Disturbance injection device, impedance measurement system and impedance measurement method

Abstract

The invention relates to a disturbance injection device, an impedance measurement system and an impedance measurement method. The disturbance injection device comprises: a disturbance injection circuit configured with at least two disturbance modes, the disturbance injection circuit generating different types of disturbance signals in different disturbance states; the disturbance injection circuit comprises a full-bridge inversion module and a filtering gating module, the midpoint of a first bridge arm of the full-bridge inversion module is connected with a power grid through the filtering gating module, and the midpoint of a second bridge arm of the full-bridge inversion module is grounded through a load; the control module is respectively connected with the full-bridge inversion module and the filtering gating module, and is used for generating a target driving signal to drive the full-bridge inversion module according to a received disturbance mode instruction, and controlling the filtering gating module to work in a target working state, so that the disturbance injection circuit works in a target disturbance mode, and a target disturbance signal is provided for a power grid; the target disturbance mode is one of the at least two disturbance modes. The device can output various disturbance signals.

Description

Technical Field

[0001] The present application relates to the technical field of power grids, and particularly to a disturbance injection device, an impedance measurement system, and an impedance measurement method. Background Art

[0002] With the gradual maturity of power electronics technology, a large number of distributed photovoltaics, wind power, energy storage, and charging piles are connected to the distribution network. The penetration rate of power electronic devices in the distribution network increases year by year, and the stability problems and harmonic over-standard problems caused by power electronic devices become increasingly prominent. The impedance of the distribution network and the connected power electronic devices is an important parameter for stability analysis and harmonic responsibility division, and its accurate acquisition is crucial.

[0003] However, the impedance measurement devices in the related art can only input a single type of disturbance signal to the distribution network. However, different disturbance modes are required in different scenarios during actual distribution network impedance measurement. Therefore, the existing impedance measurement devices with a single disturbance mode are difficult to meet the impedance measurement requirements of the distribution network. Summary of the Invention

[0004] Based on this, in view of the above technical problems, it is necessary to provide a disturbance injection device, an impedance measurement system, and an impedance measurement method that can output multiple disturbance signals.

[0005] In a first aspect, the present application proposes a disturbance injection device, which includes:

[0006] A disturbance injection circuit configured with at least two disturbance modes. The types of disturbance signals generated by the disturbance injection circuit are different in different disturbance states. The disturbance injection circuit includes a full-bridge inverter module and a filter selection module. The midpoint of the first bridge arm of the full-bridge inverter module is connected to the power grid through the filter selection module, and the midpoint of the second bridge arm of the full-bridge inverter module is grounded through a load.

[0007] A control module, respectively connected to the full-bridge inverter module and the filter selection module, for generating a target drive signal to drive the full-bridge inverter module according to the received disturbance mode instruction, and controlling the filter selection module to work in a target working state, so that the disturbance injection circuit works in a target disturbance mode to provide a target disturbance signal to the power grid. The target disturbance mode is one of the at least two disturbance modes.

[0008] In one embodiment, the filter selection module includes a filter unit and a switch unit; wherein,

[0009] The first end of the filtering unit is respectively connected to the midpoint of the first arm and the first end of the switching unit, and the second end of the filtering unit is respectively connected to the power grid and the second end of the switching unit; the filtering unit is used to filter the target disturbance signal;

[0010] The control end of the switching unit is connected to the control module, and the switching unit is used to select and conduct the path between the midpoint of the first arm and the power grid under the control of the control module; wherein, in at least some disturbance modes, the switching unit is in different on-off states.

[0011] In one embodiment, the disturbance injection circuit is configured with a sine disturbance mode and a non-sine disturbance mode, and the sine disturbance mode includes at least one of a low-frequency sine disturbance mode, a high-frequency sine disturbance mode, and a variable-frequency sine disturbance mode; wherein,

[0012] When the disturbance injection circuit operates in the low-frequency sine disturbance mode or the high-frequency sine disturbance mode, the switching unit is used to disconnect the path between the midpoint of the first arm and the power grid under the control of the control module;

[0013] When the disturbance injection circuit operates in the variable-frequency sine disturbance mode or the non-sine disturbance mode, the switching unit is used to conduct the path between the midpoint of the first arm and the power grid under the control of the control module.

[0014] In one embodiment, wherein,

[0015] The filtering unit includes at least two inductors, and the switching unit includes at least two switches; the filtering and gating module includes at least two filtering and gating sub-modules connected in series in sequence, and each filtering and gating sub-module includes the inductor and the switch connected in parallel. The first filtering and gating sub-module is connected to the midpoint of the first arm, and the last filtering and gating sub-module is connected to the power grid;

[0016] When the disturbance injection circuit operates in the low-frequency sine disturbance mode, all the switches are in the off state;

[0017] When the disturbance injection circuit operates in the high-frequency sine disturbance mode, at least one switch is in the off state and at least one switch is in the on state.

[0018] In one embodiment, wherein, the control module includes:

[0019] A mode control sub-module, configured to generate a disturbance control signal according to the disturbance mode instruction;

[0020] The modulation driving sub-module is used to generate the target driving signal according to the disturbance control signal to drive the full-bridge inverter module.

[0021] In one embodiment, the disturbance mode includes a sine disturbance mode, and the sine disturbance mode includes at least one of a low-frequency sine disturbance mode and a high-frequency sine disturbance mode; the disturbance mode instruction includes at least one of a low-frequency sine disturbance instruction and a high-frequency sine disturbance instruction. Both the low-frequency sine disturbance instruction and the high-frequency sine disturbance instruction include the number of sine disturbance components, the amplitude of each sine disturbance component, the frequency of each sine disturbance component, and the phase of each sine disturbance component. The disturbance signal includes a sine disturbance signal, and the disturbance control signal includes a sine control signal.

[0022] The mode control sub-module includes:

[0023] The first control unit is used to generate a sine disturbance reference value according to the number of sine disturbance components, the amplitude of each sine disturbance component, the frequency of each sine disturbance component, the phase of each sine disturbance component, and a preset disturbance time.

[0024] The second control unit is connected to the first control unit and is used to obtain the voltage information of the disturbance injection circuit, and generate a sine control signal according to the sine disturbance reference value, the voltage information, a preset proportional control coefficient, a preset resonant control coefficient, a Laplace operator, a preset resonant control frequency, a preset delay time, a preset forgetting factor, a preset learning factor, and the natural base.

[0025] In one embodiment, the disturbance mode includes a sine disturbance mode, and the sine disturbance mode further includes a variable-frequency sine disturbance mode; the disturbance mode instruction includes a variable-frequency disturbance instruction, and the variable-frequency disturbance instruction includes a variable-frequency disturbance amplitude, an upper limit value of the variable-frequency disturbance frequency, a lower limit value of the variable-frequency disturbance frequency, and a duration constant. The disturbance signal includes a variable-frequency disturbance signal, and the disturbance control signal includes a variable-frequency control signal.

[0026] The mode control sub-module includes:

[0027] The third control unit is used to generate a variable-frequency control signal according to the variable-frequency disturbance amplitude, the upper limit value of the variable-frequency disturbance frequency, the lower limit value of the variable-frequency disturbance frequency, the duration constant, and a preset disturbance time.

[0028] In one embodiment, the perturbation pattern further includes a non-sinusoidal perturbation pattern, the non-sinusoidal perturbation pattern includes a pseudo-random code perturbation pattern, the perturbation pattern instruction includes a pseudo-random code perturbation instruction, the pseudo-random code perturbation instruction includes a pseudo-random code amplitude, a sequence generation frequency, a signal bit number, and a sequence length, the perturbation signal includes a pseudo-random code perturbation signal, and the perturbation control signal includes a pseudo-random control signal;

[0029] The mode control sub-module includes:

[0030] A fourth control unit, configured to generate a pseudo-random control signal according to the pseudo-random code amplitude, the sequence generation frequency, the signal bit number, and the sequence length.

[0031] In a second aspect, the present application provides an impedance measurement system, including an impedance measurement module and the perturbation injection device in any of the above embodiments; wherein, the impedance measurement module is connected to the power grid, and is configured to obtain a response signal of the power grid to the target perturbation signal, and determine an impedance result of the power grid according to the target perturbation signal and the response signal.

[0032] In a third aspect, the present application provides an impedance measurement method, applied to the impedance measurement system in the above embodiments; the method includes:

[0033] Obtain a perturbation pattern instruction;

[0034] Generate a target drive signal according to the perturbation pattern instruction to drive the full-bridge inverter module, and control the filter gating module to operate in a target operating state, so that the perturbation injection circuit operates in a target perturbation mode to provide a target perturbation signal to the power grid;

[0035] Obtain a response signal of the power grid to the target perturbation signal;

[0036] Determine an impedance result of the power grid according to the target perturbation signal and the response signal.

[0037] The above-mentioned disturbance injection device, impedance measurement system and impedance measurement method include a disturbance injection circuit and a control module. The disturbance injection circuit of the present application includes a full-bridge inverter module and a filtering and gating module. The midpoint of the first bridge arm of the full-bridge inverter module is connected to the power grid through the filtering and gating module, and the midpoint of the second bridge arm of the full-bridge inverter module is grounded through a load. The control module is respectively connected to the full-bridge inverter module and the filtering and gating module, and is used to generate a target drive signal according to the received disturbance mode instruction to drive the full-bridge inverter module to output a corresponding disturbance signal. At the same time, the control module controls the filtering and gating module to work in a target working state, so that the filtering and gating module uses an appropriate filtering mode to filter the corresponding disturbance signal output by the full-bridge inverter module, removing interference signals while avoiding filtering out the disturbance signal, and making the disturbance injection circuit work in a target disturbance mode to provide a target disturbance signal to the power grid. The disturbance injection device of the present application can input a corresponding target disturbance signal to the power grid according to the disturbance mode instruction to adapt to the impedance measurement scenario of the distribution network. Description of the Drawings

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0039] Figure 1 Schematic structural diagram of a disturbance injection device in an embodiment;

[0040] Figure 2 Schematic structural diagram of a disturbance injection device in another embodiment;

[0041] Figure 3 Schematic structural diagram of a disturbance injection device in still another embodiment;

[0042] Figure 4 Schematic structural diagram of a disturbance injection device in yet another embodiment;

[0043] Figure 5 Schematic structural diagram of a control module in an embodiment;

[0044] Figure 6 Schematic structural diagram of a control module in another embodiment;

[0045] Figure 7 Schematic structural diagram of a control module in still another embodiment;

[0046] Figure 8 Schematic flow diagram of an impedance measurement method in an embodiment. Detailed Embodiments

[0047] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant accompanying drawings. Embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0049] It can be understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another.

[0050] Spatial relationship terms such as "under", "below", "lower", "beneath", "above", "upper", etc. can be used herein to describe the relationship between one element or feature shown in the drawings and other elements or features. It should be understood that in addition to the orientation shown in the drawings, spatial relationship terms also include different orientations of the device during use and operation. For example, if the device in the drawing is flipped, an element or feature described as "under" or "beneath" or "below" another element will be oriented "above" the other element or feature. Therefore, the exemplary terms "under" and "below" can include both the upper and lower orientations. In addition, the device may also include additional orientations (such as rotating 90 degrees or other orientations), and the spatial descriptors used herein are accordingly interpreted.

[0051] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediate element. In addition, "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if there is a transfer of electrical signals or data between the connected objects.

[0052] As used herein, the singular forms "a", "an" and "the" may also include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprises / comprising" or "has / have" etc. specify the presence of the stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the related listed items.

[0053] As described in the background section, existing impedance measurement devices typically can only generate a single type of perturbation signal, such as a sine signal, a chirp signal, etc. Different signals have different advantages. For example, a sine signal has the advantage of being precisely controllable and is suitable for impedance measurement of impedance-coupled systems. A chirp signal has multiple perturbation components and has a fast measurement speed, which is suitable for occasions where rapid impedance measurement is required. However, due to the uncontrollability of the signal, it is difficult to be used in application scenarios considering coupled impedance.

[0054] In an exemplary embodiment, refer to Figure 1 , in order to overcome the deficiencies of existing single-perturbation-mode impedance measurement devices, the present application proposes a perturbation injection device, which includes: a perturbation injection circuit 10 and a control module 20.

[0055] The perturbation injection circuit 10 is configured with at least two perturbation modes. In different perturbation states, the types of perturbation signals generated by the perturbation injection circuit are different; the perturbation injection circuit 10 includes a full-bridge inverter module 11 and a filter selection module 12. The midpoint of the first bridge arm of the full-bridge inverter module 11 is connected to the power grid 30 through the filter selection module 12, and the midpoint of the second bridge arm of the full-bridge inverter module 11 is grounded through the load 40.

[0056] The control module 20 is respectively connected to the full-bridge inverter module 11 and the filter selection module 12, and is used to generate a target drive signal to drive the full-bridge inverter module according to the received perturbation mode instruction, and control the filter selection module to work in the target working state, so that the perturbation injection circuit works in the target perturbation mode to provide a target perturbation signal to the power grid; the target perturbation mode is one of at least two perturbation modes.

[0057] In one example, taking a single-phase power grid as an example, the disturbance injection circuit 10 of the present application can be connected in series on the phase line of the power grid. Specifically, the midpoint of the first bridge arm of the full-bridge inverter module 11 is connected to the phase line of the power grid 30 through the filter selection module 12, and the midpoint of the second bridge arm of the full-bridge inverter module 11 is grounded through the load 40 on the phase line. Furthermore, the disturbance injection circuit 10 can adjust its working mode according to the target drive signal output by the control module 20 and output the corresponding target disturbance signal. Similarly, in a three-phase power grid, a disturbance injection circuit 10 can be connected in series to each phase line of the power grid respectively. Under the control of the corresponding control module 20, each disturbance injection circuit 10 outputs the corresponding disturbance signal to each phase line respectively.

[0058] In this embodiment, the disturbance injection circuit 10 further includes a DC-side energy storage battery E. The full-bridge inverter module 11 is composed of four switching tubes (switching tube G1, switching tube G2, switching tube G3, and switching tube G4) and four anti-parallel diodes. Among them, the positive pole of the energy storage battery E is respectively connected to the collectors of the switching tube G1 and the switching tube G4, and the negative pole of the energy storage battery E is respectively connected to the emitters of the switching tube G2 and the switching tube G3. The emitter of the switching tube G1 is connected to the collector of the switching tube G2 and is connected to the power grid 30 through the filter selection module 12. The emitter of the switching tube G4 is connected to the collector of the switching tube G3 and is grounded through the load 40 on the phase line. The control module 20 is respectively connected to the gates of the switching tube G1, the switching tube G2, the switching tube G3, and the switching tube G4 to control the on-off of the switching tube G1, the switching tube G2, the switching tube G3, and the switching tube G4 through the target drive signal, so that the full-bridge inverter module 11 outputs the corresponding disturbance signal. At the same time, the control module 20 also controls the working state of the filter selection module. For example, when the full-bridge inverter module 11 outputs a low-frequency disturbance signal, the control module 20 can control the filter selection module to filter out high-frequency interference signals. When the full-bridge inverter module 11 outputs a high-frequency disturbance signal, the control module 20 can control the filter selection module to avoid filtering out the high-frequency disturbance signal.

[0059] The above-mentioned disturbance injection device includes a disturbance injection circuit and a control module. The disturbance injection circuit of the present application includes a full-bridge inverter module and a filtering and gating module. The midpoint of the first bridge arm of the full-bridge inverter module is connected to the power grid through the filtering and gating module, and the midpoint of the second bridge arm of the full-bridge inverter module is grounded through a load. The control module is respectively connected to the full-bridge inverter module and the filtering and gating module, and is used to generate a target driving signal according to the received disturbance mode instruction to drive the full-bridge inverter module to output a corresponding disturbance signal. At the same time, the control module controls the filtering and gating module to work in a target working state, so that the filtering and gating module uses an appropriate filtering mode to filter the corresponding disturbance signal output by the full-bridge inverter module, removing interference signals while avoiding filtering out the disturbance signal, so that the disturbance injection circuit works in a target disturbance mode to provide a target disturbance signal to the power grid. The disturbance injection device of the present application can input a corresponding target disturbance signal to the power grid according to the disturbance mode instruction to adapt to the impedance measurement scenario of the distribution network.

[0060] In an exemplary embodiment, please refer to Figure 2 , the filtering and gating module 12 includes a filtering unit 121 and a switching unit 122.

[0061] Among them, the first end of the filtering unit 121 is respectively connected to the midpoint of the first bridge arm and the first end of the switching unit 122, and the second end of the filtering unit 121 is respectively connected to the power grid 30 and the second end of the switching unit 122; the filtering unit is used to filter the target disturbance signal; the control end of the switching unit 122 is connected to the control module 20, and the switching unit 122 is used to select and conduct the path between the midpoint of the first bridge arm and the power grid 30 under the control of the control module 20; among them, in at least some disturbance modes, the switching unit 122 is in different on-off states.

[0062] In application, the filtering unit 121 may include a plurality of inductors, and the switching unit 122 may include a plurality of switches. The number of inductors in the filtering unit 121 is equal to the number of switches in the switching unit 122, and each inductor is connected in parallel with each switch in one-to-one correspondence. Furthermore, when the control module 20 receives a disturbance mode instruction, it can control the on-off states of the switches according to the disturbance mode instruction, so that the filtering unit 121 appropriately filters out interference signals.

[0063] In an exemplary embodiment, the disturbance injection circuit 10 is configured with a sine disturbance mode and a non-sine disturbance mode. The sine disturbance mode includes at least one of a low-frequency sine disturbance mode, a high-frequency sine disturbance mode, and a variable-frequency sine disturbance mode. The filtering unit 121 includes at least two inductors, and the switching unit 122 includes at least two switches; the filtering and gating module 12 includes at least two filtering and gating sub-modules connected in series in sequence. The filtering and gating sub-module includes an inductor and a switch connected in parallel. The first filtering and gating sub-module is connected to the midpoint of the first bridge arm, and the last filtering and gating sub-module is connected to the power grid.

[0064] The disturbance injection circuit 10 operates in a low-frequency sine disturbance mode or a high-frequency sine disturbance mode. The switch unit 122 is used to disconnect the path between the midpoint of the first bridge arm and the power grid 30 under the control of the control module 20. When the disturbance injection circuit operates in a variable-frequency sine disturbance mode or a non-sine disturbance mode, the switch unit 122 is used to connect the path between the midpoint of the first bridge arm and the power grid 30 under the control of the control module 20.

[0065] When the disturbance injection circuit 10 operates in a low-frequency sine disturbance mode, all switches are in the off state. When the disturbance injection circuit operates in a high-frequency sine disturbance mode, at least one switch is in the off state and at least one switch is in the on state.

[0066] In one example, refer to Figure 3 , taking the filtering unit 121 including two inductors (inductor L1 and inductor L2) and the switch unit 122 including two switches (switch S1 and switch S2) as an example for illustration. The inductor L1 and the switch S1 are connected in parallel to form the first filtering and gating sub-module, and the inductor L2 and the switch S2 are connected in parallel to form the second filtering and gating sub-module. Among them, the inductance values of the inductor L1 and the inductor L2 can be different.

[0067] When the disturbance injection circuit 10 operates in a low-frequency sine disturbance mode, the switch S1 and the switch S2 are turned off under the action of the control module 20, so that the inductor L1 and the inductor L2 are connected in series to provide a larger equivalent filtering inductor for the target disturbance signal to achieve a better filtering effect. When the disturbance injection circuit operates in a high-frequency sine disturbance mode, the switch S1 or the switch S2 is turned off under the action of the control module 20 to make the equivalent filtering inductor smaller to avoid high-frequency disturbances being filtered out. When the disturbance injection circuit 10 operates in a variable-frequency sine disturbance mode or a non-sine disturbance mode, the disturbance injection circuit 10 does not require filtering, and the control module 20 can control the switch S1 or the switch S2 to be turned off.

[0068] In an exemplary embodiment, refer to Figure 4 , the control module 20 includes a mode control sub-module 21 and a modulation and drive sub-module 22. The mode control sub-module 21 is used to generate a disturbance control signal according to a disturbance mode instruction. The modulation and drive sub-module 22 is respectively connected to the mode control sub-module 21 and the full-bridge inverter module 11, and is used to generate a target drive signal according to the disturbance control signal to drive the full-bridge inverter module 11.

[0069] Among them, the mode control sub-module 21 is used to receive a disturbance mode instruction, and the disturbance mode instruction may include parameters such as the frequency, amplitude, and phase of the disturbance signal that relevant technicians expect to impose on the power grid. After receiving the disturbance mode instruction, the mode control sub-module 21 can generate a corresponding disturbance control signal according to the disturbance mode instruction, so that the modulation drive sub-module 22 is used to generate a target drive signal according to the disturbance control signal to drive the full-bridge inverter module 11 to output a corresponding disturbance signal. In addition, the mode control sub-module 21 can also be connected to the switch unit 122 to control the on-off states of the switches in the switch unit 122 after receiving the disturbance mode instruction, so that the filtering unit 121 appropriately filters out interference signals.

[0070] In an exemplary embodiment, both the low-frequency sine disturbance instruction and the high-frequency sine disturbance instruction include the number of sine disturbance components, the amplitude of each sine disturbance component, the frequency of each sine disturbance component, and the phase of each sine disturbance component. The disturbance signal includes a sine disturbance signal, and the disturbance control signal includes a sine control signal.

[0071] The mode control sub-module 21 includes: a first control unit 211 and a second control unit 212.

[0072] The first control unit 211 is used to generate a sine disturbance reference value according to the number of sine disturbance components, the amplitude of each sine disturbance component, the frequency of each sine disturbance component, the phase of each sine disturbance component, and a preset disturbance time. The second control unit 212 is connected to the first control unit 211 and is used to obtain the voltage information of the disturbance injection circuit, and generate a sine control signal according to the sine disturbance reference value, the voltage information, a preset proportional control coefficient, a preset resonant control coefficient, a Laplace operator, a preset resonant control frequency, a preset delay time, a preset forgetting factor, a preset learning factor, and the natural base.

[0073] When the disturbance injection circuit 10 needs to input a low-frequency sine disturbance or a high-frequency sine disturbance to the power grid, its control principle is similar. Specifically, the first control unit 211 can generate a sine disturbance reference value according to the number of sine disturbance components, the amplitude of each sine disturbance component, the frequency of each sine disturbance component, the phase of each sine disturbance component, and a preset disturbance time , and its formula can be as formula (1):

[0074]

[0075] where N represents the number of sine disturbance components included in the multi-frequency sine disturbance. If it is a single-frequency sine disturbance, then N = 1, and i represents the i-th sine disturbance component. represents the amplitude of the i-th sine disturbance component, represents the frequency of the i-th sine disturbance component, represents the phase of the i-th sine disturbance component, and t represents the preset disturbance time.

[0076] The second control unit 212 includes a proportional-resonant control 2121 and a repetitive controller 2122. The second control unit 212 can obtain the voltage across the disturbance injection circuit , and input the error after comparing the sine disturbance reference value with the voltage into the proportional-resonant control 2121 and the repetitive controller 2122. The signals output by the proportional-resonant control 2121 and the repetitive controller 2122 together constitute a sine control signal , and its calculation formula is as shown in formula (2):

[0077]

[0078] Wherein, is the proportional control coefficient, is the resonant control coefficient, s is the Laplace operator, is the resonant control frequency, Ts is the delay time, is the forgetting factor, is the learning factor, and e is the natural base.

[0079] The modulation drive sub-module 22 may include a first modulation unit 221 and a switch instruction generation unit 222. The first modulation unit 221 is respectively connected to the second control unit 212 and the switch instruction generation unit 222 to receive the sine control signal , and generate a PWM (Pulse Width Modulation) signal according to the sine control signal . The PWM signal is output to the switch instruction generation unit to form the target drive signals of the switching tubes G1 to G4 in the full-bridge inverter module.

[0080] In an exemplary embodiment, please refer to Figure 6 , the disturbance mode instruction further includes a variable-frequency disturbance instruction. The variable-frequency disturbance instruction includes a variable-frequency disturbance amplitude, a variable-frequency disturbance frequency upper limit value, a variable-frequency disturbance frequency lower limit value, and a duration constant. The disturbance signal includes a variable-frequency disturbance signal, and the disturbance control signal includes a variable-frequency control signal. The mode control sub-module 21 further includes a third control unit 213. The third control unit 213 can generate a variable-frequency control signal according to the variable-frequency disturbance amplitude, the variable-frequency disturbance frequency upper limit value, the variable-frequency disturbance frequency lower limit value, the duration constant, and the preset disturbance time.

[0081] It can be understood that the variable-frequency sine signal, also known as the chirp signal, is a signal whose frequency changes (increases or decreases) over time. When relevant technicians send a variable-frequency perturbation instruction to the control module 20, they can define parameters such as the amplitude of the variable-frequency perturbation signal, the upper limit value of the frequency, and the lower limit value of the frequency. The third control unit 213 can then generate a variable-frequency control signal according to the relevant parameters in the variable-frequency perturbation instruction. , and its formula can be as shown in formula (3):

[0082]

[0083] Wherein, represents the variable-frequency perturbation amplitude, represents the upper limit value of the variable-frequency perturbation frequency, represents the lower limit value of the variable-frequency perturbation frequency, represents the duration constant, which refers to the time required for the instantaneous frequency of the variable-frequency perturbation signal to increase from the lower frequency limit to the upper frequency limit . represents the preset perturbation time.

[0084] The modulation drive sub-module 22 may further include a second modulation unit 223. The second modulation unit 223 is respectively connected to the third control unit 213 and the switch instruction generation unit 222. The second modulation unit 223 is used to convert the variable-frequency control signal into a PWM signal in the variable-frequency perturbation mode. The method of this modulation process is that when the variable-frequency control signal is positive, the PWM signal is at a high level. Conversely, when the variable-frequency control signal is negative, the PWM signal is at a low level. The generated PWM signal is input to the switch instruction generation unit 222 to form a drive signal. During this process, when the PWM signal is at a high level, the drive signal controls the switch tubes G1 and G3 to conduct, and the switch tubes G2 and G4 to turn off. When the PWM signal is at a low level, the drive signal controls the switch tubes G1 and G3 to turn off, and the switch tubes G2 and G4 to conduct.

[0085] In an exemplary embodiment, the perturbation mode further includes a non-sine perturbation mode. The non-sine perturbation mode includes a pseudo-random code perturbation mode, that is, a PRBS (Pseudo-Random Binary Sequence) perturbation mode. The perturbation mode instruction includes a pseudo-random code perturbation instruction, the perturbation signal includes a pseudo-random code perturbation signal, and the perturbation control signal includes a pseudo-random control signal;

[0086] Please refer to Figure 7, the mode control sub-module 21 further includes a fourth control unit 214, which is used to generate a pseudo-random control signal according to the pseudo-random code amplitude, sequence generation frequency, signal bit number, and sequence length.

[0087] The main parameters of the pseudo-random code perturbation instruction include the pseudo-random code amplitude M PRBS , the sequence generation frequency f PRBS , the signal bit number n, and the sequence length L, where the sequence length L and the signal bit number n satisfy: , after the main parameters of the signal are determined, a pseudo-random control signal can be generated by the fourth control unit 214 .

[0088] The modulation drive sub-module 22 may further include a third modulation unit 224, which is respectively connected to the fourth control unit 214 and the switch instruction generation unit 222. The third modulation unit 224 is used to convert the pseudo-random control signal into a PWM signal of the pseudo-random perturbation mode. The method of this modulation process is that when the pseudo-random control signal is at a high level, the PWM signal is at a high level. Conversely, when the pseudo-random control signal is at a low level, the PWM signal is at a low level. The generated PWM signal is input to the switch instruction generation unit 222 to form a drive signal. During this process, when the PWM signal is at a high level, the drive signal controls the switch tubes G1 and G3 to conduct, and the switch tubes G2 and G4 to turn off. When the PWM signal is at a low level, the drive signal controls the switch tubes G1 and G3 to turn off, and the switch tubes G2 and G4 to conduct.

[0089] In an exemplary embodiment, the present application proposes an impedance measurement system, including an impedance measurement module and the perturbation injection device in any of the above embodiments; wherein, the impedance measurement module is respectively connected to the perturbation injection device and the power grid, and is used to obtain the target perturbation signal and the response signal of the power grid to the target perturbation signal, and determine the impedance result of the power grid according to the target perturbation signal and the response signal.

[0090] In an exemplary embodiment, the present application proposes an impedance measurement method, which is applied to the impedance measurement system in the above embodiment; the method includes steps S801 to S804.

[0091] S801: Obtain the perturbation mode instruction.

[0092] S802: Generate a target drive signal according to the perturbation mode instruction to drive the full-bridge inverter module, and control the filter gating module to work in the target working state, so that the perturbation injection circuit works in the target perturbation mode to provide a target perturbation signal to the power grid.

[0093] S803: Obtain the response signal of the power grid to the target disturbance signal.

[0094] S804: Determine the impedance result of the power grid according to the target disturbance signal and the response signal.

[0095] In a detailed embodiment, taking the filtering unit 121 including two inductors (inductor L1 and inductor L2), and the switching unit 122 including two switches (switch S1 and switch S2) as an example, and assuming that the inductance values of inductor L1 and inductor L2 are different, and the inductance value of inductor L1 is 4mH, and the inductance value of inductor L2 is 2mH. When the control module 20 receives the low-frequency sine disturbance mode instruction, first control switch S1 and switch S2 to disconnect, so that inductor L1 and inductor L2 are in series, providing a larger equivalent filtering inductor for the target disturbance signal to achieve a better filtering effect. At the same time, the first control unit 211 can generate a sine disturbance reference value according to the number of sine disturbance components, the amplitude of each sine disturbance component, the frequency of each sine disturbance component, the phase of each sine disturbance component, and the preset disturbance time , the second control unit 212 according to the sine disturbance reference value and the voltage across the disturbance injection circuit , using proportional-resonant control 2121 and a repetitive controller 2122 to output a sine control signal , the first modulation unit 221 receives the sine control signal , according to the sine control signal to generate a PWM (Pulse Width Modulation) signal, and the PWM signal is output to the switch command generation unit to form the target drive signal of the switching tubes G1 to G4 in the full-bridge inverter module. Among them, in order to reduce losses, a lower switching frequency fs can be adopted in the low-frequency band. For example, when outputting a low-frequency sine disturbance, set the switching frequency fs of each switching tube in the full-bridge inverter module to 20fp according to the sine disturbance frequency f. It should be noted that if it is a multi-sine disturbance mode operation, f here refers to the component with the highest frequency among multiple sine disturbance components.

[0096] When the control module 20 receives the high-frequency sine disturbance mode instruction, first control switch S1 to close and switch S2 to disconnect. Inductor L1 is short-circuited, and inductor L2 alone constitutes the filter of the disturbance injection circuit. The power grid is usually not sensitive to high-frequency voltage disturbances. Therefore, when outputting high-frequency disturbances, a smaller value of the filtering inductor can be taken to avoid high-frequency disturbances being filtered by the filter. At the same time, the first control unit 211 can generate a sine disturbance reference value according to the number of sine disturbance components, the amplitude of each sine disturbance component, the frequency of each sine disturbance component, the phase of each sine disturbance component, and the preset disturbance time , the second control unit 212 according to the sine disturbance reference value and the voltage across the perturbation injection circuit , using proportional-resonant control 2121 and repetitive controller 2122 to output a sinusoidal control signal , the first modulation unit 221 receives the sinusoidal control signal , according to the sinusoidal control signal generate a PWM (Pulse Width Modulation) signal, and the PWM signal is output to the switch command generation unit to form the target drive signals of switches G1 to G4 in the full-bridge inverter module. Among them, in order to maintain the quality of the output high-frequency sine wave, the switching frequency fs of the switch should be as large as possible, but limited by the maximum switching frequency Fmax of the switch itself. When outputting high-frequency sine perturbations, set the switching frequency of the impedance measurement device according to the sine perturbation frequency f to satisfy: fs = 10f or fs = Fmax. If it is operating in a multi-sine perturbation mode, here f refers to the component with the highest frequency among multiple sine perturbation components. At the same time, to ensure the quality of the perturbation waveform, the sine perturbation frequency f should not be higher than Fmax / 6.

[0097] When the control module 20 receives a variable-frequency perturbation command, first control switches S1 and S2 to disconnect. At the same time, the third control unit 213 generates a variable-frequency control signal according to the variable-frequency perturbation amplitude, upper limit of the variable-frequency perturbation frequency, lower limit of the variable-frequency perturbation frequency, duration constant, and preset perturbation time. The second modulation unit 223 converts the variable-frequency control signal into a PWM signal in the variable-frequency perturbation mode, and the generated PWM signal is input to the switch command generation unit 222 to form a drive signal. Among them, the upper limit of the variable-frequency perturbation frequency should not be greater than the maximum switching frequency Fmax of the switch itself.

[0098] When the control module 20 receives a pseudo-random code perturbation command, first control switches S1 and S2 to disconnect. At the same time, the fourth control unit 214 generates a pseudo-random control signal according to the pseudo-random code amplitude M PRBS , sequence generation frequency f PRBS , number of signal bits n, and sequence length L , and the third modulation unit 224 then converts the pseudo-random control signal into a PWM signal in the pseudo-random perturbation mode, and the switch command generation unit 222 then forms a drive signal according to the PWM signal in the pseudo-random perturbation mode. Among them, the sequence generation frequency f PRBS is not greater than the maximum switching frequency Fmax of the switch itself.

[0099] It can be understood that the disturbance injection device of the present application can inject various different types of disturbance signals into the power grid. Furthermore, relevant technical personnel can choose to use the low-frequency sine disturbance mode, high-frequency sine disturbance mode, variable-frequency disturbance mode, or pseudo-random disturbance mode to carry out impedance measurement based on the characteristics of the measured power grid and impedance measurement requirements, meeting the wide-band impedance measurement requirements of the distribution network in multiple scenarios.

[0100] In the description of this specification, the description referring to terms such as "some embodiments", "other embodiments", "ideal embodiments", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0101] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0102] The above-described embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A disturbance injection device, characterized in that: The device comprises: A disturbance injection circuit is configured with at least two disturbance modes, and the disturbance injection circuit generates different types of disturbance signals under different disturbance states; the disturbance injection circuit comprises a full-bridge inverter module and a filter gating module, the midpoint of a first bridge arm of the full-bridge inverter module is connected to a power grid through the filter gating module, and the midpoint of a second bridge arm of the full-bridge inverter module is grounded through a load; A control module is respectively connected to the full-bridge inverter module and the filter gating module, and is used to generate a target drive signal to drive the full-bridge inverter module according to a received disturbance mode instruction, and control the filter gating module to operate in a target operating state, so that the disturbance injection circuit operates in a target disturbance mode to provide a target disturbance signal to the power grid; the target disturbance mode is one of the at least two disturbance modes.

2. The disturbance injection device according to claim 1, characterized in that: The filtering and gating module includes a filtering unit and a switching unit; wherein, The first end of the filter unit is connected to the midpoint of the first bridge arm and the first end of the switch unit respectively, and the second end of the filter unit is connected to the power grid and the second end of the switch unit respectively; the filter unit is used to filter the target disturbance signal; The control end of the switch unit is connected to the control module, and the switch unit is used to select a path between the midpoint of the first bridge arm and the power grid under the control of the control module; wherein, in at least a partial disturbance mode, the switch unit is in different on-off states.

3. The disturbance injection device according to claim 2, characterized in that: The disturbance injection circuit is configured with a sinusoidal disturbance mode and a non-sinusoidal disturbance mode, wherein the sinusoidal disturbance mode includes at least one of a low-frequency sinusoidal disturbance mode, a high-frequency sinusoidal disturbance mode and a variable-frequency sinusoidal disturbance mode; wherein, The disturbance injection circuit operates in the low-frequency sinusoidal disturbance mode or the high-frequency sinusoidal disturbance mode, and the switch unit is used to disconnect the path between the midpoint of the first bridge arm and the power grid under the control of the control module; The disturbance injection circuit operates in the variable frequency sinusoidal disturbance mode or the non-sinusoidal disturbance mode, and the switch unit is used to conduct the path between the midpoint of the first bridge arm and the power grid under the control of the control module.

4. The disturbance injection device according to claim 3, characterized in that: in, The filter unit includes at least two inductors, and the switch unit includes at least two switches; the filter gating module includes at least two filter gating submodules connected in series in sequence, and the filter gating submodule includes the inductor and the switch connected in parallel, the first filter gating submodule is connected to the midpoint of the first bridge arm, and the last filter gating submodule is connected to the power grid; The disturbance injection circuit operates in the low-frequency sinusoidal disturbance mode, and each of the switches is in an off state; The disturbance injection circuit operates in the high-frequency sinusoidal disturbance mode, at least one switch is in an off state, and at least one switch is in an on state.

5. The disturbance injection device according to any one of claims 1 to 4, characterized in that: in, The control module comprises: A mode control submodule, used for generating a disturbance control signal according to the disturbance mode instruction; The modulation drive submodule is used to generate the target drive signal according to the disturbance control signal to drive the full-bridge inverter module.

6. The disturbance injection device according to claim 5, characterized in that: The disturbance mode includes a sinusoidal disturbance mode, and the sinusoidal disturbance mode includes at least one of a low-frequency sinusoidal disturbance mode and a high-frequency sinusoidal disturbance mode; the disturbance mode instruction includes at least one of a low-frequency sinusoidal disturbance instruction and a high-frequency sinusoidal disturbance instruction, and the low-frequency sinusoidal disturbance instruction and the high-frequency sinusoidal disturbance instruction both include the number of sinusoidal disturbance components, the amplitude of each sinusoidal disturbance component, the frequency of each sinusoidal disturbance component and the phase of each sinusoidal disturbance component, the disturbance signal includes a sinusoidal disturbance signal, and the disturbance control signal includes a sinusoidal control signal; The mode control submodule includes: A first control unit, configured to generate a sinusoidal disturbance reference value according to the number of sinusoidal disturbance components, the amplitude of each sinusoidal disturbance component, the frequency of each sinusoidal disturbance component, the phase of each sinusoidal disturbance component and a preset disturbance time; A second control unit is connected to the first control unit, and is used to obtain voltage information of the disturbance injection circuit, and generate a sinusoidal control signal according to the sinusoidal disturbance reference value, the voltage information, a preset proportional control coefficient, a preset resonance control coefficient, a Laplace operator, a preset resonance control frequency, a preset delay time, a preset forgetting factor, a preset learning factor and a natural base.

7. The disturbance injection device according to claim 5, characterized in that: The disturbance mode includes a sinusoidal disturbance mode, and the sinusoidal disturbance mode also includes a variable frequency sinusoidal disturbance mode; the disturbance mode instruction includes a variable frequency disturbance instruction, and the variable frequency disturbance instruction includes a variable frequency disturbance amplitude, a variable frequency disturbance frequency upper limit value, a variable frequency disturbance frequency lower limit value and a duration constant; the disturbance signal includes a variable frequency disturbance signal, and the disturbance control signal includes a variable frequency control signal; The mode control submodule includes: The third control unit is used to generate a variable frequency control signal according to the variable frequency disturbance amplitude, the variable frequency disturbance frequency upper limit value, the variable frequency disturbance frequency lower limit value, the duration constant and the preset disturbance time.

8. The disturbance injection device according to claim 5, characterized in that: The disturbance mode further includes a non-sinusoidal disturbance mode, the non-sinusoidal disturbance mode includes a pseudo-random code disturbance mode, the disturbance mode instruction includes a pseudo-random code disturbance instruction, the pseudo-random code disturbance instruction includes a pseudo-random code amplitude, a sequence generation frequency, a signal bit number and a sequence length, the disturbance signal includes a pseudo-random code disturbance signal, and the disturbance control signal includes a pseudo-random control signal; The mode control submodule includes: A fourth control unit is used to generate a pseudo-random control signal according to the pseudo-random code amplitude, the sequence generation frequency, the signal bit number and the sequence length.

9. An impedance measurement system, comprising an impedance measurement module and a disturbance injection device according to any one of claims 1 to 8; wherein: The impedance measurement module is connected to the power grid and is used to obtain a response signal of the power grid to the target disturbance signal, and determine an impedance result of the power grid according to the target disturbance signal and the response signal.

10. An impedance measurement method, characterized in that: Applicable to the impedance measurement system of claim 9; the method comprising: Get disturbance mode instructions; Generate a target drive signal according to the disturbance mode instruction to drive the full-bridge inverter module, and control the filter gating module to work in a target working state, so that the disturbance injection circuit works in a target disturbance mode to provide a target disturbance signal to the power grid; Acquiring a response signal of the power grid to the target disturbance signal; An impedance result of the power grid is determined according to the target disturbance signal and the response signal.

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