation in a distribution network.

[0031] This application embodiment can generate time-annotated voltage disturbance signals containing different frequency components based on a signal source. These time-annotated voltage disturbance signals are injected into the grid connection point of the device under test (DUT) in the distribution network. The current voltage and current signals at the grid connection point are collected and input to a preset filter, outputting a voltage signal and a current signal of interest. The time-annotated phasors containing different frequency components in the voltage and current signals of interest are calculated, thereby calculating the impedance of the DUT at each frequency component. Impedance fitting is then used to obtain the impedance model of the DUT, ensuring that the results reflect the impact of real-time operating conditions on the impedance model of the DUT. Furthermore, by simultaneously constructing impedance models of multiple distributed devices at the same time point, the risk of distribution network oscillations can be effectively quantified and assessed. This solves the technical problem in related technologies where the complex structure, time-varying operating modes and parameters of power electronic equipment, and the difficulty in obtaining control structures and basic parameters make it difficult to obtain impedance models of power electronic equipment through practical analysis or theoretical derivation.

[0032] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0033] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0034] Figure 1This is a flowchart illustrating an online reverse impedance modeling method for distributed generation in a distribution network, according to an embodiment of this application.

[0035] Figure 2 This is a schematic diagram illustrating the principle of perturbation signal injection according to an embodiment of this application;

[0036] Figure 3 This is a flowchart of an online reverse impedance modeling method for distributed generation in a distribution network according to an embodiment of this application;

[0037] Figure 4 This is a schematic diagram illustrating the principle of an online reverse impedance modeling method for distributed generation in a distribution network according to an embodiment of this application;

[0038] Figure 5 This is a schematic diagram of an online reverse impedance modeling device for distributed generation in a power distribution network, according to an embodiment of this application.

[0039] Figure 6 This is a schematic diagram of the structure of an electronic device provided according to an embodiment of this application. Detailed Implementation

[0040] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0041] The following description, with reference to the accompanying drawings, describes an online reverse impedance modeling method and apparatus applicable to distributed generation in distribution networks, according to embodiments of this application. In response to the technical problems mentioned in the background section, such as the complexity of power electronic equipment structures, the time-varying nature of their operation modes and parameters, and the difficulty in obtaining control structures and basic parameters, which makes it difficult to obtain impedance models of power electronic equipment through practical analysis or theoretical derivation, this application provides an online reverse impedance modeling method suitable for distributed generation in distribution networks. In this method, a time-annotated voltage disturbance signal containing different frequency components is generated based on a signal source. This time-annotated voltage disturbance signal is injected into the grid connection point of the device under test (DUT) in the distribution network. The current voltage and current signals at the grid connection point are collected and input to a preset filter, outputting a voltage signal and a current signal of interest. The time-annotated phasors containing different frequency components in the voltage and current signals of interest are calculated, thereby calculating the impedance of the DUT at each frequency component. The impedance model of the DUT is obtained by impedance fitting, so that the results can reflect the impact of real-time operating conditions on the impedance model of the DUT. Furthermore, by simultaneously constructing impedance models of multiple distributed devices at the same time point, the oscillation risk of the distribution network can be effectively quantitatively assessed. This solves the technical problem in related technologies where the impedance model of power electronic equipment is difficult to obtain through practical analysis or theoretical derivation due to the complexity of the structure, the time-varying operation mode and parameters of the power electronic equipment, and the difficulty in obtaining the control structure and basic parameters.

[0042] Specifically, Figure 1 This is a flowchart illustrating an online reverse impedance modeling method for distributed generation in a power distribution network, provided in an embodiment of this application.

[0043] like Figure 1 As shown, the online reverse impedance modeling method applicable to distributed generation in distribution networks includes the following steps:

[0044] In step S101, a voltage disturbance signal with different frequency components and time-labeled bands is generated based on the signal source, and the voltage disturbance signal is set at time t. start Injected into the grid connection points of each device under test in the distribution network, continuing until time t. end .

[0045] Understandably, impedance models of devices under test can be constructed in the laboratory using measurement methods based on hardware-in-the-loop testing platforms. However, this only yields impedance models of devices under specific operating conditions and cannot reflect the impact of real-time operating conditions on the impedance model of devices under test.

[0046] In actual implementation, the embodiments of this application can obtain the signal source by using a pre-constructed disturbance signal before generating voltage disturbance signals with different frequency components marked on the signal source. Thus, based on the constructed disturbance signal, the impedance model of the device under test under different operating conditions can be constructed.

[0047] Furthermore, embodiments of this application can construct the perturbation signal in the form of frequency coupling, wherein the perturbation frequency is [f c1 ,f s1 ;f c2 ,f s2 ;…,f ci ,f si …,f cN ,f sN The disturbance amplitude is [u] c1 ,u s1 ;u c2 ,u s2 ;…,u ci ,u si …,u cN ,u sN The relationship between the coupling frequencies is f. ci +f si =50Hz, where i represents the i-th group of perturbations and N represents the number of injected perturbations.

[0048] As one possible implementation, the signal generator in this embodiment can generate voltage perturbation signals Δu of each frequency component according to the perturbation signal list given, and at time t start Injected into the grid connection point of the equipment under test in the distribution network, continuing until time t. end The duration of the disturbance injection is Δt1, where the duration Δt1 is determined by time t. start and time t end get.

[0049] like Figure 2 As shown in the embodiment of this application, after generating the disturbance voltage signal, the signal generator can cause the grid connection point of the device under test to generate a voltage disturbance signal Δu containing a coupling frequency and a small amplitude. The disturbance signal will induce a current response Δi at the power equipment port.

[0050] Optionally, in one embodiment of this application, the formula for calculating the disturbance signal is:

[0051]

[0052] Among them, f ci f si Let u be the coupling frequency of the i-th group at the perturbation injection point. ci usi These are the disturbance amplitudes, These are the phases.

[0053] For example, embodiments of this application may assume that the coupling frequency at the i-th group at the perturbation injection point is f. ci f si The disturbance amplitudes are u ci u si The phases are respectively The three-phase voltage disturbance signal is then:

[0054]

[0055] In step S102, the current voltage signal and current current signal of the grid connection point are collected at time t1 according to the preset sampling rate and continue until time t2, and the current voltage signal and current current signal are time-stamped.

[0056] As one possible implementation, embodiments of this application can inject disturbances at time t. start Initially, according to a fixed sampling rate F s At time t1, the current voltage and current signals are collected in real time from the grid connection point of the device under test and continue until time t2, with a duration of Δt = Δt1 + Δt2. The current voltage and current signals are then time-stamped, where Δt2 is the disturbance settling time, and t... start <t1<t end And t1 < t2 < t end .

[0057] In step S103, the current voltage signal and the current current signal are respectively input to a preset filter, and the voltage signal and the current signal of interest are output. The phasors with time annotations containing different frequency components in the voltage signal and the current signal of interest are calculated respectively.

[0058] In actual implementation, the embodiments of this application can perform analog-to-digital conversion and digital filtering on the acquired current voltage signal and current current signal, filter out signals of frequency bands that are not of interest, and calculate the phasors with time annotations containing different frequency components in the current voltage signal and current current signal after filtering.

[0059] Optionally, in one embodiment of this application, the formula for constructing the preset filter is:

[0060]

[0061] Among them, H p This is a bandpass filter unit.

[0062] Specifically, the embodiments of this application can be based on a sampling rate F. sBy using a fixed-interval sampling method, the current voltage and current signals at the grid connection point of the device under test are collected to obtain the time series U. i =[U1,U2,…,U M ] and I i =[I1,I2,…,I M ], where M is the number of sampling points.

[0063] In this embodiment, 2N filters H(z) can be constructed based on the number of frequency components 2N in the disturbance signal. Each filter is implemented by cascading 2N-1 band-stop filter units and 1 band-pass filter unit, as shown in the following formula:

[0064]

[0065] Among them, H p This represents a bandpass filter unit, which can be implemented in the form of a digital filter, and its expression is:

[0066]

[0067] Among them, T s =1 / F s To use intervals; ω p = 2πf, where f is the injection frequency; the expression for A is:

[0068]

[0069] Where, Δω p =2πΔf, where Δf is the difference between the filter center frequency and the injection frequency.

[0070] This application embodiment can collect voltage and current sequences U i and I i The filtered time series U' is obtained by applying the above filter. i and I' I The filtered voltage and current time series U' i and I' I Perform a Fast Fourier Transform (FFT) to obtain the phasors of the voltage and current at the grid connection point of the device under test. and The phasors of the i-th frequency components are respectively and The current voltage signal and the current current signal are input to a preset filter, and the output voltage signal and current signal of interest are calculated. The phasor of each frequency component in the voltage signal and current signal of interest is calculated respectively.

[0071] In step S104, the impedance of the device under test at each frequency component is calculated using the time-annotated phasors containing different frequency components in the voltage and current signals of interest, so as to obtain the impedance model of the device under test by online impedance fitting.

[0072] Furthermore, in embodiments of this application, the corresponding impedance can be calculated based on the obtained time-annotated phasors containing different frequency components. Taking the i-th group of frequency components as an example, i.e. The impedance sequence of the device under test at each frequency point can be obtained by following the above method, and then the impedance model of the device under test can be obtained by parameter fitting.

[0073] Optionally, in one embodiment of this application, the impedance model is:

[0074]

[0075] Where Z is the impedance sequence, a0,…,a n b0,…,b n For the polynomial coefficients, s = jω, where j is the imaginary unit, ω is the angular frequency, and f is the injected frequency value.

[0076] Specifically, in the embodiments of this application, the impedance sequence of the device under test at each frequency point is obtained, i.e., Z = [Z c1 Z s1 Z c2 Z s2 ;…,Z ci Z si …,Z cN Z sN The impedance model of the device under test can be obtained through parameter fitting, i.e.

[0077]

[0078] Where Z is the impedance sequence, a0,…,a n b0,…,b n For the polynomial coefficients, s = jω, where j is the imaginary unit, ω is the angular frequency, f is the injected frequency value, and m < n.

[0079] Optionally, in one embodiment of this application, injecting a voltage disturbance signal into the grid connection point of the distribution network device under test includes: obtaining the number of distribution network devices under test; when the number of distribution network devices under test is at least two, timing the voltage disturbance signals of at least two distribution network devices under test based on a clock signal, and controlling at least two distribution network devices under test to simultaneously inject the timing-stamped voltage disturbance signals into the distribution network.

[0080] Understandably, in a laboratory setting, using a hardware-in-the-loop (HIL) test platform and measurement methods to construct impedance models for devices under test (DUTs), the computational capabilities of the HIL test platform limit the ability to model impedance for a single device. It cannot simultaneously construct impedance models for multiple distributed devices at the same time point, thus hindering accurate quantitative assessment of distribution network oscillation risks. This application's embodiment can obtain the number of DUTs in the distribution network. When multiple DUTs exist in the distribution network, it receives clock signals from systems such as GPS (Global Positioning System) / BeiDou, and timestamps the voltage disturbance signals and phasor calculation results. This ensures that multiple devices inject disturbance signals into the power grid simultaneously, and that the calculated phasor results represent phasor information from the same moment.

[0081] Combination Figures 2 to 4 As shown, an embodiment is used to illustrate the working principle of the online reverse impedance modeling method for distributed generation in distribution networks according to the present application.

[0082] like Figure 3 As shown, embodiments of this application may include the following steps:

[0083] Step S301: Construct perturbation parameters. In this embodiment, the perturbation signal can be constructed using frequency coupling, where the perturbation frequency is [f...]. c1 ,f s1 ;f c2 ,f s2 ;…,f ci ,f si …,f cN ,f sN The disturbance amplitude is [u] c1 ,u s1 ;u c2 ,u s2 ;…,u ci ,u si …,u cN ,u sN The relationship between the coupling frequencies is f. ci +f si =50Hz, where i represents the i-th group of perturbations and N represents the number of injected perturbations.

[0084] Step S302: Generate voltage disturbance signal. In this embodiment of the application, the signal source can generate voltage disturbance signals Δu of each frequency component according to the form given in the disturbance signal list, and inject them into the grid connection point of the equipment under test in the distribution network. The duration of the disturbance injection is Δt1.

[0085] In this embodiment, it can be assumed that the coupling frequency of the i-th group at the disturbance injection point is f. ci fsi The disturbance amplitudes are u ci u si The phases are respectively The three-phase voltage disturbance signal is then:

[0086]

[0087] Step S303: Inject the disturbance into the grid connection point of the device under test. In this embodiment, the disturbance injection can begin at the time of injection, according to a constant sampling rate F. s Voltage and current signals are collected in real time from the grid connection point of the device under test for a duration of Δt = Δt1 + Δt2, where Δt2 is the disturbance settling time. For example... Figure 2 As shown in the embodiment of this application, after generating the disturbance voltage signal, the signal generator can cause the grid connection point of the device under test to generate a voltage disturbance signal Δu containing a coupling frequency and a small amplitude. The disturbance signal will induce a current response Δi at the power equipment port.

[0088] Step S304: Signal Extraction. This embodiment of the application can perform analog-to-digital conversion and digital filtering on the acquired voltage and current signals to filter out signals in frequency bands of no interest. This embodiment of the application can extract signals according to a sampling rate F. s By using a fixed-interval sampling method, the current voltage and current signals at the grid connection point of the device under test are collected to obtain the time series U. i =[U1,U2,…,U M ] and I i =[I1,I2,…,I M ], where M is the number of sampling points.

[0089] Step S305: Digital filtering. In this embodiment, the phasors of each frequency component in the voltage and current signals can be calculated from the filtered signals. In this embodiment, based on the number 2N frequency components in the disturbance signal, 2N filters H(z) can be constructed. Each filter is implemented by cascading 2N-1 band-stop filter units and 1 band-pass filter unit, as shown in the following equation:

[0090]

[0091] Among them, H p This represents a bandpass filter unit, which can be implemented in the form of a digital filter, and its expression is:

[0092]

[0093] Among them, T s =1 / F s To use intervals; ω p = 2πf, where f is the injection frequency; the expression for A is:

[0094]

[0095] Where, Δω p =2πΔf, where Δf is the difference between the filter center frequency and the injection frequency.

[0096] This application embodiment can collect voltage and current sequences U i and I i The filtered time series U' is obtained by applying the above filter. i and I' I The filtered voltage and current time series U' i and I' I Perform a Fast Fourier Transform (FFT) to obtain the phasors of the voltage and current at the grid connection point of the device under test. and The phasors of the i-th frequency components are respectively and

[0097] Step S306: Phasor Calculation. This embodiment of the application can utilize the phasor information of each frequency component to calculate the impedance of the device under test (distributed power supply) at each frequency component. This embodiment of the application can calculate the corresponding impedance based on the obtained phasors of each frequency component. Taking the i-th frequency component as an example, i.e. The impedance sequence of the device under test at each frequency point can be obtained by following the above method, and then the impedance model of the device under test can be obtained by parameter fitting.

[0098] Step S307: Impedance calculation. In this embodiment, the impedance can be calculated based on the impedance sequence of the device under test at various frequency points, i.e., Z = [Z...]. c1 Z s1 Z c2 Z s2 ;…,Z ci Z si …,Z cN Z sN The impedance model of the device under test can be obtained through parameter fitting, i.e.

[0099]

[0100] Where Z is the impedance sequence, a0,…,a n b0,…,b n For the polynomial coefficients, s = jω, where j is the imaginary unit, ω is the angular frequency, f is the injected frequency value, and m < n.

[0101] Furthermore, when there are multiple devices under test in the distribution network, it is necessary to obtain impedance models at the same time point in order to further analyze the oscillation risk of the distribution network. To this end, embodiments of this application can be implemented as follows: Figure 4 The structure shown enables the simultaneous construction of impedance models for multiple devices under test in a power distribution network.

[0102] like Figure 4 As shown, the structure used in this application embodiment includes: a control module, a clock synchronization module, a disturbance parameter generation module, a disturbance generation module, a voltage acquisition module, a current acquisition module, a phasor calculation module, and an impedance calculation module.

[0103] The control module is used to coordinate the collaborative operation of multiple devices, generate disturbance parameters, and set the start time, duration, and end time of disturbance injection.

[0104] Clock synchronization module: Used to receive clock signals from GPS / BeiDou system and time-stamp the voltage disturbance signal and phasor calculation results from disturbance generation module to ensure that multiple devices inject disturbance signals into the power grid at the same time, and that the calculated phasor results are phasor information at the same time.

[0105] Disturbance parameter generation module: After receiving instructions from the control module, it generates parameters of the disturbance signal, such as disturbance frequency, amplitude, and phase.

[0106] Disturbance generation module: It is used to generate a disturbance signal based on the result of the disturbance parameters and inject it into the grid connection point of the device under test. In this embodiment of the application, the device under test is a distributed power source in the distribution network, which has a relatively low voltage level and low power. Therefore, the power of the disturbance generation module will not be too large and it is easy to implement.

[0107] Voltage and current acquisition module: Acquires voltage and current data of the device under test connected to the grid.

[0108] Phasor calculation module: Calculates the corresponding phasor information based on the collected voltage and current data.

[0109] Impedance calculation module: Calculates the impedance model of the device under test based on phasor information.

[0110] The online reverse impedance modeling method for distributed generation in distribution networks proposed in this application can generate time-annotated voltage disturbance signals containing different frequency components based on a signal source. These time-annotated voltage disturbance signals are injected into the grid connection point of the device under test (DUT) in the distribution network. The current voltage and current signals at the grid connection point are collected and input to a preset filter, outputting a voltage signal and a current signal of interest. The time-annotated phasors containing different frequency components in the voltage and current signals of interest are calculated, thereby calculating the impedance of the DUT at each frequency component. Impedance fitting is then used to obtain the impedance model of the DUT, ensuring that the results reflect the impact of real-time operating conditions on the impedance model of the DUT. Furthermore, by simultaneously constructing impedance models of multiple distributed devices at the same time point, the oscillation risk of the distribution network can be effectively quantified and assessed. This solves the technical problem in related technologies where the complex structure, time-varying operating modes and parameters of power electronic equipment, and the difficulty in obtaining control structures and basic parameters make it difficult to obtain impedance models of power electronic equipment through practical analysis or theoretical derivation.

[0111] Next, referring to the accompanying drawings, an online reverse impedance modeling device suitable for distributed generation in distribution networks, based on an embodiment of this application, is described.

[0112] Figure 5 This is a block diagram of an online reverse impedance modeling device for distributed generation in a power distribution network, according to an embodiment of this application.

[0113] like Figure 5 As shown, the online reverse impedance modeling device 50 for distributed power sources in distribution networks includes: an injection module 501, an acquisition module 502, a calculation module 503, and a modeling module 504.

[0114] Specifically, the injection module 501 is used to generate a voltage disturbance signal with time-labeled components containing different frequency components based on the signal source, and to transmit the voltage disturbance signal at time t. start Injected into the grid connection points of each device under test in the distribution network, continuing until time t. end .

[0115] The acquisition module 502 is used to acquire the current voltage signal and current current signal of the grid connection point starting at time t1 according to the preset sampling rate, and continue until time t2, and add time stamps to the current voltage signal and current current signal.

[0116] The calculation module 503 is used to input the current voltage signal and the current current signal into a preset filter, output the voltage signal and the current signal of interest, and calculate the phasors with time annotations containing different frequency components in the voltage signal and the current signal of interest, respectively.

[0117] Modeling module 504 is used to calculate the impedance of the device under test at each frequency component by using time-annotated phasors containing different frequency components in the voltage and current signals of interest, so as to obtain the impedance model of the device under test by online impedance fitting.

[0118] Optionally, in one embodiment of this application, the injection module 501 includes an acquisition unit and an injection unit.

[0119] The acquisition unit is used to acquire the number of devices under test in the power distribution network.

[0120] The injection unit is used to time-stamp the voltage disturbance signals of at least two distribution network devices under test based on a clock signal when there are at least two such devices, and to control at least two distribution network devices under test to simultaneously inject the time-stamped voltage disturbance signals into the distribution network.

[0121] Optionally, in one embodiment of this application, the formula for calculating the disturbance signal is:

[0122]

[0123] Among them, f ci f si Let u be the coupling frequency of the i-th group at the perturbation injection point. ci u si These are the disturbance amplitudes, These are the phases.

[0124] Optionally, in one embodiment of this application, the formula for constructing the preset filter is:

[0125]

[0126] Among them, H p This is a bandpass filter unit.

[0127] Optionally, in one embodiment of this application, the impedance model is:

[0128]

[0129] Where Z is the impedance sequence, a0,…,a n b0,…,b n For the polynomial coefficients, s = jω, where j is the imaginary unit, ω is the angular frequency, and f is the injected frequency value.

[0130] It should be noted that the foregoing explanation of the online reverse impedance modeling method embodiment applicable to distributed generation in distribution networks also applies to the online reverse impedance modeling device for distributed generation in distribution networks in this embodiment, and will not be repeated here.

[0131] The online reverse impedance modeling device for distributed generation in distribution networks, as proposed in the embodiments of this application, can generate time-annotated voltage disturbance signals containing different frequency components based on a signal source. These time-annotated voltage disturbance signals are injected into the grid connection point of the device under test (DUT) in the distribution network. The current voltage and current signals at the grid connection point are collected and input to a preset filter, outputting a voltage signal and a current signal of interest. The time-annotated phasors containing different frequency components in the voltage and current signals of interest are calculated, thereby calculating the impedance of the DUT at each frequency component. Impedance fitting is then used to obtain the impedance model of the DUT, ensuring that the results reflect the impact of real-time operating conditions on the impedance model of the DUT. Furthermore, by simultaneously constructing impedance models of multiple distributed devices at the same time point, the oscillation risk of the distribution network can be effectively quantified and assessed. This solves the technical problem in related technologies where the complex structure, time-varying operating modes and parameters of power electronic equipment, and the difficulty in obtaining control structures and basic parameters make it difficult to obtain impedance models of power electronic equipment through practical analysis or theoretical derivation.

[0132] Figure 6 A schematic diagram of the structure of an electronic device provided in an embodiment of this application. The electronic device may include:

[0133] The memory 601, the processor 602, and the computer program stored on the memory 601 and capable of running on the processor 602.

[0134] When the processor 602 executes the program, it implements the online reverse impedance modeling method for distributed power sources in the above embodiments, which is applicable to the distribution network.

[0135] Furthermore, electronic devices also include:

[0136] Communication interface 603 is used for communication between memory 601 and processor 602.

[0137] The memory 601 is used to store computer programs that can run on the processor 602.

[0138] The memory 601 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.

[0139] If the memory 601, processor 602, and communication interface 603 are implemented independently, then the communication interface 603, memory 601, and processor 602 can be interconnected via a bus to complete communication between them. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of representation, Figure 6 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0140] Optionally, in a specific implementation, if the memory 601, processor 602, and communication interface 603 are integrated on a single chip, then the memory 601, processor 602, and communication interface 603 can communicate with each other through an internal interface.

[0141] The processor 602 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application.

[0142] This embodiment also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described online reverse impedance modeling method for distributed generation in distribution networks.

[0143] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0144] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0145] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0146] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0147] It should be understood that the various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0148] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0149] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0150] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. An online reverse impedance modeling method suitable for distributed generation in distribution networks, characterized in that, Includes the following steps: Based on the signal generator, a voltage perturbation signal containing different frequency components with time-labeled bands is generated, and the voltage perturbation signal is time-labeled. t start Injected into the grid connection points of each device under test in the distribution network, continuing until time [time missing]. t end ; According to the preset sampling rate, at time t 1. Begin collecting the current voltage and current signals of the grid connection point, continuing until time 1. t 2. And add time stamps to the current voltage signal and the current current signal; Among them, according to the preset sampling rate, at time... t 1. Begin collecting the current voltage and current signals of the grid connection point, continuing until time 1. t 2. Adding time stamps to the current voltage signal and the current current signal includes: at the disturbance injection time. t start Initially, according to a fixed sampling rate F s At any moment t 1. Real-time acquisition of current voltage and current signals from the grid connection point of the device under test, continuing until the specified time. t 2, duration is t = t 1+ t 2. And add time stamps to the current voltage signal and the current current signal, where, t 2 represents the disturbance calming time. t start < t 1 < t end and t 1 < t 2< t end , t 1 represents the duration of the disturbance injection; The current voltage signal and the current current signal are respectively input to a preset filter, and the output voltage signal and current signal of interest are calculated. The time-labeled phasors containing different frequency components in the voltage signal and current signal of interest are then calculated respectively. Using the time-labeled phasors containing different frequency components in the voltage and current signals of interest, the impedance of the device under test is calculated at each frequency component, and the impedance model of the device under test is obtained by online fitting of the impedance.

2. The method according to claim 1, characterized in that, The step of injecting the voltage disturbance signal into the grid connection point of the equipment under test in the distribution network includes: Obtain the number of devices under test in the power distribution network; When there are at least two devices under test in the power distribution network, the voltage disturbance signals of the at least two devices under test are time-stamped based on a clock signal, and the at least two devices under test are controlled to simultaneously inject the time-stamped voltage disturbance signals into the power distribution network.

3. The method according to claim 1, characterized in that, The formula for calculating the voltage disturbance signal is: ， in, f ci , f si At the disturbance injection point respectively i The coupling frequency of the group u ci , u si These are the disturbance amplitudes, ci , si These are the phases.

4. The method according to claim 1, characterized in that, The formula for constructing the preset filter is as follows: ， in, H p This is a bandpass filter unit.

5. The method according to claim 1, characterized in that, The impedance model is as follows: ， Where Z is the impedance sequence. a 0, …, a n , b 0, …, b n For polynomial coefficients, , j The imaginary unit, Angular frequency, f This represents the injection frequency value.

6. An online reverse impedance modeling device suitable for distributed generation in power distribution networks, characterized in that, include: The injection module is used to generate a voltage perturbation signal with time-labeled components containing different frequency components based on the signal source, and to inject the voltage perturbation signal at time... t start Injected into the grid connection points of each device under test in the distribution network, continuing until time [time missing]. t end ; The acquisition module is used to collect data at a preset sampling rate at time 10:

00. t 1. Begin collecting the current voltage and current signals of the grid connection point, continuing until time 1. t 2. And add time stamps to the current voltage signal and the current current signal; The acquisition module is further used to detect disturbance injection at the time of disturbance injection. t start Initially, according to a fixed sampling rate F s At any moment t 1. Real-time acquisition of current voltage and current signals from the grid connection point of the device under test, continuing until the specified time. t 2, duration is t = t 1+ t 2. And add time stamps to the current voltage signal and the current current signal, where, t 2 represents the disturbance calming time. t start < t 1 < t end and t 1 < t 2< t end , t 1 represents the duration of the disturbance injection; The calculation module is used to input the current voltage signal and the current current signal into a preset filter, output the voltage signal and the current signal of interest, and calculate the time-annotated phasors containing different frequency components in the voltage signal and the current signal of interest, respectively; and The modeling module is used to calculate the impedance of the device under test at each frequency component using the time-labeled phasors containing different frequency components in the voltage signal and the current signal of interest, so as to obtain the impedance model of the device under test by fitting the impedance.

7. The apparatus according to claim 6, characterized in that, The injection module includes: The acquisition unit is used to acquire the number of devices under test in the power distribution network. An injection unit is configured to, when the number of devices under test in the power distribution network is at least two, time-stamp the voltage disturbance signals of the at least two devices under test in the power distribution network based on a clock signal, and control the at least two devices under test in the power distribution network to simultaneously inject the time-stamped voltage disturbance signals into the power distribution network.

8. The apparatus according to claim 7, characterized in that, The impedance model is as follows: ， Where Z is the impedance sequence. a 0, …, a n , b 0, …, b n For polynomial coefficients, , j The imaginary unit, Angular frequency, f This represents the injection frequency value.

9. An electronic device, characterized in that, include: The memory, the processor, and the computer program stored in the memory and executable on the processor, the processor executing the program to implement the online reverse impedance modeling method for distributed generation in distribution networks as described in any one of claims 1-5.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, The program is executed by the processor to implement the online reverse impedance modeling method for distributed generation in distribution networks as described in any one of claims 1-5.

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