Control method and device for grid-connected inverter, storage medium and terminal

Abstract

The invention discloses a control method and device for a grid-connected inverter, a storage medium and a terminal, and the control method comprises the steps: obtaining the frequency of a power grid and a preset QPR controller, calibrating a transfer function of the QPR controller based on the frequency of the power grid, and enabling the resonant frequency of the QPR controller to track a target sinusoidal signal; and obtaining the difference value between the three-phase current and the actual current of the grid-connected inverter as the input of a self-adaptive QPR controller, and controlling the actual output current to track the given current. According to the control method, the resonant frequency and the cut-off frequency of the controller are adjusted by calculating the power grid frequency, and high control gain of the controller can be guaranteed through the adaptive parameters when the power grid frequency deviates greatly.

Description

Technical Field

[0001] The present invention relates to the field of electronic circuit processing technology, and in particular to a control method, device, storage medium and terminal for a grid-connected inverter. Background Art

[0002] For grid-connected inverter control, using QPR control in an ABC coordinate system can mitigate the gain reduction caused by grid frequency deviation to a certain extent. However, when the grid frequency deviates significantly from the rated frequency, the controller gain is significantly reduced, making it impossible to accurately track the command sinusoidal signal. Existing control methods use PR control, which adjusts the resonant frequency of the PR control by online calculation of the grid frequency to ensure tracking of the sinusoidal current signal. However, even small deviations between the calculated grid frequency and the actual frequency can lead to significant attenuation of the controller gain. Summary of the Invention

[0003] In view of this, the main object of the present invention is to provide a control method, device, storage medium and terminal for a grid-connected inverter.

[0004] To achieve the above object, the technical solution of the present invention is implemented as follows: a control method for a grid-connected inverter, wherein the grid-connected inverter is connected to a three-phase power grid; comprising the following steps: obtaining the grid frequency f g and preset QPR controller, based on the grid frequency f g , calibrate the transfer function of the QPR controller so that the resonant frequency of the QPR controller tracks the target sinusoidal signal, the frequency of the target sinusoidal signal is the grid frequency f g The resonant frequency includes: the resonant angular frequency ω n and resonant cutoff frequency ω cn ; Get the preset output current value corresponding to phase A of the grid-connected inverter And the actual sampling current i a , the preset output current value corresponding to phase B And the actual sampling current i b , and the preset output current value corresponding to phase C And the actual sampling current i c ; Get the deviation deviation deviation The deviation Δi a , deviation Δi b and the deviation Δi c Input to the QPR controller; the QPR controller first converts the deviation Δi a , deviation Δi b and the deviation Δic Transform to the stationary αβ coordinate system and obtain Δi α and Δi β , and then use Park transformation to transform Δi α and Δi β Rotate to the synchronously rotating dq coordinate system to generate the direct axis error Δi d and quadrature axis error Δi q ; In the dq coordinate system, based on the preset discretized QPR difference equation for Δi d and Δi q The QPR controller output value is used to adjust the current of the grid-connected inverter.

[0005] As an improvement to the embodiment of the present invention, the "obtaining the grid frequency f g "Specifically includes: obtaining the voltage u corresponding to phase A of the three-phase power grid ga , u corresponding to phase B gb and u corresponding to phase C gc , for the three voltages u ga 、u gb and u gc Perform abc / dq coordinate transformation to obtain the voltage d-axis component u of the power grid d and the q-axis component u q ;Control the voltage q-axis component u of the grid through a digital controller q =0, by introducing the fundamental angular reference frequency ω0 of the power grid into the digital controller output, the angular frequency ω of the power grid is obtained. g , the frequency of the power grid f g =ω g / 2π.

[0006] As an improvement to the embodiment of the present invention, the “based on the grid frequency f g , calibrating the transfer function of the QPR controller so that its resonant frequency tracks a sinusoidal signal that is an integer multiple of the grid frequency" specifically includes: according to the transfer function of the QPR controller, g The input is given to the transfer function of the QPR controller and is calculated based on the grid frequency f g , update the resonant angular frequency ω in the transfer function of the QPR controller n and resonant cutoff frequency ω cn , and the resonant angular frequency ω n and resonant cutoff frequency ω cn The grid frequency is f g An integer multiple of .

[0007] As an improvement to the embodiment of the present invention, the discretized QPR differential equation is specifically: y(k)=b0x(k)+b1x(k-1)+b2x(k-2)-a1y(k-1)-a2y(k-2), wherein y() is the output of the QPR controller, and x() is the input of the QPR controller. b1=k p a1, b2 = k p (1+a2)-b0, n is a natural number, k r is the resonance coefficient of the QPR controller, k p is the proportional coefficient of the QPR controller, T s is the sampling period of the QPR controller.

[0008] As an improvement to an embodiment of the present invention, the “regulating the current of the grid-connected inverter based on the output value of the QPR controller” specifically includes: generating a PWM drive signal based on the output value of the QPR controller, and using the PWM drive signal to control the IGBT switch tube in the grid-connected inverter, thereby regulating the current of the grid-connected inverter.

[0009] The embodiment of the present invention further provides a control device for a grid-connected inverter, wherein the grid-connected inverter is connected to a three-phase power grid; the control device comprises the following modules: an information acquisition module for acquiring a grid frequency f g and preset QPR controller, based on the grid frequency f g , calibrate the transfer function of the QPR controller so that the resonant frequency of the QPR controller tracks the target sinusoidal signal, the frequency of the target sinusoidal signal is the grid frequency f g The resonant frequency includes: the resonant angular frequency ω n and resonant cutoff frequency ω cn ; A first processing module for obtaining a preset output current value corresponding to phase A of the grid-connected inverter And the actual sampling current i a , the preset output current value corresponding to phase B And the actual sampling current i b , and the preset output current value corresponding to phase C And the actual sampling current i c ; Get the deviation deviation deviation The deviation Δi a , deviation Δi b and the deviation Δi c Input to the QPR controller; the QPR controller first converts the deviation Δi a, deviation Δi b and the deviation Δi c Transform to the stationary αβ coordinate system and obtain Δi α and Δi β , and then use Park transformation to transform Δi α and Δi β Rotate to the synchronously rotating dq coordinate system to generate the direct axis error Δi d and quadrature axis error Δi q The second processing module is used to calculate Δi based on the preset discretized QPR differential equation in the dq coordinate system. d and Δi q The QPR controller output value is used to adjust the current of the grid-connected inverter.

[0010] As an improvement of the embodiment of the present invention, the information acquisition module is further used to: obtain the voltage u corresponding to phase A of the three-phase power grid ga , u corresponding to phase B gb and u corresponding to phase C gc , for the three voltages u ga 、u gb and u gc Perform abc / dq coordinate transformation to obtain the voltage d-axis component u of the power grid d and the q-axis component u q ;Control the voltage q-axis component u of the grid through a digital controller q =0, by introducing the fundamental angular reference frequency ω0 of the power grid into the digital controller output, the angular frequency ω of the power grid is obtained. g , the frequency of the power grid f g =ω g / 2π.

[0011] As an improvement of the embodiment of the present invention, the information acquisition module is further used to: according to the transfer function of the QPR controller, the grid frequency f g The input is given to the transfer function of the QPR controller and is calculated based on the grid frequency f g , update the resonant angular frequency ω in the transfer function of the QPR controller n and resonant cutoff frequency ω cn , and the resonant angular frequency ω n and resonant cutoff frequency ω cn The grid frequency is f g An integer multiple of .

[0012] An embodiment of the present invention also provides a terminal, comprising: one or more processors; a memory on which one or more programs are stored, and when the one or more programs are executed by the one or more processors, the one or more processors implement the above-mentioned control method.

[0013] An embodiment of the present invention further provides a storage medium storing a computer program, which implements the above-mentioned control method when executed by a processor.

[0014] The control method, device, storage medium, and terminal for a grid-connected inverter provided by embodiments of the present invention have the following advantages: The control method includes: obtaining a grid frequency and a preset QPR controller; calibrating the transfer function of the QPR controller based on the grid frequency so that the resonant frequency of the QPR controller tracks a target sinusoidal signal; and obtaining the difference between the three-phase current and the actual current of the grid-connected inverter as input to an adaptive QPR controller to control the actual output current to track a given current. By calculating the grid frequency to adjust the resonant frequency and cutoff frequency of the controller, the control method can ensure a high control gain of the controller through adaptive parameters when the grid frequency has a large offset. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic flow chart of a control method for a grid-connected inverter provided in an embodiment of the present invention;

[0016] Figure 2 This is a schematic diagram of a control method for a grid-connected inverter provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0017] The present invention will be described in detail below with reference to the embodiments shown in the accompanying drawings. However, the embodiments do not limit the present invention, and any structural, methodological, or functional changes made by those skilled in the art based on the embodiments are all within the scope of protection of the present invention.

[0018] The following description and accompanying drawings sufficiently illustrate the specific embodiments herein to enable those skilled in the art to practice them. Portions and features of some embodiments may be included in or substituted for portions and features of other embodiments. The scope of the embodiments herein includes the entire scope of the claims, including all available equivalents thereof. Herein, the terms "first," "second," and the like are used solely to distinguish one element from another and do not require or imply any actual relationship or order between these elements. In practice, the first element can also be referred to as the second element, and vice versa. Furthermore, the terms "comprise," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a structure, device, or apparatus comprising a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such structure, device, or apparatus. Without further limitation, an element defined by the phrase "comprising a..." does not preclude the presence of other identical elements in the structure, device, or apparatus comprising the element. The various embodiments herein are described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. Similar or identical parts between the various embodiments can be referenced to each other.

[0019] The terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like used herein to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are intended only to facilitate the description of this document and simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the present invention. In the description herein, unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, they can be mechanical or electrical connections, or they can be internal connections between two elements, they can be directly connected, or they can be indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0020] The first embodiment of the present invention provides a control method for a grid-connected inverter, wherein the grid-connected inverter is connected to a three-phase power grid; Figure 1 and Figure 2 As shown, the following steps are included:

[0021] Step 101: Obtain the grid frequency f g and preset QPR controller, based on the grid frequency f g , calibrate the transfer function of the QPR controller so that the resonant frequency of the QPR controller tracks the target sinusoidal signal, the frequency of the target sinusoidal signal is the grid frequency fg The resonant frequency includes: the resonant angular frequency ω n and resonant cutoff frequency ω cn .

[0022] Step 102: Obtain the preset output current value corresponding to phase A of the grid-connected inverter And the actual sampling current i a , the preset output current value corresponding to phase B And the actual sampling current i b , and the preset output current value corresponding to phase C And the actual sampling current i c ; Get the deviation deviation deviation The deviation Δi a , deviation Δi b and the deviation Δi c Input to the QPR controller; the QPR controller first converts the deviation Δi a , deviation Δi b and the deviation Δi c Transform to the stationary αβ coordinate system and obtain Δi α and Δi β , and then use Park transformation to transform Δi α and Δi β Rotate to the synchronously rotating dq coordinate system to generate the direct axis error Δi d and quadrature axis error Δi q .

[0023] Step 103: In the dq coordinate system, based on the preset discretized QPR differential equation, Δi d and Δi q The QPR controller output value is used to adjust the current of the grid-connected inverter.

[0024] Here, based on the output of the QPR controller and the feedforward of the grid voltage, the response speed of the inverter can be increased and the instantaneous current impact of grid connection can be reduced, and finally a PWM modulation signal is obtained. The PWM modulation signal is compared with the carrier signal to generate a PWM drive signal to drive the IGBT switch tube of the grid-connected inverter.

[0025] The transfer function of the QPR controller is: Among them, k p is the proportionality coefficient, k r is the resonance coefficient, ω cn is the resonant cutoff frequency. n is the resonant angular frequency. From the above formula, we can know that the gain of the QPR controller at the angular frequency ω is: It can be seen that when the frequency ω=ω n When the controller gain is maximum: Amp(ω n )=k p +k r , when the grid fundamental frequency offset is Δω, according to the above formula, its gain at the actual grid fundamental frequency is: Among them, the frequency offset of the nth harmonic is nΔω. According to the gain expression of the controller in the above formula, the gain of the nth harmonic at the actual harmonic frequency is

[0026] To make the grid frequency offset, the QPR controller keeps the gains of the fundamental wave and the nth harmonic consistent, and the formula Amp(ω0+Δω)=Amp(nω0+nΔω) is obtained. In summary, ω cn =nω c0 , In addition, as the angular frequency ω shifts the resonant angular frequency ω n , the controller gain will be significantly attenuated, and the controller cannot achieve the diagonal frequency ω n Accurate tracking of the sinusoidal current command will result in a large steady-state error.

[0027] The control method of the grid-connected inverter proposed in the present invention adjusts the resonant frequency and cutoff frequency of the controller by calculating the grid frequency. When the grid frequency has a large deviation, the controller can ensure a high control gain by adaptive parameters, and can also follow the sinusoidal signal of the high-order harmonics when the calculated frequency has a certain deviation.

[0028] In this embodiment, the "obtaining the grid frequency f g "Specifically includes: obtaining the voltage u corresponding to phase A of the three-phase power grid ga , u corresponding to phase B gb and u corresponding to phase C gc , for the three voltages u ga 、u gb and u gc Perform abc / dq coordinate transformation to obtain the voltage d-axis component u of the power grid d and the q-axis component u q .

[0029] Here, a high-precision ADC (Analog-Digital Conversion) module can be set in the inverter, and the high-precision ADC module can sample the three-phase voltage u of the three-phase grid in real time. ga 、u gb and u gc, and a second-order generalized integrator (SOGI) is used for signal preprocessing to eliminate sampling noise. Then, based on the phase-locked loop (PLL) technology, the Clarke transform is performed on the voltage of the three-phase power grid, and the three-phase stationary coordinate system (abc coordinate system) is converted to a two-phase stationary coordinate system (αβ coordinate system). The αβ coordinate system is then rotated to a synchronous rotating coordinate system (dq coordinate system) through Park transform, and finally the direct axis component u of the voltage of the power grid is obtained. d and quadrature axis component u q Among them, u d The component represents the voltage amplitude information of the power grid, u q The component reflects the phase deviation. This transformation process provides accurate voltage vector information for subsequent reactive power compensation and grid connection control. The entire coordinate transformation process can be implemented using a 32-bit floating-point DSP (Digital Signal Processing).

[0030] The voltage q-axis component u of the grid is controlled by a digital controller q =0, by introducing the fundamental angular reference frequency ω0 of the power grid into the digital controller output, the angular frequency ω of the power grid is obtained. g , the frequency of the power grid f g =ω g / 2π.

[0031] Here, the voltage d-axis component u of the grid can be controlled by a digital controller (such as a PI regulator or a PR regulator). d and the q-axis component u q Closed-loop control is performed, and a feedforward compensation term of the grid's fundamental angular reference frequency ω0 is introduced at the output of the digital controller to offset the phase lag caused by the dynamic frequency change of the grid. After the feedforward signal is superimposed on the output of the digital controller, an adaptive filtering algorithm is used to eliminate high-frequency noise, and then an improved sliding mode observer (SMO) or extended Kalman filter (EKF) is used to estimate the actual angular frequency ω of the grid voltage in real time. g This solution can significantly improve the dynamic response speed of the phase-locked loop and effectively enhance the synchronization stability of the inverter when the grid frequency fluctuates.

[0032] The angular frequency ω of the actual power grid can be estimated in real time gDigital integration (using either a trapezoidal integration method or an improved adaptive integration algorithm) is performed to obtain a highly accurate grid voltage synchronization phase θ. A phase compensation module is incorporated into the integration process to eliminate integration drift errors and ensure long-term phase tracking stability. Simultaneously, based on the physical relationship between angular velocity and frequency (f = ω / 2π), the actual grid frequency f is calculated in real time using a 32-bit fixed-point arithmetic unit. A moving average filter (MAF) or a low-pass filter (LPF) is used to suppress frequency measurement noise. This phase and frequency information is transmitted to a PWM (Pulse Width Modulation) generator via a high-speed SPI (Serial Peripheral Interface), providing a precise reference signal for the inverter's grid-connected synchronization control.

[0033] In this embodiment, the “based on the grid frequency f g , calibrating the transfer function of the QPR controller so that its resonant frequency tracks a sinusoidal signal that is an integer multiple of the grid frequency" specifically includes: according to the transfer function of the QPR controller, g The input is given to the transfer function of the QPR controller and is calculated based on the grid frequency f g , update the resonant angular frequency ω in the transfer function of the QPR controller n and resonant cutoff frequency ω cn , and the resonant angular frequency ω n and resonant cutoff frequency ω cn The grid frequency is f g An integer multiple of .

[0034] Here, the mathematical expression of the transfer function based on the QPR controller is By real-time monitoring of the frequency f of the power grid g , dynamically adjust the key parameters in the transfer function:

[0035] Resonant angular frequency ω n , according to the fundamental frequency relationship of the power grid ω n =2πf g , the resonant center frequency parameters are updated in real time within the digital signal processor (DSP). A hardware-timed interrupt-triggered parameter update mechanism (e.g., a 1kHz refresh rate) ensures that the resonant point always accurately tracks the fundamental frequency when the grid frequency fluctuates within the 45-65Hz range, avoiding the gain attenuation problem of traditional fixed-parameter QPR when the frequency shifts.

[0036] Resonant cutoff frequency ω cn Adaptive adjustment: let the cutoff frequency ω cn=2πΔf (Δf is the allowable frequency deviation), Δf can be set to ±2Hz. When the grid frequency change rate df is detected g When / dt>1Hz / s, automatically widen ω cn To enhance the robustness of the controller to frequency mutations.

[0037] In this embodiment, the discretized QPR differential equation is specifically: y(k)=b0x(k)+b1x(k-1)+b2x(k-2)-a1y(k-1)-a2y(k-2), where y() is the output of the QPR controller and x() is the input of the QPR controller. b1=k p a1, b2 = k p (1+a2)-b0, n is a natural number, k r is the resonance coefficient of the QPR controller, k p is the proportional coefficient of the QPR controller, T s is the sampling period of the QPR controller.

[0038] Here, the QPR controller is implemented in a digital chip, which requires digital discretization of the controller. Tustin transform can be used to discretize the controller. However, Tustin transform can only maintain a good linear relationship between the s domain and the z domain in the low frequency band. Therefore, Tustin transform has higher discretization accuracy when the resonant frequency is low. For higher frequency harmonic components, pre-corrected Tustin transform can be used: Where, ω is the resonant angular frequency to be corrected; T s is the sampling period. Compared with the ordinary Tustin transform, the correction coefficient ω / (tan(ωT s / 2)) instead of the original coefficient 2 / T s , thus ensuring that the controller has equal amplitude at the resonant frequency ω. Thus, the transfer function of the QPR controller in the z domain can be obtained: in, b1=k p a1, b2 = k p (1+a2)-b0, According to the above formula, the differential equation in the digital chip is: y(k)=b0x(k)+b1x(k-1)+b2x(k-2)-a1y(k-1)-a2y(k-2), where y() is the output of the QPR controller and x() is the input of the QPR controller.

[0039] In this embodiment, Figure 2As shown, the "regulating the current of the grid-connected inverter based on the output value of the QPR controller" specifically includes: generating a PWM drive signal based on the output value of the QPR controller, and using the PWM drive signal to control the IGBT switch tube in the grid-connected inverter, thereby regulating the current of the grid-connected inverter.

[0040] Here, based on the control signal output by the QPR controller, it is converted into a PWM drive signal with a specific frequency and duty cycle through the PWM generation module of a digital signal processor (DSP) or a field programmable gate array (FPGA). The carrier frequency of the PWM signal is usually set to a range of several kilohertz to tens of kilohertz (such as 10kHz-20kHz), and the specific value needs to be determined according to the characteristics of the IGBT switch tube and the system design requirements. The generated PWM signal is isolated by an optical coupler and amplified by the drive circuit, and then acts on the gate of the IGBT switch tube on the bridge arm of the grid-connected inverter. By controlling the complementary conduction and shutdown timing of the upper and lower tubes of each phase bridge arm, the output voltage of the inverter AC side is precisely regulated. This regulation mechanism is ultimately reflected in the closed-loop control of the grid-connected current waveform, amplitude and phase, ensuring that the inverter output current and the grid voltage maintain the same frequency and phase, and the total harmonic distortion (THD) meets the grid-connected standard requirements (such as IEEE 1547 or GB / T 19939). At the same time, the system will monitor the range of PWM duty cycle in real time, and ensure that it is adjusted within the effective range (usually 0-100%) through anti-saturation processing to avoid waveform distortion caused by over-modulation.

[0041] In this embodiment, the “based on the grid frequency f g , calibrating the transfer function of the QPR controller so that its resonant frequency tracks a sinusoidal signal that is an integer multiple of the grid frequency" specifically includes: according to the transfer function of the QPR controller, g The input is given to the transfer function of the QPR controller and is calculated based on the grid frequency f g , update the resonant angular frequency ω in the transfer function of the QPR controller n and resonant cutoff frequency ω cn , and the resonant angular frequency ω n and resonant cutoff frequency ω cn The grid frequency is f g An integer multiple of .

[0042] Here, the mathematical expression of the transfer function based on the QPR controller is By real-time monitoring of the frequency f of the power grid g , dynamically adjust the key parameters in the transfer function:

[0043] Resonant angular frequency ω n , according to the fundamental frequency relationship of the power grid ωn =2πf g , the resonant center frequency parameters are updated in real time within the digital signal processor (DSP). A hardware-timed interrupt-triggered parameter update mechanism (e.g., a 1kHz refresh rate) ensures that the resonant point always accurately tracks the fundamental frequency when the grid frequency fluctuates within the 45-65Hz range, avoiding the gain attenuation problem of traditional fixed-parameter QPR when the frequency shifts.

[0044] Resonant cutoff frequency ω cn Adaptive adjustment: let the cutoff frequency ω cn =2πΔf (Δf is the allowable frequency deviation), Δf can be set to ±2Hz. When the grid frequency change rate df is detected g When / dt>1Hz / s, automatically widen ω cn To enhance the robustness of the controller to frequency mutations.

[0045] A second embodiment of the present invention provides a control device for a grid-connected inverter, wherein the grid-connected inverter is connected to a three-phase power grid and includes the following modules:

[0046] Information acquisition module, used to obtain the grid frequency f g and preset QPR controller, based on the grid frequency f g , calibrate the transfer function of the QPR controller so that the resonant frequency of the QPR controller tracks the target sinusoidal signal, the frequency of the target sinusoidal signal is the grid frequency f g The resonant frequency includes: the resonant angular frequency ω n and resonant cutoff frequency ω cn .

[0047] The first processing module is used to obtain the preset output current value corresponding to phase A of the grid-connected inverter And the actual sampling current i a , the preset output current value corresponding to phase B And the actual sampling current i b , and the preset output current value corresponding to phase C And the actual sampling current i c ; Get the deviation deviation deviation The deviation Δi a , deviation Δi b and the deviation Δi c Input to the QPR controller; the QPR controller first converts the deviation Δi a , deviation Δi b and the deviation Δi cTransform to the stationary αβ coordinate system and obtain Δi α and Δi β , and then use Park transformation to transform Δi α and Δi β Rotate to the synchronously rotating dq coordinate system to generate the direct axis error Δi q and quadrature axis error Δi q .

[0048] The second processing module is used to calculate Δi based on the preset discretized QPR differential equation in the dq coordinate system. d and Δi q The QPR controller output value is used to adjust the current of the grid-connected inverter.

[0049] In this embodiment, the information acquisition module is further used to: obtain the voltage u corresponding to phase A of the three-phase power grid ga , u corresponding to phase B gb and u corresponding to phase C gc , for the three voltages u ga 、u gb and u gc Perform abc / dq coordinate transformation to obtain the voltage d-axis component u of the power grid d and the q-axis component u q ;Control the voltage q-axis component u of the grid through a digital controller q =0, by introducing the fundamental angular reference frequency ω0 of the power grid into the digital controller output, the angular frequency ω of the power grid is obtained. g , the frequency of the power grid f g =ω g / 2π.

[0050] In this embodiment, the information acquisition module is further used to: according to the transfer function of the QPR controller, the grid frequency f g The input is given to the transfer function of the QPR controller and is calculated based on the grid frequency f g , update the resonant angular frequency ω in the transfer function of the QPR controller n and resonant cutoff frequency ω cn , and the resonant angular frequency ω n and resonant cutoff frequency ω cn The grid frequency is f g An integer multiple of .

[0051] Embodiment 3 of the present invention provides a terminal, comprising: one or more processors; a memory on which one or more programs are stored, and when the one or more programs are executed by the one or more processors, the one or more processors implement the control method according to embodiment 1.

[0052] A fourth embodiment of the present invention provides a storage medium having a computer program stored thereon, wherein the program, when executed by a processor, implements the control method according to the first embodiment.

[0053] It should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation method can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0054] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A control method for a grid-connected inverter, wherein the grid-connected inverter is connected to a three-phase power grid; characterized in that: The following steps are involved: Get the grid frequency f g and preset QPR controller, based on the grid frequency f g , calibrate the transfer function of the QPR controller so that the resonant frequency of the QPR controller tracks the target sinusoidal signal, the frequency of the target sinusoidal signal is the grid frequency f g The resonant frequency includes: the resonant angular frequency ω n and resonant cutoff frequency ω cn ; Obtain the preset output current value corresponding to phase A of the grid-connected inverter And the actual sampling current i a , the preset output current value corresponding to phase B And the actual sampling current i b , and the preset output current value corresponding to phase C And the actual sampling current i c ; Get the deviation deviation deviation The deviation Δi a , deviation Δi b and the deviation Δi c Input to the QPR controller; the QPR controller first converts the deviation Δi a , deviation Δi b and the deviation Δi c Transform to the stationary αβ coordinate system and obtain Δi α and Δi β , and then use Park transformation to transform Δi α and Δi β Rotate to the synchronously rotating dq coordinate system to generate the direct axis error Δi d and quadrature axis error Δi q ; In the dq coordinate system, based on the preset discretized QPR difference equation for Δi d and Δi q The QPR controller output value is used to adjust the current of the grid-connected inverter.

2. The control method according to claim 1, characterized in that: The "obtaining grid frequency f g Specifically include: Get the voltage u corresponding to phase A of the three-phase power grid ga , u corresponding to phase B gb and u corresponding to phase C gc , for the three voltages u ga 、u gb and u gc Perform abc / dq coordinate transformation to obtain the voltage d-axis component u of the power grid d and the q-axis component u q ; The voltage q-axis component u of the grid is controlled by a digital controller q =0, by introducing the fundamental angular reference frequency ω0 of the power grid into the digital controller output, the angular frequency ω of the power grid is obtained. g , the frequency of the power grid f g =ω g / 2π.

3. The control method according to claim 2, characterized in that: The "based on the grid frequency f g , calibrating the transfer function of the QPR controller so that its resonant frequency tracks a sinusoidal signal that is an integer multiple of the grid frequency” specifically includes: According to the transfer function of the QPR controller, the grid frequency f g The input is given to the transfer function of the QPR controller and is calculated based on the grid frequency f g , update the resonant angular frequency ω in the transfer function of the QPR controller n and resonant cutoff frequency ω cn , and the resonant angular frequency ω n and resonant cutoff frequency ω cn The grid frequency is f g An integer multiple of .

4. The control method according to claim 3, characterized in that: The discretized QPR difference equation is specifically: y(k)=b0x(k)+b1x(k-1)+b2x(k-2)-a1y(k-1)-a2y(k-2), where y() is the output of the QPR controller and x() is the input of the QPR controller. b1=k p a1, b2 = k p (1+a2)-b0, n is a natural number, k r is the resonance coefficient of the QPR controller, k p is the proportional coefficient of the QPR controller, T s is the sampling period of the QPR controller.

5. The control method according to claim 4, characterized in that: The “regulating the current of the grid-connected inverter based on the output value of the QPR controller” specifically includes: Based on the output value of the QPR controller, a PWM drive signal is generated, and the PWM drive signal is used to control the IGBT switch tube in the grid-connected inverter, thereby adjusting the current of the grid-connected inverter.

6. A control device for a grid-connected inverter, wherein the grid-connected inverter is connected to a three-phase power grid; characterized in that: Includes the following modules: Information acquisition module, used to obtain the grid frequency f g and preset QPR controller, based on the grid frequency f g , calibrate the transfer function of the QPR controller so that the resonant frequency of the QPR controller tracks the target sinusoidal signal, the frequency of the target sinusoidal signal is the grid frequency f g The resonant frequency includes: the resonant angular frequency ω n and resonant cutoff frequency ω cn ; The first processing module is used to obtain the preset output current value corresponding to phase A of the grid-connected inverter And the actual sampling current i a , the preset output current value corresponding to phase B And the actual sampling current i b , and the preset output current value corresponding to phase C And the actual sampling current i c ; Get the deviation deviation deviation The deviation Δi a , deviation Δi b and the deviation Δi c Input to the QPR controller; the QPR controller first converts the deviation Δi a , deviation Δi b and the deviation Δi c Transform to the stationary αβ coordinate system and obtain Δi α and Δi β , and then use Park transformation to transform Δi α and Δi β Rotate to the synchronously rotating dq coordinate system to generate the direct axis error Δi d and quadrature axis error Δi q ; The second processing module is used to calculate Δi based on the preset discretized QPR differential equation in the dq coordinate system. d and Δi q The QPR controller output value is used to adjust the current of the grid-connected inverter.

7. The control device according to claim 6, characterized in that The information acquisition module is also used for: Get the voltage u corresponding to phase A of the three-phase power grid ga , u corresponding to phase B gb and u corresponding to phase C gc , for the three voltages u ga 、u gb and u gc Perform abc / dq coordinate transformation to obtain the voltage d-axis component u of the power grid d and the q-axis component u q ; The voltage q-axis component u of the grid is controlled by a digital controller q =0, by introducing the fundamental angular reference frequency ω0 of the power grid into the digital controller output, the angular frequency ω of the power grid is obtained. g , the frequency of the power grid f g =ω g / 2π.

8. The control device according to claim 7, characterized in that: The information acquisition module is also used for: According to the transfer function of the QPR controller, the grid frequency f g The input is given to the transfer function of the QPR controller and is calculated based on the grid frequency f g , update the resonant angular frequency ω in the transfer function of the QPR controller n and resonant cutoff frequency ω cn , and the resonant angular frequency ω n and resonant cutoff frequency ω cn The grid frequency is f g An integer multiple of .

9. A terminal, characterized in that: include: one or more processors; A memory having one or more programs stored thereon, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the control method according to any one of claims 1 to 5.

10. A storage medium, characterized in that: A computer program is stored thereon, and when the program is executed by a processor, the control method according to any one of claims 1 to 5 is implemented.

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