Active-disturbance-rejection control method with fast periodic harmonic signal suppression capability

Abstract

The invention relates to an active-disturbance-rejection control method with a fast periodic harmonic signal suppression capability, and the method comprises the steps: building a kinetic model based on the controlled object parameters of a single-phase grid-connected inverter; based on the kinetic model, constructing an ESO based on a plug-in repetitive controller; and carrying out harmonic current suppression on the single-phase grid-connected inverter by using the ESO based on the plug-in repetitive controller. According to the invention, plug-in repetitive control is embedded into a disturbance error observation channel of ESO, and an active-disturbance-rejection control method with a rapid periodic harmonic signal suppression capability is provided. According to the method, the limitation of the ESO observation bandwidth is broken through, and the high-frequency harmonic suppression capability of the ESO is improved. And the repetitive controller is designed based on a perfect cancellation theory, so that the error convergence speed of the repetitive controller is improved, and the harmonic suppression capability of the control system is further optimized.

Description

Technical Field

[0001] The present invention relates to the technical field of auto-disturbance rejection control, and in particular to an auto-disturbance rejection control method with the ability to suppress fast-periodic harmonic signals. Background Art

[0002] In recent years, renewable energy power generation technology has been vigorously developed. As a key device for renewable energy power generation, power electronic inverters play a vital role in energy conversion and storage. However, with the continuous expansion of renewable energy power generation, the power system presents the "double high" characteristics of "high proportion of renewable energy" and "high proportion of power electronics". In weak grid conditions, single-phase grid-connected inverters face a large amount of harmonic interference caused by non-ideal factors such as grid voltage distortion, which seriously threatens the stable operation of the grid-connected inverter system. Active disturbance rejection control (ADRC) can regard the adverse factors affecting the control performance of the system as total disturbances, and use the extended state observer (ESO) to estimate and compensate the total disturbance to improve the system's anti-disturbance ability. However, as an important component of ADRC, the observation bandwidth of ESO is limited by sensor noise, resulting in insufficient estimation of rapidly changing sinusoidal interference signals, which limits the application of ADRC in grid-connected inverters.

[0003] Active disturbance rejection control (ADRC) defines the disturbance and modeling uncertainty faced by the system as "total disturbance", and estimates and compensates the total disturbance through the extended state observer (ESO), thereby achieving disturbance suppression capability. In view of the problem that the grid impedance uncertainty and model parameter perturbation of the grid-connected inverter system under weak power grids lead to the degradation of system control performance or even instability, some scholars use ADRC to improve the robustness of the three-phase grid-connected inverter system under weak power grid conditions. In this method, the sinusoidal reference signal and the sinusoidal disturbance signal are transformed into constant or slowly changing disturbance signals in the framework of a synchronous rotating coordinate system, and then the total disturbance of the three-phase grid-connected inverter system is estimated and compensated by ESO. However, in the two-phase stationary coordinate system, the total disturbance of the single-phase grid-connected inverter system mainly exists in the form of a large number of rapidly changing sinusoidal signals. The above-mentioned method of active disturbance rejection current control method is difficult to achieve high-precision estimation and compensation of a large number of rapidly changing high-frequency sinusoidal interference signals in the single-phase grid-connected inverter system. This will lead to a decrease in the control performance of the ADRC control system and fail to guarantee the quality of the power output in the single-phase grid-connected inverter. Therefore, in order to improve the anti-interference ability and output power quality of the new energy single-phase grid-connected inverter system, it is necessary to study an auto-disturbance control technology with the ability to suppress fast-cycle harmonic signals. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the traditional anti-disturbance control controller estimates a large number of rapidly changing harmonic interference signals under weak power grids inaccurately, resulting in a decrease in the control performance of the grid-connected inverter system. The present invention discloses an anti-disturbance control technology with the ability to suppress fast periodic harmonic signals. The plug-in repetitive controller has excellent harmonic suppression capability and a relatively fast dynamic response speed. It is embedded in the linear extended state observer of the anti-disturbance control controller to enhance the observation accuracy and speed of the linear extended state observer for harmonic disturbance signals, thereby enhancing the estimation accuracy and compensation capability of the anti-disturbance control controller for current harmonic signals. The anti-disturbance control technology with the ability to suppress fast periodic harmonic signals proposed by the present invention not only retains the robustness of the traditional anti-disturbance control technology under the uncertainty of system modeling, but also can effectively suppress periodic harmonic interference signals. The anti-disturbance control technology with the ability to process fast periodic harmonic signals proposed by the present invention makes up for the disadvantage that the traditional anti-disturbance control technology cannot effectively process periodic harmonic signals, and expands the application scope of the anti-disturbance control controller.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] An auto-disturbance rejection control method with the ability to suppress fast-periodic harmonic signals, comprising:

[0007] Based on the controlled object parameters of the single-phase grid-connected inverter, a dynamic model is constructed;

[0008] Based on the dynamic model, an ESO based on an insertable repetitive controller is constructed;

[0009] The ESO based on the plug-in repetitive controller is used to suppress harmonic current of a single-phase grid-connected inverter.

[0010] Optionally, the controlled object parameters include: inverter side filter inductance, grid voltage, DC side input voltage, switching frequency, sampling frequency, and dead time.

[0011] Optionally, the differential equation of the kinetic model is:

[0012]

[0013] Among them, i g (s) represents the grid-connected current, u inv (s) represents the voltage on the inverter side, L represents the filter inductance on the inverter side, and s represents the Laplace operator.

[0014] Optionally, a method of constructing an ESO based on a plug-in repetitive controller includes:

[0015] Perform a first-order Taylor expansion on the differential equation of the dynamic model to obtain its difference equation in the discrete time domain, and construct a traditional ESO framework; design a plug-in repetitive controller based on perfect cancellation theory, including an internal model filter and a low-pass filter;

[0016] The above plug-in repetitive controller is embedded into the traditional ESO framework, and an active disturbance rejection control method with the ability to suppress fast periodic harmonic signals is obtained.

[0017] Optionally, the internal model filter is:

[0018] Q(z)=0.25z+0.5+0.25z -1

[0019] Where Q(z) represents the internal model filter, and z represents the variable in the complex frequency domain;

[0020] The low-pass filter is:

[0021]

[0022] Among them, S(z) represents a low-pass filter, G PI (z) = 2w0 + w0 2 T s z / (z-1), ω0 is the observer bandwidth, T s Indicates the sampling time.

[0023] Optionally, the ESO of the plug-in repetitive controller is expressed as:

[0024]

[0025] Among them, G RC (z) = k r G CRC (z)S(z), k r represents the repetitive controller gain, S(z) represents the low-pass filter, G CRC (z) represents the discrete transfer function of the traditional repetitive controller, represents the current estimation signal at the previous moment, Represents the current estimation signal at the current moment, T s represents the sampling time, b0=1 / L0, L0 is the known part of the model, u k (z) represents the control signal at the current moment, E k (z) represents the error signal at the current moment, i g,k (z) represents the output current of the control system at the current moment, Represents the disturbance estimation signal of the previous moment, h1=2w0, h2=w0 2 , w0 is the observation bandwidth of ESO, G RC (z) represents an insertable repetitive controller, represents the integrator output signal at the previous moment, Represents the integrator output signal at the current moment.

[0026] The beneficial effects of the present invention are:

[0027] The present invention embeds the plug-in repetitive control into the disturbance error observation channel of the ESO, and proposes an auto-disturbance rejection control method with the ability to suppress fast periodic harmonic signals. This method breaks through the limitation of the ESO observation bandwidth and improves the ESO's ability to suppress high-frequency harmonics. The repetitive controller is designed based on the perfect cancellation theory, which improves the error convergence speed of the repetitive controller and further optimizes the harmonic suppression ability of the control system. The effectiveness of the proposed control strategy is proved by experiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0029] Figure 1This is a flow chart of an auto-disturbance rejection control method with fast periodic harmonic signal suppression capability according to an embodiment of the present invention;

[0030] Figure 2 A schematic diagram of the structure of a single-phase grid-connected inverter system according to an embodiment of the present invention;

[0031] Figure 3 A structural block diagram of an auto-disturbance rejection control technology for suppressing fast periodic harmonic signals according to an embodiment of the present invention;

[0032] Figure 4 A comparison diagram of the harmonic disturbance suppression capabilities of the conventional ADRC and ADRCFPHS according to an embodiment of the present invention;

[0033] Figure 5 The current waveform and THD output by the conventional ADRC control system of the embodiment of the present invention; wherein (a) is a waveform diagram of the grid voltage and output current, and (b) is a spectrum analysis diagram of the grid-connected current;

[0034] Figure 6 The current waveform and THD output by the ADRCFPHS control system of the embodiment of the present invention; wherein (a) is a waveform diagram of the grid voltage and output current, and (b) is a spectrum analysis diagram of the grid-connected current;

[0035] Figure 7 When the inductance L=3mH according to the embodiment of the present invention, the current waveform and THD output by the ADRCFPHS control system; wherein (a) is a waveform diagram of the grid voltage and output current, and (b) is a spectrum analysis diagram of the grid-connected current. DETAILED DESCRIPTION

[0036] 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.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] like Figure 1 As shown, this embodiment proposes an auto-disturbance rejection control method with the ability to suppress fast periodic harmonic signals, including:

[0039] Based on the controlled object parameters of the single-phase grid-connected inverter, a dynamic model is constructed;

[0040] Performing a first-order Taylor expansion on the differential equation of the dynamic model to obtain its differential equation in the discrete time domain, and constructing a traditional ESO framework;

[0041] Design of plug-in repetitive controller based on perfect cancellation theory, including internal model filter and low-pass filter;

[0042] The above plug-in repetitive controller is embedded into the traditional ESO framework, and an active disturbance rejection control method with the ability to suppress fast periodic harmonic signals is obtained;

[0043] In view of the problem that the single-phase grid-connected inverter system has poor anti-disturbance capability and reduced output power quality under weak grid conditions with non-ideal factors such as grid voltage distortion and model parameter perturbation, this embodiment proposes an active disturbance rejection control with fast periodic harmonic signals suppression (ADRCFPHS) method with fast periodic harmonic signal suppression capability, embeds a plug-in repetitive controller into the ESO disturbance estimation loop, improves the gain at the frequency of a specific subharmonic disturbance signal, and accurately observes the sinusoidal disturbance signal caused by weak grid background harmonics and model parameter perturbation at a relatively low observation bandwidth. This control strategy not only retains the high-precision tracking capability of the plug-in repetitive controller for a large number of rapidly changing sinusoidal interference signals, but also significantly enhances the robustness of the single-phase grid-connected inverter control system in the face of uncertain factors.

[0044] Specifically, in this embodiment, a dynamic model of the controlled object is established. The structure of a single-phase grid-connected inverter is as follows: Figure 2 As shown in the figure, the inverter system as a controlled system includes four IGBT switches and an L filter, where the equivalent gain of the inverter bridge circuit is k pwm ≈1; the parameters of the controlled object are shown in Table 1 below:

[0045] Table 1. Controlled object parameters

[0046]

[0047] The differential equation from uinv to ig is:

[0048]

[0049] In actual inverter systems, there are bound to be parameter perturbations and inaccurate modeling problems. The nominal value during modeling is called L0. Considering the uncertainty of system modeling and external disturbances caused by grid voltage, the dynamic model of the L-type grid-connected inverter can be restated in the framework of the ADRC as follows:

[0050]

[0051] In the formula, b0=1 / L0 represents the known part of the model; f represents the "total disturbance" that needs to be estimated and compensated, including system modeling uncertainty and external disturbances caused by the power grid, such as grid impedance uncertainty, grid voltage distortion, grid voltage drop and other non-ideal factors in the actual weak grid grid-connected inverter system. The total disturbance f is estimated and compensated by ESO, so that the controlled object is compensated as an integral series type, which is the core idea of ​​the ADRC algorithm to resist internal and external disturbances. However, the observation bandwidth of ESO is limited by sensor noise, resulting in the ADRC can only effectively suppress non-periodic interference, and the ability to suppress periodic interference signals is insufficient, which limits the application of ADRC in single-phase grid-connected inverters.

[0052] Furthermore, building an ESO based on a pluggable repetitive controller includes:

[0053] The differential equation of the grid-connected inverter dynamic model is expanded by first-order Taylor to obtain its differential equation in the discrete time domain and construct a traditional ESO framework.

[0054] Design of plug-in repetitive controller based on perfect cancellation theory, including internal model filter and low-pass filter;

[0055] The above plug-in repetitive controller is embedded into the traditional ESO framework, and an active disturbance rejection control method with the ability to suppress fast periodic harmonic signals is obtained;

[0056] Specifically, in this embodiment, an ESO based on a plug-in repetitive controller is designed. The differential equation of the dynamic model of the L-type grid-connected inverter is subjected to a first-order Taylor expansion, and the differential equation in the discrete time domain is obtained as follows:

[0057] i g,k+1 (z) = i g,k (z)+T s b0u k (z)+T s f k (z)

[0058] The structure diagram of the proposed automatic disturbance rejection control technology with the ability to suppress fast periodic harmonic signals is shown in the figure below. Figure 3 As shown. The reason why the traditional anti-disturbance algorithm cannot effectively suppress the harmonic disturbance signal is that the observation bandwidth of the ESO is limited, resulting in insufficient estimation accuracy of the harmonic disturbance signal. Therefore, the invention optimizes the structure of the ESO by adopting an inserted repetitive controller, thereby improving the estimation accuracy of the ESO for the harmonic disturbance signal, thereby improving the harmonic suppression capability of the anti-disturbance current controller, so that it has the ability to compensate for both periodic and non-periodic disturbances.

[0059] According to the internal model principle, the periodic reference signal is embedded into the internal model, which can achieve error-free tracking of the reference signal and harmonic suppression. The internal model transfer function of the conventional repetitive controller (CRC) is: T0 is the period of the reference signal; converted to a discrete transfer function Among them, G CRC (z) represents the discrete transfer function of the traditional repetitive controller, Q(z) represents the internal model filter, and N = f s / f0, where f s is the sampling frequency, f0 is the reference current frequency; Q(z) is an internal model filter, which can use a low-pass filter or an internal model coefficient to improve the stability of the system and the robustness to frequency fluctuations; N = f s / f ref is the RC control delay number, f s and f ref are the sampling period and the reference signal frequency respectively. Figure 3 As shown in , the repetitive controller is inserted into the ESO disturbance estimation channel to improve the ESO's observation accuracy of harmonic disturbance signals. Figure 3 , the improved ESO expression is as follows:

[0060]

[0061] Among them, G RC (z) = k r G CRC (z)S(z), k r is the repetitive controller gain, S(z) is a low-pass filter used to attenuate the high-frequency signal of the internal model of the repetitive controller to ensure the stability of the control system; T s =0.0001s; h1=2ω0, h2=ω0 2 , where ω0 is the observer bandwidth. According to Figure 3 , the reference current tracking transfer function G of the improved ADRCFPHS control system can be obtained rt (z) and the disturbance rejection transfer function G dr (z) is as follows:

[0062]

[0063] Among them, G PRC (z) = [h1 + h2T s z / (z-1)][1+G RC (z)] The comparison of the total disturbance estimation capabilities of traditional ADRC and ADRCFPHS is shown in Figure 4As shown, it can be seen that the auto-disturbance rejection control technology with the ability to suppress fast periodic harmonic signals proposed in this embodiment not only has stronger disturbance observation accuracy in the low frequency band than the traditional auto-disturbance rejection control technology, but also overcomes the defect that the traditional auto-disturbance rejection controller cannot observe the harmonic disturbance signal.

[0064] Furthermore, an internal model filter Q(z) is designed. The internal model filter Q(z) can be selected as a low-pass filter or a constant less than 1 can be selected as the internal model coefficient. When Q(z) selects a low-pass filter, in the low frequency band (within 1000Hz), |Q(z)|=1, that is, the gain at the resonant frequency less than 1000Hz is infinite, and RC can achieve error-free tracking of signals within the cutoff frequency. At this time, the tracking performance and harmonic suppression effect of the system are excellent. Select Q(z)=0.25z+0.5+0.25z -1 .

[0065] Furthermore, a low-pass filter S(z) is designed. S(z) further improves the stability of the repetitive control system. By properly designing S(z), the robustness and error convergence speed performance of the repetitive control system can be improved. According to the conclusion of the stability analysis, S(z) can be designed based on the complete cancellation theory.

[0066]

[0067] Furthermore, the observer bandwidth ω0 and the control bandwidth k are designed p . The reference current signal frequency of the single-phase grid-connected inverter is 50Hz, and the harmonic frequency is an integer multiple of the fundamental frequency. The observer bandwidth ω0 should be large enough, and the value of ω0 should be in the middle range, not too large or too small, to ensure the estimation accuracy of the ESO for low-frequency periodic disturbances. However, the bandwidth ω0 of the ESO should not be too large, otherwise it will amplify high-frequency noise and cause instability in the self-disturbance rejection control system. Therefore, the bandwidth ω0 of the observer must be balanced between system stability and anti-interference performance. According to the stability analysis, when k r =1, after the repetitive controller compensates the frequency characteristics of the controlled object according to the complete cancellation theory, the stability of the extended state observer of ADRCFPHS is only related to ω0. The harmonic suppression ability of ADRCFPHS is less affected by the bandwidth of the observer. Even if the observer is very small, ADRCFPHS still has a strong harmonic suppression ability at the harmonic frequency, and ω0 = 300π is selected.

[0068] Increase the control bandwidth k p It can improve the dynamic response speed of the ADRC, but k p The larger the value, the smaller the stability margin of the system. Therefore, it is necessary to select a larger k under the premise of ensuring the stability of the control system. p Select k pis 5000.

[0069] Furthermore, the stability of the ADRCFPHS control system is analyzed. According to whether the root of the system characteristic equation is within the unit circle, the stability of the ADRCFPHS closed-loop system is analyzed. Figure 3 It can be seen that the closed-loop transfer function of ESO can be expressed as:

[0070]

[0071] Among them, G PI (z) = h1 + h2T s z / (z-1). The characteristic equation of the ESO closed-loop transfer function can be written as:

[0072] [1-z -1 +G PI (z)T s z -2 ][1-Q(z)z -N +k r Q(z)z -N S(z)P0(z)]=0,

[0073] in, According to the complete cancellation theory, when S(z) = 1 / P0(z), the repetitive controller can obtain superior control performance and has a faster error convergence speed. ESO is implemented by algorithm, and there is no parameter perturbation problem in the actual hardware system. This is conducive to the realization of the complete cancellation theory. Therefore, the stability compensator S(z) can be designed as:

[0074]

[0075] When k r =1, substituting S(z) into the characteristic equation of the ESO closed-loop transfer function yields:

[0076] z 3 -2z 2 +(1+h1T s +h2T s 2 )z-h1T s =0

[0077] According to the Juli criterion, it can be calculated that the roots of the characteristic equation must satisfy the following conditions in the unit circle:

[0078]

[0079] Establish as Figure 2The single-phase grid-connected inverter simulation model shown in the figure is used; the traditional ADRC and ADRCFPHS controllers are used to achieve harmonic current suppression of the new energy single-phase grid-connected inverter, and the quality of the power output of different control systems is observed and compared to verify the effectiveness of the ADRCFPHS method proposed in the present invention. Harmonics are added to the power grid to simulate the weak grid voltage distortion condition. The harmonic content is shown in Table 2, and the grid voltage THD is 7.72%.

[0080] Table 2. Power grid background harmonic content

[0081]

[0082] The current waveform and THD output by the traditional ADRC and ADRCFPHS control systems are as follows: Figure 5 (in, Figure 5 Figure (a) shows the waveform of the grid voltage and output current. Figure 5 (b) is the spectrum analysis diagram of grid-connected current) and Figure 6 (in, Figure 6 Figure (a) shows the waveform of the grid voltage and output current. Figure 6 (b) is the spectrum analysis diagram of the grid-connected current. The experimental results show that the proposed automatic disturbance rejection control technology with the ability to suppress fast-cycle harmonic signals has stronger harmonic suppression capability than the traditional automatic disturbance rejection control technology.

[0083] The modeling uncertainty experiment (inverter circuit parameter perturbation) was conducted to verify the robustness of the anti-disturbance control technology with the ability to suppress fast periodic harmonic signals proposed in this embodiment. The inverter circuit inductance during modeling was 3.8mH. When the actual inductance value of the inductor L was 3mH (parameter perturbation condition), the control technology proposed in this embodiment was used to control the waveform and THD of the system output current. Figure 7 As shown; among them, Figure 7 Figure (a) shows the waveform of the grid voltage and output current. Figure 7 Figure (b) is a spectrum analysis diagram of the grid-connected current. The experimental results show that the self-disturbance rejection control technology with fast periodic harmonic signal suppression capability proposed in this embodiment has excellent harmonic disturbance suppression capability and is robust to modeling uncertainty.

[0084] In view of the problem that the single-phase grid-connected inverter system has poor anti-interference ability and reduced output power quality under weak grid conditions with non-ideal factors such as grid voltage distortion, grid impedance uncertainty, and model parameter perturbation, this embodiment proposes an active disturbance rejection current harmonics suppression (ADRCFPHS) technology with the ability to suppress fast periodic harmonic signals, embeds a plug-in repetitive controller into the ESO disturbance estimation loop, improves the gain at the frequency of specific subharmonic disturbance signals, and accurately observes the sinusoidal disturbance signals caused by weak grid background harmonics and model parameter perturbations at a relatively low observation bandwidth. This control strategy not only retains the high-precision tracking capability of the repetitive controller for a large number of rapidly changing sinusoidal interference signals, but also significantly enhances the robustness of the single-phase grid-connected inverter control system in the face of uncertain factors. The specific advantages are as follows:

[0085] The structure is simple and easy to implement. The block diagram of an auto-disturbance rejection control technology with the ability to suppress fast-cycle harmonic signals is shown in the figure below. Figure 3 As shown in the figure, only an inserted repetitive controller is added to the traditional ESO framework, which has a simple structure. According to the perfect cancellation theory, the parameter design of the inserted repetitive controller is simple, the structure is simple and efficient, and it is easy to implement;

[0086] Strong harmonic suppression capability. By embedding the plug-in repetitive controller into the ESO, a high-precision sinusoidal interference compensation strategy specifically for fast-changing sinusoidal interference signals and model parameter uncertainty is proposed, which accurately estimates and compensates for high-frequency harmonic disturbance signals of a specific order, and enhances the tracking performance of the grid-connected inverter system for the reference current signal and the compensation effect of specific harmonic signals. The comparison of the harmonic disturbance suppression capabilities of the traditional ADRC and ADRCFPHS is shown in the figure below. Figure 4 As shown in the figure, the proposed ADRCFPHS strategy not only has stronger disturbance observation accuracy in the low frequency band than the traditional ADRC strategy, but also overcomes the defect that the traditional ADRC cannot observe harmonic disturbance signals;

[0087] Improve the robustness of the system and strengthen anti-interference ability. By embedding the plug-in repetitive controller into the ESO, the tracking performance of the reference current signal and the compensation effect of the specific subharmonic signal of the self-disturbance rejection control system are enhanced, and the high robustness of the grid-connected inverter system under sinusoidal interference and uncertainty interference is improved. Figure 7 As shown in the figure, when the inverter circuit parameters are perturbed, the proposed control technology can output low THD and high-quality current while having good robustness.

[0088] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. An auto-disturbance rejection control method with the ability to suppress fast-periodic harmonic signals, characterized in that: include: Based on the controlled object parameters of the single-phase grid-connected inverter, a dynamic model is constructed; Based on the dynamic model, an ESO based on an insertable repetitive controller is constructed; The ESO based on the plug-in repetitive controller is used to suppress harmonic current of a single-phase grid-connected inverter.

2. The auto-disturbance rejection control method with the ability to suppress fast-periodic harmonic signals according to claim 1, characterized in that: The controlled object parameters include: inverter side filter inductance, grid voltage, DC side input voltage, switching frequency, sampling frequency, and dead time.

3. The auto-disturbance rejection control method with the ability to suppress fast-periodic harmonic signals according to claim 1, characterized in that: The differential equation of the kinetic model is: Among them, i g (s) represents the grid-connected current, u inv (s) represents the voltage on the inverter side, L represents the filter inductance on the inverter side, and s represents the Laplace operator.

4. The auto-disturbance rejection control method with the ability to suppress fast-periodic harmonic signals according to claim 1, characterized in that: The approach to building an ESO based on a pluggable repetitive controller includes: Performing a first-order Taylor expansion on the differential equation of the dynamic model to obtain its differential equation in the discrete time domain, and constructing a traditional ESO framework; Design of plug-in repetitive controller based on perfect cancellation theory, including internal model filter and low-pass filter; The plug-in repetitive controller is embedded into the traditional ESO framework to obtain the ESO based on the plug-in repetitive controller.

5. The auto-disturbance rejection control method with the ability to suppress fast-periodic harmonic signals according to claim 4, characterized in that: The internal model filter is: Q(z)=0.25z+0.5+0.25z -1 Where Q(z) represents the internal model filter, and z represents the variable in the complex frequency domain; The low-pass filter is: Among them, S(z) represents a low-pass filter, G PI (z) = 2w0 + w0 2 T s z / (z-1), ω0 is the observer bandwidth, T s Indicates the sampling time.

6. The auto-disturbance rejection control method with the ability to suppress fast-periodic harmonic signals according to claim 1, characterized in that: The expression of the ESO of the plug-in repetitive controller is: Where GRC(z)=k r GCRC(z)S(z),k r represents the repetitive controller gain, S(z) represents the low-pass filter, GCRC(z) represents the discrete transfer function of the traditional repetitive controller, represents the current estimation signal at the previous moment, Represents the current estimation signal at the current moment, T s represents the sampling time, b0=1 / L0, L0 is the known part of the model, u k (z) represents the control signal at the current moment, E k (z) represents the error signal at the current moment, i g,k (z) represents the output current of the control system at the current moment, represents the disturbance estimation signal at the previous moment, h1=2w0, h2=w02, w0 is the observation bandwidth of ESO, G RC (z) represents an insertable repetitive controller, represents the integrator output signal at the previous moment, Represents the integrator output signal at the current moment.

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