Inverter control method and system and photovoltaic inverter

Abstract

The invention provides an inverter control method and system and a photovoltaic inverter, and belongs to the technical field of resonance suppression, and the method comprises the steps: carrying out the sampling of a target signal in the inverter, and obtaining the target amplitude and target resonant frequency of the target signal; and then, when the target amplitude is greater than a preset threshold value, inputting the target resonant frequency into a preset parameter control function to obtain a damping control parameter, so that the damping control parameter suitable for the current working condition is calculated when the resonance phenomenon in the inverter is obvious, and the inverter is controlled based on the damping control parameter. Therefore, the damping control parameters can perform targeted damping adjustment on the inverter according to the resonance condition under the current inverter working condition, so that the resonance of the inverter is effectively suppressed while the power loss is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of resonance suppression, and in particular to an inverter control method, system, and photovoltaic inverter. Background Art

[0002] Photovoltaic inverters are used to convert DC power into AC power and connect it to the grid simultaneously. They achieve efficient power conversion by controlling the on and off of switching devices. A photovoltaic inverter includes an inverter bridge and a filtering structure, located between the DC input voltage source and the grid interface. For example, the filtering structure can employ an LCL filter, which includes an inverter-side inductor, a grid-side inductor, and a filter capacitor to smooth the output voltage waveform. However, due to the interaction between the capacitors and inductors in the filtering structure, resonant peaks appear in the filter structure's amplitude-frequency curve, which can easily lead to resonant instability of the photovoltaic inverter.

[0003] Currently, to improve the stability of photovoltaic inverters, a resistor is typically placed in series with the filter capacitor to provide effective damping, increasing the inverter's internal resistance to zero and suppressing resonance. However, if the series resistor is too large, it can easily lead to excessive power loss, while if it is too small, it may not provide sufficient damping to effectively suppress resonance. Therefore, how to effectively suppress the inverter's resonance while reducing power loss is a pressing issue. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present application provides an inverter control method, system and photovoltaic inverter.

[0005] In a first aspect, the present application provides an inverter control method, comprising:

[0006] Sampling a target signal in the inverter; wherein the target signal includes a voltage signal across a filter capacitor of a filter structure in the inverter or a first current signal flowing through an inverter-side inductor;

[0007] Obtaining a target amplitude and a target resonant frequency of the target signal;

[0008] When the target amplitude is greater than a preset threshold, the target resonant frequency is input into a preset parameter control function to obtain a damping control parameter, and the inverter is controlled based on the damping control parameter.

[0009] Optionally, obtaining a target amplitude and a target resonant frequency of the target signal includes:

[0010] Performing spectrum analysis on the target signal through Fourier transform to obtain a frequency domain signal of the target signal;

[0011] The maximum amplitude in the frequency domain signal is used as the target amplitude, and the frequency corresponding to the target amplitude is used as the target resonant frequency.

[0012] Optionally, also include:

[0013] Acquiring a control transfer function of the inverter, and obtaining a damping control function of the inverter according to the control transfer function;

[0014] Obtaining a resonant frequency function of the filtering structure;

[0015] Establishing a correlation function between the control parameter and the damping ratio and the resonant frequency according to the damping control function and the resonant frequency function;

[0016] The preset parameter control function is obtained according to the set target damping ratio and the correlation function.

[0017] Optionally, establishing a correlation function between the control parameter, the damping ratio, and the resonant frequency according to the damping control function and the resonant frequency function includes:

[0018] Obtaining a first corresponding relationship among the damping ratio, the control parameter, and the filter structure parameter according to the damping control function;

[0019] Determining a delay time of the control parameter according to a sampling time of the target signal, and performing Laplace transform on the delay time to obtain a delay parameter;

[0020] Correcting the first corresponding relationship according to the delay parameter to obtain a second corresponding relationship among the delay parameter, the control parameter, and the filter structure parameter;

[0021] Obtaining a third corresponding relationship between the resonant frequency and the filter structure parameters according to the resonant frequency function;

[0022] According to the second corresponding relationship and the third corresponding relationship, a correlation function between the control parameter, the damping ratio and the resonant frequency is established.

[0023] Optionally, obtaining the preset parameter control function according to the target damping ratio and the correlation function includes:

[0024] The delay parameter in the correlation function is calculated using the Euler formula to obtain a delay real number term including the sampling time and the resonant frequency; based on the delay real number term and the target damping ratio, a fourth correspondence between the control parameter and the resonant frequency is obtained in combination with the correlation function, and the fourth correspondence is used as the preset parameter control function.

[0025] Optionally, inputting the target resonant frequency into a preset parameter control function to obtain a damping control parameter includes:

[0026] Get the frequency range corresponding to the positive and negative jump of the damping control parameter;

[0027] When the target resonant frequency is within the frequency range, using a preset parameter as the damping control parameter;

[0028] When the target resonant frequency is not within the frequency range, the target resonant frequency is input into the preset parameter control function to obtain the damping control parameter.

[0029] Optionally, the controlling the inverter based on the damping control parameter includes:

[0030] Acquire a target value of the inverter-side inductor, and obtain a deviation value according to the target value and the first current signal;

[0031] Inputting the deviation value into a preset proportional-integral controller to obtain a proportional-integral control parameter;

[0032] Acquire a second current signal flowing through the filter capacitor, and obtain a damping adjustment parameter according to the second current signal and the damping control parameter;

[0033] A current control parameter is obtained according to the proportional-integral control parameter and the damping adjustment parameter, and the inverter is controlled according to the current control parameter.

[0034] In a second aspect, in one embodiment, the present application provides an inverter control system, including:

[0035] A sampling unit, configured to sample a target signal in the inverter; wherein the target signal is a voltage signal across a filter capacitor of a filter structure in the inverter or a first current signal of an inverter-side inductor;

[0036] a signal processing unit, configured to process the target signal to obtain a target amplitude and a target resonant frequency;

[0037] A control unit is configured to input the target resonant frequency into a preset parameter control function to obtain a damping control parameter when the target amplitude is greater than a preset threshold value, and control the inverter based on the damping control parameter.

[0038] In a third aspect, in one embodiment, the present application provides a photovoltaic inverter comprising a memory and a processor; the memory stores a computer program, and the processor is used to run the computer program in the memory to execute the steps in the inverter control method in any of the above embodiments.

[0039] In a fourth aspect, in one embodiment, the present application provides a storage medium, wherein the storage medium stores a computer program, and the computer program is loaded by a processor to execute the steps in the inverter control method in any of the above embodiments.

[0040] In summary, in this application, first, by sampling the target signal in the inverter and obtaining the target amplitude and target resonant frequency of the target signal, the severity of the resonance phenomenon under the current working condition is obtained. When the target amplitude exceeds the preset threshold value, it means that the resonance phenomenon in the inverter is more obvious. At this time, the target resonant frequency is input into the preset parameter control function to dynamically calculate the damping control parameters suitable for the current working condition, and the inverter is controlled based on the damping control parameters, so that the damping control parameters can be used to adjust the damping of the inverter in a targeted manner according to the resonance condition under the current inverter working condition, thereby avoiding the increase in loss caused by excessive damping or the poor resonance suppression effect caused by too little damping, thereby effectively suppressing the resonance of the inverter while reducing power loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0042] Figure 1 This is a schematic diagram of an inverter structure in one embodiment of the present application;

[0043] Figure 2 This is a flow chart of an inverter control method in one embodiment of the present application;

[0044] Figure 3 A flow chart of a method for generating a preset parameter control function in one embodiment of the present application;

[0045] Figure 4 This is a flow chart of a method for generating a correlation function in one embodiment of the present application;

[0046] Figure 5 A flow chart of a method for generating current control parameters in one embodiment of the present application;

[0047] Figure 6This is a block diagram of an inverter control system in one embodiment of the present application;

[0048] Figure 7 This is a schematic diagram of a photovoltaic inverter in one embodiment of the present application. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0050] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include one or more of the described features. In the description of this application, "plurality" means two or more, unless otherwise specifically qualified. In this application, the word "exemplary" is used to mean "serving as an example, illustration, or illustration." Any embodiment described in this application as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. The following description is provided to enable anyone skilled in the art to implement and use the present application. In the following description, details are listed for illustrative purposes. It should be understood that one of ordinary skill in the art will recognize that the present application can be implemented without these specific details. In other instances, well-known structures and processes are not described in detail to avoid obscuring the description of this application with unnecessary detail. Therefore, this application is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

[0051] As an example of an application scenario of the inverter control method, the inverter control method can be applied to a photovoltaic inverter, or the devices included in the photovoltaic inverter do not constitute a limitation on the embodiments of the present application. That is, the number of devices and types of devices included in the application scenario of the inverter control method, or the number of devices and types of devices included in each device do not affect the overall implementation of the technical solution in the embodiments of the present application, and can all be regarded as equivalent replacements or derivatives of the technical solution claimed to be protected in the embodiments of the present application.

[0052] Reference Figure 1 , Figure 1 The photovoltaic inverter includes a DC input voltage source V dcThe inverter bridge VSC1 and the filter structure between the inverter bridge VSC1 and the grid interface are not specifically limited here. The filter structure may include an inverter side inductor L1, a filter inductor L2, a grid side inductor L g and filter capacitor C1, as an example, the grid voltage u at the grid interface g It can be 600V, the grid frequency f can be 60Hz, and the DC input voltage source V dc The output can be 1300V, and the rated power of the inverter can be 250kW. The inductance value of the inverter-side inductor L1 can be 100uH, the capacitance value of the filter capacitor C1 can be 35uF, and the inductance value of the filter inductor L2 can be 5uH. Here, R represents a virtual resistor implemented through the steps in the inverter control method. The virtual resistor R does not actually consume electrical energy, but is used to change the dynamic characteristics of the inverter, thereby optimizing the inverter's resonance phenomenon.

[0053] Those skilled in the art will understand that the above application scenario is merely an application scenario corresponding to the technical solution of the present application, and does not constitute a limitation on the application scenario of the technical solution of the present application. The photovoltaic inverter may also include a memory for storing information related to the inverter control method.

[0054] It should be noted that the application scenario of the above-mentioned inverter control method is merely an example. The application scenario of the inverter control method described in the embodiment of the present application is intended to more clearly illustrate the technical solution of the embodiment of the present application, and does not constitute a limitation on the technical solution provided in the embodiment of the present application.

[0055] Based on the application scenario of the above inverter control method, an embodiment of the inverter control method is proposed.

[0056] First, as Figure 2 As shown, in one embodiment, the present application provides an inverter control method, which includes steps S11 to S13, which are described in detail below.

[0057] Step S11: sampling the target signal in the inverter.

[0058] The target signal includes the voltage signal across the filter capacitor in the inverter's filter structure or the first current signal flowing through the inverter-side inductor. Because the filter capacitor and the inverter-side inductor are directly connected to the pulse signal output by the inverter's inverter bridge, the voltage signal and the first current signal contain widely distributed harmonics. Due to resonant impedance amplification, the voltage signal and the first current signal are more likely to form prominent harmonic points. Therefore, either the voltage signal or the first current signal can be selected as the target signal.

[0059] Step S12: Obtain the target amplitude and target resonant frequency of the target signal.

[0060] Step S13: When the target amplitude is greater than a preset threshold, the target resonant frequency is input into a preset parameter control function to obtain a damping control parameter, and the inverter is controlled based on the damping control parameter.

[0061] The preset parameter control function is a corresponding relationship between a target resonant frequency and a damping control parameter, so that the corresponding damping control parameter can be quickly obtained after the target resonant frequency is obtained.

[0062] In the above embodiment, first, the target signal in the inverter is sampled, and the target amplitude and target resonant frequency of the target signal are obtained to determine the severity of the resonance phenomenon under the current operating conditions. When the target amplitude exceeds a preset threshold, it indicates that the resonance phenomenon in the inverter is more obvious. At this time, the target resonant frequency is input into a preset parameter control function to dynamically calculate the damping control parameters suitable for the current operating conditions. The inverter is controlled based on the damping control parameters, so that the damping control parameters can be used to adjust the damping of the inverter in a targeted manner according to the resonance conditions under the current inverter operating conditions, thereby avoiding increased losses due to excessive damping or poor resonance suppression effects due to insufficient damping, thereby effectively suppressing the resonance of the inverter while reducing power losses.

[0063] As an implementation of step S12, step S12 includes steps S121 and S122, which are described in detail below.

[0064] Step S121: Perform spectrum analysis on the target signal through Fourier transform to obtain a frequency domain signal of the target signal.

[0065] The frequency domain signal is a spectrum diagram composed of the harmonic content (amplitude) of the target signal at each frequency.

[0066] Step S122: taking the maximum amplitude in the frequency domain signal as the target amplitude, and taking the frequency corresponding to the target amplitude as the target resonant frequency.

[0067] As an example, the target amplitude may appear at the frequency corresponding to a harmonic order in the frequency domain signal, or the target amplitude may appear at the frequencies corresponding to two interval harmonic orders; if the target amplitude has a unique corresponding harmonic order in the frequency domain signal, the frequency corresponding to the harmonic order is used as the target resonant frequency. If the target amplitude appears at the frequencies corresponding to the two interval harmonic orders, the frequency corresponding to the harmonic order between the two interval harmonic orders is taken as the target resonant frequency. For example, if the target amplitude appears at the 74th harmonic and the 76th harmonic, the target resonant frequency can be the frequency corresponding to the 75th harmonic.

[0068] In the above embodiment, a Fourier transform is performed on the target signal to convert the time-domain target signal into a frequency-domain signal. Next, a frequency-domain analysis is used to determine the target amplitude and target resonant frequency. This allows for targeted suppression of the most pronounced resonance in the frequency-domain signal. Suppressing this resonance effectively suppresses resonances at other frequencies, thereby achieving the goal of suppressing resonance at all frequencies.

[0069] Reference Figure 3 As a further implementation of the inverter control method, the inverter control method includes steps S21 to S24, which are described in detail below.

[0070] Step S21: Acquire a control transfer function of the inverter, and obtain a damping control function of the inverter according to the control transfer function.

[0071] As an example, Figure 1 Taking the filter structure shown in the figure as an example, the transfer function can be expressed as:

[0072]

[0073] Among them, L1 is the inductance value of the inverter side inductor, L2 is the inductance value of the filter inductor; L g K is the inductance of the grid-side inductor, which is related to the grid inductive reactance; C1 is the capacitance of the filter capacitor. pwm , K fi , K pi and K ii is the setting parameter in the proportional-integral controller; s is a complex variable that represents the frequency domain characteristics of the control system.

[0074] The damping control function can be expressed as: Among them, K is an unknown control parameter, that is, it is used to obtain the damping control parameter. There is a linear relationship between K and the virtual resistance R. That is, the larger K is, the larger the resistance of the virtual resistance R is, and the greater the damping of the inverter is.

[0075] Step S22: Obtain the resonant frequency function of the filtering structure.

[0076] As an example, Figure 1 Taking the filter structure shown in the figure as an example, the resonant frequency function can be expressed as:

[0077] Among them, ω rRepresents the resonant frequency. In the resonant frequency function, the inductance of the inverter-side inductor, the inductance of the filter inductor, and the capacitance of the filter capacitor are fixed values, while the inductance of the grid-side inductor varies with grid fluctuations. Therefore, the target resonant frequency cannot be accurately determined using the resonant frequency function. Frequency domain analysis is required to determine the target resonant frequency.

[0078] Step S23: establishing a correlation function between the control parameter and the damping ratio and the resonant frequency according to the damping control function and the resonant frequency function.

[0079] As an example, combining the damping control function and the resonant frequency function, the correlation function can be expressed as: Among them, ε vr Represents the damping ratio; K pwm is a known value, and the correlation function is the control parameter K, the damping ratio ε vr and the resonant frequency ω r The corresponding relationship between them.

[0080] Step S24: obtaining a preset parameter control function according to the set target damping ratio and the correlation function.

[0081] As an example, since the filter structure of the inverter is a second-order system, the target damping ratio may be in the range of 0.6-0.8, and the preferred target damping ratio is 0.707.

[0082] As an example, when the target damping ratio is 0.707, the preset parameter control function can be expressed as In the preset parameter control function, only the resonant frequency ω r is an unknown parameter. In the case of resonance suppression, the resonant frequency ω r The target resonant frequency is taken, that is, the resonant frequency corresponding to the maximum amplitude, so that the generated damping control parameters can suppress the most obvious resonance.

[0083] In the above implementation, a damping control function is first derived from the inverter's control transfer function to understand the inverter's damping characteristics. Next, a correlation function is established between the control parameters, the damping ratio, and the resonant frequency, combined with the resonant frequency function of the filter structure, to specifically suppress the most pronounced resonance. Finally, based on the set target damping ratio and the correlation function, a preset parameter control function is derived to obtain the damping control parameters that meet the target damping ratio under the current operating conditions.

[0084] Reference Figure 4 As an implementation of step S23, step S23 includes steps S231 to S235, which are described in detail below.

[0085] Step S231: Obtain a first corresponding relationship between the damping ratio, the control parameter, and the filter structure parameter according to the damping control function.

[0086] Step S232: determining the delay time of the control parameter according to the sampling time of the target signal, and performing Laplace transform on the delay time to obtain the delay parameter.

[0087] As an example, the delay time can be a preset multiple of the sampling time. For example, 1.5 times of the sampling time can be selected as the delay time. The delay parameter can be expressed as Where Ts represents the sampling time.

[0088] Step S233: Correct the first corresponding relationship according to the delay parameter to obtain a second corresponding relationship among the delay parameter, the control parameter and the filter structure parameter.

[0089] As an example, since the execution of the control parameter takes a certain time, it will be affected by the digital delay of the controller. By introducing the delay parameter into the first correspondence, the second correspondence is obtained to offset the influence of the digital delay.

[0090] Step S234: obtaining a third corresponding relationship between the resonant frequency and the filter structure parameters according to the resonant frequency function.

[0091] Step S235: establishing a correlation function between the control parameter, the damping ratio and the resonant frequency according to the second corresponding relationship and the third corresponding relationship.

[0092] As an example, when the delay parameter is introduced, the correlation function can be expressed as:

[0093]

[0094] Furthermore, when the delay parameter is introduced, the preset parameter control function can be expressed as:

[0095]

[0096] In the above embodiment, first, a first correspondence between the damping ratio, the control parameter and the filter structure parameter is established according to the damping control function, and then the delay length of the control parameter is determined according to the sampling time of the target signal, and it is converted into a delay parameter through Laplace transform to quantify the influence of the digital delay. The first correspondence is then corrected using the delay parameter to obtain a second correspondence by introducing the delay parameter, and a third correspondence between the resonant frequency and the filter structure parameter is established according to the resonant frequency function. Finally, by combining the second correspondence and the third correspondence, a correlation function is established between the control parameter and the damping ratio and the resonant frequency. By introducing the correlation function of the delay parameter, the influence of the digital delay brought by the controller is effectively offset, making the suppression of the resonance phenomenon more accurate.

[0097] As an implementation of step S24, step S24 includes steps S241 and S242, which are described in detail below.

[0098] Step S241: Calculate the delay parameter in the correlation function using the Euler formula to obtain a real number term of the delay including the sampling time and the resonant frequency.

[0099] As an example, the delay parameter can be expressed as Since the damping control parameter that has a linear relationship with the virtual resistance R is ultimately required, only the delay real number term cos1.5ω in the delay parameter needs to be considered. r T s Then, for the imaginary term jsin1.5ω r T s It does not affect the generation of the final damping control parameters, so the imaginary term in the delay parameter can be ignored.

[0100] Step S242: obtaining a fourth corresponding relationship between the control parameter and the resonant frequency according to the real number term of the delay and the target damping ratio in combination with the correlation function, and using the fourth corresponding relationship as a preset parameter control function.

[0101] As an example, the preset parameter control function can be expressed as: At this point, just substitute the target resonant frequency into ω r , that is, the damping control parameters can be obtained.

[0102] In the above implementation, the delay parameter in the correlation function is calculated using the Euler formula, resulting in a real-number delay term encompassing the sampling time and the resonant frequency. Combining the target damping ratio with the real-number delay term, a fourth correspondence between the control parameter and the resonant frequency is constructed and used as a predefined parameter control function to achieve more accurate resonance suppression for the inverter.

[0103] As an implementation of step S13, step S13 includes steps S131 to S133, which are described in detail below.

[0104] Step S131: Obtain the frequency range corresponding to the positive and negative jump of the damping control parameter.

[0105] As an example, according to the preset parameter control function, each target resonant frequency has a corresponding damping control parameter. Depending on the target resonant frequency, the damping control parameter can be a positive value or a negative value. When the damping control parameter changes from a positive value to a negative value or from a negative value to a positive value, the damping control parameter undergoes a positive-negative jump.

[0106] As an example, under ideal conditions, the frequency corresponding to the positive and negative jumps of the damping control parameter is πf s / 3; where f s is the target signal sampling frequency. In actual operation, the frequency corresponding to the positive and negative jumps will have errors, so the frequency range is set so that the frequencies corresponding to the positive and negative jumps after the error are also within the frequency range. For example, you can use πf s / 3 sets the frequency range as the center point.

[0107] Step S132: When the target resonant frequency is within the frequency range, the preset parameters are used as damping control parameters.

[0108] As an example, the preset parameter may be a value close to zero, for example, the preset parameter may be +0.05 or -0.05. In this case, even if the sign of the damping control parameter is wrong, the resonance of the inverter will not be aggravated due to its small value.

[0109] Step S133: When the target resonant frequency is not within the frequency range, the target resonant frequency is input into a preset parameter control function to obtain a damping control parameter.

[0110] In the above embodiment, when the target resonant frequency is within the frequency range, the positive and negative sign jump of the damping control parameter may occur. If the damping control parameter calculated by the preset parameter control function is directly used at this time, it may cause the calculated damping control parameter to have a sign opposite to the damping control parameter actually required, resulting in an excessively large error in the damping control parameter. In order to avoid the sign error of the damping control parameter caused by calculation error or inverter fluctuation, the preset parameter is directly used as the damping control parameter, thereby effectively avoiding the resonance aggravation phenomenon caused by the sign error of the damping control parameter. For the case where the target resonant frequency is not within the jump frequency range, the target resonant frequency is input into the preset parameter control function to more accurately calculate the damping control parameter and optimize the effect of resonance suppression.

[0111] Reference Figure 5As an implementation method of controlling the inverter based on the damping control parameter, controlling the inverter based on the damping control parameter includes steps S31 to S34, which are described in detail below.

[0112] Step S31: obtaining a target value of the inverter-side inductor, and obtaining a deviation value according to the target value and the first current signal.

[0113] The target value is a value set according to the actual operation requirements of the inverter.

[0114] Step S32: input the deviation value into a preset proportional-integral controller to obtain proportional-integral control parameters.

[0115] Step S33: obtaining a second current signal flowing through the filter capacitor, and obtaining a damping adjustment parameter according to the second current signal and the damping control parameter.

[0116] Step S34: obtaining a current control parameter according to the proportional-integral control parameter and the damping adjustment parameter, and controlling the inverter according to the current control parameter.

[0117] In the above embodiment, the target value of the inverter-side inductor is first obtained, and the target value is subtracted from the first current signal to obtain a deviation value. The deviation value is input into a preset proportional-integral controller so that the proportional-integral controller can adjust its output according to the input deviation value. Then, the second current signal flowing through the filter capacitor is obtained, and the damping adjustment parameter is calculated in combination with the preset damping control parameter. The damping adjustment parameter is used to characterize the magnitude of the damping in the inverter in order to suppress resonance. Finally, the output of the proportional-integral controller is subtracted from the damping adjustment parameter to obtain a current control parameter. This current control parameter ensures that the inverter can operate according to the predetermined target value while also suppressing the resonance phenomenon generated in the inverter.

[0118] Second, as Figure 6 As shown, in one embodiment, the present application provides an inverter control system, including a sampling unit, a signal processing unit and a control unit.

[0119] The sampling unit is configured to sample a target signal in the inverter. The target signal is a voltage signal across a filter capacitor in the inverter's filter structure or a first current signal in an inverter-side inductor. The signal processing unit is configured to process the target signal to obtain a target amplitude and a target resonant frequency. The control unit is configured to input the target resonant frequency into a preset parameter control function when the target amplitude exceeds a preset threshold value to obtain a damping control parameter, and to control the inverter based on the damping control parameter.

[0120] The sampling unit, the signal processing unit and the control unit are respectively used to execute steps S11 to S13 in the inverter control method.

[0121] In a third aspect, in one embodiment, the present application provides a photovoltaic inverter, such as Figure 7 As shown, it shows the structure of the photovoltaic inverter involved in this application, specifically:

[0122] The photovoltaic inverter may include one or more processing core processors 401, one or more computer-readable storage media memories 402, a power supply 403, an input unit 404 and other components. Those skilled in the art will understand that Figure 7 The structure of the photovoltaic inverter shown in the figure does not constitute a limitation on the photovoltaic inverter, and may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently.

[0123] Processor 401 is the control center of the photovoltaic inverter. It connects all components of the inverter using various interfaces and circuits. By running or executing software programs and / or modules stored in memory 402 and accessing data stored in memory 402, it performs various functions of the photovoltaic inverter and processes data, thereby providing overall monitoring of the photovoltaic inverter. Optionally, processor 401 may include one or more processing cores. Preferably, processor 401 integrates an application processor and a modem processor. The application processor primarily handles the operating system, user interface, and computer programs, while the modem processor primarily handles wireless communications. It is understood that the modem processor may not be integrated into processor 401.

[0124] The memory 402 can be used to store software programs and modules. The processor 401 executes various functional applications and data processing by running the software programs and modules stored in the memory 402. The memory 402 may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system, a computer program required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area may store data created according to the use of the server, etc. In addition, the memory 402 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 device. Accordingly, the memory 402 may also include a memory controller to provide the processor 401 with access to the memory 402.

[0125] The photovoltaic inverter also includes a power supply 403 that supplies power to various components. Preferably, the power supply 403 can be logically connected to the processor 401 via a power management system, thereby enabling the power management system to manage charging, discharging, and power consumption. The power supply 403 can also include one or more DC or AC power supplies, a recharging system, a power failure detection circuit, a power converter or photovoltaic inverter, a power status indicator, and other arbitrary components.

[0126] The photovoltaic inverter may further include an input unit 404 , which may be configured to receive input digital or character information.

[0127] Although not shown, the photovoltaic inverter may also include a display unit, etc., which will not be described in detail here. Specifically, in this embodiment, when the photovoltaic inverter is a model training photovoltaic inverter, the processor 401 in the photovoltaic inverter will load the executable files corresponding to one or more computer program processes into the memory 402 according to the following instructions. The processor 401 then runs the computer program stored in the memory 402 to perform the steps of the inverter control method.

[0128] Those skilled in the art will appreciate that all or part of the steps in any of the methods of the above embodiments may be accomplished by a computer program, or by controlling related hardware through a computer program. The computer program may be stored in a computer-readable storage medium and loaded and executed by a processor.

[0129] In a fourth aspect, in one embodiment, the present application provides a storage medium storing a plurality of computer programs, which can be loaded by a processor to execute steps in the inverter control method.

[0130] It will be understood by those skilled in the art that any reference to memory, storage, database, or other medium used in the various embodiments provided herein may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink), DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM).

[0131] Since the computer program stored in the storage medium can execute the steps in the inverter control method in any embodiment provided in the present application, the beneficial effects that can be achieved by the inverter control method in any embodiment provided in the present application can be achieved. Please refer to the previous embodiments for details and will not be repeated here.

[0132] The specific implementation of the above operations can be found in the previous embodiments and will not be repeated here.

[0133] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, please refer to the detailed description of other embodiments above and will not be repeated here.

[0134] The above is a detailed introduction to an inverter control method, system and photovoltaic inverter provided by the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core ideas of the present application. At the same time, for technical personnel in this field, based on the ideas of the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present application.

[0135] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, 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, they should be considered to be within the scope of this specification.

Claims

1. An inverter control method, characterized in that: include: Sampling a target signal in the inverter; wherein the target signal includes a voltage signal across a filter capacitor of a filter structure in the inverter or a first current signal flowing through an inverter-side inductor; Obtaining a target amplitude and a target resonant frequency of the target signal; When the target amplitude is greater than a preset threshold, the target resonant frequency is input into a preset parameter control function to obtain a damping control parameter, and the inverter is controlled based on the damping control parameter.

2. The inverter control method according to claim 1, characterized in that: The obtaining of the target amplitude and the target resonant frequency of the target signal includes: Performing spectrum analysis on the target signal by Fourier transform to obtain a frequency domain signal of the target signal; The maximum amplitude in the frequency domain signal is used as the target amplitude, and the frequency corresponding to the target amplitude is used as the target resonant frequency.

3. The inverter control method according to claim 2, characterized in that: Also includes: Acquire a control transfer function of the inverter, and obtain a damping control function of the inverter according to the control transfer function; Obtaining a resonant frequency function of the filter structure; According to the damping control function and the resonant frequency function, establishing a correlation function between the control parameter and the damping ratio and the resonant frequency; The preset parameter control function is obtained according to the set target damping ratio and the correlation function.

4. The inverter control method according to claim 3, characterized in that: The step of establishing a correlation function between the control parameter, the damping ratio and the resonant frequency according to the damping control function and the resonant frequency function comprises: According to the damping control function, a first corresponding relationship among the damping ratio, the control parameter and the filter structure parameter is obtained; Determining the delay time of the control parameter according to the sampling time of the target signal, and performing Laplace transform on the delay time to obtain the delay parameter; Correcting the first corresponding relationship according to the delay parameter to obtain a second corresponding relationship between the delay parameter, the control parameter and the filter structure parameter; According to the resonant frequency function, a third corresponding relationship between the resonant frequency and the filter structure parameter is obtained; According to the second corresponding relationship and the third corresponding relationship, a correlation function between the control parameter, the damping ratio and the resonant frequency is established.

5. The inverter control method according to claim 4, characterized in that: The step of obtaining the preset parameter control function according to the target damping ratio and the correlation function comprises: The delay parameter in the correlation function is calculated by using the Euler formula to obtain a delay real number term including the sampling time and the resonant frequency; According to the time delay real number term and the target damping ratio, a fourth corresponding relationship between the control parameter and the resonant frequency is obtained in combination with the correlation function, and the fourth corresponding relationship is used as the preset parameter control function.

6. The inverter control method according to claim 1, characterized in that: The step of inputting the target resonant frequency into a preset parameter control function to obtain a damping control parameter includes: Get the frequency range corresponding to the positive and negative jump of the damping control parameter; When the target resonant frequency is within the frequency range, using a preset parameter as the damping control parameter; When the target resonant frequency is not within the frequency range, the target resonant frequency is input into the preset parameter control function to obtain the damping control parameter.

7. The inverter control method according to claim 1, characterized in that: The controlling the inverter based on the damping control parameter includes: Acquire a target value of the inverter-side inductor, and obtain a deviation value according to the target value and the first current signal; Inputting the deviation value into a preset proportional-integral controller to obtain a proportional-integral control parameter; Acquire a second current signal flowing through the filter capacitor, and obtain a damping adjustment parameter according to the second current signal and the damping control parameter; A current control parameter is obtained according to the proportional-integral control parameter and the damping adjustment parameter, and the inverter is controlled according to the current control parameter.

8. An inverter control system, characterized in that: include: A sampling unit, used to sample a target signal in the inverter; wherein the target signal is a voltage signal across a filter capacitor of a filter structure in the inverter or a first current signal of an inverter-side inductor; A signal processing unit, used to process the target signal to obtain a target amplitude and a target resonant frequency; A control unit is used to input the target resonant frequency into a preset parameter control function to obtain a damping control parameter when the target amplitude is greater than a preset threshold value, and control the inverter based on the damping control parameter.

9. A photovoltaic inverter, characterized in that: It comprises a memory and a processor; the memory stores a computer program, and the processor is used to run the computer program in the memory to execute the steps in the inverter control method according to any one of claims 1 to 7.

10. A storage medium, characterized in that: The storage medium stores a computer program, and the computer program is loaded by a processor to execute the steps in the inverter control method according to any one of claims 1 to 7.

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