Grid-connected inverter stability control method and device based on wide-band damping layered design

Abstract

The embodiment of the application discloses a grid-connected inverter stable control method and device based on wide-frequency damping layered design, which comprises the following steps: calculating the instantaneous active power of the grid-connected inverter system according to the two-phase voltage of the grid-side capacitor and the two-phase current of the inverter-side inductor; calculating the grid current d-axis instruction signal according to the set active instruction value, q-axis voltage and instantaneous active power through the active power control loop, and calculating the grid current q-axis instruction signal according to the set grid-side capacitor voltage instruction signal and two-phase voltage through the alternating voltage control loop; calculating the two-phase control signal of the inverter according to the grid current d-axis instruction signal and q-axis instruction signal and the two-phase voltage and two-phase current through the alternating current control loop; converting the two-phase control signal of the inverter into a three-phase inverter control signal, and controlling the turn-on and turn-off of the power device through the three-phase inverter control signal. The embodiment of the application can improve the operation stability of the grid-connected inverter.

Description

Technical Field

[0001] This invention relates to the field of power electronic systems technology, and in particular to a method and device for stable control of grid-connected inverters based on wideband damping hierarchical design. Background Technology

[0002] With the increasing proportion of new energy generating units in the power system, the power system dominated by traditional synchronous machines is gradually evolving into a new type of power system dominated by power electronic converters. However, new energy power generation systems are usually located in the "Three Norths" region (Northeast, North, and Northwest China), far from load centers. Large-capacity, long-distance transmission and transformer leakage inductance result in non-negligible grid impedance. Furthermore, with the continuous integration of new energy power plants, their grid-connected capacity is constantly increasing, causing the grid to exhibit low inertia and high impedance characteristics, i.e., weak grid characteristics. Under weak grid conditions, broadband oscillations are prone to occur, seriously affecting the power generation quality of new energy grid-connected systems and the operational safety of the power grid. Summary of the Invention

[0003] This application provides a grid-connected inverter stability control method and device based on wideband damping layered design. It comprehensively considers the influence of high-frequency damping, low-frequency damping and the coupling relationship between the two on the frequency domain negative damping region of the inverter output admittance, thereby significantly improving the operating stability of the grid-connected inverter.

[0004] The first aspect of this application provides a grid-connected inverter stability control method based on wideband damping hierarchical design, applied to a new energy grid-connected inverter system. The main circuit of the new energy grid-connected inverter system includes a three-phase full-bridge inverter, inverter-side inductors, grid-side capacitors, and grid impedance. The method includes: The three-phase voltage of the grid-side capacitor and the three-phase current of the inverter-side inductor are collected, and the three-phase voltage and the three-phase current are converted into two-phase voltage and two-phase current, respectively. The instantaneous active power of the new energy grid-connected inverter system is calculated based on the two-phase voltage and the two-phase current. The active power control loop calculates the grid current d-axis command signal based on the set active power command value, the q-axis voltage in the two-phase voltage, and the instantaneous active power. The AC voltage control loop calculates the grid current q-axis command signal based on the set grid-side capacitor voltage command signal and the two-phase voltage. The two-phase control signal of the three-phase full-bridge inverter is calculated through the AC current control loop based on the grid current d-axis command signal and the grid current q-axis command signal, as well as the two-phase voltage and the two-phase current. The two-phase control signals of the three-phase full-bridge inverter are converted into three-phase inverter control signals, and the power devices are turned on and off through the three-phase inverter control signals.

[0005] Optionally, converting the three-phase voltage and the three-phase current into two-phase voltage and two-phase current respectively includes: The three-phase voltage is converted into a two-phase voltage using the Park transformation. The q-axis voltage of the two-phase voltage is input to the phase-locked loop to obtain the phase angle of the q-axis voltage and the phase-locked loop perturbation frequency; The three-phase current is transformed using the phase angle to obtain the two-phase current.

[0006] Optionally, the formulas for calculating the phase angle and the phase-locked loop perturbation frequency are as follows: , .

[0007] in, The phase angle, The frequency of the phase-locked loop (PLL) disturbance. Let q be the q-axis voltage of the two-phase voltages. It is a phase-locked loop PI controller. This is the proportional adjustment coefficient of the phase-locked loop. This is the integral adjustment coefficient of the phase-locked loop. The rated angular frequency of the grid voltage. For the Laplace operator.

[0008] Optionally, the formula for calculating the instantaneous active power is as follows: , in, and For two-phase voltage, and Let d and q represent two-phase currents, where d and q represent different axes in the two phases, respectively.

[0009] Optionally, the calculation formula for the d-axis command signal of the power grid current is: , in, This is the d-axis command signal for the grid current. It is a PI controller for active power control loop. This is the proportional adjustment coefficient for the active power control loop. The integral adjustment coefficient of the active power control loop; The set active power command value, The control equations for the low-pass filter are as follows: The control equations are for a second-order integral controller with d-axis capacitor voltage feedforward. The d-axis power grid frequency offset feedforward control equation is given.

[0010] Optionally, the calculation formula for the q-axis command signal of the power grid current is:

[0011] in, This is the q-axis command signal for the grid current. This is the set command signal for the grid-side capacitor voltage. For AC voltage control loop PI controller, This is the proportional adjustment coefficient for the AC voltage control loop. The integral adjustment coefficient of the AC voltage control loop; The control equations are for a second-order integral controller with q-axis capacitor voltage feedforward. The q-axis power grid frequency offset feedforward control equation is given.

[0012] Optionally, the two-phase control signal equations of the three-phase full-bridge inverter are:

[0013] in, and These are the two-phase control signals for the three-phase full-bridge inverter. It is a current loop PI controller. This is the proportional adjustment coefficient for the current loop. This is the integral adjustment coefficient for the current loop; , Let represent the proportional control coefficient and the first-order integral control equation in the d-axis capacitor voltage feedforward integral controller. , Let be the proportional control coefficient and the first-order integral control equation in the q-axis capacitor voltage feedforward integral controller. This is a high-frequency damping control equation composed of capacitor voltage feedforward and current feedforward.

[0014] A second aspect of this application provides a grid-connected inverter stability control device based on a wideband damping hierarchical design, applied to a new energy grid-connected inverter system. The main circuit of the new energy grid-connected inverter system includes a three-phase full-bridge inverter, inverter-side inductors, grid-side capacitors, and grid impedance. The device includes: The signal acquisition and conversion unit is used to acquire the three-phase voltage of the grid-side capacitor and the three-phase current of the inverter-side inductor, and convert the three-phase voltage and the three-phase current into two-phase voltage and two-phase current, respectively. The instantaneous active power calculation unit is used to calculate the instantaneous active power of the new energy grid-connected inverter system based on the two-phase voltage and the two-phase current. The grid current command signal calculation unit is used to calculate the grid current d-axis command signal based on the set active power command value, the q-axis voltage in the two-phase voltage and the instantaneous active power through the active power control loop, and to calculate the grid current q-axis command signal based on the set grid-side capacitor voltage command signal and the two-phase voltage through the AC voltage control loop. The inverter control signal calculation unit is used to calculate the two-phase control signal of the three-phase full-bridge inverter through the AC current control loop, based on the grid current d-axis command signal and the grid current q-axis command signal, as well as the two-phase voltage and the two-phase current. The signal conversion and switching control unit is used to convert the two-phase control signals of the three-phase full-bridge inverter into three-phase inverter control signals, and to control the switching on and off of power devices through the three-phase inverter control signals.

[0015] A third aspect of this application provides an electronic device, including: a processor and a memory; The processor is connected to a memory, wherein the memory is used to store computer programs and the processor is used to invoke the computer programs to execute the methods as described in the first aspect of the embodiments of this application.

[0016] A fourth aspect of this application provides a computer-readable storage medium storing a computer program, the computer program including program instructions, which, when executed by a processor, perform the method as described in the first aspect of this application.

[0017] In this embodiment, the three-phase voltage of the grid-side capacitor and the three-phase current of the inverter-side inductor are collected, and the three-phase voltage and the three-phase current are converted into two-phase voltage and two-phase current, respectively. The instantaneous active power of the new energy grid-connected inverter system is calculated based on the two-phase voltage and two-phase current. Through the active power control loop, the grid current d-axis command signal is calculated based on the set active power command value, the q-axis voltage in the two-phase voltage, and the instantaneous active power. Through the AC voltage control loop, the grid current q-axis command signal is calculated based on the set grid-side capacitor voltage command signal and the two-phase voltage. Through the AC current control loop, the two-phase control signal of the three-phase full-bridge inverter is calculated based on the grid current d-axis command signal, the grid current q-axis command signal, the two-phase voltage, and the two-phase current. The two-phase control signal of the three-phase full-bridge inverter is converted into a three-phase inverter control signal, and the power devices are controlled to turn on and off through the three-phase inverter control signal.

[0018] As can be seen, in this embodiment, capacitor voltage and current feedforward are first used to enhance high-frequency stability. Based on this, low-frequency damping is designed by comprehensively considering the effects of AC voltage support, active power control, and phase-locked loop. This achieves a synergistic design of high-frequency and low-frequency damping, utilizing feedforward compensation to eliminate the mutual coupling between high and low frequency bands. This effectively improves the grid-connected inverter's ability to suppress oscillations in various frequency bands, significantly enhancing the operational stability of the grid-connected inverter. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, 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.

[0020] Figure 1 A schematic diagram of the structure of a new energy grid-connected inverter system provided in one embodiment of this application is shown.

[0021] Figure 2 A flowchart illustrating a grid-connected inverter stability control method based on broadband damping hierarchical design according to an embodiment of this application is shown. Figure 3 The following is a waveform diagram of the output voltage and current of the grid-connected inverter before and after the grid frequency shift when the control strategy of this application is adopted, according to an embodiment of this application. Figure 4 This paper shows a schematic diagram of the structure of a grid-connected inverter stability control device based on a wideband damping hierarchical design according to an embodiment of this application; Figure 5 A schematic diagram of the structure of a computer device provided in one embodiment of this application is shown. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0023] Please refer to Figure 1 This document illustrates a schematic diagram of a new energy grid-connected inverter system according to an embodiment of this application. The new energy grid-connected inverter system consists of two parts: a main circuit and a controller. The topology diagram of the main circuit is shown below. Figure 1The upper part is shown. The main circuit includes an AC low-voltage power grid, a filter, and a converter connected in sequence. The filter includes an output filter inductor. And the grid-side capacitor C, which is used to attenuate high-frequency switching harmonics. , respectively flowing through The three-phase currents in a stationary three-phase coordinate system (abc). The impedance of the AC weak current grid is... Ignoring DC-side voltage fluctuations in the converter, an ideal DC source is used. Replaces the converter power supply.

[0024] The topology diagram of the controller is as follows: Figure 1 The lower half is shown. The grid-connected common coupling point (PCC) of the main circuit and controller is located at... C and The control flow is as shown within the dashed box in the diagram. First, data is collected using multi-channel sampling technology. Three-phase current , and the three-phase voltage of C , The three-phase voltage of C is converted through Park transformation. , Converted to two-phase voltage .Will The input is fed into a phase-locked loop (PLL), which can acquire the data in real time. The phase information is output, and the phase angle is determined. and phase-locked loop perturbation frequency Phase angle and phase-locked loop perturbation frequency The calculation formula is as follows: , .

[0025] in, It is a phase-locked loop PI controller. This is the proportional adjustment coefficient of the phase-locked loop. This is the integral adjustment coefficient of the phase-locked loop. The rated angular frequency of the grid voltage. For the Laplace operator.

[0026] Then according to , Three-phase current , It can be transformed into two-phase current through Park. Among them, the three phases are the three axes abc of the stationary coordinate system, and the two phases are the two coordinate axes dq of the rotating coordinate system.

[0027] Based on the two-phase voltages obtained above and two-phase current The instantaneous active power output of the system can then be calculated. Instantaneous active power The calculation formula is: , The two-phase voltages obtained above and phase-locked loop perturbation frequency and the calculated instantaneous active power and the set active power command value The input to the Active Power Control (APC) loop can obtain the grid current d-axis command signal. d-axis command signal of grid current The calculation formula is: , in, It is a PI controller for active power control loop. This is the proportional adjustment coefficient for the active power control loop. The integral adjustment coefficient of the active power control loop; The control equations for the low-pass filter are as follows: The control equations are for a second-order integral controller with d-axis capacitor voltage feedforward. The feedforward control equations for the d-axis grid frequency offset are expressed as follows: , , , in, This is the cutoff frequency of the low-pass filter. and These are the second-order and third-order integral adjustment coefficients of the d-axis capacitor voltage feedforward integral controller, respectively.

[0028] The two-phase voltages obtained above , and phase-locked loop perturbation frequency and the set grid-side capacitor voltage command signal The input to the Auto Voltage Control (AVC) loop can obtain the q-axis command signal of the grid current. Its expression is:

[0029] in, For AC voltage control loop PI controller, This is the proportional adjustment coefficient for the AC voltage control loop. The integral adjustment coefficient of the AC voltage control loop; The control equations are for a second-order integral controller with q-axis capacitor voltage feedforward. The q-axis grid frequency offset feedforward control equations are expressed as follows: , , in, and These are the second-order and third-order integral adjustment coefficients of the q-axis capacitor voltage feedforward integral controller, respectively.

[0030] The above-obtained d-axis command signal of the grid current and q-axis command signal and two-phase voltage and two-phase current The inverter control signal is obtained by inputting it to the Alternating Current Control (ACC) loop. , The inverter control signal equation is as follows:

[0031] in, It is a current loop PI controller. This is the proportional adjustment coefficient for the current loop. This is the integral adjustment coefficient for the current loop. , Let represent the proportional control coefficient and the first-order integral control equation in the d-axis capacitor voltage feedforward integral controller. , Let be the proportional control coefficient and the first-order integral control equation in the q-axis capacitor voltage feedforward integral controller. The high-frequency damping control equations, composed of capacitor voltage feedforward and current feedforward, are expressed as follows: , , , , , in, , These are the proportional and first-order integral control coefficients in the d-axis capacitor voltage feedforward integral controller. , These are the proportional and first-order integral control coefficients in the q-axis capacitor voltage feedforward integral controller. This is the capacitor feedforward differential adjustment coefficient. The sampling period is The sampling delay is m, and the modulation ratio is m.

[0032] According to the phase angle The two-phase inverter control signal , Converted into three-phase inverter control signals via Clark and / or Park transform. , , Then, through pulse width modulation (PWM), the switching signals of the power devices in the inverter are generated, and the drive circuit controls the power devices to turn on and off.

[0033] As can be seen, in this embodiment, capacitor voltage and current feedforward are first used to enhance high-frequency stability. Based on this, low-frequency damping is designed by comprehensively considering the effects of AC voltage support, active power control, and phase-locked loop. This achieves a synergistic design of high-frequency and low-frequency damping, utilizing feedforward compensation to eliminate the mutual coupling between high and low frequency bands. This effectively improves the grid-connected inverter's ability to suppress oscillations in various frequency bands, significantly enhancing the operational stability of the grid-connected inverter.

[0034] Furthermore, considering the combined effects of AC voltage support, active power control, and phase-locked loop, low-frequency damping is designed by using multi-order integral feedforward of capacitor voltage. The third-order integral feedforward is inherently consistent with frequency droop control, thereby further providing frequency support for the system. This can demonstrate good performance over a wide short-circuit ratio (SCR) range and significantly improve the operational stability of the grid-connected inverter.

[0035] Please refer to Figure 2 This document illustrates a flowchart of a grid-connected inverter stability control method based on a wideband damping hierarchical design, according to an embodiment of this application. This method can be applied to... Figure 1 The new energy grid-connected inverter system shown may include the following steps: Step 201: Collect the three-phase voltage of the grid-side capacitor and the three-phase current of the inverter-side inductor, and convert the three-phase voltage and the three-phase current into two-phase voltage and two-phase current, respectively.

[0036] The acquisition method can be multi-channel sampling technology.

[0037] Specifically, the step of converting the three-phase voltage and the three-phase current into two-phase voltage and two-phase current respectively includes: The three-phase voltage is converted into a two-phase voltage using the Park transformation. The q-axis voltage of the two-phase voltage is input to the phase-locked loop to obtain the phase angle of the q-axis voltage and the phase-locked loop perturbation frequency; The three-phase current is transformed using the phase angle to obtain the two-phase current.

[0038] The formulas for calculating the phase angle and the phase-locked perturbation frequency are as follows: , .

[0039] in, The phase angle, The frequency of the phase-locked loop (PLL) disturbance. Let q be the q-axis voltage of the two-phase voltages. It is a phase-locked loop PI controller. This is the proportional adjustment coefficient of the phase-locked loop. This is the integral adjustment coefficient of the phase-locked loop. The rated angular frequency of the grid voltage. For the Laplace operator.

[0040] Step 202: Calculate the instantaneous active power of the new energy grid-connected inverter system based on the two-phase voltage and the two-phase current.

[0041] The formula for calculating the instantaneous active power is as follows: , in, and For two-phase voltage, and It is a two-phase current.

[0042] Step 203: Through the active power control loop, calculate the grid current d-axis command signal based on the set active power command value, the q-axis voltage in the two-phase voltage and the instantaneous active power; and through the AC voltage control loop, calculate the grid current q-axis command signal based on the set grid-side capacitor voltage command signal and the two-phase voltage.

[0043] The calculation formula for the d-axis command signal of the power grid current is as follows: , in, This is the d-axis command signal for the grid current. It is a PI controller for active power control loop. This is the proportional adjustment coefficient for the active power control loop. The integral adjustment coefficient of the active power control loop; The set active power command value, The control equations for the low-pass filter are as follows: The control equations are for a second-order integral controller with d-axis capacitor voltage feedforward. The feedforward control equations for the d-axis grid frequency offset are expressed as follows: , , , in, This is the cutoff frequency of the low-pass filter. and These are the second-order and third-order integral adjustment coefficients of the d-axis capacitor voltage feedforward integral controller, respectively.

[0044] The calculation formula for the q-axis command signal of the power grid current is as follows:

[0045] in, This is the q-axis command signal for the grid current. This is the set command signal for the grid-side capacitor voltage. It is an AC voltage control loop PI controller. This is the proportional adjustment coefficient for the AC voltage control loop. The integral adjustment coefficient of the AC voltage control loop; The control equations are for a second-order integral controller with q-axis capacitor voltage feedforward. The q-axis grid frequency offset feedforward control equations are expressed as follows: , , in, and These are the second-order and third-order integral adjustment coefficients of the q-axis capacitor voltage feedforward integral controller, respectively.

[0046] It should be noted that the grid current d-axis command signal and the grid current q-axis command signal can be calculated simultaneously or sequentially; the order of calculation is not limited here.

[0047] As can be seen from the embodiments of this application, when comprehensively considering the effects of AC voltage support, active power control and phase-locked loop, low-frequency damping is designed by multi-order integral feedforward of capacitor voltage. Among them, the third-order integral feedforward is inherently consistent with the frequency droop control, thereby further providing frequency support for the system. It can show good results in the wide short-circuit ratio (SCR) range, which significantly improves the operating stability of the grid-connected inverter.

[0048] Step 204: Calculate the two-phase control signal of the three-phase full-bridge inverter using the AC current control loop, based on the grid current d-axis command signal, the grid current q-axis command signal, the two-phase voltage, and the two-phase current.

[0049] The two-phase control signal equations of the three-phase full-bridge inverter are as follows:

[0050] in, and These are the two-phase control signals for the three-phase full-bridge inverter. It is a current loop PI controller. This is the proportional adjustment coefficient for the current loop. This is the integral adjustment coefficient for the current loop; , Let represent the proportional control coefficient and the first-order integral control equation in the d-axis capacitor voltage feedforward integral controller. , Let be the proportional control coefficient and the first-order integral control equation in the q-axis capacitor voltage feedforward integral controller. The high-frequency damping control equations, composed of capacitor voltage feedforward and current feedforward, are expressed as follows: , , , , , in, , These are the proportional and first-order integral control coefficients in the d-axis capacitor voltage feedforward integral controller. , These are the proportional and first-order integral control coefficients in the q-axis capacitor voltage feedforward integral controller. This is the capacitor feedforward differential adjustment coefficient. The sampling period is The sampling delay is m, and the modulation ratio is m.

[0051] It should be noted that the PI controller is currently the most common control method in industrial automation systems. In automated production processes, PI controllers are widely used for precise control of some fuzzy industrial processes. The PI controller has two adjustment parameters: proportional gain and integral time. For example, when applied to a current-loop PI controller, the proportional gain is the current-loop proportional adjustment coefficient mentioned above. The integral time is the current loop integral adjustment coefficient mentioned above. For example, when applied to a phase-locked loop (PLL) PI controller, the proportional gain is the proportional adjustment coefficient of the PLL. The integral time is the integral adjustment coefficient of the phase-locked loop. .

[0052] Step 205: Convert the two-phase control signal of the three-phase full-bridge inverter into a three-phase inverter control signal, and control the power devices to turn on and off through the three-phase inverter control signal.

[0053] For example, based on the phase angle The two-phase inverter control signal , Converted into three-phase inverter control signals via Clark and / or Park transform. , , Then, through pulse width modulation (PWM), switching signals for the power devices in the inverter are generated, which are then controlled by the drive circuit to turn the power devices on and off.

[0054] In this embodiment, the three-phase voltage of the grid-side capacitor and the three-phase current of the inverter-side inductor are collected, and the three-phase voltage and the three-phase current are converted into two-phase voltage and two-phase current, respectively. The instantaneous active power of the new energy grid-connected inverter system is calculated based on the two-phase voltage and two-phase current. Through the active power control loop, the grid current d-axis command signal is calculated based on the set active power command value, the q-axis voltage in the two-phase voltage, and the instantaneous active power. Through the AC voltage control loop, the grid current q-axis command signal is calculated based on the set grid-side capacitor voltage command signal and the two-phase voltage. Through the AC current control loop, the two-phase control signal of the three-phase full-bridge inverter is calculated based on the grid current d-axis command signal, the grid current q-axis command signal, the two-phase voltage, and the two-phase current. The two-phase control signal of the three-phase full-bridge inverter is converted into a three-phase inverter control signal, and the power devices are controlled to turn on and off through the three-phase inverter control signal.

[0055] In one specific embodiment of this application, Figure 1 The parameters of the new energy grid-connected inverter system shown are as follows: , , ; , , ; , , ; , ; , , , , ;

[0056] Substitute the above parameters Figure 2 The grid-connected inverter stability control method based on wideband damping hierarchical design in the embodiments can be plotted using... Figure 2 The stability control method for grid-connected inverters based on wideband damping hierarchical design in the embodiments and the method without using Figure 2 The output voltage and current waveforms of the grid-connected inverter when the grid frequency deviates in the grid frequency control method based on wideband damping hierarchical design in the embodiment.

[0057] from Figure 3 It is evident that, after adopting the embodiments in this application, the grid-connected inverter under weak power grid conditions can operate stably, with no distortion in output current and output voltage, and the output current changes with the grid frequency. The output current decreases as the grid frequency increases, and the active power also decreases accordingly, reflecting the droop characteristic in the control. Without the embodiment described in this application, the output current and output voltage are undistorted, and the active power increases with the grid frequency. The increase in output amplitude does not change the value, and it does not have droop characteristics.

[0058] Figure 4 This illustration shows a schematic diagram of a grid-connected inverter stability control device based on a wideband damping hierarchical design, provided in one embodiment of this application. The device is applied to a new energy grid-connected inverter system. The main circuit of the new energy grid-connected inverter system includes a three-phase full-bridge inverter, inverter-side inductors, grid-side capacitors, and grid impedance. The device includes: The signal acquisition and conversion unit 401 is used to acquire the three-phase voltage of the grid-side capacitor and the three-phase current of the inverter-side inductor, and convert the three-phase voltage and the three-phase current into two-phase voltage and two-phase current respectively. The instantaneous active power calculation unit 402 is used to calculate the instantaneous active power of the new energy grid-connected inverter system based on the two-phase voltage and the two-phase current. The grid current command signal calculation unit 403 is used to calculate the grid current d-axis command signal based on the set active power command value, the q-axis voltage in the two-phase voltage and the instantaneous active power through the active power control loop, and to calculate the grid current q-axis command signal based on the set grid-side capacitor voltage command signal and the two-phase voltage through the AC voltage control loop. Inverter control signal calculation unit 404 is used to calculate the two-phase control signal of the three-phase full-bridge inverter through AC current control loop, based on the grid current d-axis command signal and the grid current q-axis command signal, as well as the two-phase voltage and the two-phase current. The signal conversion and switching control unit 405 is used to convert the two-phase control signal of the three-phase full-bridge inverter into a three-phase inverter control signal, and to control the power devices to turn on and off through the three-phase inverter control signal.

[0059] Figure 5 A schematic diagram of the structure of a computer device provided in one embodiment of this application is shown, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements the functions of the computer system of the grid-connected inverter phase-locked loop stability control method based on phase-locked offset compensation in any of the above embodiments.

[0060] This application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a computer, causes the computer to perform the functions of the computer system of the grid-connected inverter stability control method based on wideband damping hierarchical design in any of the above embodiments.

[0061] This application also provides a computer program product containing instructions that, when executed by a computer, cause the computer to perform the functions of the computer system of the grid-connected inverter stability control method based on wideband damping hierarchical design in any of the above embodiments.

[0062] It is understood that the specific examples in this application are only intended to help those skilled in the art better understand the implementation methods of this application, and are not intended to limit the scope of the invention.

[0063] It is understood that in the various embodiments of this application, the sequence number of each process 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 limit the implementation process of the embodiments of this application in any way.

[0064] It is understood that the various implementation methods described in this application can be implemented individually or in combination, and the implementation methods in this application are not limited in this respect.

[0065] Unless otherwise stated, all technical and scientific terms used in the embodiments of this application have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items. The singular forms "a," "the," and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0066] It is understood that the processor in the embodiments of this application can be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method embodiments can be completed by the integrated logic circuits in the processor's hardware or by instructions in software form. The processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly embodied in the execution of a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules can be located in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory; the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method.

[0067] It is understood that the memory in the embodiments of this application may be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. Specifically, non-volatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory may be random access memory (RAM). It should be noted that the memory in the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0068] 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 implementation should not be considered beyond the scope of this application.

[0069] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the aforementioned method implementations, and will not be repeated here.

[0070] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of 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 mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0071] 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, depending on actual needs.

[0072] In addition, the functional units in the various embodiments of this application 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.

[0073] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0074] The above are merely specific embodiments of this application, but the scope of protection of this invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this invention should be determined by the scope of the claims.

Claims

1. A stability control method for grid-connected inverters based on wideband damping hierarchical design, characterized in that, The method is applied to a new energy grid-connected inverter system, wherein the main circuit of the new energy grid-connected inverter system includes a three-phase full-bridge inverter, inverter-side inductance, grid-side capacitor, and grid impedance. The three-phase voltage of the grid-side capacitor and the three-phase current of the inverter-side inductor are collected, and the three-phase voltage and the three-phase current are converted into two-phase voltage and two-phase current, respectively. The instantaneous active power of the new energy grid-connected inverter system is calculated based on the two-phase voltage and the two-phase current. The active power control loop calculates the grid current d-axis command signal based on the set active power command value, the q-axis voltage in the two-phase voltage, and the instantaneous active power. The AC voltage control loop calculates the grid current q-axis command signal based on the set grid-side capacitor voltage command signal and the two-phase voltage. The two-phase control signal of the three-phase full-bridge inverter is calculated through the AC current control loop based on the grid current d-axis command signal and the grid current q-axis command signal, as well as the two-phase voltage and the two-phase current. The two-phase control signals of the three-phase full-bridge inverter are converted into three-phase inverter control signals, and the power devices are turned on and off through the three-phase inverter control signals.

2. The method according to claim 1, characterized in that, The step of converting the three-phase voltage and the three-phase current into two-phase voltage and two-phase current respectively includes: The three-phase voltage is converted into a two-phase voltage using the Park transformation. The q-axis voltage of the two-phase voltage is input to the phase-locked loop to obtain the phase angle of the q-axis voltage and the phase-locked loop perturbation frequency; The three-phase current is transformed using the phase angle to obtain the two-phase current.

3. The method according to claim 2, characterized in that, The formulas for calculating the phase angle and the phase-locked perturbation frequency are as follows: ， 。 in, The phase angle, The frequency of the phase-locked loop (PLL) disturbance. Let q be the q-axis voltage of the two-phase voltages. It is a phase-locked loop PI controller. This is the proportional adjustment coefficient of the phase-locked loop. This is the integral adjustment coefficient of the phase-locked loop. The rated angular frequency of the grid voltage. For the Laplace operator.

4. The method according to claim 3, characterized in that, The formula for calculating the instantaneous active power is as follows: ， in, and For two-phase voltage, and Let d and q represent two-phase currents, where d and q represent different axes in the two phases, respectively.

5. The method according to claim 4, characterized in that, The calculation formula for the d-axis command signal of the power grid current is: in, This is the d-axis command signal for the grid current. It is a PI controller for active power control loop. This is the proportional adjustment coefficient for the active power control loop. The integral adjustment coefficient of the active power control loop; The set active power command value, The control equations for the low-pass filter are as follows: The control equations are for a second-order integral controller with d-axis capacitor voltage feedforward. The d-axis power grid frequency offset feedforward control equation is given.

6. The method according to claim 4, characterized in that, The formula for calculating the q-axis command signal of the power grid current is: in, q-axis command signal for grid current This is the set command signal for the grid-side capacitor voltage. For AC voltage control loop PI controller, This is the proportional adjustment coefficient for the AC voltage control loop. The integral adjustment coefficient of the AC voltage control loop; The control equations are for a second-order integral controller with q-axis capacitor voltage feedforward. The q-axis power grid frequency offset feedforward control equation is given.

7. The method according to claim 6, characterized in that, The two-phase control signal equations of the three-phase full-bridge inverter are as follows: in, and These are the two-phase control signals for the three-phase full-bridge inverter. It is a current loop PI controller. This is the proportional adjustment coefficient for the current loop. This is the integral adjustment coefficient for the current loop; , Let represent the proportional control coefficient and the first-order integral control equation in the d-axis capacitor voltage feedforward integral controller. , Let be the proportional control coefficient and the first-order integral control equation in the q-axis capacitor voltage feedforward integral controller. This is a high-frequency damping control equation composed of capacitor voltage feedforward and current feedforward.

8. A grid-connected inverter stability control device based on wideband damping hierarchical design, characterized in that, An inverter system for grid-connected new energy sources is used, wherein the main circuit of the grid-connected new energy source inverter system includes a three-phase full-bridge inverter, inverter-side inductors, grid-side capacitors, and grid impedance. The device includes: The signal acquisition and conversion unit is used to acquire the three-phase voltage of the grid-side capacitor and the three-phase current of the inverter-side inductor, and convert the three-phase voltage and the three-phase current into two-phase voltage and two-phase current, respectively. The instantaneous active power calculation unit is used to calculate the instantaneous active power of the new energy grid-connected inverter system based on the two-phase voltage and the two-phase current. The grid current command signal calculation unit is used to calculate the grid current d-axis command signal based on the set active power command value, the q-axis voltage in the two-phase voltage and the instantaneous active power through the active power control loop, and to calculate the grid current q-axis command signal based on the set grid-side capacitor voltage command signal and the two-phase voltage through the AC voltage control loop. The inverter control signal calculation unit is used to calculate the two-phase control signal of the three-phase full-bridge inverter through the AC current control loop, based on the grid current d-axis command signal and the grid current q-axis command signal, as well as the two-phase voltage and the two-phase current. The signal conversion and switching control unit is used to convert the two-phase control signals of the three-phase full-bridge inverter into three-phase inverter control signals, and to control the switching on and off of power devices through the three-phase inverter control signals.

9. An electronic device, characterized in that, include: Processor and memory; The processor is connected to a memory, wherein the memory is used to store a computer program, and the processor is used to invoke the computer program to perform the method as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, the computer program including program instructions that, when executed by a processor, perform the method as described in any one of claims 1-7.

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