Broadband oscillation suppression method and device for three-phase grid-connected inverter and medium

Abstract

The invention provides a broadband oscillation suppression method and device for a three-phase grid-connected inverter and a medium, and belongs to the field of new energy grid-connected broadband oscillation suppression. According to the impedance characteristic of the three-phase grid-connected inverter, a voltage feedback transfer function is designed, the transfer function is subjected to equivalence, complex coefficients in the transfer function are replaced, and the broadband oscillation suppression of the three-phase grid-connected inverter is achieved. And the method has definite physical significance and realizability. Meanwhile, a digital peak filter is introduced to serve as a frequency component selection channel, a delayer serves as a phase correction channel, a frequency component selection device only allowing a target frequency component to pass through is formed, a designed voltage feedback transfer function is combined, and a complete damping channel with a broadband oscillation suppression effect is formed. According to the channel, only the impedance characteristic of the target frequency can be changed, the impedance characteristic of the non-target frequency band is not influenced, the damping borrowing phenomenon is avoided, meanwhile, the coefficient can be changed according to the oscillation frequency, and full-band broadband oscillation can be suppressed.

Description

Technical Field

[0001] The present invention belongs to the field of broadband oscillation suppression of new energy grid-connected power, and specifically relates to a broadband oscillation suppression method, equipment and medium for a three-phase grid-connected inverter. Background Art

[0002] Renewable energy represented by wind and solar power has been widely used. Unlike traditional power systems, large-scale power electronic devices are continuously connected to the power grid, and the power system is gradually showing a trend of power electronics. Therefore, the problem of broadband oscillation caused by the interaction between power electronic equipment and the power grid cannot be ignored. Such oscillation may cause damage to various equipment in the power system at the least; at the worst, it may cause large-scale disconnection of new energy units from the grid, system shutdown or even partial decoupling of the power grid, affecting the stability of the power system.

[0003] Among the existing oscillation suppression technologies, additional damping channels are mainly used. The additional damping control changes the original impedance characteristics by feeding back the electrical quantity to the control loop through the compensator without changing the original control structure, thereby increasing the damping effect. However, the additional damping channels currently proposed usually have the phenomenon of "borrowing damping" (changing the impedance characteristics of non-target frequency bands, thereby increasing the oscillation risk of this frequency band), and are only applicable to some frequency bands, which has certain limitations. Summary of the invention

[0004] The present invention provides a method for suppressing broadband oscillation of a three-phase grid-connected inverter. The method can change the coefficient according to the oscillation frequency, thereby suppressing broadband oscillation in the entire frequency band and improving the stability of the power system.

[0005] Methods include: S1. Based on the voltage feedback channel, the feedback value is configured to the current control inner loop of the three-phase grid-connected inverter, and the sequence impedance model of the three-phase grid-connected inverter is obtained; S2. Define the denominator of the sequence impedance as 0 and configure the voltage feedback channel transfer function; S3, using a fast Fourier algorithm to detect the oscillation frequency of the grid-connected voltage of the three-phase grid-connected inverter; S4. Calculate an equivalent factor according to the detected oscillation frequency, and replace the equivalent factor with an imaginary unit in the voltage feedback channel transfer function for equivalent transformation, so that the voltage feedback channel before and after the equivalent has the same amplitude and phase response at the oscillation frequency; S5. According to the detected oscillation frequency, a digital peak filter of the corresponding frequency is obtained, and a delay coefficient of the delay device is calculated based on the phase response of the digital peak filter to perform frequency component selection and phase correction; S6. The grid-connected voltage dq-axis signal, which is subjected to frequency component selection by a digital spike filter and phase correction by a delay device, is used as the input of the voltage feedback transfer function, and the output of the voltage feedback transfer function is added to the current inner loop as an additional quantity, so as to reshape the impedance characteristics of the oscillation frequency and realize oscillation suppression of the frequency.

[0006] It should be further explained that step S1 also includes: defining the positive sequence impedance of the three-phase grid-connected inverter and negative sequence impedance for:

[0007]

[0008] in, The phase angle at which the grid-connected fundamental frequency voltage leads the grid-connected fundamental frequency current; is the amplitude of the fundamental frequency component of the grid-connected current; is the amplitude of the fundamental frequency component of the grid-connected voltage; is the expression related to the phase-locked loop transfer function under positive sequence disturbance, is the expression related to the phase-locked loop transfer function under negative sequence disturbance, , is a constant, , They are filter inductor and filter resistor respectively; , are the DC side capacitance and DC voltage of the inverter respectively; is the grid-connected voltage phase angle output by the phase-locked loop; is the phase-locked loop transfer function; , The d-axis and q-axis components of the grid-connected voltage are obtained by park transformation; , The d-axis and q-axis components of the grid-connected current obtained by park transformation; , are the reference values ​​of the d-axis and q-axis components of the grid-connected current; is the transfer function of the inner current loop; , are the d-axis and q-axis components of the bridge arm voltage of the three-phase grid-connected inverter.

[0009] It should be further explained that in the method, , , , The expressions are:

[0010]

[0011]

[0012] .

[0013] It should be further explained that in step S2, the sequence impedance denominator is defined as 0, and the voltage feedback channel transfer function is configured , voltage feedback channel transfer function Includes: Voltage feedback channel transfer function for positive sequence disturbances And the voltage feedback channel transfer function for negative sequence disturbances ;

[0014] .

[0015] It should be further explained that in step S4, the formula for calculating the equivalent factor is: .

[0016] It should be further explained that the transfer function after equivalent transformation is:

[0017] .

[0018] It should be further explained that the amplitude-frequency response of the peak filter in S5 is:

[0019] in, is the amplitude response of the digital peak filter, expressed as: .

[0020] It should be further explained that in step S5, by setting the delay time of the delay device , to perform phase correction, The calculation formula is:

[0021] in, The digital peak filter calculated by Matlab is Phase response at frequency; The digital peak filter calculated by Matlab is Phase response at frequency.

[0022] According to another embodiment of the present application, an electronic device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method for suppressing wide-band oscillation of a three-phase grid-connected inverter when executing the program.

[0023] According to another embodiment of the present application, a storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method for suppressing wide-band oscillation of a three-phase grid-connected inverter are implemented.

[0024] It can be seen from the above technical solutions that the present invention has the following advantages: The broadband oscillation suppression method of the three-phase grid-connected inverter provided in the present application can adjust the impedance characteristics of the inverter at the oscillation frequency by calculating the equivalent factor and replacing the imaginary unit in the transfer function, so as to make it more conducive to the suppression of oscillation. Based on the equivalent transformation, it can be ensured that the voltage feedback channel has the same amplitude and phase response at the oscillation frequency, thereby maintaining the stability of the power system. The oscillation frequency component can be accurately selected by using a digital spike filter. By calculating the delay coefficient of the delay device and performing phase correction, it can be ensured that the phase response of the inverter at the oscillation frequency is consistent with the expectation. By also adding the output of the voltage feedback transfer function as an additional amount to the current inner loop, the impedance characteristics of the inverter at the oscillation frequency can be reshaped, and the oscillation can be suppressed. Enhance the robustness of the power system. In addition, by suppressing oscillations, the quality of grid-connected voltage and current can be improved, the interference of harmonics and noise can be reduced, and the operation stability of the power system can be improved.

[0025] The broadband oscillation suppression method for three-phase grid-connected inverter provided in this application is also applicable to both positive-sequence disturbances and negative-sequence disturbances, and the design process of positive-sequence disturbances is basically the same. It is only necessary to change the coefficient of the voltage feedback channel transfer function according to the frequency of the disturbance and the positive and negative sequences, and there is no need to make major changes to the structure of the transfer function. And only the impedance characteristics of the target frequency (oscillation frequency) are changed, and the impedance characteristics of the non-target frequency band are not changed, and the oscillation risk of the non-target frequency band will not be increased, avoiding the phenomenon of "borrowed damping" in the traditional additional damping channel, and the key coefficient is related to the oscillation frequency. The coefficient that responds to different oscillation frequencies is suitable for broadband oscillations in the full frequency band. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solution of the present invention, the accompanying drawings required for use in the description will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0027] Figure 1It is a flow chart of a method for suppressing wide-band oscillation of a three-phase grid-connected inverter; Figure 2 The present invention is a flow chart of an embodiment of a method for suppressing wide-band oscillation of a three-phase grid-connected inverter; Figure 3 It is a schematic diagram of a three-phase grid-connected inverter; Figure 4 The current inner loop structure diagram of the three-phase grid-connected inverter with an additional voltage feedback channel; Figure 5 Schematic diagram of the oscillation suppression damping channel; Figure 6 It is a schematic diagram of the positive sequence impedance measurement value; Figure 7 It is a schematic diagram having the same amplitude-frequency response and phase-frequency response; Figure 8 is a schematic diagram of amplitude response; Fig. 9 is a phase response diagram; Fig.10 This is a schematic diagram of the correction results; Fig.11 This is a simulation example diagram; Fig.12 This is the time domain simulation result diagram; Fig.13 This is an example diagram of an electronic device. DETAILED DESCRIPTION

[0028] The method for suppressing broadband oscillation of a three-phase grid-connected inverter provided in the present application designs a voltage feedback transfer function according to the impedance characteristics of the three-phase grid-connected inverter itself, and performs an equivalent operation on the transfer function, replacing the complex coefficients therein, so that it has a clear physical meaning and feasibility. At the same time, a digital spike filter is introduced as a frequency component selection channel and a delay device is introduced as a phase correction channel to form a frequency component selection device that only allows the target frequency component to pass through. Combined with the designed voltage feedback transfer function, a complete damping channel with broadband oscillation suppression is formed. The damping channel formed in the present application can only change the impedance characteristics of the target frequency without affecting the impedance characteristics of the non-target frequency band, and the "borrowed damping" phenomenon will not occur. At the same time, the coefficient can be changed according to the oscillation frequency, so that broadband oscillations of the entire frequency band can be suppressed.

[0029] The specific process of the method for suppressing wide-band oscillation of a three-phase grid-connected inverter will be described in detail below. For the purpose of illustration rather than limitation, specific details such as specific system structures and technologies are proposed to facilitate a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application can also be implemented in other embodiments without these specific details.

[0030] The phrases such as "one embodiment" or "some embodiments" described in the present application mean that the specific features, structures or characteristics described in the embodiment are included in one or more embodiments of the present application. Therefore, the phrases such as "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments" etc. that appear in different places in the present application do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways.

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] See also Figure 1 The figure is a flow chart of a method for suppressing broadband oscillation of a three-phase grid-connected inverter in a specific embodiment, the method comprising: S1. Based on the voltage feedback channel, the feedback value is configured to the current control inner loop of the three-phase grid-connected inverter, and the sequence impedance model of the three-phase grid-connected inverter is obtained.

[0033] In some embodiments, a voltage feedback channel is defined, and the feedback voltage signal is introduced into the current control inner loop of the three-phase grid-connected inverter. A sequence impedance model is established, and after the voltage feedback is introduced into the current control inner loop, the sequence impedance model of the three-phase grid-connected inverter is established.

[0034] This embodiment introduces voltage feedback to improve the dynamic response characteristics of the current control inner loop and enhance the power system's ability to suppress grid voltage disturbances. The oscillation characteristics of the established sequence impedance model can provide an analytical basis for oscillation suppression strategies.

[0035] It can be seen that this embodiment reduces the impact of grid voltage fluctuation on the inverter output current and improves grid-connected stability by optimizing the current control inner loop.

[0036] S2. Define the sequence impedance denominator as 0 and configure the voltage feedback channel transfer function.

[0037] In some embodiments, based on the sequence impedance model, the denominator is set to 0 to solve the oscillation frequency or resonance point of the system, and then the transfer function of the voltage feedback channel is configured according to the solved oscillation frequency or resonance point.

[0038] It can be seen that this embodiment can identify the oscillation mode and the resonance point by defining the sequence impedance denominator as 0. Then, according to the identified oscillation mode, the transfer function of the voltage feedback channel is optimized to improve the oscillation suppression effect: by optimizing the voltage feedback channel, the suppression capability of specific frequency oscillation is improved.

[0039] S3. Detect the oscillation frequency of the grid-connected voltage of the three-phase grid-connected inverter using a fast Fourier algorithm.

[0040] In this embodiment, the waveform data of the grid-connected voltage of the three-phase grid-connected inverter is collected in real time, and the collected voltage waveform data is subjected to fast Fourier transform to convert the time domain signal into a frequency domain signal. In this way, the oscillation frequency component can be identified in the frequency domain signal.

[0041] Optionally, the oscillation frequency component in the grid voltage is monitored in real time by using an FFT algorithm, so that an oscillation event in the grid voltage can be detected.

[0042] S4: Calculate an equivalent factor according to the detected oscillation frequency, and replace the equivalent factor with an imaginary unit in the voltage feedback channel transfer function for equivalent transformation, so that the voltage feedback channel before and after the equivalent has the same amplitude and phase response at the oscillation frequency.

[0043] This embodiment can calculate the equivalent factor according to the detected oscillation frequency. The method can ensure that the voltage feedback channel before and after the equivalent transformation has the same amplitude and phase response at the oscillation frequency based on complex number operations and mathematical derivation.

[0044] For equivalent transformation, the calculated equivalent factor can be used to replace the imaginary unit in the voltage feedback channel transfer function to perform equivalent transformation. In this way, the voltage feedback channel is ensured to have the same amplitude and phase response characteristics at the oscillation frequency as before the transformation through equivalent transformation.

[0045] S5: According to the detected oscillation frequency, a digital peak filter of the corresponding frequency is obtained, and based on the phase response of the digital peak filter, a delay coefficient of the delay device is calculated to perform frequency component selection and phase correction.

[0046] This embodiment may configure a digital peak filter, and design a digital peak filter of a corresponding frequency according to the detected oscillation frequency, so as to ensure that the filter has the desired amplitude-frequency and phase-frequency response characteristics at a specific frequency.

[0047] This embodiment can calculate the delay coefficient of the delay device based on the phase response characteristics of the digital spike filter to ensure that the delay device can compensate for the phase delay introduced by the filter.

[0048] When selecting and correcting frequency components, a component of a specific frequency can be selected through a digital spike filter, and a phase correction can be performed through a delay device to ensure that the voltage feedback channel has an accurate amplitude and phase response at the oscillation frequency.

[0049] S6: The grid-connected voltage dq-axis signal, which is subjected to frequency component selection by a digital spike filter and phase correction by a delay device, is used as the input of the voltage feedback transfer function, and the output of the voltage feedback transfer function is added to the current inner loop as an additional quantity, so as to reshape the impedance characteristics of the oscillation frequency and realize oscillation suppression of the frequency.

[0050] In some embodiments, the dq axis signal of the grid-connected voltage is subjected to frequency component selection through a digital peak filter, and phase correction processing is performed through a delay device. The processed dq axis signal is then used as an input of a voltage feedback transfer function. By using the processed dq axis signal as an input of the voltage feedback transfer function, suppression of specific frequency oscillation is achieved.

[0051] The wide-band oscillation suppression method of the three-phase grid-connected inverter of this embodiment achieves precise suppression of specific frequency oscillations by introducing voltage feedback, establishing a sequence impedance model, detecting the oscillation frequency, performing equivalent transformation, configuring a digital spike filter and a delay device, thereby improving the stability and performance of the three-phase grid-connected inverter in a complex power grid environment.

[0052] Further, as a refinement and expansion of the specific implementation of the above embodiment, in order to fully illustrate the specific implementation process of this embodiment, as shown below Figure 2 As shown, the specific implementation process of the wide-band oscillation suppression method of the three-phase grid-connected inverter is provided below.

[0053] S101. Based on the voltage feedback channel, a feedback value is configured to the current control inner loop of the three-phase grid-connected inverter, and a sequence impedance model of the three-phase grid-connected inverter is obtained.

[0054] In some embodiments, the three-phase grid-connected inverter may adopt an L-type filter structure, as shown in FIG. Figure 3 shown. Figure 3 middle, , , is the grid voltage, , , is the grid-connected current; , They are filter inductor and filter resistor respectively; , are the DC side capacitance and DC voltage of the inverter respectively; is the grid-connected voltage phase angle output by the phase-locked loop; is the phase-locked loop transfer function; , The d-axis and q-axis components of the grid-connected voltage are obtained by park transformation; , The d-axis and q-axis components of the grid-connected current obtained by park transformation; , are the reference values ​​of the d-axis and q-axis components of the grid-connected current; is the transfer function of the inner current loop; , are the d-axis and q-axis components of the bridge arm voltage of the three-phase grid-connected inverter.

[0055] like Figure 4 As shown, it is the current inner loop structure of the additional voltage feedback channel of the three-phase grid-connected inverter in step S1.

[0056] like Figure 4 middle is the angular frequency of the fundamental voltage; is the transfer function of the voltage feedback channel. , go through The output added to the inner current loop is called an additional voltage feedback channel.

[0057] Derivation of positive sequence impedance of three-phase grid-connected inverter after adding voltage feedback channel based on harmonic linearization method and negative sequence impedance for:

[0058]

[0059] in, The phase angle at which the grid-connected fundamental frequency voltage leads the grid-connected fundamental frequency current; is the amplitude of the fundamental frequency component of the grid-connected current; is the amplitude of the fundamental frequency component of the grid-connected voltage. is a positive sequence disturbance (assuming the frequency is ) is an expression related to the phase-locked loop transfer function, is a negative sequence disturbance (assuming the frequency is ) is an expression related to the phase-locked loop transfer function, , are constants related to system parameters, and their expressions are: ; ; ; .

[0060] This embodiment takes the positive sequence impedance as an example. Figure 6 The red solid line is the theoretical impedance value of the channel without voltage feedback; the blue solid line is the theoretical impedance value with voltage feedback; the red circle is the impedance measurement value without voltage feedback obtained by frequency sweep; the green plus sign is the impedance measurement value with voltage feedback obtained by frequency sweep.

[0061] It can be seen that the sequence impedance model derived from the impedance theoretical value without voltage feedback and the impedance theoretical value with voltage feedback are both correct.

[0062] S102, define the sequence impedance denominator as 0, and configure the voltage feedback channel transfer function.

[0063] In this embodiment, the voltage feedback channel transfer function is:

[0064]

[0065] In order to achieve the effect of impedance reshaping, the present embodiment makes and The denominator is 0, so we get expression.

[0066] This embodiment of is the voltage feedback channel transfer function applicable to positive sequence disturbance ; is the voltage feedback channel transfer function applicable to negative sequence disturbance .

[0067] S103, using a fast Fourier algorithm to detect the oscillation frequency of the grid-connected voltage of the three-phase grid-connected inverter.

[0068] In this embodiment, the voltage signal can be subjected to a fast Fourier transform algorithm FFT analysis to obtain the spectrum information of the signal. The fast Fourier transform algorithm FFT analysis can obtain the amplitude and phase information of different frequency components in the signal. By analyzing the FFT results, the oscillation frequency component in the grid-connected voltage can be identified.

[0069] Based on the oscillation frequency detected by FFT, combined with the control strategy of the grid-connected inverter and the characteristics of the power grid, the oscillation mechanism is analyzed. According to the oscillation mechanism, the corresponding oscillation suppression is formulated. The formulated oscillation suppression can be applied to the control process of the grid-connected inverter.

[0070] S104, calculating an equivalent factor according to the detected oscillation frequency, and replacing the imaginary unit in the voltage feedback channel transfer function with the equivalent factor to perform an equivalent transformation, so that the voltage feedback channel before and after the equivalence has the same amplitude and phase response at the oscillation frequency.

[0071] In this embodiment, the formula for calculating the equivalent factor is:

[0072] When the detected oscillation frequency is hour, exist Frequency and Imaginary Units Equivalent; when the detected oscillation frequency is hour, exist Frequency and Imaginary Units Equivalent; replace it , In , the equivalent transfer function is:

[0073]

[0074] After making equivalent substitutions, , In and , and exist , The amplitude and phase responses are the same.

[0075] In positive order and For example, Figure 7 Shows the before and after and For example, at the target frequency ( ) have the same amplitude-frequency response and phase-frequency response.

[0076] S105 . Obtain a digital peak filter of a corresponding frequency according to the detected oscillation frequency, calculate a delay coefficient of a delay device based on a phase response of the digital peak filter, and perform frequency component selection and phase correction.

[0077] The amplitude-frequency response of the ideal peak filter in this embodiment is:

[0078] in, is the amplitude response of the digital peak filter, expressed as:

[0079] This embodiment can filter out , The medium frequency is not or The amount.

[0080] After being processed by the digital spike filter, , Contains only or However, due to the phase-frequency response of the digital filter, This produces a phase shift, so setting is the delay time of the delay device for phase correction.

[0081] The calculation formula is:

[0082] in, The digital peak filter calculated by Matlab is Phase response at frequency; The digital peak filter calculated by Matlab is The phase response at the frequency. According to the above formula, the phase shift caused by the digital peak filter can be offset by the delay device, thereby realizing the frequency component selection without phase shift.

[0083] Figure 8 The peak frequency calculated by Matlab is The magnitude response of the digital spike filter, Fig. 9 is the phase response. It can be seen that at the target frequency The filter response is 1 only near the peak, and the rest of the frequencies are close to 0.

[0084] According to this peak filter Phase response calculate , and set it as the coefficient of the delay to offset the phase response caused by the peak filter. The correction result is as follows Fig.10 shown.

[0085] Fig.10 The red solid line is the original Signal, blue is after peak filter filtering and phase correction Signal, in order to see the effect of phase correction more clearly, set the original The signal contains only After a period of time, the two signals overlap, indicating that the phase correction is successful and the phase offset caused by the spike filter is eliminated.

[0086] S106. The grid-connected voltage dq-axis signal, which is subjected to frequency component selection by a digital spike filter and phase correction by a delay device, is used as the input of a voltage feedback transfer function, and the output of the voltage feedback transfer function is added as an additional quantity to the current inner loop, so as to reshape the impedance characteristics of the oscillation frequency and realize oscillation suppression of the frequency.

[0087] In this embodiment, the frequency selection module, phase correction module, and amplitude-frequency response module formed by the digital peak filter combined with the delay device and the voltage feedback channel are called a complete oscillation suppression damping channel. Figure 5 As shown, Figure 5 medium signal First, it enters the digital peak filter to select the frequency component, and then enters the frequency selection module, phase correction module, and amplitude-frequency response module formed by the delay device and the voltage feedback channel, realizing the signal processing of the oscillation suppression damping channel.

[0088] In this embodiment, , First, the frequency components are selected through the digital peak filter. After being processed by the digital peak filter, , Contains only or However, due to the phase-frequency response of the digital filter, This produces a phase shift, so setting is the delay time of the delay device to perform phase correction. At this time, the signal obtained only contains the frequency components and no frequency offset , Or only the frequency components and no frequency offset , .

[0089] and go through The positive sequence impedance The denominator of is 0, thus suppressing the frequency Similarly, , go through The positive sequence impedance The denominator of is 0, thus suppressing the frequency oscillation.

[0090] This embodiment of Fig.11A simulation example is used to illustrate. The positive sequence impedance of the three-phase grid-connected inverter is realized in red, and the black is realized as the grid impedance. It can be seen that the two meet the oscillation condition at 474Hz, that is, the amplitude is equal, the phase difference is 180°, and the system will oscillate with a frequency of 474Hz. After the damping channel designed by the present invention, the impedance of the system impedance only changes at 474Hz, and does not affect other impedance characteristics, as shown by the red circle in the figure. At this time, the oscillation should be suppressed. The specific time domain simulation results are shown in Fig.12 shown. Fig.12 It means that the oscillation in the previous second is successfully suppressed after being put into the damping channel designed by the present invention in the first second, which verifies the effectiveness of the present invention.

[0091] like Fig.13 As shown, the present application also provides an electronic device, including: a display module 103, a memory 102, a processor 101, and a computer program stored in the memory 102 and executable on the processor 101, wherein the processor 101 implements the steps of the three-phase grid-connected inverter wide-band oscillation suppression method when executing the program.

[0092] Those skilled in the art will appreciate that the electronic device structure involved in the embodiments of the present invention does not constitute a limitation on the electronic device, and the electronic device may include more or fewer components than shown, or combine certain components, or arrange different components. In the embodiments of the present invention, the electronic device includes but is not limited to a laptop computer, a desktop computer, a workbench, a personal digital assistant, a server, a blade server, a mainframe computer, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the embodiments of the present application described and / or required herein.

[0093] In the embodiment of the present application, the processor 101 can be implemented by using at least one of an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), a processor, a controller, a microcontroller, a microprocessor, and an electronic unit designed to perform the functions described herein. In some cases, such an implementation can be implemented in a controller. For software implementation, implementations such as processes or functions can be implemented with separate software modules that allow execution of at least one function or operation. The software code can be implemented by a software application (or program) written in any appropriate programming language, and the software code can be stored in a memory and executed by a controller.

[0094] The display module 103 is used to display information input by the user or information provided to the user. The display module 103 may include a display panel, which may be configured in the form of a liquid crystal display (LCD), an organic light-emitting diode (OLED), etc.

[0095] The memory 102 may be used to store software programs and various data. The memory may include a high-speed random access memory and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0096] In addition, the electronic device includes some functional modules not shown, which will not be described in detail here.

[0097] The present application also provides a storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the steps of the method for suppressing wide-band oscillation of a three-phase grid-connected inverter.

[0098] The storage medium can adopt any combination of one or more readable media. The readable medium can be a readable signal medium or a readable storage medium. The readable storage medium can be, for example, but not limited to, a system, device or device of electricity, magnetism, light, electromagnetic, infrared, or semiconductor, or any combination of the above. More specific examples (non-exhaustive list) of readable storage media include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0099] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for suppressing broadband oscillation of a three-phase grid-connected inverter, characterized in that: Methods include: S1. Based on the voltage feedback channel, the feedback value is configured to the current control inner loop of the three-phase grid-connected inverter, and the sequence impedance model of the three-phase grid-connected inverter is obtained; S2. Define the denominator of the sequence impedance as 0 and configure the voltage feedback channel transfer function; S3, using a fast Fourier algorithm to detect the oscillation frequency of the grid-connected voltage of the three-phase grid-connected inverter; S4. Calculate an equivalent factor according to the detected oscillation frequency, and replace the equivalent factor with an imaginary unit in the voltage feedback channel transfer function for equivalent transformation, so that the voltage feedback channel before and after the equivalent has the same amplitude and phase response at the oscillation frequency; S5. According to the detected oscillation frequency, a digital peak filter of the corresponding frequency is obtained, and a delay coefficient of the delay device is calculated based on the phase response of the digital peak filter to perform frequency component selection and phase correction; S6. The grid-connected voltage dq-axis signal, which is subjected to frequency component selection by a digital spike filter and phase correction by a delay device, is used as the input of the voltage feedback transfer function, and the output of the voltage feedback transfer function is added to the current inner loop as an additional quantity, so as to reshape the impedance characteristics of the oscillation frequency and realize oscillation suppression of the frequency.

2. The method for suppressing broadband oscillation of a three-phase grid-connected inverter according to claim 1, characterized in that: Step S1 also includes: defining the positive sequence impedance of the three-phase grid-connected inverter and negative sequence impedance for: in, The phase angle at which the grid-connected fundamental frequency voltage leads the grid-connected fundamental frequency current; is the amplitude of the fundamental frequency component of the grid-connected current; is the amplitude of the fundamental frequency component of the grid-connected voltage; is the expression related to the phase-locked loop transfer function under positive sequence disturbance, is the expression related to the phase-locked loop transfer function under negative sequence disturbance, , is a constant, , They are filter inductor and filter resistor respectively; , are the DC side capacitance and DC voltage of the inverter respectively; is the grid-connected voltage phase angle output by the phase-locked loop; is the phase-locked loop transfer function; , The d-axis and q-axis components of the grid-connected voltage are obtained by park transformation; , The d-axis and q-axis components of the grid-connected current obtained by park transformation; , are the reference values ​​of the d-axis and q-axis components of the grid-connected current; is the transfer function of the inner current loop; , are the d-axis and q-axis components of the bridge arm voltage of the three-phase grid-connected inverter.

3. The method for suppressing broadband oscillation of a three-phase grid-connected inverter according to claim 2, characterized in that: In the method, , , , The expressions are: 。 4. The method for suppressing broadband oscillation of a three-phase grid-connected inverter according to claim 1 or 2, characterized in that: In step S2, define the sequence impedance denominator as 0 and configure the voltage feedback channel transfer function , voltage feedback channel transfer function Includes: Voltage feedback channel transfer function for positive sequence disturbances And the voltage feedback channel transfer function for negative sequence disturbances ; 。 5. The method for suppressing broadband oscillation of a three-phase grid-connected inverter according to claim 4, characterized in that: In step S4, the formula for calculating the equivalent factor is: 。 6. The method for suppressing broadband oscillation of a three-phase grid-connected inverter according to claim 5, characterized in that: The transfer function after equivalent transformation is: 。 7. The method for suppressing broadband oscillation of a three-phase grid-connected inverter according to claim 1 or 2, characterized in that: The amplitude-frequency response of the peak filter in S5 is: 。 in, is the amplitude response of the digital peak filter, expressed as: 。 8. The method for suppressing broadband oscillation of a three-phase grid-connected inverter according to claim 7, characterized in that: In step S5, the delay time of the delay device is set , to perform phase correction, The calculation formula is: in, The digital peak filter calculated by Matlab is Phase response at frequency; The digital peak filter calculated by Matlab is Phase response at frequency.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the steps of the method for suppressing wide-band oscillation of a three-phase grid-connected inverter as claimed in any one of claims 1 to 7 are implemented.

10. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for suppressing wide-band oscillation of a three-phase grid-connected inverter as claimed in any one of claims 1 to 7 are implemented.

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