A converter control method, device, system and storage medium

Abstract

This invention discloses a converter control method, device, system, and storage medium. The method includes: acquiring the instantaneous AC voltage at the point of common coupling (PCC) and a preset reference AC voltage; acquiring the current fluctuation flowing into the capacitor at the PCC through voltage loop control; calculating the inductor current fluctuation between the converter and the PCC based on the current fluctuation, the AC current flowing into the weak current grid system, and the AC current flowing out of the converter, and acquiring the AC side voltage reference value of the converter through current loop control; and generating the switching transistor trigger signal of the converter through modulation technology. This converter control method realizes the instantaneous voltage control of the PCC point through single-phase instantaneous current. Since the instantaneous current is an intermediate link in the control, this control method has the advantages of both current source control and voltage source control, namely, preventing fault current from exceeding the limit and ensuring voltage source access to the system.

Description

Technical Field

[0001] This invention relates to the fields of power electronics technology and power system control technology, specifically to a converter control method, device, system, and storage medium. Background Technology

[0002] With the continuous development of new energy technologies, new energy power generation based on power electronics technology will gradually replace traditional synchronous generators and become the main power source for future new power systems. Future new power systems will differ significantly from traditional power grids in terms of power structure, topology, stability mechanisms, and operation control and protection methods. Voltage source converters, with their flexibility, efficiency, and stability, will play a crucial role in the high penetration rate of new energy integration.

[0003] Because current power systems are voltage-source dominated, control algorithms based on controlled current sources (such as vector current control) are incompatible with them. Simply using a voltage-source dominated control algorithm could result in output current exceeding the equipment's tolerance limits, causing damage. While current power systems can accommodate some current sources, large-scale current source integration could introduce potential problems to power system operation, such as stability issues. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a converter control method, apparatus, system and storage medium to solve the technical problem that the control algorithm used in the prior art for voltage source control in power systems dominated by voltage sources may cause equipment damage.

[0005] The technical solution proposed in this invention is as follows:

[0006] The first aspect of this invention provides a converter control method, wherein the converter is connected to a weak grid system. For each single phase, the control method includes: acquiring the instantaneous AC voltage at the point of common coupling (PCC) and a preset reference AC voltage; acquiring the current fluctuation of the capacitor flowing into the PCC through voltage loop control based on the instantaneous AC voltage and the preset reference AC voltage; acquiring the AC side voltage reference value of the converter through current loop control based on the inductor current fluctuation between the converter and the PCC calculated from the current fluctuation, the AC current flowing into the weak grid system, and the AC current flowing out of the converter; and modulating the AC side voltage reference value of the converter through modulation technology to generate a switching transistor trigger signal for the converter.

[0007] Optionally, based on the instantaneous AC voltage and a preset reference AC voltage, the current fluctuation flowing into the capacitor at the point of common coupling is obtained through voltage loop control, including: obtaining the capacitor voltage fluctuation at the point of common coupling by subtracting the instantaneous AC voltage and the preset reference AC voltage; and calculating the capacitor voltage fluctuation by performing a first proportional derivative to obtain the current fluctuation flowing into the capacitor at the point of common coupling.

[0008] Optionally, the proportional coefficient calculated by the first proportional derivative is the quotient of the capacitance value and the sampling time.

[0009] Optionally, based on the current fluctuation, the AC current flowing into the weak grid system, and the AC current flowing out of the converter, a reference value for the AC side voltage of the converter is obtained through current loop control. This includes: obtaining the inductor current fluctuation between the converter and the point of common coupling by subtracting the sum of the current fluctuation and the AC current flowing into the weak grid system from the AC current flowing out of the converter; performing a second proportional derivative calculation on the inductor current fluctuation to obtain the inductor voltage fluctuation; and summing the inductor voltage fluctuation and the AC voltage at the point of common coupling to obtain the reference value for the AC side voltage of the converter.

[0010] Optionally, the proportional coefficient calculated by the second proportional derivative is the quotient of the inductance value and the sampling time.

[0011] Optionally, before performing the second proportional derivative calculation on the inductor current fluctuation, the method further includes: performing a limiting calculation on the inductor current fluctuation; after obtaining the AC side voltage reference value of the converter, the method further includes: performing a sample-and-hold calculation on the AC side voltage reference value of the converter.

[0012] Optionally, the modulation techniques include: PWM modulation, NLM modulation, two-level voltage output modulation, three-level voltage output modulation, and multi-level voltage output modulation.

[0013] A second aspect of this invention provides a converter control device, comprising: a parameter acquisition module for acquiring an instantaneous AC voltage at the point of common coupling (PCC) and a preset reference AC voltage; a first control module for acquiring, based on the instantaneous AC voltage and the preset reference AC voltage, a voltage loop control to acquire the current fluctuation of the capacitor flowing into the PCC; a second control module for acquiring a reference value of the AC side voltage of the converter based on the current fluctuation, the AC current flowing into the weak current grid system, and the AC current flowing out of the converter, calculated as the inductor current fluctuation between the converter and the PCC, and a current loop control; and a modulation module for modulating the reference value of the AC side voltage of the converter using modulation technology to generate a switching transistor trigger signal for the converter.

[0014] Optionally, the first control module includes: a first difference module, used to obtain the capacitor voltage fluctuation at the common connection point by subtracting the instantaneous AC voltage from a preset reference AC voltage; and a first differential module, used to perform a first proportional differential calculation on the capacitor voltage fluctuation to obtain the current fluctuation flowing into the capacitor at the common connection point.

[0015] Optionally, the proportional coefficient calculated by the first proportional derivative is the quotient of the capacitance value and the sampling time.

[0016] Optionally, the second control module includes: a current calculation module, used to obtain the inductor current fluctuation between the converter and the point of common coupling by subtracting the sum of the current fluctuation and the AC current flowing into the weak grid system from the AC current flowing out of the converter; a second differential module, used to perform a second proportional differential calculation on the inductor current fluctuation to obtain the inductor voltage fluctuation; and a summation module, used to sum the inductor voltage fluctuation and the AC voltage at the point of common coupling to obtain a reference value for the AC side voltage of the converter.

[0017] Optionally, the proportional coefficient calculated by the second proportional derivative is the quotient of the inductance value and the sampling time.

[0018] Optionally, the converter control device further includes: a limiting module for performing limiting calculations on the inductor current fluctuation; and a sample-and-hold module for performing sample-and-hold calculations on the AC side voltage reference value of the converter.

[0019] Optionally, the modulation techniques include: PWM modulation, NLM modulation, two-level voltage output modulation, three-level voltage output modulation, and multi-level voltage output modulation.

[0020] A third aspect of the present invention provides a converter control system, comprising: a converter, an LC filter circuit, a low-voltage power grid system, and a control system. One end of the converter is connected to one end of the filter circuit, and the other end of the filter circuit is connected to the low-voltage power grid system through a common connection point. The control system outputs a switching transistor trigger signal to the converter using the converter control method described in the first aspect and any one of the first aspects of the present invention.

[0021] A fourth aspect of the present invention provides a computer-readable storage medium storing computer instructions for causing the computer to perform the converter control method as described in the first aspect and any one of the first aspects of the present invention.

[0022] The technical solution provided by this invention has the following effects:

[0023] The converter control method, device, system, and storage medium provided in this invention acquire the instantaneous AC voltage at the point of common coupling (PCC) and a preset reference AC voltage. Through voltage loop control, the current fluctuation flowing into the capacitor at the PCC is obtained. This allows for current loop modulation of the inductor current fluctuation between the converter and the PCC, calculated using the AC current flowing into the weak current grid and the AC current flowing out of the converter. Ultimately, a reference value for the AC side voltage of the converter is obtained to control the converter switching transistors. This converter control method achieves instantaneous voltage control at the PCC point using single-phase instantaneous current (AC current flowing out of the converter). Since the instantaneous current is an intermediate link in the control process, this control method combines the advantages of both current source control and voltage source control, ensuring that fault current does not exceed limits and that a voltage source is integrated into the system. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a flowchart of a converter control method according to an embodiment of the present invention;

[0026] Figure 2 A system circuit diagram for connecting a converter to a weak grid system provided in an embodiment of the present invention;

[0027] Figure 3 This is an equivalent circuit diagram of a converter connected to a weak power grid system provided in an embodiment of the present invention;

[0028] Figure 4 This is a control block diagram of a converter control method according to an embodiment of the present invention;

[0029] Figure 5 This is a structural block diagram of a converter control system according to an embodiment of the present invention;

[0030] Figure 6 This is a structural block diagram of a converter control device according to an embodiment of the present invention;

[0031] Figure 7 This is a schematic diagram of the structure of a computer-readable storage medium provided according to an embodiment of the present invention;

[0032] Figure 8 This is a schematic diagram of the structure of an electronic device provided according to an embodiment of the present invention. Detailed Implementation

[0033] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0034] The terms "first," "second," "third," "fourth," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0035] According to an embodiment of the present invention, a converter control method is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0036] This embodiment provides a converter control method that can be used in electronic devices such as computers, mobile phones, and tablets. Figure 1 This is a flowchart of a converter control method according to an embodiment of the present invention, wherein the converter is connected to a weak power grid system, such as... Figure 1 As shown, for each single phase, the control method includes the following steps:

[0037] Step S101: Obtain the instantaneous AC voltage at the point of common coupling and the preset reference AC voltage. This embodiment of the invention uses... Figure 2 The system circuit diagram shown, illustrating a converter connected to a weak current grid, serves as an example of a specific application scenario for converter control. The converter, in this case, is connected via an LC filter circuit and an inductor L... load It is then connected to a weak grid. A weak grid refers to a three-phase ideal power supply U S It needs to pass through a large inductor L load Then, it is connected to the converter, L S The larger the inductance value, the weaker the power grid.

[0038] Current control methods primarily utilize phase-locked loops (PLLs) to obtain the phase information of the AC grid voltage, and then effectively control the three-phase voltage of the converter in a synchronous rotating coordinate system based on this phase information. For strong grids, PLLs can accurately lock onto the grid's phase information. However, in future new power systems dominated by high proportions of renewable energy and power electronic devices, the AC grid strength weakens, and the voltage amplitude support at the PCC point is insufficient. PLLs struggle to accurately lock onto the grid's phase information, making it difficult to achieve effective control of the converter's three-phase voltage using current control methods.

[0039] Therefore, in this embodiment of the invention, by acquiring the instantaneous AC voltage of the Point of Common Coupling (PCC) and a preset reference AC voltage, the tracking control of the instantaneous voltage at the PCC is achieved, thus realizing the purpose of effectively connecting the converter to the weak current grid. It should be noted that since the converter is connected to the weak current grid system, and the weak current grid system is an AC system, for each single phase, the system circuit for the converter connecting to the weak current grid can adopt... Figure 3 The equivalent circuit shown is analyzed. That is, the control method provided in the embodiment of the present invention is used to control the converter for phases A, B, and C respectively.

[0040] Step S102: Based on the instantaneous AC voltage and the preset reference AC voltage, the current fluctuation flowing into the capacitor at the common coupling point is obtained through voltage loop control. Specifically, since the output current of the voltage source may exceed the limit that the equipment can withstand when only voltage control is used, causing damage to the equipment, voltage loop control is used to obtain the current by proportional-derivative conversion of the voltage, thereby achieving subsequent current modulation.

[0041] Step S103: Based on the current fluctuation, the AC current flowing into the weak grid system, and the AC current flowing out of the converter, the inductor current fluctuation between the converter and the point of common coupling is calculated. Then, through current loop control, a reference value for the AC side voltage of the converter is obtained. Specifically, the inductor current fluctuation between the converter and the point of common coupling can be obtained by calculating the current fluctuation, the AC current flowing into the weak grid system, and the AC current flowing out of the converter. Simultaneously, through current loop control, the voltage is obtained by proportional-derivative operations on the current, thereby achieving effective control of the three-phase voltage of the voltage source converter.

[0042] Step S104: Modulate the AC side voltage reference value of the converter using modulation technology to generate a switching transistor trigger signal for the converter. In this embodiment of the invention, the converter is a voltage source converter. The AC side voltage reference value of the converter output from the current loop is modulated into a switching signal that can trigger the switching transistor of the converter, so as to achieve stable control of the converter by controlling the three-phase inductor current to track the instantaneous voltage at the PCC point in real time.

[0043] The modulation techniques include: PWM modulation, NLM modulation, two-level voltage output modulation, three-level voltage output modulation, and multi-level voltage output modulation. The control output reference state quantities of the voltage loop and current loop provided in this embodiment can be modulated using various existing modulation techniques to generate converter switching transistor trigger signals.

[0044] The converter control method provided in this invention obtains the instantaneous AC voltage at the point of common coupling (PCC) and a preset reference AC voltage. Through voltage loop control, it acquires the current fluctuation flowing into the capacitor at the PCC. This allows for current loop modulation of the inductor current fluctuation between the converter and the PCC, calculated using the AC current flowing into the weak current grid and the AC current flowing out of the converter. Ultimately, a reference value for the AC side voltage of the converter is obtained to control the converter switching transistors. This converter control method achieves instantaneous voltage control at the PCC point using single-phase instantaneous current (AC current flowing out of the converter). Since the instantaneous current is an intermediate link in the control process, this control method combines the advantages of both current source control and voltage source control, ensuring that fault current does not exceed limits and that a voltage source is connected to the system.

[0045] In one embodiment, based on the instantaneous AC voltage and a preset reference AC voltage, the current fluctuation flowing into the capacitor at the point of common coupling is obtained through voltage loop control, including: obtaining the capacitor voltage fluctuation at the point of common coupling by subtracting the instantaneous AC voltage and the preset reference AC voltage; and calculating the capacitor voltage fluctuation by performing a first proportional derivative to obtain the current fluctuation flowing into the capacitor at the point of common coupling.

[0046] The voltage fluctuation at the point of common coupling is expressed as Δu. c =u pcc -u pccref u pcc u represents the instantaneous AC voltage at the point of common coupling. pccref This represents the preset reference AC voltage. The first proportional-derivative calculation is expressed by the following formula: Δi c This represents the current fluctuation flowing into the capacitor at the point of common coupling, where C represents the capacitance value in the LC filter circuit, and f represents the sampling frequency, which is the reciprocal of the sampling time T. When PWM is used to modulate the converter output voltage, this sampling frequency is the PWM carrier frequency.

[0047] In one embodiment, based on the current fluctuation, the AC current flowing into the weak grid system, and the AC current flowing out of the converter, a reference value for the AC side voltage of the converter is obtained through current loop control. This includes: obtaining the inductor current fluctuation between the converter and the point of common coupling by subtracting the sum of the current fluctuation and the AC current flowing into the weak grid system from the AC current flowing out of the converter; performing a second proportional derivative calculation on the inductor current fluctuation to obtain the inductor voltage fluctuation; and summing the inductor voltage fluctuation and the AC voltage at the point of common coupling to obtain the reference value for the AC side voltage of the converter.

[0048] The inductor current fluctuation is expressed as Δi L =Δi c +i out -i, i out Let i represent the AC current flowing into the weak grid system, and i represent the AC current flowing out of the converter; the second proportional derivative is calculated using the following formula: L represents the inductance value of the LC filter circuit, Δu L This represents the inductor voltage fluctuation. The AC side voltage reference value of the converter is represented as u. ref =Δu L +u pcc .

[0049] In one embodiment, before performing the second proportional-differential calculation on the inductor current fluctuation, the method further includes: performing a limiting calculation on the inductor current fluctuation; after obtaining the AC side voltage reference value of the converter, the method further includes: performing a sample-and-hold calculation on the AC side voltage reference value of the converter. The limiting calculation can be implemented by inputting the inductor current fluctuation into a limiting circuit. The sample-and-hold calculation is implemented using a sampler with limiting function.

[0050] In one implementation, such as Figure 4 As shown, the converter control method is implemented using the following process: Obtain the instantaneous AC voltage u at the point of common coupling. pcc And perform differential processing on the preset reference AC voltage. pccref The capacitance voltage fluctuation Δu at the point of common coupling is obtained. c The capacitor voltage fluctuation Δu c The current fluctuation Δi flowing into the capacitor at the point of common coupling is obtained by calculating the proportional derivative with the capacitance value C and the sampling time T as proportionality coefficients. c The current fluctuation Δi c and the alternating current i flowing into the weak power grid system out The summation is then subtracted from the AC current i flowing out of the converter to obtain the inductor current fluctuation Δi. LThe inductor current fluctuation is limited, and the limiting result is used to calculate the inductor voltage fluctuation Δu by proportional derivative with the inductance value L and sampling time T as proportionality coefficients. L The inductor voltage fluctuation Δu L Summing u with the AC voltage at the point of common coupling pcc Obtain the AC side voltage reference value u of the converter. ref The AC side voltage reference value u of the converter ref After sampling and holding, the switching transistor trigger signal of the converter is generated.

[0051] This invention also provides a converter control system, such as... Figure 5 As shown, the system includes: a converter, an LC filter circuit, a low-voltage power grid system, and a control system. One end of the converter is connected to one end of the filter circuit, and the other end of the filter circuit is connected to the low-voltage power grid system through a common coupling point. The control system outputs a switching transistor trigger signal to the converter using the converter control method described in any of the above embodiments. The modulation technique shown in the figure is PWM modulation; other modulation techniques can also be used, and this embodiment of the invention is not limited to these. During control, the above control method can be applied to each of the three phases a, b, and c separately.

[0052] The converter control system provided in this embodiment of the invention acquires the instantaneous AC voltage at the point of common coupling (PCC) and a preset reference AC voltage. Through voltage loop control, it acquires the current fluctuation of the capacitor flowing into the PCC. This allows for current loop modulation of the inductor current fluctuation between the converter and the PCC, calculated using the AC current flowing into the weak current grid and the AC current flowing out of the converter. Ultimately, a reference value for the AC side voltage of the converter is obtained to control the converter switching transistors. This converter control system implements a method for controlling the instantaneous voltage at the PCC point using single-phase instantaneous current (AC current flowing out of the converter). Since the instantaneous current is an intermediate link in the control, this control method has the advantages of both current source control and voltage source control, namely, preventing fault current from exceeding limits and ensuring voltage source access to the system.

[0053] In one embodiment, by combining the control system and corresponding system circuits (filter circuit and converter) in the converter control system, analysis in the s-domain, i.e., the complex frequency domain, can be performed. During complex frequency domain analysis, the controlled objects are the inductor and capacitor in the LC filter circuit. Through complex frequency domain analysis, the LC filter circuit is converted into its corresponding transfer function form. The control system and system circuits, combined, constitute the equivalent system block diagram shown in the figure. The delay element in this equivalent system... This indicates that the control system experienced a delay of T / 2, where T represents the period of the control system.

[0054] Through complex frequency domain analysis, the output voltage U in the complex frequency domain pcc (Instantaneous AC voltage at the point of common coupling) and input signal U pcc_ref (Preset reference AC voltage) and disturbance i out The relationship between them is:

[0055] U pcc =H1(s)·U pcc_ref +H2(s)·i out

[0056] Here, H1(s) and H2(s) represent transfer functions.

[0057] The transfer function is derived and calculated using the following formula. In the analysis and calculation, current, voltage, etc., are represented by uppercase letters to indicate that they are constant values, while the control methods mentioned above use lowercase letters to indicate the instantaneous values ​​obtained. Specifically, formulas (1) to (5) can be determined through the equivalent system.

[0058]

[0059]

[0060] U ref =U1e -sT / 2 Formula (3)

[0061]

[0062]

[0063] Substituting formula (1) into formula (2) yields formula (6).

[0064]

[0065] Rewrite formula (6) as formula (7):

[0066] U ref =(s 2 LC+1)U pcc +sLI out Formula (7)

[0067] Substituting formula (4) into formula (5) yields formula (8):

[0068]

[0069] Substituting formula (1) into formula (8) yields formula (9).

[0070]

[0071] Substituting formula (9) into formula (3) yields formulas (10) and (11).

[0072]

[0073]

[0074] Substituting formula (7) into formula (11) and rearranging, we obtain formula (12).

[0075]

[0076] From this, we can obtain formula (13).

[0077] U pcc =H1(s)U pcc_ref -H2(s)I out Formula (13)

[0078] Therefore, the two transfer functions can be expressed as follows:

[0079] For a detailed description of the functions of the converter control system provided in this embodiment, please refer to the converter control method description in the above embodiments.

[0080] This invention also provides a converter control device, such as... Figure 6 As shown, the device includes:

[0081] The parameter acquisition module is used to acquire the instantaneous AC voltage of the common connection point and the preset reference AC voltage; for details, please refer to the corresponding part of the above method embodiment, which will not be repeated here.

[0082] The first control module is used to obtain the current fluctuation of the capacitor flowing into the common connection point through voltage loop control based on the instantaneous AC voltage and the preset reference AC voltage; for details, please refer to the corresponding part of the above method embodiment, which will not be repeated here.

[0083] The second control module is used to calculate the inductor current fluctuation between the converter and the point of common coupling based on the current fluctuation, the AC current flowing into the weak grid system, and the AC current flowing out of the converter, and to obtain the AC side voltage reference value of the converter through current loop control; for details, please refer to the corresponding part of the above method embodiment, which will not be repeated here.

[0084] The modulation module is used to modulate the AC side voltage reference value of the converter using modulation technology to generate the switching transistor trigger signal of the converter. For details, please refer to the corresponding section of the above method embodiment, which will not be repeated here.

[0085] The converter control device provided in this embodiment of the invention acquires the instantaneous AC voltage at the point of common coupling (PCC) and a preset reference AC voltage. Through voltage loop control, it acquires the current fluctuation of the capacitor flowing into the PCC. This allows for current loop modulation of the inductor current fluctuation between the converter and the PCC, calculated using the AC current flowing into the weak current grid and the AC current flowing out of the converter. Ultimately, a reference value for the AC side voltage of the converter is obtained to control the converter switching transistors. This converter control device implements a method for controlling the instantaneous voltage at the PCC point using single-phase instantaneous current (AC current flowing out of the converter). Since the instantaneous current is an intermediate link in the control process, this control method has the advantages of both current source control and voltage source control, namely, preventing fault current from exceeding limits and ensuring voltage source access to the system.

[0086] For a detailed description of the functions of the converter control device provided in this embodiment, please refer to the description of the converter control method in the above embodiments.

[0087] In one embodiment, the first control module includes: a first difference module, used to obtain the capacitor voltage fluctuation at the common coupling point by subtracting the instantaneous AC voltage from a preset reference AC voltage; and a first differential module, used to perform a first proportional differential calculation on the capacitor voltage fluctuation to obtain the current fluctuation flowing into the capacitor at the common coupling point.

[0088] In one embodiment, the proportional coefficient for the first proportional derivative calculation is the quotient of the capacitance value and the sampling time.

[0089] In one embodiment, the second control module includes: a current calculation module, used to obtain the inductor current fluctuation between the converter and the point of common coupling by subtracting the sum of the current fluctuation and the AC current flowing into the weak grid system from the AC current flowing out of the converter; a second differential module, used to perform a second proportional differential calculation on the inductor current fluctuation to obtain the inductor voltage fluctuation; and a summation module, used to sum the inductor voltage fluctuation and the AC voltage at the point of common coupling to obtain a reference value for the AC side voltage of the converter.

[0090] In one embodiment, the proportional coefficient calculated by the second proportional derivative is the quotient of the inductance value and the sampling time.

[0091] In one embodiment, the converter control device further includes: a limiting module for performing limiting calculations on the inductor current fluctuation; and a sample-and-hold module for performing sample-and-hold calculations on the AC side voltage reference value of the converter.

[0092] In one embodiment, the modulation technology includes: PWM modulation technology, NLM modulation technology, two-level voltage output modulation technology, three-level voltage output modulation technology, and multi-level voltage output modulation technology.

[0093] This invention also provides a storage medium, such as... Figure 7 As shown, a computer program 601 is stored on it. When executed by a processor, this program implements the steps of the converter control method in the above embodiments. The storage medium also stores audio and video stream data, feature frame data, interactive request signaling, encrypted data, and preset data sizes. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk drive (HDD), or solid-state drive (SSD), etc.; the storage medium may also include combinations of the above types of memory.

[0094] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk drive (HDD), or solid-state drive (SSD), etc.; the storage medium can also include combinations of the above types of memory.

[0095] This invention also provides an electronic device, such as... Figure 8 As shown, the electronic device may include a processor 51 and a memory 52, wherein the processor 51 and the memory 52 may be connected via a bus or other means. Figure 8 Taking the example of a connection between China and Israel via a bus.

[0096] Processor 51 can be a central processing unit (CPU). Processor 51 can also be 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, or combinations of the above types of chips.

[0097] The memory 52, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and modules, such as the corresponding program instructions / modules in the embodiments of the present invention. The processor 51 executes various functional applications and data processing of the processor by running the non-transitory software programs, instructions, and modules stored in the memory 52, thereby implementing the converter control method in the above method embodiments.

[0098] The memory 52 may include a program storage area and a data storage area. The program storage area may store applications required for operating the device and at least one function; the data storage area may store data created by the processor 51, etc. Furthermore, the memory 52 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, the memory 52 may optionally include memory remotely located relative to the processor 51, and these remote memories may be connected to the processor 51 via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0099] The one or more modules are stored in the memory 52, and when executed by the processor 51, they perform the following: Figure 1 The converter control method in the embodiment shown in Figure 4.

[0100] For specific details regarding the aforementioned electronic devices, please refer to the relevant documentation. Figures 1 to 4 The relevant descriptions and effects in the illustrated embodiments are for understanding purposes only and will not be repeated here.

[0101] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A converter control method, characterized in that, The converter is connected to a weak power grid system. For each single phase, the control method includes: Obtain the instantaneous AC voltage at the point of common coupling and the preset reference AC voltage; Based on the instantaneous AC voltage and the preset reference AC voltage, the current fluctuation flowing into the capacitor at the common connection point is obtained through voltage loop control. Based on the instantaneous AC voltage and the preset reference AC voltage, the current fluctuation flowing into the capacitor at the point of common coupling is obtained through voltage loop control, including: The voltage fluctuation of the capacitor at the common connection point is obtained by subtracting the instantaneous AC voltage from the preset reference AC voltage. The voltage fluctuation of the capacitor is calculated by performing a first proportional derivative to obtain the current fluctuation flowing into the capacitor at the common connection point. The inductor current fluctuation between the converter and the point of common coupling is calculated based on the current fluctuation, the AC current flowing into the weak grid system and the AC current flowing out of the converter. The reference value of the AC side voltage of the converter is obtained through current loop control. The inductor current fluctuation between the converter and the point of common coupling is calculated based on the current fluctuation, the AC current flowing into the weak grid system, and the AC current flowing out of the converter. Through current loop control, a reference value for the AC side voltage of the converter is obtained, including: The inductor current fluctuation between the converter and the point of common coupling is obtained by summing the current fluctuation and the AC current flowing into the weak grid system and subtracting the AC current flowing out of the converter. The inductor voltage fluctuation is obtained by performing a second proportional derivative calculation on the inductor current fluctuation. The inductor voltage fluctuation and the AC voltage at the common connection point are summed to obtain the AC side voltage reference value of the converter. The AC side voltage reference value of the converter is modulated using modulation technology to generate the switching transistor trigger signal of the converter.

2. The converter control method according to claim 1, characterized in that, The proportional coefficient calculated by the first proportional derivative is the quotient of the capacitance value and the sampling time.

3. The converter control method according to claim 1, characterized in that, The proportional coefficient calculated by the second proportional derivative is the quotient of the inductance value and the sampling time.

4. The converter control method according to claim 1, characterized in that, Before performing the second proportional derivative calculation on the inductor current fluctuation, the method further includes: The fluctuation of the inductor current is calculated with a limiting effect. After obtaining the AC side voltage reference value of the converter, the following steps are also included: The AC side voltage reference value of the converter is sampled and held for calculation.

5. The converter control method according to claim 1, characterized in that, The modulation techniques include: PWM modulation, NLM modulation, two-level voltage output modulation, three-level voltage output modulation, and multi-level voltage output modulation.

6. A converter control device, characterized in that, include: The parameter acquisition module is used to acquire the instantaneous AC voltage at the point of common coupling and the preset reference AC voltage; The first control module is used to obtain the current fluctuation of the capacitor flowing into the common connection point through voltage loop control based on the instantaneous AC voltage and the preset reference AC voltage. Based on the instantaneous AC voltage and the preset reference AC voltage, the current fluctuation flowing into the capacitor at the point of common coupling is obtained through voltage loop control, including: The voltage fluctuation of the capacitor at the common connection point is obtained by subtracting the instantaneous AC voltage from the preset reference AC voltage. The voltage fluctuation of the capacitor is calculated by performing a first proportional derivative to obtain the current fluctuation flowing into the capacitor at the common connection point. The second control module is used to calculate the inductor current fluctuation between the converter and the point of common coupling based on the current fluctuation, the AC current flowing into the weak grid system and the AC current flowing out of the converter, and to obtain the AC side voltage reference value of the converter through current loop control. The inductor current fluctuation between the converter and the point of common coupling is calculated based on the current fluctuation, the AC current flowing into the weak grid system, and the AC current flowing out of the converter. Through current loop control, a reference value for the AC side voltage of the converter is obtained, including: The inductor current fluctuation between the converter and the point of common coupling is obtained by summing the current fluctuation and the AC current flowing into the weak grid system and subtracting the AC current flowing out of the converter. The inductor voltage fluctuation is obtained by performing a second proportional derivative calculation on the inductor current fluctuation. The inductor voltage fluctuation and the AC voltage at the common connection point are summed to obtain the AC side voltage reference value of the converter. The modulation module is used to modulate the AC side voltage reference value of the converter using modulation technology to generate the switching transistor trigger signal of the converter.

7. A converter control system, characterized in that, include: The system includes a converter, an LC filter circuit, a low-voltage power grid system, and a control system. One end of the converter is connected to one end of the filter circuit, and the other end of the filter circuit is connected to the low-voltage power grid system via a point of common coupling. The control system outputs a switching transistor trigger signal to the converter using the converter control method according to any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to perform the converter control method as described in any one of claims 1-5.

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