Grid-connected converter control method and device, electronic equipment and storage medium

Abstract

The application belongs to the technical field of electric power, and provides a grid-connected converter control method and device, electronic equipment and storage medium. The method comprises the following steps: obtaining a DC side voltage of a grid-connected converter; calculating an outer voltage loop output value according to the DC side voltage and a preset DC side voltage given value; determining an adjustment value according to the DC side voltage and a pre-calculated damping coefficient; adjusting the outer voltage loop output value based on the adjustment value to obtain an active current given value of an inner current loop, and controlling the grid-connected converter according to the active current given value of the inner current loop. The application can improve the DC side damping characteristics of the grid-connected converter and enhance the system stability.

Description

Technical Field

[0001] This invention belongs to the field of power technology, and in particular relates to a grid-connected converter control method, device, electronic equipment and storage medium. Background Technology

[0002] In recent years, distributed generation, primarily based on clean energy, has seen widespread development, with an increasing number of energy storage devices and new energy power generation devices, mainly photovoltaic and wind power, being connected to the power grid. To address the flexibility of new energy power generation devices and ensure power supply reliability, DC distribution network technology has been proposed as a solution.

[0003] When a DC distribution network is connected to the grid, the AC / DC grid-connected converter, as the interface circuit between the DC distribution network and the grid, needs to maintain the DC bus voltage through power control. For typical AC / DC grid-connected converters, the outer voltage loop control mainly uses a PI controller. When designing PI parameters, considering its disturbance rejection characteristics, it is necessary to design according to a typical Type II system and tune the PI parameters to an underdamped state. However, the dynamic and disturbance rejection characteristics of PI parameters designed according to a typical Type II system are affected by the intermediate frequency bandwidth, and the two will have opposite effects on the system control characteristics. Therefore, there is a certain contradiction between system following and disturbance rejection characteristics in the design, and it is impossible to completely balance them in engineering design. Generally, an intermediate frequency bandwidth of 5 is selected in engineering design, but at this time, the damping characteristics of DC side voltage control are still poor, the DC side voltage overshoot is large, and the system stability is poor. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a grid-connected converter control method, apparatus, electronic device and storage medium to improve the DC-side damping characteristics of the grid-connected converter and enhance system stability.

[0005] A first aspect of this invention provides a grid-connected converter control method, comprising:

[0006] Obtain the DC-side voltage of the grid-connected converter;

[0007] Calculate the external voltage loop output value based on the DC-side voltage and the preset DC-side voltage setpoint;

[0008] The adjustment value is determined based on the DC side voltage and the pre-calculated damping coefficient;

[0009] The output value of the external voltage loop is adjusted based on the adjustment value to obtain the active current setpoint of the internal current loop. The grid-connected converter is then controlled according to the active current setpoint of the internal current loop.

[0010] In conjunction with the first aspect, as one possible implementation of the first aspect, the external voltage loop output value is calculated based on the DC-side voltage and a preset DC-side voltage setpoint, including:

[0011] Calculate the difference between the DC-side voltage and the preset DC-side voltage setpoint;

[0012] The difference is input into the preset external voltage loop PI controller to obtain the external voltage loop output value.

[0013] In conjunction with the first aspect, as one possible implementation of the first aspect, the adjustment value is determined based on the DC-side voltage and the pre-calculated damping coefficient, including:

[0014] Multiply the DC-side voltage by the damping coefficient to obtain the adjustment value;

[0015] The formula for calculating the damping coefficient is:

[0016]

[0017] In the formula, k d k is the damping coefficient. vp k vi Here are the outer loop PI parameters for voltage, C is the DC side capacitance, and S... de For steady-state duty cycle, Y G T is the equivalent conductance on the DC side. C It is the equivalent time constant of the inner current loop system.

[0018] In conjunction with the first aspect, as one possible implementation of the first aspect, the grid-connected converter is controlled based on the active current setpoint of the inner current loop, including:

[0019] Obtain the d-axis and q-axis components of the current on the AC side of the grid-connected converter;

[0020] The difference between the d-axis component of the current and the given value of the active current is calculated, and the difference is input into the first PI controller of the preset current loop to obtain the d-axis voltage signal.

[0021] The difference between the q-axis component of the current and the preset reactive current setpoint is calculated, and the difference is input into the second PI controller of the preset inner current loop to obtain the q-axis voltage signal.

[0022] The d-axis voltage signal is decoupled by feedforward to obtain the d-axis voltage reference value, and the q-axis voltage signal is decoupled by feedforward to obtain the q-axis voltage reference value. Based on the d-axis voltage reference value and the q-axis voltage reference value, the switches of the grid-connected converter are controlled.

[0023] A second aspect of the present invention provides a grid-connected converter control device, comprising:

[0024] The acquisition module is used to acquire the DC-side voltage of the grid-connected converter;

[0025] The calculation module is used to calculate the external voltage loop output value based on the DC-side voltage and the preset DC-side voltage setpoint; and to determine the adjustment value based on the DC-side voltage and the pre-calculated damping coefficient.

[0026] The control module is used to adjust the output value of the external voltage loop based on the adjustment value to obtain the active current setpoint of the internal current loop, and to control the grid-connected converter according to the active current setpoint of the internal current loop.

[0027] In conjunction with the second aspect, as one possible implementation of the second aspect, the computation module is specifically used for:

[0028] Calculate the difference between the DC-side voltage and the preset DC-side voltage setpoint;

[0029] The difference is input into the preset external voltage loop PI controller to obtain the external voltage loop output value.

[0030] In conjunction with the second aspect, as one possible implementation of the second aspect, the computation module is specifically used for:

[0031] Multiply the DC-side voltage by the damping coefficient to obtain the adjustment value;

[0032] The formula for calculating the damping coefficient is:

[0033]

[0034] In the formula, k d k is the damping coefficient. vp k vi Here are the outer loop PI parameters for voltage, C is the DC side capacitance, and S... de For steady-state duty cycle, Y G T is the equivalent conductance on the DC side. C It is the equivalent time constant of the inner current loop system.

[0035] In conjunction with the second aspect, as one possible implementation of the second aspect, the control module is specifically used for:

[0036] Obtain the d-axis and q-axis components of the current on the AC side of the grid-connected converter;

[0037] The difference between the d-axis component of the current and the given value of the active current is calculated, and the difference is input into the first PI controller of the preset current loop to obtain the d-axis voltage signal.

[0038] The difference between the q-axis component of the current and the preset reactive current setpoint is calculated, and the difference is input into the second PI controller of the preset inner current loop to obtain the q-axis voltage signal.

[0039] The d-axis voltage signal is decoupled by feedforward to obtain the d-axis voltage reference value, and the q-axis voltage signal is decoupled by feedforward to obtain the q-axis voltage reference value. Based on the d-axis voltage reference value and the q-axis voltage reference value, the switches of the grid-connected converter are controlled.

[0040] A third aspect of the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the grid-connected converter control method of the first aspect described above.

[0041] A fourth aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the grid-connected converter control method of the first aspect described above.

[0042] The beneficial effects of the embodiments of the present invention compared with the prior art are as follows:

[0043] In this embodiment of the invention, the adjustment value is determined based on the DC-side voltage and the pre-calculated damping coefficient. This adjustment value is then used to adjust the output value of the external voltage loop, forming a new inner-loop active current setpoint. In other words, by introducing a damping control loop into the external voltage loop, the system model order is reduced, significantly enhancing the damping characteristics of the DC-side voltage control and improving system stability without weakening disturbance rejection. This solves the problem in the prior art where there is a contradiction between system following and disturbance rejection characteristics, making it impossible to simultaneously consider both in the design. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a structural block diagram of the grid-connected converter system provided in an embodiment of the present invention;

[0046] Figure 2 This is a block diagram of a grid-connected converter control provided in an embodiment of the present invention;

[0047] Figure 3 This is a flowchart illustrating the grid-connected converter control method provided in an embodiment of the present invention;

[0048] Figure 4 This is a simulation waveform diagram of the method provided in this embodiment of the invention under the following working conditions;

[0049] Figure 5This is a simulation waveform diagram of the method provided in this embodiment of the invention under working condition two;

[0050] Figure 6 This is an experimental waveform diagram of the method provided in this embodiment of the invention under working condition three;

[0051] Figure 7 This is an experimental waveform diagram of the method provided in this embodiment of the invention under operating condition four;

[0052] Figure 8 This is a schematic diagram of the structure of the grid-connected converter control device provided in an embodiment of the present invention;

[0053] Figure 9 This is a schematic diagram of the structure of the electronic device provided in an embodiment of the present invention. Detailed Implementation

[0054] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0055] To illustrate the technical solution described in this invention, specific embodiments are described below.

[0056] This invention provides a full-state feedback control strategy to improve the DC-side damping characteristics of an AC / DC grid-connected converter. This control strategy is applied to grid-connected systems that require DC voltage control. The system may include a three-phase AC / DC grid-connected converter, an AC-side inductor, a DC-side capacitor, an AC power grid, etc.

[0057] First, a brief introduction to the structure of the AC / DC grid-connected converter system will be given. Figure 1 This is a structural block diagram of the AC / DC grid-connected converter system provided by the present invention. See also... Figure 1 As shown, the AC / DC grid-connected converter system includes an AC / DC grid-connected converter and an AC power grid. The main circuit of the grid-connected converter includes a DC-side energy storage capacitor C, an IGBT three-phase bridge circuit, and an AC-side filter inductor L. The AC power grid line impedance is considered. Power can flow bidirectionally in the system. dc e is the DC-side voltage of the grid-connected converter. j (j=a,b,c) is the AC side voltage of the converter, u jN (j = a, b, c) represents the AC grid voltage, i j (j=a,b,c) represents the three-phase grid-connected current.

[0058] In this embodiment, to better understand the scheme, a grid-connected converter control block diagram is also provided, such as... Figure 2 As shown. Figure 3 This is a flowchart of the grid-connected converter control method provided in this embodiment.

[0059] Please see also Figure 2 and Figure 3 As shown, the grid-connected converter control method provided in this embodiment of the invention specifically includes the following steps:

[0060] Step S101: Obtain the DC side voltage u of the grid-connected converter. dc .

[0061] Step S102, based on the DC side voltage u dc and the preset DC side voltage setpoint Calculate the output value of the external voltage loop.

[0062] Step S103, based on the DC side voltage u dc The adjustment value is determined based on the pre-calculated damping coefficient kd.

[0063] Step S104: Adjust the output value of the external voltage loop based on the adjustment value to obtain the active current setpoint of the internal current loop. Based on the active current setpoint of the inner current loop Control the grid-connected converter.

[0064] In this embodiment, the traditional grid-connected converter control method directly uses the output value of the external voltage loop as the active current setpoint of the internal current loop. However, since the grid-connected converter operates in the distribution network and its disturbance rejection characteristics need to be considered, the external voltage loop is often designed as a typical Type II system, and its PI parameter tuning will be underdamped. When designed as a typical Type II system, its dynamic and disturbance rejection characteristics are affected by the intermediate frequency bandwidth. As the intermediate frequency bandwidth increases, the two will have opposite effects on the system control characteristics, resulting in a certain contradiction between dynamic and disturbance rejection characteristics, which cannot be balanced in engineering design. At the same time, when selecting the intermediate frequency bandwidth, considering both characteristics, a bandwidth of 5 is chosen, which results in poor damping and a large DC-side voltage overshoot.

[0065] This embodiment introduces a damping control loop into the outer voltage loop, that is, based on the DC side voltage u dc and the pre-calculated damping coefficient k dThis method adjusts the output value of the external voltage loop by modifying the inner loop current setpoint, introducing damping, which is equivalent to connecting a resistor in parallel across the DC-side capacitor. Unlike actual resistors, which suffer from excessive losses, this virtual resistor enhances the damping characteristics of the external voltage loop. Furthermore, it can downgrade the original system from a typical Type II system to a typical Type I system, improving system stability without weakening its disturbance rejection, effectively enhancing the DC-side damping characteristics, and enabling the grid-connected converter to achieve superior performance indicators.

[0066] As can be seen, the embodiment of the present invention determines the adjustment value based on the DC-side voltage and the pre-calculated damping coefficient, and adjusts the output value of the external voltage loop using this adjustment value to form a new inner loop active current setpoint. That is, by introducing a damping control loop into the external voltage loop, the model order of the system is reduced, which significantly enhances the damping characteristics of the DC-side voltage control, enhances the system stability, and does not weaken the disturbance rejection capability. This solves the problem in the prior art that there is a contradiction between system following and disturbance rejection characteristics, and that the design cannot simultaneously take these into account.

[0067] As one possible implementation, in step S102, the external voltage loop output value is calculated based on the DC-side voltage and a preset DC-side voltage setpoint, which can be detailed as follows:

[0068] Calculate the difference between the DC-side voltage and the preset DC-side voltage setpoint;

[0069] The difference is input into the preset external voltage loop PI controller to obtain the external voltage loop output value.

[0070] In this embodiment, see Figure 2 As shown, the DC side voltage u dc and DC side voltage setpoint The difference is compared and controlled by the PI controller of the external voltage loop to obtain the output value of the external voltage loop.

[0071] As one possible implementation, in step S103, the adjustment value is determined based on the DC-side voltage and the pre-calculated damping coefficient, which can be detailed as follows:

[0072] Multiply the DC-side voltage by the damping coefficient to obtain the adjustment value.

[0073] The formula for calculating the damping coefficient is:

[0074]

[0075] In the formula, k d k is the damping coefficient. vp k vi Here are the outer loop PI parameters for voltage, C is the DC side capacitance, and S... de For steady-state duty cycle, Y GT is the equivalent conductance on the DC side. C It is the equivalent time constant of the inner current loop system.

[0076] In this embodiment, a method for calculating the optimal damping coefficient is also provided.

[0077] When analyzing the voltage outer loop, the inner loop system can be simplified to a first-order system. The current loop bandwidth is often designed to be 1 / 20 of the switching frequency. The current loop system can be simplified as follows:

[0078]

[0079] In the formula, f s Let be the switching frequency, s be a complex frequency domain variable, and T be... C It is the equivalent time constant of the inner current loop system.

[0080] The open-loop transfer function of the external voltage loop after introducing damping is:

[0081]

[0082] As can be seen from the above formula, there exists a zero point. If the damping coefficient k is adjusted... d By canceling out the zeros and poles, the order of the outer loop system can be reduced, k d The calculation method is as follows:

[0083]

[0084] In the formula, k d k is the damping coefficient. vp k vi Here are the outer loop PI parameters for voltage, C is the DC side capacitance, and S... de For steady-state duty cycle, Y G T is the equivalent conductance on the DC side. C It is the equivalent time constant of the inner current loop system.

[0085] By introducing an optimal damping coefficient, the original system, typically a Type II system, can be downgraded to a typical Type I system, with a significant enhancement in damping. The voltage outer-loop control characteristics of the original system are mainly determined by the outer-loop PI parameters, and the overshoot caused by its integral regulation can only be suppressed by proportional regulation. When damping is introduced, the overshoot caused by integral regulation can be suppressed by damping, adding a degree of freedom in regulation and making the control system more flexible.

[0086] As one possible implementation, step S104, which involves controlling the grid-connected converter based on the active current setpoint of the inner current loop, can be detailed as follows:

[0087] Obtain the d-axis and q-axis components of the current on the AC side of the grid-connected converter;

[0088] The difference between the d-axis component of the current and the given value of the active current is calculated, and the difference is input into the first PI controller of the preset current loop to obtain the d-axis voltage signal.

[0089] The difference between the q-axis component of the current and the preset reactive current setpoint is calculated, and the difference is input into the second PI controller of the preset inner current loop to obtain the q-axis voltage signal.

[0090] The d-axis voltage signal is decoupled by feedforward to obtain the d-axis voltage reference value, and the q-axis voltage signal is decoupled by feedforward to obtain the q-axis voltage reference value. Based on the d-axis voltage reference value and the q-axis voltage reference value, the switches of the grid-connected converter are controlled.

[0091] In this embodiment, see Figure 1 and Figure 2 As shown, the active current i in the synchronous rotating coordinate system dq is obtained by transforming the active current setpoint and the grid-side sampled current through coordinates abc / aB / dq. d The difference is then compared and controlled by a PI regulator to output the d-axis voltage signal u. sd Simultaneously, the q-axis component i of the grid-side current after coordinate transformation q Compared with the preset reactive current reference quantity i q * Comparison is performed, and the difference is controlled by a PI regulator to output the q-axis voltage signal u. sq The d-axis voltage signal u is regulated by a PI controller. sd and q-axis voltage signal u sq Then, the d-axis voltage reference quantity u is obtained through feedforward decoupling control. d and q-axis voltage reference quantity u q Finally, u d with u q After the dq / ap inverse transformation, the PWM switching signal is obtained.

[0092] The effectiveness of the grid-connected converter control method provided in this implementation will be verified below.

[0093] Under operating condition one (voltage step, DC voltage jumps from 400V to 450V in 0.2s): The simulation waveform in this embodiment is as follows. Figure 4 As shown in the simulation waveform, when the damping coefficient is taken as the optimal coefficient, the response curve with added damping basically achieves no overshoot and has good speed.

[0094] Under operating condition two (DC voltage fluctuation under load disturbance, 2000W power absorbed by constant power load in 0.2s, 2000W power released by constant power load in 0.3s): the simulation waveform of this embodiment is as follows. Figure 5As shown in the simulation waveform, the damped system exhibits better stability when facing power disturbances. It does not become unstable when faced with power disturbances, and the DC voltage recovers quickly, demonstrating strong resistance to power disturbances.

[0095] Under operating condition three (voltage step, DC voltage jumps from 350V to 450V): the experimental waveforms in this embodiment are as follows. Figure 6 As shown, the experimental waveforms are basically consistent with the simulation. The DC voltage response curve with added damping basically achieves no overshoot and has good speed, indicating that the DC-side damping characteristics of the system are good.

[0096] Under operating condition four (load disturbance, the change in DC-side voltage when the DC-side load absorbs a sudden increase in power): the experimental waveforms in this embodiment are as follows. Figure 7 As shown in the experimental waveform, it can be seen that when faced with power disturbances, the voltage recovery is basically the same as in the simulation, and it has a strong ability to resist power disturbances.

[0097] The control strategy for improving the DC-side damping characteristics of AC / DC grid-connected converters provided by this invention introduces a damping control loop into the voltage outer loop control loop and combines it with the calculation of the optimal damping coefficient to achieve a model order reduction of the system. This reduces the original typical Type II system to a typical Type I system, effectively enhancing system stability without weakening disturbance rejection, and significantly enhancing the damping characteristics of DC-side voltage control.

[0098] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0099] See Figure 8 As shown, an embodiment of the present invention provides a grid-connected converter control device, the device 80 comprising:

[0100] The acquisition module 81 is used to acquire the DC side voltage of the grid-connected converter.

[0101] The calculation module 82 is used to calculate the output value of the external voltage loop based on the DC side voltage and the preset DC side voltage setpoint; and to determine the adjustment value based on the DC side voltage and the pre-calculated damping coefficient.

[0102] The control module 83 is used to adjust the output value of the external voltage loop based on the adjustment value to obtain the active current setpoint of the internal current loop, and to control the grid-connected converter according to the active current setpoint of the internal current loop.

[0103] As one possible implementation, the computing module 82 is specifically used for:

[0104] Calculate the difference between the DC-side voltage and the preset DC-side voltage setpoint;

[0105] The difference is input into the preset external voltage loop PI controller to obtain the external voltage loop output value.

[0106] As one possible implementation, the computing module 82 is specifically used for:

[0107] Multiply the DC-side voltage by the damping coefficient to obtain the adjustment value;

[0108] The formula for calculating the damping coefficient is:

[0109]

[0110] In the formula, k d k is the damping coefficient. vp k vi Here are the outer loop PI parameters for voltage, C is the DC side capacitance, and S... de For steady-state duty cycle, Y G T is the equivalent conductance on the DC side. C It is the equivalent time constant of the inner current loop system.

[0111] As one possible implementation, control module 83 is specifically used for:

[0112] Obtain the d-axis and q-axis components of the current on the AC side of the grid-connected converter;

[0113] The difference between the d-axis component of the current and the given value of the active current is calculated, and the difference is input into the first PI controller of the preset current loop to obtain the d-axis voltage signal.

[0114] The difference between the q-axis component of the current and the preset reactive current setpoint is calculated, and the difference is input into the second PI controller of the preset inner current loop to obtain the q-axis voltage signal.

[0115] The d-axis voltage signal is decoupled by feedforward to obtain the d-axis voltage reference value, and the q-axis voltage signal is decoupled by feedforward to obtain the q-axis voltage reference value. Based on the d-axis voltage reference value and the q-axis voltage reference value, the switches of the grid-connected converter are controlled.

[0116] Figure 9 This is a schematic diagram of the electronic device 90 provided in an embodiment of the present invention. Figure 9 As shown, the electronic device 90 of this embodiment includes: a processor 91, a memory 92, and a computer program 93 stored in the memory 92 and executable on the processor 91, such as a grid-connected converter control program. When the processor 91 executes the computer program 93, it implements the steps in the various grid-connected converter control method embodiments described above, for example... Figure 3Steps S101 to S104 are shown. Alternatively, when processor 91 executes computer program 93, it implements the functions of each module in the above-described device embodiments, for example... Figure 8 The functions of modules 81 to 83 are shown.

[0117] For example, computer program 93 may be divided into one or more modules / units, one or more of which are stored in memory 92 and executed by processor 91 to complete the present invention. One or more modules / units may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of computer program 93 in electronic device 90.

[0118] Electronic device 90 can be a desktop computer, laptop, handheld computer, cloud server, or other computing device. Electronic device 90 may include, but is not limited to, a processor 91 and a memory 92. Those skilled in the art will understand that... Figure 9 This is merely an example of electronic device 90 and does not constitute a limitation on electronic device 90. It may include more or fewer components than shown, or combine certain components, or different components. For example, electronic device 90 may also include input / output devices, network access devices, buses, etc.

[0119] The processor 91 may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0120] The memory 92 can be an internal storage unit of the electronic device 90, such as a hard disk or RAM of the electronic device 90. The memory 92 can also be an external storage device of the electronic device 90, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the electronic device 90. Furthermore, the memory 92 can include both internal and external storage units of the electronic device 90. The memory 92 is used to store computer programs and other programs and data required by the electronic device 90. The memory 92 can also be used to temporarily store data that has been output or will be output.

[0121] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0122] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0123] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0124] In the embodiments provided by this invention, it should be understood that the disclosed devices / electronic devices and methods can be implemented in other ways. For example, the device / electronic device embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0125] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0126] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0127] If integrated modules / units are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. Computer-readable media can include: any entity or device capable of carrying computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in a computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electrical carrier signals and telecommunication signals.

[0128] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A grid-connected converter control method, characterized in that, include: Obtain the DC-side voltage of the grid-connected converter; Calculate the external voltage loop output value based on the DC-side voltage and the preset DC-side voltage setpoint; The adjustment value is determined based on the DC-side voltage and the pre-calculated damping coefficient; The output value of the external voltage loop is adjusted based on the adjustment value to obtain the active current setpoint of the internal current loop, and the grid-connected converter is controlled according to the active current setpoint of the internal current loop. The step of determining the adjustment value based on the DC-side voltage and the pre-calculated damping coefficient includes: multiplying the DC-side voltage by the damping coefficient to obtain the adjustment value; Among them, the open-loop transfer function of the external voltage loop after introducing the damping coefficient. for: By adjusting the damping coefficient k d The zeros and poles of the open-loop transfer function of the external voltage loop are canceled to reduce the order of the external voltage loop system; the damping coefficient is calculated using the following formula: In the formula, k d The damping coefficient is... k vp , k vi These are the outer loop PI parameters for the voltage. C For DC side capacitors, S de For steady-state duty cycle, Y G This is the equivalent conductance on the DC side. T C The equivalent time constant of the inner current loop system. s These are variables in the complex frequency domain.

2. The grid-connected converter control method as described in claim 1, characterized in that, Based on the DC-side voltage and the preset DC-side voltage setpoint, calculate the external voltage loop output value, including: Calculate the difference between the DC-side voltage and the preset DC-side voltage setpoint; The difference is input to the preset PI controller of the external voltage loop to obtain the output value of the external voltage loop.

3. The grid-connected converter control method as described in claim 1, characterized in that, The grid-connected converter is controlled based on the active current setpoint of the inner current loop, including: Obtain the d-axis and q-axis components of the current on the AC side of the grid-connected converter; The difference between the d-axis component of the current and the given value of the active current is calculated, and the difference is input into the first PI controller of the preset current loop to obtain the d-axis voltage signal. The difference between the q-axis component of the current and the preset reactive current setpoint is calculated, and the difference is input into the second PI controller of the preset inner current loop to obtain the q-axis voltage signal. The d-axis voltage signal is decoupled by feedforward to obtain the d-axis voltage reference value, and the q-axis voltage signal is decoupled by feedforward to obtain the q-axis voltage reference value. Based on the d-axis voltage reference value and the q-axis voltage reference value, the switches of the grid-connected converter are controlled.

4. A grid-connected converter control device, characterized in that, include: The acquisition module is used to acquire the DC-side voltage of the grid-connected converter; The calculation module is used to calculate the external voltage loop output value based on the DC-side voltage and the preset DC-side voltage setpoint. The adjustment value is determined based on the DC-side voltage and the pre-calculated damping coefficient; The control module is used to adjust the output value of the external voltage loop based on the adjustment value to obtain the active current setpoint of the internal current loop, and to control the grid-connected converter according to the active current setpoint of the internal current loop. The calculation module is specifically used to: multiply the DC-side voltage by the damping coefficient to obtain the adjustment value; Among them, the open-loop transfer function of the external voltage loop after introducing the damping coefficient. for: By adjusting the damping coefficient k d The zeros and poles of the open-loop transfer function of the external voltage loop are canceled to reduce the order of the external voltage loop system; the damping coefficient is calculated using the following formula: In the formula, k d The damping coefficient is... k vp , k vi These are the outer loop PI parameters for the voltage. C For DC side capacitors, S de For steady-state duty cycle, Y G This is the equivalent conductance on the DC side. T C The equivalent time constant of the inner current loop system. s These are variables in the complex frequency domain.

5. The grid-connected converter control device as described in claim 4, characterized in that, The calculation module is specifically used for: Calculate the difference between the DC-side voltage and the preset DC-side voltage setpoint; The difference is input to the preset PI controller of the external voltage loop to obtain the output value of the external voltage loop.

6. The grid-connected converter control device as described in claim 4, characterized in that, The control module is specifically used for: Obtain the d-axis and q-axis components of the current on the AC side of the grid-connected converter; The difference between the d-axis component of the current and the given value of the active current is calculated, and the difference is input into the first PI controller of the preset current loop to obtain the d-axis voltage signal. The difference between the q-axis component of the current and the preset reactive current setpoint is calculated, and the difference is input into the second PI controller of the preset inner current loop to obtain the q-axis voltage signal. The d-axis voltage signal is decoupled by feedforward to obtain the d-axis voltage reference value, and the q-axis voltage signal is decoupled by feedforward to obtain the q-axis voltage reference value. Based on the d-axis voltage reference value and the q-axis voltage reference value, the switches of the grid-connected converter are controlled.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1 to 3.

8. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1 to 3.

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