Method and device for determining parameters of proportional resonance controller, equipment and medium

Abstract

The invention discloses a method, device and equipment for determining parameters of a proportional resonance controller and a medium, the proportional resonance controller is applied to a current controller of a three-phase grid-connected inverter, the parameters of the proportional resonance controller comprise a proportionality coefficient, a first damping coefficient and a second damping coefficient, the first damping coefficient is greater than the second damping coefficient, and the second damping coefficient is greater than the first damping coefficient. The three-phase grid-connected inverter further comprises a filter. The proportional resonance controller is low in parameter coupling, can be independently designed, and is simple in engineering implementation; in the target open-loop transfer function, the proportionality coefficient determines the basic proportional gain, the damping coefficient controls the attenuation speed of the corresponding resonance factor, the difference between the first damping coefficient and the second damping coefficient can influence the gain bandwidth, and the larger the difference between the first damping coefficient and the second damping coefficient is, the more significant the attenuation speed difference between the second resonance factor and the first resonance factor is. The wider the high gain interval at the specific frequency of the power grid is, the higher gain is still kept even if the frequency of the power grid fluctuates, and the adaptability and robustness to the frequency deviation of the power grid are improved.

Description

Technical Field

[0001] This application belongs to the field of grid-connected control technology, and in particular relates to a method, device, equipment and medium for determining the parameters of a proportional resonant controller. Background Technology

[0002] In three-phase grid-connected systems such as photovoltaic inverters, energy storage inverters, and wind power converters, inductor-capacitor-inductor (LCL) filters are prone to causing system oscillations at the resonant frequency. To eliminate system oscillations, resistors are usually connected in series or in parallel in the LCL filter to suppress system resonance. However, due to the presence of external resistors, system losses increase, which in turn leads to a decrease in system efficiency.

[0003] In related technologies, current controllers are typically used to control the current of three-phase grid-connected inverters, such as proportional-integral (PI) controllers or proportional-resonant (PR) controllers. Since PI controllers can only track DC signals without steady-state error, AC signals need to be converted to DC signals, requiring DQ-axis coordinate transformation and DQ-axis decoupling, resulting in complex control algorithms and high implementation difficulty. However, the strong coupling between the proportional coefficient and resonant coefficient of PR controllers can affect the stability of proportional regulation. Conventional PR controllers also suffer from narrow bandwidth; when the grid frequency deviates from the fundamental grid frequency, the resonant gain drops sharply, leading to a weakening of the control effect. Summary of the Invention

[0004] The proportional resonant controller parameter determination method, apparatus, equipment, and medium provided in this application have low coupling between parameters, can be designed independently, and are simple to implement in engineering. The gain bandwidth is determined by the difference between the first damping coefficient and the second damping coefficient. The larger the difference, the more significant the difference in the attenuation rate between the second resonant factor and the first resonant factor, resulting in a wider high-gain range at a specific frequency of the power grid. Even if there are frequency fluctuations, a high gain can still be maintained, improving the adaptability and robustness to power grid frequency deviations.

[0005] In a first aspect, embodiments of this application provide a method for determining the parameters of a proportional resonant controller. The proportional resonant controller is applied to the current controller of a three-phase grid-connected inverter. The parameters of the proportional resonant controller include a proportional coefficient, a first damping coefficient, and a second damping coefficient. The first damping coefficient is greater than the second damping coefficient. The three-phase grid-connected inverter also includes a filter. The method includes: Obtain specific frequencies, switching frequencies, and filtering parameters of the power grid; The specific grid frequency, switching frequency, and filter parameters are input into a preset open-loop transfer function to determine the target open-loop transfer function corresponding to the three-phase grid-connected inverter. The preset open-loop transfer function is determined based on the expression of the proportional resonant controller and the transfer function expression of the filter. The expression of the proportional resonant controller includes a proportional factor, a first resonant factor, and a second resonant factor. The proportional factor is determined based on the proportional coefficient, the first resonant factor is determined based on the first damping coefficient, and the second resonant factor is determined based on the second damping coefficient and the grid connection frequency. Based on preset constraints and the target open-loop transfer function, the gain equation set corresponding to the three-phase grid-connected inverter is determined. Solve the gain equations to determine the values ​​of the proportional coefficient, the first damping coefficient, and the second damping coefficient.

[0006] According to any of the foregoing embodiments of the first aspect of this application, before inputting the specific power grid frequency, switching frequency, and filter parameters into a preset open-loop transfer function, the method further includes: Obtain the expressions for the proportional resonant controller and the transfer function of the filter; The product of the proportional resonant controller and the filter is determined as the preset open-loop transfer function.

[0007] According to any of the foregoing embodiments of the first aspect of this application, obtaining the expression for the proportional resonant controller includes: The scaling factor is determined based on the scaling coefficient, the first resonance factor is determined based on the first damping coefficient, and the second resonance factor is determined based on the second damping coefficient. Based on the scaling factor, the first resonance factor, and the second resonance factor, the expression for the proportional resonance controller is determined.

[0008] According to any of the foregoing embodiments of the first aspect of this application, determining the expression of the proportional resonance controller based on the scaling factor, the first resonance factor, and the second resonance factor includes: The target resonance factor is determined based on the ratio of the second resonance factor to the second resonance factor. The expression for the proportional resonance controller is determined based on the product of the scaling factor and the target resonance factor.

[0009] According to any of the foregoing embodiments of the first aspect of this application, determining a scaling factor based on a scaling coefficient, determining a first resonance factor based on a first damping coefficient, and determining a second resonance factor based on a second damping coefficient includes: The scaling factor is determined by the scaling coefficient. The first resonance factor will be calculated according to the following formula:

[0010] The second resonance factor will be calculated according to the following formula:

[0011] The expression for the proportional resonance controller is determined based on the product of the scaling factor and the target resonance factor, including: The expression for the proportional resonant controller is determined as follows:

[0012] in, This represents a proportional resonant controller. This represents the proportionality coefficient. Indicates the first damping coefficient. Indicates the second damping coefficient. The angular frequency corresponding to a specific frequency of the power grid. This represents the Laplace operator.

[0013] According to any of the foregoing embodiments of the first aspect of this application, the filter includes an inverter-side inductor, a filter capacitor, a grid-connected inductor, and a virtual resistor. The filter parameters include the inverter-side inductor value, the filter capacitor value, the grid-connected inductor value, and the virtual resistor value. Accordingly, obtaining the expression for the proportional resonant controller includes: Based on the inverter-side inductance value, filter capacitor value, grid-connected inductance value, and virtual resistance value, the transfer function expression of the filter is determined as follows:

[0014] in, The transfer function of the filter is represented by... Indicates the inductance value on the inverter side. Indicates the inductance value on the grid-connected side. Indicates the value of the filter capacitor. Indicates the virtual resistance value. This represents the Laplace operator.

[0015] According to any of the foregoing embodiments of the first aspect of this application, based on preset constraints and the target open-loop transfer function, the gain equation set corresponding to the three-phase grid-connected inverter is determined, including: Based on the constraints of the target open-loop transfer function at a specific frequency of the power grid, the first gain equation is determined. Based on the constraints of the target open-loop transfer function at the power grid fluctuation frequency, the second gain equation is determined. The third gain equation is determined based on the constraints of the target open-loop transfer function at the preset crossover frequency; the preset crossover frequency is determined based on the switching frequency. Based on the first gain equation, the second gain equation, and the third gain equation, the gain equation set corresponding to the three-phase grid-connected inverter is determined.

[0016] According to any of the foregoing embodiments of the first aspect of this application, the amplitude-frequency characteristic of the target open-loop transfer function is expressed in logarithmic form. Accordingly, based on the constraints of the target open-loop transfer function at a specific frequency of the power grid, a first gain equation is determined, including: Based on the fact that the amplitude-frequency characteristic of the target open-loop transfer function at a specific frequency of the power grid satisfies the first preset amplitude-frequency, the first gain equation is determined. Based on the constraints of the target open-loop transfer function at the power grid fluctuation frequency, the second gain equation is determined, including: The second gain equation is determined based on the fact that the amplitude-frequency characteristic of the target open-loop transfer function at the power grid fluctuation frequency satisfies the second preset amplitude frequency; the second preset amplitude frequency is determined based on the first preset amplitude frequency and the amplitude-frequency attenuation. Based on the constraints of the target open-loop transfer function at the preset crossover frequency, the third gain equation is determined, including: Based on the fact that the amplitude-frequency characteristic of the target open-loop transfer function at the preset crossover frequency satisfies the third preset amplitude frequency, the third gain equation is determined.

[0017] Secondly, embodiments of this application also provide a device for determining the parameters of a proportional resonant controller. The proportional resonant controller is applied to the current controller of a three-phase grid-connected inverter. The parameters of the proportional resonant controller include a proportional coefficient, a first damping coefficient, and a second damping coefficient. The first damping coefficient is greater than the second damping coefficient. The three-phase grid-connected inverter also includes a filter. The device includes: The acquisition module is used to acquire specific frequencies, switching frequencies, and filtering parameters of the power grid. The first determining module inputs the specific grid frequency, switching frequency, and filter parameters into a preset open-loop transfer function to determine the target open-loop transfer function corresponding to the three-phase grid-connected inverter. The preset open-loop transfer function is determined based on the expression of the proportional resonant controller and the transfer function expression of the filter. The expression of the proportional resonant controller includes a proportional factor, a first resonant factor, and a second resonant factor. The proportional factor is determined based on the proportional coefficient, the first resonant factor is determined based on the first damping coefficient, and the second resonant factor is determined based on the second damping coefficient and the grid connection frequency. The second determination module is used to determine the gain equation set corresponding to the three-phase grid-connected inverter based on preset constraints and the target open-loop transfer function. The third determining module is used to solve the gain equations and determine the values ​​of the proportional coefficient, the first damping coefficient, and the second damping coefficient.

[0018] Thirdly, embodiments of this application also provide an electronic device, which includes: a processor and a memory storing computer program instructions; The processor executes computer program instructions to implement any of the above methods for determining the parameters of the proportional resonant controller.

[0019] Fourthly, embodiments of this application also provide a computer-readable storage medium storing computer program instructions, which, when executed by a processor, implement any of the methods for determining the parameters of a proportional resonant controller described above.

[0020] Fifthly, embodiments of this application also provide a computer program product, wherein the instructions in the computer program product, when executed by the processor of an electronic device, cause the electronic device to execute any of the above-described methods for determining the parameters of a proportional resonant controller.

[0021] This application discloses a method, apparatus, device, and medium for determining the parameters of a proportional resonant controller. The proportional resonant controller is applied to the current controller of a three-phase grid-connected inverter. The parameters of the proportional resonant controller include a proportional gain, a first damping coefficient, and a second damping coefficient. The first damping coefficient is greater than the second damping coefficient. The three-phase grid-connected inverter also includes a filter. The proportional resonant controller has low coupling between its parameters, can be designed independently, and is simple to implement in engineering. In the target open-loop transfer function, the proportional gain determines the basic proportional gain, the first damping coefficient controls the decay rate of the strongly damped resonant factor (i.e., the first resonant factor), and the second damping coefficient controls the decay rate of the weakly damped resonant factor (i.e., the second resonant factor). The difference between the first and second damping coefficients affects the gain bandwidth. The larger the difference, the more significant the difference in decay rates between the second and first resonant factors, resulting in a wider high-gain range at a specific grid frequency. Even with grid frequency fluctuations, a high gain can still be maintained, improving adaptability and robustness to grid frequency shifts. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a flowchart illustrating a method for determining the parameters of a proportional resonant controller according to an embodiment of this application. Figure 2 This is a control block diagram of a three-phase grid-connected inverter provided in an embodiment of this application; Figure 3 This is an equivalent circuit diagram of a three-phase grid-connected inverter provided in an embodiment of this application; Figure 4 This is a control block diagram of another three-phase grid-connected inverter provided in the embodiments of this application; Figure 5 This is a schematic diagram illustrating the evolution of the proportional resonant controller expression provided in the embodiments of this application; Figure 6 yes Figure 1 A detailed flowchart of S130 in the method for determining the parameters of the proportional resonant controller is shown. Figure 7 yes Figure 1 The diagram shows another detailed process flow diagram of S130 in the method for determining the parameters of the proportional resonant controller. Figure 8 This is a schematic diagram of the amplitude-frequency response curve provided in the embodiments of this application; Figure 9 This is a schematic diagram of the phase frequency response curve provided in the embodiments of this application; Figure 10 This is a waveform comparison diagram of the reference current and the actual current provided in the embodiments of this application; Figure 11 This is a schematic diagram comparing the amplitude and phase of the reference current and the actual current provided in the embodiments of this application; Figure 12 This is a waveform diagram of three-phase grid-connected voltage and current provided in an embodiment of this application; Figure 13 This is a schematic diagram of the structure of a device for determining the parameters of a proportional resonant controller provided in an embodiment of this application; Figure 14 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application; Detailed Implementation

[0024] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0025] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0026] In related technologies, using a PI controller as a current controller requires DQ axis coordinate transformation and DQ axis decoupling. Since there are multiple branch nodes and summing modules on the DQ axis in the grid-connected system, it is difficult to achieve DQ axis decoupling. If DQ axis decoupling is to be achieved, feedforward control needs to be introduced, which will increase the system complexity and may also introduce high-frequency noise and make it impossible to handle unknown disturbances.

[0027] However, the proportional gain and resonant gain of conventional PR controllers are strongly coupled, which affects the stability of proportional regulation. They also have the problem of narrow bandwidth. When the grid frequency deviates from the grid fundamental frequency, the resonant gain drops sharply, resulting in a weakening of the control effect.

[0028] To address the aforementioned technical problems, this application provides a method, apparatus, device, and medium for determining the parameters of a proportional resonant controller. This proportional resonant controller is applied to the current controller of a three-phase grid-connected inverter. The parameters of the proportional resonant controller include a proportional gain, a first damping coefficient, and a second damping coefficient. The first damping coefficient is greater than the second damping coefficient. The three-phase grid-connected inverter also includes a filter. The proportional resonant controller exhibits low coupling between its parameters, allowing for independent design and simple engineering implementation. In the target open-loop transfer function, the proportional gain determines the basic proportional gain, the first damping coefficient controls the decay rate of the strongly damped resonant factor (i.e., the first resonant factor), and the second damping coefficient controls the decay rate of the weakly damped resonant factor (i.e., the second resonant factor). The difference between the first and second damping coefficients affects the gain bandwidth; the larger the difference, the more significant the difference in decay rates between the second and first resonant factors, resulting in a wider high-gain range at a specific grid frequency. Even with grid frequency fluctuations, a high gain can be maintained, improving adaptability and robustness to grid frequency shifts.

[0029] The method for determining the parameters of the proportional resonant controller provided in the embodiments of this application will be introduced first below.

[0030] In this application, a proportional resonant controller is used as the current controller in a three-phase grid-connected inverter. The parameters of the proportional resonant controller include a proportional coefficient, a first damping coefficient, and a second damping coefficient, with the first damping coefficient being greater than the second damping coefficient. The three-phase grid-connected inverter also includes a filter. In the current control strategy of the three-phase grid-connected inverter, the proportional resonant controller is used to achieve zero steady-state error tracking of the grid-connected current to the grid's fundamental AC signal, while suppressing harmonic distortion, improving current control accuracy and system dynamic response speed. The filter is used to efficiently filter out high-frequency switching harmonics from the inverter output, and through reasonable design, suppresses its own resonance to ensure the sinusoidal nature of the grid-connected current and system stability. Through the coordinated operation of the proportional resonant controller and the filter, the three-phase grid-connected inverter can output a high-quality current with the same frequency and phase as the grid and extremely low harmonic content, meeting grid connection technical specifications.

[0031] Figure 1 A flowchart illustrating a method for determining the parameters of a proportional resonant controller according to an embodiment of this application is shown. Figure 1 As shown, the method for determining the parameters of the proportional resonant controller may include the following steps: S110~S140.

[0032] S110: Obtain the specific frequency, switching frequency, and filtering parameters of the power grid.

[0033] Among them, the grid characteristic frequency refers to the grid connection frequency, that is, the grid fundamental frequency, which may include 50Hz or 60Hz.

[0034] Switching frequency refers to the switching frequency of power switching devices in a three-phase grid-connected inverter, and the unit is usually kilohertz (kHz).

[0035] Filtering parameters refer to the parameters of the components of a filter. Taking an LCL filter as an example, an LCL filter includes an inverter-side inductor, a filter capacitor, a grid-connected inductor, and a damping element (passive or active damping). Accordingly, the filtering parameters may include the inverter-side inductance value, the filter capacitor value, and the grid-connected inductance value. When the damping element is passive (physical resistance), the filtering parameters also include a resistance value; when the damping element is active (virtual resistance), the filtering parameters also include a virtual resistance value. The filtering parameters can be obtained using all methods known to those skilled in the art, and will not be elaborated upon here.

[0036] As an example, taking an LCL inverter as an example, an LCL inverter includes an inverter-side inductor, a grid-connected inductor, a filter capacitor, and a virtual resistor; given that the inverter's DC bus voltage is 2300V, the switching frequency is 15kHz, the AC line voltage is 1140V, the output power is 700kW, and the grid frequency is 50Hz, calculate the inductance value of the inverter-side inductor. =0.2mH, the inductance value of the grid-connected side inductor 50uH, filter capacitor value C=80uF, virtual resistor 1Ω.

[0037] S120 inputs the specific grid frequency, switching frequency, and filter parameters into the preset open-loop transfer function to determine the target open-loop transfer function corresponding to the three-phase grid-connected inverter.

[0038] In this embodiment, the preset open-loop transfer function is determined based on the expressions for the proportional resonant controller and the filter. As an example, the control strategy of a three-phase grid-connected inverter mainly includes two control loops: a proportional resonant controller and a filter. Correspondingly, the preset open-loop transfer function includes the expressions for the proportional resonant controller and the filter.

[0039] The expression for a proportional resonant controller is determined based on its parameters, specifically the proportional gain, the first damping factor, and the second damping factor. The expression includes a proportional factor, a first resonant factor, and a second resonant factor. The proportional factor is determined based on the proportional gain, the first resonant factor is determined based on the first damping factor, and the second resonant factor is determined based on the second damping factor and the grid connection frequency.

[0040] The transfer function expression of the filter is determined based on the hardware structure and control strategy of the three-phase grid-connected inverter. For example, if the filter is an LCL filter and active damping is used to suppress system resonance, the corresponding transfer function expression includes the inverter-side inductance, the grid-connected inductance, the filter capacitor, and the virtual resistance. As another example, if the filter is an LCL filter and passive damping is used to suppress system resonance, the corresponding transfer function expression includes the inverter-side inductance, the grid-connected inductance, the filter capacitor, and the physical resistance. Since the filter's transfer function expression is determined based on the hardware structure and control strategy, once the filter parameters are set, the filter's performance is relatively stable.

[0041] In this step, the target open-loop transfer function for the three-phase grid-connected inverter is obtained by inputting the specific grid frequency, switching frequency, and filtering parameters into a preset open-loop transfer function. Different three-phase grid-connected inverters have different parameters or application scenarios, meaning the specific grid frequency, switching frequency, and filtering parameters differ, resulting in different target open-loop transfer functions.

[0042] In the target open-loop transfer function, the proportional gain determines the basic proportional gain, the first damping coefficient controls the decay rate of the strongly damped resonant factor (i.e., the first resonant factor), and the second damping coefficient controls the decay rate of the weakly damped resonant factor (i.e., the second resonant factor). The difference between the first and second damping coefficients affects the gain bandwidth; the larger the difference, the more significant the difference in decay rates between the second and first resonant factors, resulting in a wider high-gain range at a specific grid frequency. Even with grid frequency fluctuations, a high gain can still be maintained, improving adaptability and robustness to grid frequency shifts. The proportional gain, first damping coefficient, and second damping coefficient have low coupling and can be designed independently.

[0043] S130. Based on preset constraints and the target open-loop transfer function, determine the gain equation set corresponding to the three-phase grid-connected inverter.

[0044] The target switching gain transfer function is used to calculate the loop gain of the three-phase grid-connected inverter.

[0045] In this step, based on multiple preset constraints, the loop gain corresponding to the target open-loop transfer function is limited to a preset range or a certain constant value, thereby obtaining the gain equation set.

[0046] As an example, preset constraints may include: when the grid frequency equals the crossover frequency, the corresponding loop gain is equal to 1.

[0047] The loop gain is maximized when the grid frequency equals a specific grid frequency, but this loop gain cannot be infinitely large and needs to be limited to an acceptable value, such as 10,000. As an example, a preset constraint could be: when the grid frequency equals a specific grid frequency, the corresponding loop gain is equal to 10,000.

[0048] In practical applications, the grid frequency fluctuates within a certain range. According to the national standard GB / T15945, the grid frequency fluctuation range for converters is ±0.5Hz. When the grid frequency deviates from a specific grid frequency, the corresponding loop gain will decrease, but it is desirable for the loop gain to remain at a relatively high value. As an example, preset constraints may include: when the grid frequency is equal to the specific grid frequency ±0.5Hz, determining the corresponding loop gain based on the maximum loop gain and the acceptable gain attenuation value.

[0049] S140. Solve the gain equations to determine the values ​​of the proportional coefficient, the first damping coefficient, and the second damping coefficient.

[0050] In this step, the gain equations in the gain equation system are solved simultaneously to obtain the values ​​of the unknowns in the equations, that is, the values ​​of the proportional coefficient, the first damping coefficient, and the second damping coefficient.

[0051] Furthermore, using a proportional resonant controller as the current controller only requires designing... The control flow diagram in the coordinate system is concise and... If the variables in the coordinate system are not coupled, then decoupling is not required, making the control algorithm easier to implement.

[0052] The method for determining the parameters of a proportional resonant controller provided in this application includes: acquiring a specific grid frequency, a switching frequency, and filter parameters; inputting the specific grid frequency, switching frequency, and filter parameters into a preset open-loop transfer function to determine the target open-loop transfer function corresponding to the three-phase grid-connected inverter; wherein, the preset open-loop transfer function is determined based on the expression of the proportional resonant controller and the transfer expression of the filter, the expression of the proportional resonant controller includes a proportional factor, a first resonant factor, and a second resonant factor, the proportional factor being determined based on the proportional coefficient, the first resonant factor being determined based on the first damping coefficient, and the second resonant factor being determined based on the second damping coefficient and the grid connection frequency; determining the gain equation set corresponding to the three-phase grid-connected inverter based on preset constraints and the target open-loop transfer function; solving the gain equation set to determine the values ​​of the proportional coefficient, the first damping coefficient, and the second damping coefficient. This proportional resonant controller has low parameter coupling, can be designed independently, and is simple to implement in engineering. In the target open-loop transfer function, the proportional coefficient determines the basic proportional gain, the first damping coefficient controls the decay rate of the strong damping resonant factor (i.e., the first resonant factor), and the second damping coefficient controls the decay rate of the weak damping resonant factor (i.e., the second resonant factor). The difference between the first damping coefficient and the second damping coefficient can affect the gain bandwidth. The larger the difference between the two, the more significant the difference in the decay rate between the second resonant factor and the first resonant factor. The higher the high gain range at a specific frequency of the power grid, the higher the gain can be maintained even if there are fluctuations in the power grid frequency, thus improving the adaptability and robustness to power grid frequency deviation.

[0053] In some embodiments, before "inputting the specific grid frequency, switching frequency, and filter parameters into a preset open-loop transfer function," the method may further include the following steps: Obtain the expressions for the proportional resonant controller and the transfer function of the filter; The product of the proportional resonant controller and the filter is determined as the preset open-loop transfer function.

[0054] Combination Figure 2 The control strategy for three-phase grid-connected inverters mainly includes proportional resonant controllers. and filter Two control links. The controller's error correction capability is combined with the dynamic response characteristics of the controlled object (i.e., the filter) to form a complete open-loop control link, thereby analyzing the performance of the closed-loop system (e.g., stability, accuracy, and response speed) through the open-loop transfer function.

[0055] As an example, the default open-loop transfer function The expression for is shown in formula (1).

[0056]

[0057] in, This represents a proportional resonant controller. This represents the transfer function of the filter.

[0058] The transfer function expression of the closed-loop system is shown in Equation (2).

[0059]

[0060] The preset open-loop transfer function directly determines the characteristics of the closed-loop system: when | |≫1 hour, That is, the closed-loop system can track the input without distortion, corresponding to the high gain of the proportional resonant controller at a specific frequency of the power grid; when | |≪1 hour, That is, the output of the closed-loop system is determined by the open-loop characteristics, which corresponds to the attenuation of the filter in the high-frequency band to ensure that harmonics are suppressed.

[0061] By using frequency domain tools (such as Bode plots) to intuitively analyze the system's stability, steady-state accuracy, and dynamic response, we can ensure that the controller's "tracking capability" and the filter's "harmonic suppression capability" work together to ultimately achieve zero steady-state error, low harmonics, and highly stable grid-connected current output.

[0062] In some embodiments, "obtaining the expression for the proportional resonant controller" may include the following steps: The scaling factor is determined based on the scaling coefficient, the first resonance factor is determined based on the first damping coefficient, and the second resonance factor is determined based on the second damping coefficient. Based on the scaling factor, the first resonance factor, and the second resonance factor, the expression for the proportional resonance controller is determined.

[0063] In this embodiment, the scaling factor is determined based on the scaling coefficient. As an example, the scaling coefficient is determined as the scaling factor.

[0064] The first resonant factor is determined based on the first damping coefficient, which controls the decay rate of the first resonant factor (i.e., the strongly damped resonant factor). Similarly, the second resonant factor is determined based on the second damping coefficient, which controls the decay rate of the second resonant factor (i.e., the weakly damped resonant factor). The larger the difference between the first and second damping coefficients, the more significant the difference in decay rates between the second and first resonant factors. This results in a wider high-gain range at specific grid frequencies, maintaining high gain even with grid frequency fluctuations, thus improving adaptability and robustness to grid frequency shifts.

[0065] In some embodiments, "determining the expression of the proportional resonance controller based on the scaling factor, the first resonance factor, and the second resonance factor" may include the following steps: The target resonance factor is determined based on the ratio of the second resonance factor to the second resonance factor. The expression for the proportional resonance controller is determined based on the product of the scaling factor and the target resonance factor.

[0066] In this embodiment, when the grid frequency is near a specific grid frequency, the difference between the first damping coefficient and the second damping coefficient plays a crucial role. The second resonant factor corresponding to the second damping coefficient decays slowly near the specific grid frequency, maintaining a high loop gain, while the first resonant factor corresponding to the first damping coefficient decays rapidly, resulting in a relatively low loop gain. Therefore, the ratio of the second resonant factor to the first resonant factor is ≫1, and the output of the proportional resonant controller... The first resonant factor is much larger than the scaling factor, resulting in high-gain tracking of specific frequency signals of the power grid. When the power grid frequency deviates from the specific frequency, for example, when the power grid frequency is much larger or much smaller than the specific frequency, the first resonant factor and the second resonant factor are approximately equal. Therefore, the ratio of the second resonant factor to the second resonant factor is approximately equal to 1. The output of the proportional resonant controller is approximately equal to the scaling factor, exhibiting only proportional adjustment, which can avoid excessive response to low-frequency interference or high-frequency noise.

[0067] In some embodiments, "determining the scaling factor based on the scaling coefficient, determining the first resonance factor based on the first damping coefficient, and determining the second resonance factor based on the second damping coefficient" may include the following steps: The scaling factor is determined by the scaling coefficient. The first resonance factor will be calculated according to formula (3). :

[0068] The second resonance factor will be calculated according to formula (4). :

[0069] The expression for the proportional resonance controller is determined based on the product of the scaling factor and the target resonance factor, including: The expression for the proportional resonant controller is shown in formula (5).

[0070]

[0071] in, This represents a proportional resonant controller. This represents the proportionality coefficient. Indicates the first damping coefficient. Indicates the second damping coefficient. The angular frequency corresponding to a specific frequency of the power grid. , Indicates a specific frequency of the power grid. This represents the Laplace operator.

[0072] In this embodiment, the expression for the proportional resonant controller means: through the proportional coefficient Scaling the ratio of two resonant factors with the same frequency but different damping coefficients at a specific frequency in the power grid. Selective gain enhancement occurs in the vicinity, while maintaining stable proportional characteristics at non-grid-specific frequencies. Specifically, this manifests as: when the grid frequency is at a specific grid frequency... When the frequency is near the first damping coefficient and the second damping coefficient, the difference plays a crucial role, and the second resonance factor corresponding to the second damping coefficient is at a specific frequency of the power grid. The nearby damping factor decays slowly, maintaining a high loop gain, while the first resonant factor corresponding to the first damping coefficient decays rapidly, resulting in a relatively low loop gain. Therefore... The output of the resonant controller This generates a specific frequency signal for the power grid. High-gain tracking. When the grid frequency deviates from a specific grid frequency. At times, for example, when the grid frequency is much higher than a specific grid frequency. or much lower than the specific frequency of the power grid The first resonance factor and the second resonance factor are approximately equal, therefore The output of the proportional resonant controller is It only exhibits proportional adjustment, which can avoid excessive response to low-frequency interference or high-frequency noise.

[0073] In some embodiments, such as Figure 3 As shown, the filter includes inverter-side inductor L1, filter capacitor C, grid-connected-side inductor L2, and virtual resistor R. C Virtual resistance R C It is connected in parallel with the filter capacitor C, that is, the filter is an LCL filter, and the filter parameters include the inverter side inductance value, the filter capacitor value, the grid-connected side inductance value, and the virtual resistance value.

[0074] Accordingly, "obtaining the expression for the proportional resonant controller" may include the following steps: Based on the inverter-side inductance value, filter capacitor value, grid-connected inductance value, and virtual resistance value, the transfer function expression of the filter is determined as shown in formula (6).

[0075]

[0076] in, The transfer function of the filter is represented by... Indicates the inductance value on the inverter side. Indicates the inductance value on the grid-connected side. Indicates the value of the filter capacitor. Indicates the virtual resistance value. This represents the Laplace operator.

[0077] In this embodiment, the filter uses active damping (i.e., virtual resistance R). C The LCL filter uses a control algorithm to replace physical resistors to achieve damping. This retains the advantages of high-frequency strong filtering and miniaturization of LCL filters, while solving the problems of high loss and poor adaptability of passive damping. It achieves efficient, flexible and low-cost grid-connected control while maintaining harmonic suppression and system stability.

[0078] The process of determining the proportional resonant controller expression provided in the embodiments of this application will be described below.

[0079] For example, the control block diagram of a three-phase grid-connected inverter is as follows: Figure 4 As shown, the control strategy of a three-phase grid-connected inverter mainly includes a proportional resonant controller. and filter Two control loops, the simplified control block diagram is as follows: Figure 2 As shown, the preset switching gain transfer function corresponding to the three-phase grid-connected inverter is determined as shown in formula (1).

[0080]

[0081] The goal of current control for a three-phase grid-connected inverter is to control the inverter's output current. With reference current As consistent as possible. Due to the filter It is a finite value; to achieve consistency, the proportional resonant controller needs to be adjusted. Enlarge it as much as possible.

[0082]

[0083] Based on the above analysis, the expression for the proportional resonant controller initially proposed by the inventor is shown in formula (8).

[0084]

[0085] Combination Figure 5 Although this proportional resonant controller can achieve a high loop gain at a specific frequency of the power grid, it cannot guarantee a high crossover frequency. The lower the crossover frequency, the worse the corresponding system tracking performance.

[0086] The inventors improved the expression of the proportional resonant controller, and the improved expression of the proportional resonant controller is shown in formula (9).

[0087]

[0088] Among them, the first damping coefficient Greater than the second damping coefficient Combining Figure 5 The improved proportional resonant controller achieves a higher loop gain at the grid's constant frequency, but it cannot change the loop gain in the low-frequency and high-frequency ranges, and therefore cannot change the amplitude-frequency characteristics at the cross-frequency.

[0089] Ultimately, the inventors added a scaling factor to the formula to form the expression for the preset open-loop transfer function as shown in formula (5). When analyzing the loop gain, the amplitude-frequency characteristics are expressed in logarithmic form, thus limiting the scaling factor. The relationship between the proportional gain and the target resonance factor is multiplication. When converted to logarithmic form, the logarithmic form of the proportional gain is added to the logarithmic form of the target resonance factor. This allows adjustment of the amplitude-frequency response at the crossover frequency to obtain the specified crossover frequency. Simultaneously, this proportional resonant controller can also achieve high loop gain at specific frequencies of the power grid.

[0090] In some embodiments, "determining the gain equation set corresponding to the three-phase grid-connected inverter based on preset constraints and the target open-loop transfer function", i.e., S130 may include the following steps: S131~S134, such as... Figure 6 As shown.

[0091] S131. Based on the constraints of the target open-loop transfer function at a specific frequency of the power grid, determine the first gain equation.

[0092] In this step, the loop gain is maximized when the grid frequency equals a specific grid frequency. However, this loop gain cannot be infinitely large and needs to be limited to an acceptable value, such as 10000. As an example, a preset constraint could be: when the grid frequency equals a specific grid frequency, the corresponding loop gain is 10000, i.e. .

[0093] S132. Based on the constraints of the target open-loop transfer function under the power grid fluctuation frequency, determine the second gain equation.

[0094] In practical applications, the grid frequency fluctuates within a certain range. According to the national standard GB / T15945, the grid frequency fluctuation range for converters is ±0.5Hz. When the grid frequency deviates from a specific grid frequency, the corresponding loop gain will decrease, but it is desirable for the loop gain to remain at a relatively high value. Preset constraints may include: when the grid frequency is equal to the specific grid frequency ±0.5Hz, determining the corresponding loop gain based on the maximum loop gain and the acceptable gain attenuation value.

[0095] As an example, the product of the maximum loop gain and a first preset coefficient is determined as the gain attenuation value. The value of the first preset coefficient can be set according to actual needs; for example, the value range of the first preset coefficient is 0.1 to 0.3.

[0096] S133. Based on the constraint conditions of the target open-loop transfer function at the preset crossover frequency, determine the third gain equation.

[0097] Among them, the preset crossing frequency It is determined based on the switching frequency. As an example, the product of the switching frequency and a second preset coefficient is used to determine the preset crossover frequency. The value of the second preset coefficient can be set according to actual needs, for example, the second preset coefficient is equal to 1 / 10.

[0098] The crossover frequency is a critical point in the system's transition from stable to unstable. When the grid frequency equals the preset crossover frequency... When the loop gain is 1, the corresponding loop gain is equal to 1. 1.

[0099] S134. Based on the first gain equation, the second gain equation, and the third gain equation, determine the gain equation set corresponding to the three-phase grid-connected inverter.

[0100] In this embodiment, by setting constraints on the target open-loop transfer function at three locations—a specific frequency of the power grid, the frequency of power grid fluctuations, and the crossover frequency—three gain equations are obtained, forming a set of gain equations. The unknowns in the set of equations are the parameters of the proportional resonant controller (proportional coefficient, first damping coefficient, and second damping coefficient). By solving the equations, the values ​​of the proportional coefficient, first damping coefficient, and second damping coefficient can be determined quickly and accurately.

[0101] In some embodiments, the amplitude-frequency characteristics of the target open-loop transfer function are expressed in logarithmic form. As an example, using... This represents the amplitude-frequency characteristic of the target open-loop transfer function.

[0102] Accordingly, "determining the first gain equation based on the constraints of the target open-loop transfer function at a specific frequency of the power grid," i.e., S131, may include the following steps: S1311, as follows Figure 7 As shown.

[0103] S1311. Based on the fact that the amplitude-frequency characteristics of the target open-loop transfer function at a specific frequency of the power grid satisfy the first preset amplitude-frequency, determine the first gain equation.

[0104] For example, taking a target open-loop transfer function with a loop gain of 10000 at a specific frequency of the power grid as an example, that is... The first preset amplitude frequency is 80dB, and the corresponding first gain equation is: , .

[0105] "Based on the constraints of the target open-loop transfer function under the power grid fluctuation frequency, determine the second gain equation," that is, S132 may include the following steps: S1321, as follows Figure 7 As shown.

[0106] S1321. Based on the fact that the amplitude-frequency characteristic of the target open-loop transfer function at the power grid fluctuation frequency satisfies the second preset amplitude-frequency, determine the second gain equation.

[0107] The second preset amplitude frequency is determined based on the first preset amplitude frequency and the amplitude attenuation amount. As an example, the difference between the first preset amplitude frequency and the amplitude attenuation amount is determined as the second preset amplitude frequency.

[0108] For example, taking the target open-loop transfer function at a specific frequency ±0.5Hz in the power grid as an example, the corresponding amplitude-frequency attenuation is 3dB. The second preset amplitude frequency is 77dB, and the corresponding first gain equation is: , .

[0109] "Based on the constraint conditions of the target open-loop transfer function at the preset crossover frequency, the third gain equation is determined," that is, S133 may include the following steps: S1331, as follows Figure 7 As shown.

[0110] S1331. Based on the fact that the amplitude-frequency characteristic of the target open-loop transfer function at the preset crossover frequency satisfies the third preset amplitude-frequency, determine the third gain equation.

[0111] For example, taking the case where the loop gain of the target open-loop transfer function is equal to 1 at a preset crossover frequency, that is... ,but The third preset amplitude frequency is 0dB, and the corresponding first gain equation is: , .

[0112] As an example, given that the DC bus voltage of a three-phase grid-connected inverter is 2300V, the switching frequency is 15kHz, the AC line voltage is 1140V, the output power is 700kW, and the grid frequency is 50Hz, calculations show that... =0.2mH, 50uH, C=80uF, Ω, preset crossover frequency parameter =1500Hz. Based on the constraints of the target open-loop function at three locations: a specific frequency of the power grid (50Hz), a power grid fluctuation frequency (±0.5Hz), and a crossover frequency (1500Hz), the gain equations are obtained as shown in formula (10).

[0113]

[0114] By solving the above system of equations, we can determine... =1.83448, =4.22698, =0.009987545.

[0115] like Figure 8 As shown, crossover frequency At 1500Hz, the loop gain is 1, and the corresponding amplitude-frequency response is 0dB; at the grid frequency of 50Hz, the amplitude is 80dB.

[0116] like Figure 9 As shown, crossover frequency At 1500Hz, the loop phase frequency characteristic corresponds to an angle of -135°, which is 45° away from -180°, indicating that the system is stable.

[0117] exist The waveforms of the reference current and feedback current (i.e., the actual current on the grid-connected side) under the shaft are as follows: Figure 10 As shown, the reference current and the feedback current are basically the same, indicating that the proportional resonant controller has good tracking performance.

[0118] like Figure 11 As shown, analysis using Fast Fourier Transform (FFT) reveals that... In the coordinate system, the amplitude and phase of the reference current and the actual current are consistent.

[0119] Subsequent simulations verified the waveforms of the three-phase grid-connected voltage and current, as follows: Figure 12As shown, V_3phSourcevoltage1, V_3phSourcevoltage2, and V_3phSourcevoltage3 represent the phase voltage waveforms of the three-phase power grid. These are sinusoidal waves with a 120° phase difference, serving as the voltage reference sources for the grid-connected system. L4Inductorcurrent, L5Inductorcurrent, and L6Inductorcurrent represent the current waveforms of the three-phase grid-connected inductors. These waveforms are in phase and frequency synchronized with the corresponding phase's grid voltage, indicating that the inverter's output grid-connected current accurately tracks the grid voltage. The current waveforms are almost distortion-free and perfectly aligned with the grid voltage phase, demonstrating that the proportional resonant controller and filter work together to effectively achieve zero steady-state error tracking of the actual current (the grid's fundamental AC signal) while suppressing harmonic interference, thus meeting the grid-connected technical specifications for current quality.

[0120] Based on the method for determining the parameters of a proportional resonant controller provided in the above embodiments, this application also provides specific implementations of a device for determining the parameters of a proportional resonant controller. Please refer to the following embodiments.

[0121] This proportional resonant controller is used in the current controller of a three-phase grid-connected inverter. The parameters of the proportional resonant controller include a proportional coefficient, a first damping coefficient, and a second damping coefficient. The first damping coefficient is greater than the second damping coefficient. The three-phase grid-connected inverter also includes a filter. See also... Figure 13 The proportional resonant controller parameter determination device 200 provided in this application embodiment includes the following modules: acquisition module 201, first determination module 202, second determination module 203 and third determination module 204.

[0122] The acquisition module 201 is used to acquire specific power grid frequencies, switching frequencies, filter parameters, and virtual resistance values; The first determining module 202 inputs the specific grid frequency, switching frequency, filter parameters, and virtual resistance value into a preset open-loop transfer function to determine the target open-loop transfer function corresponding to the three-phase grid-connected inverter. The preset open-loop transfer function is determined based on the expression of the proportional resonant controller and the transfer function expression of the filter. The expression of the proportional resonant controller includes a proportional factor, a first resonant factor, and a second resonant factor. The proportional factor is determined based on the proportional coefficient, the first resonant factor is determined based on the first damping coefficient, and the second resonant factor is determined based on the second damping coefficient and the grid connection frequency. The second determining module 203 is used to determine the gain equation set corresponding to the three-phase grid-connected inverter based on preset constraints and the target open-loop transfer function. The third determining module 204 is used to solve the gain equation system and determine the values ​​of the proportional coefficient, the first damping coefficient, and the second damping coefficient.

[0123] The proportional resonant controller parameter determination device provided in this application embodiment has low coupling between parameters, can be designed independently, and is simple to implement in engineering. In the target open-loop transfer function, the proportional coefficient determines the basic proportional gain, the first damping coefficient controls the decay rate of the strong damping resonant factor (i.e., the first resonant factor), and the second damping coefficient controls the decay rate of the weak damping resonant factor (i.e., the second resonant factor). The difference between the first damping coefficient and the second damping coefficient can affect the gain bandwidth. The larger the difference between the two, the more significant the difference in decay rate between the second resonant factor and the first resonant factor. The higher the high gain range at a specific frequency of the power grid, the higher the gain can be maintained even if there are fluctuations in the power grid frequency, thus improving the adaptability and robustness to power grid frequency deviation.

[0124] In some embodiments, the device may further include: a second acquisition module and a fourth determination module; before inputting the specific grid frequency, switching frequency and filter parameters into the preset open-loop transfer function, the second acquisition module is used to acquire the expression of the proportional resonant controller and the transfer function expression of the filter; the fourth determination module is used to determine the product of the proportional resonant controller and the filter as the preset open-loop transfer function.

[0125] In some embodiments, the second acquisition module is used to acquire an expression for the proportional resonant controller, which may include: determining a proportional factor based on a proportional coefficient, determining a first resonant factor based on a first damping coefficient, and determining a second resonant factor based on a second damping coefficient; and determining an expression for the proportional resonant controller based on the proportional factor, the first resonant factor, and the second resonant factor.

[0126] In some embodiments, the second acquisition module is used to determine the expression of the proportional resonance controller based on the scaling factor, the first resonance factor, and the second resonance factor, which may include: determining the target resonance factor based on the ratio of the second resonance factor to the target resonance factor; and determining the expression of the proportional resonance controller based on the product of the scaling factor and the target resonance factor.

[0127] In some embodiments, the second acquisition module is configured to determine a scaling factor based on a scaling coefficient, a first resonance factor based on a first damping coefficient, and a second resonance factor based on a second damping coefficient, and may include: The scaling factor is determined by the scaling coefficient. The first resonance factor will be calculated according to formula (3):

[0128] The second resonance factor will be calculated according to formula (4):

[0129] The second acquisition module is used to determine the expression of the proportional resonance controller based on the product of the scaling factor and the target resonance factor, including: The expression for the proportional resonant controller is shown in formula (5).

[0130]

[0131] in, This represents a proportional resonant controller. This represents the proportionality coefficient. Indicates the first damping coefficient. Indicates the second damping coefficient. The angular frequency corresponding to a specific frequency of the power grid. This represents the Laplace operator.

[0132] In some embodiments, the filter includes an inverter-side inductor, a filter capacitor, and a grid-connected inductor. The filter parameters include the inverter-side inductor value, the filter capacitor value, and the grid-connected inductor value. The proportional resonant controller is equivalent to a virtual resistor connected in parallel with the filter capacitor. Accordingly, the second acquisition module is used to acquire the expression of the proportional resonant controller, which may include: Based on the inverter-side inductance value, filter capacitor value, grid-connected inductance value, and virtual resistance value, the transfer function expression of the filter is determined as shown in formula (6):

[0133] in, The transfer function of the filter is represented by... Indicates the inductance value on the inverter side. Indicates the inductance value on the grid-connected side. Indicates the value of the filter capacitor. Indicates the virtual resistance value. This represents the Laplace operator.

[0134] In some embodiments, the second determining module is used to determine the gain equation set corresponding to the three-phase grid-connected inverter based on preset constraints and a target open-loop transfer function. This may include: determining a first gain equation based on constraints of the target gain transfer function at a specific grid frequency; determining a second gain equation based on constraints of the target open-loop transfer function at grid fluctuation frequencies; determining a third gain equation based on constraints of the target open-loop transfer function at a preset crossover frequency; the preset crossover frequency is determined based on the switching frequency; and determining the gain equation set corresponding to the three-phase grid-connected inverter based on the first gain equation, the second gain equation, and the third gain equation.

[0135] In some embodiments, the amplitude-frequency characteristics of the target open-loop transfer function are represented in logarithmic form. Accordingly, the second determining module is used to determine the first gain equation based on the constraints of the target open-loop transfer function at a specific frequency of the power grid. This may include: determining the first gain equation based on the fact that the amplitude-frequency characteristics of the target open-loop transfer function at a specific frequency of the power grid satisfy a first preset amplitude-frequency.

[0136] The second determining module is used to determine the second gain equation based on the constraints of the target open-loop transfer function at the grid fluctuation frequency. It may include: determining the second gain equation based on the fact that the amplitude-frequency characteristics of the target open-loop transfer function at the grid fluctuation frequency satisfy a second preset amplitude frequency; the second preset amplitude frequency is determined based on the first preset amplitude frequency and the amplitude-frequency attenuation.

[0137] The second determining module is used to determine the third gain equation based on the constraints of the target open-loop transfer function at the preset crossover frequency. This may include: determining the third gain equation based on the fact that the amplitude-frequency characteristics of the target open-loop transfer function at the preset crossover frequency satisfy the third preset amplitude-frequency.

[0138] Figure 14 A schematic diagram of the hardware structure of the electronic device provided in an embodiment of this application is shown.

[0139] An electronic device may include a processor 301 and a memory 302 storing computer program instructions.

[0140] Specifically, the processor 301 may include a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits that can be configured to implement the embodiments of this application.

[0141] Memory 302 may include mass storage for data or instructions. For example, and not limitingly, memory 302 may include a hard disk drive (HDD), floppy disk drive, flash memory, optical disk, magneto-optical disk, magnetic tape, or Universal Serial Bus (USB) drive, or a combination of two or more of these. Where appropriate, memory 302 may include removable or non-removable (or fixed) media. Where appropriate, memory 302 may be internal or external to an electronic device. In a particular embodiment, memory 302 is a non-volatile solid-state memory.

[0142] Memory may include read-only memory (ROM), random access memory (RAM), disk storage media devices, optical storage media devices, flash memory devices, and electrical, optical, or other physical / tangible memory storage devices. Therefore, typically, memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the methods according to one aspect of this disclosure.

[0143] The processor 301 reads and executes computer program instructions stored in the memory 302 to implement any of the methods for determining the proportional resonant controller parameters in the above embodiments.

[0144] In one example, the electronic device may also include a communication interface 303 and a bus 304. For example, Figure 14 As shown, the processor 301, memory 302, and communication interface 303 are connected through bus 304 and complete communication with each other.

[0145] The communication interface 303 is mainly used to realize communication between various modules, devices, units and / or equipment in the embodiments of this application.

[0146] Bus 304 includes hardware, software, or both, that couples components of an online data flow metering device together. For example, and not limitingly, the bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), a Hypertext Transfer (HT) interconnect, an Industry Standard Architecture (ISA) bus, an Infinite Bandwidth Interconnect, a Low Pin Count (LPC) bus, a memory bus, a Micro Channel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local Bus (VESA Local Bus, VLB) bus, or other suitable buses, or a combination of two or more of these. Where appropriate, bus 304 may include one or more buses. Although specific buses are described and illustrated in the embodiments of this application, this application considers any suitable bus or interconnection.

[0147] Furthermore, in conjunction with the method for determining the proportional resonant controller parameters in the above embodiments, this application embodiment can provide a computer storage medium for implementation. This computer storage medium stores computer program instructions; when these computer program instructions are executed by a processor, they implement any of the methods for determining the proportional resonant controller parameters in the above embodiments.

[0148] This application also provides a computer program product, including a computer program, which, when executed, implements any of the proportional resonant controller parameter determination methods described in the above embodiments.

[0149] It should be clarified that this application is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of this application is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of this application.

[0150] The functional blocks shown in the above-described structural diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. Programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable-ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0151] It should also be noted that the exemplary embodiments mentioned in this application describe methods or systems based on a series of steps or apparatus. However, this application is not limited to the order of the above steps; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0152] The aspects of this disclosure have been described above with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It should be understood that each block in the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that these instructions, executable via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field-programmable logic circuit. It is also understood that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can also be implemented by special-purpose hardware performing the specified functions or actions, or can be implemented by a combination of special-purpose hardware and computer instructions.

[0153] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A method for determining the parameters of a proportional resonant controller, characterized in that, The proportional resonant controller is applied to the current controller of a three-phase grid-connected inverter. The parameters of the proportional resonant controller include a proportional coefficient, a first damping coefficient, and a second damping coefficient, wherein the first damping coefficient is greater than the second damping coefficient. The three-phase grid-connected inverter also includes a filter. The method includes: Obtain specific frequencies, switching frequencies, and filtering parameters of the power grid; The specific grid frequency, the switching frequency, and the filter parameters are input into a preset open-loop transfer function to determine the target open-loop transfer function corresponding to the three-phase grid-connected inverter. The preset open-loop transfer function is determined based on the expression of the proportional resonant controller and the transfer function expression of the filter. The expression of the proportional resonant controller includes a proportional factor, a first resonant factor, and a second resonant factor. The proportional factor is determined based on the proportional coefficient, the first resonant factor is determined based on the first damping coefficient, and the second resonant factor is determined based on the second damping coefficient and the grid connection frequency. Based on the preset constraints and the target open-loop transfer function, the gain equation set corresponding to the three-phase grid-connected inverter is determined. Solve the gain equations to determine the values ​​of the proportional coefficient, the first damping coefficient, and the second damping coefficient.

2. The method according to claim 1, characterized in that, Before inputting the specific frequency of the power grid, the switching frequency, and the filtering parameters into a preset open-loop transfer function, the method further includes: Obtain the expression for the proportional resonant controller and the transfer function expression for the filter; The product of the proportional resonant controller and the filter is determined as the preset open-loop transfer function.

3. The method according to claim 2, characterized in that, The process of obtaining the expression for the proportional resonant controller includes: The scaling factor is determined based on the scaling coefficient, the first resonance factor is determined based on the first damping coefficient, and the second resonance factor is determined based on the second damping coefficient. The expression for the proportional resonance controller is determined based on the scaling factor, the first resonance factor, and the second resonance factor.

4. The method according to claim 3, characterized in that, Determining the expression for the proportional resonance controller based on the scaling factor, the first resonance factor, and the second resonance factor includes: The target resonance factor is determined based on the ratio of the second resonance factor to the second resonance factor. The expression for the proportional resonance controller is determined based on the product of the scaling factor and the target resonance factor.

5. The method according to claim 4, characterized in that, The step of determining the scaling factor based on the scaling coefficient, determining the first resonance factor based on the first damping coefficient, and determining the second resonance factor based on the second damping coefficient includes: The scaling factor is defined as the scaling coefficient. The first resonance factor will be calculated according to the following formula: ， The second resonance factor will be calculated according to the following formula: ， Determining the expression for the proportional resonance controller based on the product of the scaling factor and the target resonance factor includes: The expression for the proportional resonant controller is determined as follows: ， in, This refers to the proportional resonant controller. This represents the proportionality coefficient. This represents the first damping coefficient. This represents the second damping coefficient. The angular frequency corresponding to a specific frequency of the power grid. This represents the Laplace operator.

6. The method according to claim 2, characterized in that, The filter includes an inverter-side inductor, a filter capacitor, a grid-connected inductor, and a virtual resistor. The filter parameters include the inverter-side inductor value, the filter capacitor value, the grid-connected inductor value, and the virtual resistance value. Correspondingly, obtaining the transfer function expression of the proportional resonant controller includes: Based on the inverter-side inductance value, the filter capacitor value, the grid-connected inductance value, and the virtual resistance value, the transfer function expression of the filter is determined as follows: ， in, The transfer function of the filter is represented by . This indicates the inductance value on the inverter side. This indicates the grid-connected side inductance value. This indicates the value of the filter capacitor. This represents the virtual resistance value. This represents the Laplace operator.

7. The method according to claim 1, characterized in that, The determination of the gain equations corresponding to the three-phase grid-connected inverter based on preset constraints and the target open-loop transfer function includes: Based on the constraints of the target open-loop transfer function at a specific frequency of the power grid, the first gain equation is determined. Based on the constraints of the target open-loop transfer function at the power grid fluctuation frequency, the second gain equation is determined. Based on the constraints of the target open-loop transfer function at the preset crossover frequency, the third gain equation is determined; the preset crossover frequency is determined based on the switching frequency. Based on the first gain equation, the second gain equation, and the third gain equation, the gain equation set corresponding to the three-phase grid-connected inverter is determined.

8. The method according to claim 7, characterized in that, The amplitude-frequency characteristic of the target open-loop transfer function is expressed in logarithmic form. Correspondingly, determining the first gain equation based on the constraints of the target open-loop transfer function at a specific frequency of the power grid includes: Based on the fact that the amplitude-frequency characteristic of the target open-loop transfer function at a specific frequency of the power grid satisfies the first preset amplitude-frequency, the first gain equation is determined. The determination of the second gain equation based on the constraints of the target open-loop transfer function at the power grid fluctuation frequency includes: The second gain equation is determined based on the fact that the amplitude-frequency characteristic of the target open-loop transfer function at the power grid fluctuation frequency satisfies the second preset amplitude frequency; the second preset amplitude frequency is determined based on the first preset amplitude frequency and the amplitude-frequency attenuation. The determination of the third gain equation based on the constraint conditions of the target open-loop transfer function at the preset crossover frequency includes: Based on the fact that the amplitude-frequency characteristic of the target open-loop transfer function at the preset crossover frequency satisfies the third preset amplitude frequency, the third gain equation is determined.

9. A device for determining the parameters of a proportional resonant controller, characterized in that, The proportional resonant controller is applied to the current controller of a three-phase grid-connected inverter. The parameters of the proportional resonant controller include a proportional coefficient, a first damping coefficient, and a second damping coefficient, wherein the first damping coefficient is greater than the second damping coefficient. The three-phase grid-connected inverter also includes a filter. The device includes: The acquisition module is used to acquire specific frequencies, switching frequencies, and filtering parameters of the power grid. The first determining module inputs the specific grid frequency, the switching frequency, and the filter parameters into a preset open-loop transfer function to determine the target open-loop transfer function corresponding to the three-phase grid-connected inverter. The preset open-loop transfer function is determined based on the expression of the proportional resonant controller and the transfer function expression of the filter. The expression of the proportional resonant controller includes a proportional factor, a first resonant factor, and a second resonant factor. The proportional factor is determined based on the proportional coefficient, the first resonant factor is determined based on the first damping coefficient, and the second resonant factor is determined based on the second damping coefficient and the grid connection frequency. The second determining module is used to determine the gain equation set corresponding to the three-phase grid-connected inverter based on preset constraints and the target open-loop transfer function; The third determining module is used to solve the gain equations and determine the values ​​of the proportional coefficient, the first damping coefficient, and the second damping coefficient.

10. An electronic device, characterized in that, The electronic device includes: a processor and a memory storing computer program instructions; When the processor executes the computer program instructions, it implements the method for determining the parameters of the proportional resonant controller as described in any one of claims 1-8.

11. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer program instructions, which, when executed by a processor, implement the method for determining the parameters of the proportional resonant controller as described in any one of claims 1-8.

12. A computer program product, characterized in that, When the instructions in the computer program product are executed by the processor of the electronic device, the electronic device performs the method for determining the parameters of the proportional resonant controller as described in any one of claims 1-8.

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