Adjusting method and system of network construction converter, electronic equipment and storage medium

Abstract

The invention provides an adjusting method and system for a network construction converter, electronic equipment and a storage medium, and the method comprises the steps: switching the network construction converter from a droop control mode to a fault current limiting mode under the condition of a network fault of the network construction converter; under the condition that the network construction converter network is in the fault current limiting mode, the control of a voltage loop of the network construction converter network fails, and the maximum current amplitude allowed to flow through by the network construction converter and the output value of the voltage loop are determined; and obtaining a current loop reference value according to the maximum current amplitude and the output value of the voltage loop. Rapid fault recovery of the network construction converter can be realized, the network construction converter is prevented from being locked in a current limiting mode after the fault is removed, and the transient stability of the network construction converter is improved.

Description

Technical Field

[0001] This application relates to the technical field of grid-connected systems, and more particularly to a method, system, electronic device, and storage medium for regulating a grid-connected converter. Background Technology

[0002] With the large-scale grid connection of converter interface resources, represented by wind power and photovoltaics, the proportion of traditional synchronous generators is continuously decreasing, and the strength of the power system is gradually weakening. Grid control can autonomously establish system voltage and frequency, and has higher stability and robustness in weak grids, gradually becoming a better control method for the penetration of new energy sources.

[0003] Grid-controlled converters exhibit controlled voltage source characteristics. During a short-circuit fault, the grid-controlled converter automatically injects a very large current; however, due to limitations in semiconductor devices, the current that the grid-controlled converter can withstand is limited. Therefore, to achieve low-voltage ride-through in the grid, the grid-controlled converter needs to operate with current limiting. One commonly used current limiting method is the direct current limiting method, which directly limits the reference value of the inner current loop, turning the grid-controlled converter into a controlled current source, achieving good fault current limiting effects. However, because the direct current limiting method alters the converter's virtual power angle curve, it may cause the grid-controlled converter to remain locked in current-limiting mode after the fault is cleared, preventing it from resuming normal operation. Summary of the Invention

[0004] This application provides a method, system, electronic device, and storage medium for regulating a grid converter to solve the problems existing in related technologies. The technical solution is as follows: In a first aspect, embodiments of this application provide a method for regulating a grid converter, including: In the event of a network failure in the grid converter, the grid converter switches from the droop control mode to the fault current limiting mode. When the grid converter network is in fault current limiting mode, the control of the voltage loop of the grid converter network fails, and the maximum current amplitude allowed to flow through the grid converter and the output value of the voltage loop are determined. The current loop reference value is obtained based on the maximum current amplitude and the output value of the voltage loop.

[0005] In one embodiment of this application, it further includes: When the grid-connected converter is in droop control mode, obtain droop control information; Based on the droop control information, a PWM modulation signal is obtained.

[0006] In one embodiment of this application, obtaining the PWM modulation signal based on the droop control information includes: The droop control information includes: active droop coefficient, reactive droop coefficient, rated active power, rated reactive power, rated voltage amplitude, and rated voltage angular frequency. Based on the active power droop coefficient, the reactive power droop coefficient, the rated value of active power, the rated value of reactive power, the rated value of voltage amplitude, and the rated value of voltage angular frequency, the voltage reference amplitude and phase reference value at the PCC point are obtained. The PWM modulation signal is obtained based on the voltage reference amplitude and the phase reference value.

[0007] In one embodiment of this application, obtaining the current loop reference value based on the maximum current amplitude and the output value of the voltage loop includes: When the current loop reference value is less than or equal to the maximum current amplitude, the current loop output value is equal to the current loop reference value; When the current loop reference value is greater than the maximum current amplitude, the d-axis component of the current loop reference value is the maximum current amplitude, and the q-axis component is 0. In the fault current limiting mode, the integral coefficient of the voltage loop PI controller is 0.

[0008] Secondly, embodiments of this application provide a regulation system for a grid converter, comprising: A switching module is used to switch the grid converter from the droop control mode to the fault current limiting mode in the event of a network failure in the grid converter. The determination module is used to determine the maximum allowable current amplitude and voltage loop output value of the grid converter when the grid converter network is in fault current limiting mode and the voltage loop control of the grid converter network fails. The module is used to obtain a current loop reference value based on the maximum current amplitude and the output value of the voltage loop.

[0009] In one embodiment of this application, it further includes: When the grid-connected converter is in droop control mode, obtain droop control information; Based on the droop control information, a PWM modulation signal is obtained.

[0010] In one embodiment of this application, obtaining the PWM modulation signal based on the droop control information includes: The droop control information includes: active droop coefficient, reactive droop coefficient, rated active power, rated reactive power, rated voltage amplitude, and rated voltage angular frequency. Based on the active power droop coefficient, the reactive power droop coefficient, the rated value of active power, the rated value of reactive power, the rated value of voltage amplitude, and the rated value of voltage angular frequency, the voltage reference amplitude and phase reference value at the PCC point are obtained. The PWM modulation signal is obtained based on the voltage reference amplitude and the phase reference value.

[0011] In one embodiment of this application, obtaining the current loop reference value based on the maximum current amplitude and the output value of the voltage loop includes: When the current loop reference value is less than or equal to the maximum current amplitude, the current loop output value is equal to the current loop reference value; When the current loop reference value is greater than the maximum current amplitude, the d-axis component of the current loop reference value is the maximum current amplitude, and the q-axis component is 0. In the fault current limiting mode, the integral coefficient of the voltage loop PI controller is 0.

[0012] Thirdly, embodiments of this application provide an electronic device, which includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the above-described grid converter regulation method.

[0013] Fourthly, embodiments of this application provide a computer-readable storage medium that stores computer instructions, wherein when the computer instructions are executed on a computer, the methods in any of the above-described embodiments are performed.

[0014] The advantages or beneficial effects of the above technical solutions include at least the following: In this embodiment, the adjustment method of the grid-connected converter includes: in the event of a grid-connected converter network fault, the grid-connected converter switches from the droop control mode to a fault current-limiting mode; when the grid-connected converter network is in fault current-limiting mode, the control of the voltage loop of the grid-connected converter network fails, and the maximum allowable current amplitude and voltage loop output value are determined; based on the maximum current amplitude and voltage loop output value, a current loop reference value is obtained. This embodiment's adjustment method considers the conditions for the converter to enter and exit the current-limiting mode, and adopts an adaptive adjustment method for the active power droop coefficient to improve the converter's fault recovery capability and transient stability. It can effectively suppress changes in the virtual power angle during a fault, improving transient stability. It achieves rapid fault recovery of the grid-connected converter, avoiding the grid-connected converter from locking in the current-limiting mode after fault clearance, thus improving the transient stability of the grid-connected converter. It effectively solves the problem that the direct current limiting method alters the virtual power angle curve of the converter, which may cause the grid-connected converter to remain locked in the current-limiting mode after fault clearance, preventing it from resuming normal operation.

[0015] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of this application will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0016] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0017] Figure 1 This is a schematic diagram of the grid-connected structure of a grid-connected converter regulation method according to an embodiment of this application; Figure 2(a) is a block diagram of a grid converter control method according to an embodiment of the present application; Figure 2(b) is a voltage and current dual-loop control block diagram of a grid converter regulation method according to an embodiment of the present application; Figure 3(a) is a diagram showing the operating point trajectory of a grid converter when the voltage does not drop significantly in the adjustment method of the grid converter according to an embodiment of the present application, and the grid converter meets the conditions for exiting the fault current limiting mode. Figure 3(b) is a diagram showing the operating point trajectory of a grid converter that does not meet the conditions for exiting the fault current limiting mode when the voltage does not drop significantly in the regulation method of the grid converter according to an embodiment of the present application. Figure 4(a) shows the operating point trajectory of the grid converter when the voltage drops severely in the regulation method of the grid converter according to an embodiment of the present application, where the grid converter meets the conditions for exiting the fault current limiting mode. Figure 4(b) shows the operating point trajectory of the grid converter when the voltage drops severely in the regulation method of the grid converter according to an embodiment of the present application, where the grid converter does not meet the conditions for exiting the fault current limiting mode. Figure 5 A fault critical clearing time diagram of a regulation method for a grid converter according to an embodiment of this application and an existing regulation method; Figure 6 This is a block diagram of an electronic device used to implement the regulation method of the grid converter in the embodiments of this application. Detailed Implementation

[0018] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this application. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0019] In related technologies, with the large-scale grid connection of converter interface resources, represented by wind power and photovoltaics, the proportion of traditional synchronous generators is constantly decreasing, and the strength of the power system is gradually weakening. Grid control can autonomously establish system voltage and frequency, and has higher stability and robustness in weak grids, gradually becoming a better control method for the penetration of new energy sources.

[0020] Grid-controlled converters exhibit controlled voltage source characteristics. During short-circuit faults, grid-controlled converters automatically inject extremely large current values; however, due to limitations in semiconductor devices, the current values ​​that grid-controlled converters can withstand are limited. Therefore, to achieve low-voltage ride-through in the grid, grid-controlled converters need to operate with current limiting. One commonly used current limiting method is the direct current limiting method, which directly limits the reference value of the inner current loop, transforming the grid-controlled converter into a controlled current source, achieving good fault current limiting effects. However, because the direct current limiting method alters the converter's virtual power angle curve, it may cause the grid-controlled converter to remain locked in current-limiting mode after the fault is cleared, preventing it from resuming normal operation. Based on the above problems, this invention proposes a fault recovery performance improvement strategy based on an adaptive active power droop coefficient, which can effectively suppress changes in the virtual power angle during faults and improve transient stability.

[0021] Figure 1 This is a schematic diagram of the grid-connected structure of a grid-connected converter regulation method according to an embodiment of this application; like Figures 1-5 As shown, a method for regulating a grid-connected converter includes: S110: In the event of a network failure in the grid converter, the grid converter switches from the droop control mode to the fault current limiting mode. S120: When the grid converter network is in fault current limiting mode, the control of the voltage loop of the grid converter network fails, and the maximum current amplitude allowed to flow through the grid converter and the output value of the voltage loop are determined. The current loop reference value is obtained based on the maximum current amplitude and the output value of the voltage loop.

[0022] The adjustment method of the grid converter in this embodiment can be supported by hardware provided by the host device, and the adjustment method of the grid converter can be executed in the host device.

[0023] In this embodiment, the adjustment method of the grid-connected converter includes: in the event of a grid-connected converter network fault, the grid-connected converter switches from the droop control mode to a fault current-limiting mode; when the grid-connected converter network is in fault current-limiting mode, the control of the voltage loop of the grid-connected converter network fails, and the maximum allowable current amplitude and voltage loop output value are determined; based on the maximum current amplitude and voltage loop output value, a current loop reference value is obtained. This embodiment's adjustment method considers the conditions for the converter to enter and exit the current-limiting mode, and adopts an adaptive adjustment method for the active power droop coefficient to improve the converter's fault recovery capability and transient stability. It can effectively suppress changes in the virtual power angle during a fault, improving transient stability. It achieves rapid fault recovery of the grid-connected converter, avoiding the grid-connected converter from locking in the current-limiting mode after fault clearance, thus improving the transient stability of the grid-connected converter. It effectively solves the problem that the direct current limiting method alters the virtual power angle curve of the converter, which may cause the grid-connected converter to remain locked in the current-limiting mode after fault clearance, preventing it from resuming normal operation.

[0024] Figure 1 This is a grid-connected system structure diagram illustrating the regulation method of the grid-connected converter. , These represent the output filter inductor and filter capacitor of the converter, respectively. Indicates flow The current, For flow The current; This indicates the voltage at the PCC grid connection point. This represents the grid-connected current of the converter; , Indicates line resistance and inductance. This indicates the grid voltage.

[0025] In an embodiment of this application, Figure 2(a) is a control block diagram of the adjustment method for the grid-connected converter. When the grid-connected converter network is operating normally, the converter is in droop control mode. At this time, droop control information is obtained, including: active power droop coefficient, reactive power droop coefficient, rated active power, rated reactive power, rated voltage amplitude, and rated voltage angular frequency. The expression for the operating state of the grid-connected converter under the droop control module is as follows: , , in, This is the active power droop coefficient. This is the reactive power droop factor. This is the rated value of active power. This is the rated value of reactive power. This is the rated voltage amplitude. This is the rated value of the voltage angular frequency.

[0026] After droop control, the converter obtains the reference amplitude of the PCC point voltage. After obtaining the phase reference value θ, the grid converter obtains the PWM modulation signal through dual-loop control of voltage loop and current loop.

[0027] Figure 2(b) shows the voltage and current dual-loop control block diagram of the grid converter in the dq coordinate system, where the voltage reference value on the d-axis is the output of the reactive power loop. The voltage reference value for the q-axis is 0; , They are respectively The d-axis and q-axis components; , They are respectively The d-axis and q-axis components; , These are the d-axis and q-axis components of the voltage loop output, respectively; , These are the d-axis and q-axis components after the current limiting circuit, which are the actual reference values ​​of the current loop; , These are the d-axis and q-axis components of the current loop output, respectively, and are the modulation signals of the output voltage of the bridge arm of the grid converter.

[0028] In the event of a grid-connected converter network fault, such as a short-circuit fault, the grid-connected converter switches from the droop control mode to the fault current limiting mode. In the fault current limiting mode, the converter employs an adaptive fault recovery adjustment method based on the active power droop parameter. The expression for the active power droop parameter in the fault current limiting mode is: , In the formula This represents the active power droop coefficient in normal mode. This is the voltage of the power grid fault. For about The function is expressed as: .

[0029] In fault-limiting current mode, if the voltage loop control fails, determine the maximum allowable current amplitude and voltage loop output value for the grid converter; based on the maximum current amplitude and voltage loop output value, obtain the current loop reference value. Its expression is: , In the formula This refers to the maximum current amplitude that is allowed to flow through the grid converter. This is the reference value for the current loop. Less than or equal to When the current loop reference value is equal to the voltage loop output value, when... Greater than At that time, the d-axis component of the current loop reference value is The q-axis component is 0. To avoid voltage loop saturation leading to fault recovery failure, the integral coefficient kiv of the voltage loop PI controller is set to 0 in fault current limiting mode.

[0030] During normal operation, The expression for the output active power of the grid converter is: .

[0031] In fault current limiting mode, the output current of the grid converter remains constant, i.e. , and The expression for is: , in ; Therefore, the expression for the output active power under fault current limiting mode is: .

[0032] The current limiting condition for a grid-connected converter under normal operating conditions (i.e., the grid-connected converter switches from the droop control mode to the fault current limiting mode) is as follows: .

[0033] The condition for transitioning from fault current limiting mode to normal operating mode (droop control mode) is: Under rate limiting conditions Therefore, in fault current limiting mode The calculation formula is: , in, This refers to the proportional gain of the PI controller in the voltage loop of the grid-connected converter. Therefore, the condition for the grid-connected converter to exit fault current-limiting mode is derived as follows: .

[0034] Based on the above analysis, the virtual power angle curve of the grid converter can be plotted, and its operating point trajectory can be analyzed.

[0035] Figures 3(a) and 3(b) show the trajectory of the operating point of the grid converter when the grid voltage drop is not severe. At this time, the output power of the grid converter after current limiting is greater than P0. At the moment of the fault, the operating point of the grid converter jumps to point a. F1 At this point, the actual active power output of the grid-connected converter is greater than P0, δ will gradually decrease, and the operating point of the grid-connected converter will shift to the left. After the fault is cleared, the operating point of the grid-connected converter will jump to U. g =U n On the current-limiting power angle curve.

[0036] As shown in Figure 3(a), the grid-connected converter meets the conditions for exiting the fault current limiting mode at the instant of fault recovery, and the operating point of the grid-connected converter moves to point b. F1 When the fault is cleared, the operating point jumps to b. lim At point b, the grid-connected converter is able to exit the fault current-limiting mode, and thus the operating point jumps back to point b on the normal power angle curve. The grid-connected converter resumes normal operation and eventually stabilizes at point a under the action of the active power loop.

[0037] As shown in Figure 3(b), the grid-connected converter does not meet the conditions for exiting the fault current limiting mode at the moment of fault recovery, and the operating point of the grid-connected converter moves to d. F1 When the fault is cleared, the operating point jumps to d. lim At point e, the grid-connected converter will continue to operate in current-limiting mode, the virtual power angle of the grid-connected converter will continue to decrease, the operating point will shift to the left, and eventually it will stabilize at point e.

[0038] As shown in Figures 4(a) and 4(b), the operating point trajectory of the grid converter during a severe grid voltage drop is observed. At this time, the output power of the grid converter after current limiting is less than P0. At the instant of the fault, the grid converter jumps from point a to point a... F2 The actual active power output is less than P0, δ continuously increases, and the operating point shifts to the right. After the fault is cleared, the operating point jumps to U. g =U n On the current-limiting power angle curve.

[0039] As shown in Figure 4(a), when the grid-connected converter meets the conditions for exiting the fault current limiting mode at the instant of fault recovery, the operating point of the grid-connected converter moves to g. F2 When the fault is cleared, the operating point jumps to g. lim g lim The output active power at point h is greater than P0, and δ gradually decreases. lim When the current limiting mode is reached, the grid-connected converter exits the current limiting mode, and its operating point jumps to point h on the normal power angle curve. The grid-connected converter resumes normal operation and eventually stabilizes at point a.

[0040] As shown in Figure 4(b), when the grid-connected converter does not meet the conditions for exiting the fault current limiting mode at the moment of fault recovery, the operating point of the grid-connected converter moves to i. F2 When the fault is cleared, the operating point jumps to i. lim point. i lim The active power at point k is less than P0, δ gradually increases, the operating point continues to move to the right, and eventually stabilizes at point k.

[0041] Analysis shows that grid-connected converters under the d-axis priority current limiting method have two fault clearance angles, with the minimum clearance angle δ... min For δ c Maximum and minimum limit resection angle δ max For δ f If the value during the fault period exceeds [δ] min δ max If the fault occurs, the grid-connected converter will not be able to resume normal operation after the fault is cleared. Although the output active power command can be satisfied at points e and k, the grid-connected converter behaves as a current source at this time, and its output voltage cannot be controlled, which does not conform to the essence of grid-connected control. Therefore, this situation needs to be avoided.

[0042] Based on the above analysis, δ max and δ min Furthermore, by utilizing mathematical analysis tools such as the Runge-Kutta iterative algorithm and least squares fitting, different U values ​​can be plotted. g Numerical curves of fault clearing critical time (CCT) for grid-connected converters at different drop depths, such as... Figure 5 As shown in the figure. The solid line in the figure represents the low-voltage ride-through standard for grid-connected converters. Within the standard curve and above, the grid-connected converter should be able to operate continuously without disconnecting from the grid. Therefore, the CCT numerical curve of the grid-connected converter should be located to the right of the standard curve to meet the grid operation requirements. Figure 5 As shown, the CCT value under the original strategy cannot be achieved in all U... gThe low-voltage ride-through standard is met at the drop depth. After using the improved active power droop parameter adaptive control, the CCT value is significantly improved, meeting the low-voltage ride-through standard, and the transient stability of the grid converter is improved.

[0043] In one embodiment of this application, it further includes: When the grid-connected converter is in droop control mode, obtain droop control information; Based on the droop control information, a PWM modulation signal is obtained.

[0044] In this embodiment, the grid converter is in droop control mode under normal operating conditions. The PWM modulation signal is obtained through droop control information to realize the controlled voltage source characteristics of the grid converter.

[0045] In one embodiment of this application, obtaining the PWM modulation signal based on the droop control information includes: The droop control information includes: active droop coefficient, reactive droop coefficient, rated active power, rated reactive power, rated voltage amplitude, and rated voltage angular frequency. Based on the active power droop coefficient, the reactive power droop coefficient, the rated value of active power, the rated value of reactive power, the rated value of voltage amplitude, and the rated value of voltage angular frequency, the voltage reference amplitude and phase reference value at the PCC point are obtained. The PWM modulation signal is obtained based on the voltage reference amplitude and the phase reference value.

[0046] In this embodiment, Figure 2(a) is a control block diagram of the adjustment method of the grid converter. When the grid converter network is working normally, the grid converter is in droop control mode. At this time, droop control information is obtained, which includes: active power droop coefficient, reactive power droop coefficient, rated active power, rated reactive power, rated voltage amplitude, and rated voltage angular frequency. The expression for the working state of the grid converter under the droop control module is as follows: , , in, This is the active power droop coefficient. This is the reactive power droop factor. This is the rated value of active power. This is the rated value of reactive power. This is the rated voltage amplitude. This is the rated value of the voltage angular frequency.

[0047] After droop control, the converter obtains the reference amplitude of the PCC point voltage. and phase reference value θ Then, the grid converter obtains the PWM modulation signal through dual-loop control of voltage loop and current loop.

[0048] In one embodiment of this application, obtaining the current loop reference value based on the maximum current amplitude and the output value of the voltage loop includes: When the current loop reference value is less than or equal to the maximum current amplitude, the current loop output value is equal to the current loop reference value; When the current loop reference value is greater than the maximum current amplitude, the d-axis component of the current loop reference value is the maximum current amplitude, and the q-axis component is 0. In the fault current limiting mode, the integral coefficient of the voltage loop PI controller is 0.

[0049] In the event of a grid-connected converter network fault, such as a short-circuit fault, the grid-connected converter switches from the droop control mode to the fault current limiting mode. In the fault current limiting mode, the converter employs an adaptive fault recovery adjustment method based on the active power droop parameter. The expression for the active power droop parameter in the fault current limiting mode is: , In the formula, This represents the active power droop coefficient in normal mode. This is the voltage of the power grid fault. For about The function is expressed as: .

[0050] In fault-limiting current mode, if the voltage loop control fails, determine the maximum allowable current amplitude and voltage loop output value for the grid converter; based on the maximum current amplitude and voltage loop output value, obtain the current loop reference value. Its expression is: ,

[0051] In the formula This refers to the maximum current amplitude that is allowed to flow through the grid converter. This is the reference value for the current loop. Less than or equal to When the current loop reference value is equal to the voltage loop output value, when... Greater than At that time, the d-axis component of the current loop reference value is The q-axis component is 0. To avoid voltage loop saturation leading to fault recovery failure, the integral coefficient kiv of the voltage loop PI controller is set to 0 in fault current limiting mode.

[0052] Secondly, embodiments of this application provide a regulation system for a grid converter, comprising: A switching module is used to switch the grid converter from the droop control mode to the fault current limiting mode in the event of a network failure in the grid converter. The determination module is used to determine the maximum allowable current amplitude and voltage loop output value of the grid converter when the grid converter network is in fault current limiting mode and the voltage loop control of the grid converter network fails. The module is used to obtain a current loop reference value based on the maximum current amplitude and the output value of the voltage loop.

[0053] In this embodiment, the regulation system of the grid-connected converter includes: in the event of a grid-connected converter network fault, the grid-connected converter switches from the droop control mode to a fault current-limiting mode; when the grid-connected converter network is in fault current-limiting mode, the control of the voltage loop of the grid-connected converter network fails, and the maximum allowable current amplitude and voltage loop output value are determined; based on the maximum current amplitude and voltage loop output value, a current loop reference value is obtained. The regulation system of this embodiment considers the conditions for the converter to enter and exit the current-limiting mode, and adopts an adaptive adjustment method for the active power droop coefficient to improve the converter's fault recovery capability and transient stability. It can effectively suppress changes in the virtual power angle during a fault, improving transient stability. It achieves rapid fault recovery of the grid-connected converter, avoiding the grid-connected converter from locking in the current-limiting mode after fault clearance, thus improving the transient stability of the grid-connected converter. It effectively solves the problem that the direct current limiting method alters the virtual power angle curve of the converter, which may cause the grid-connected converter to remain locked in the current-limiting mode after fault clearance, preventing it from resuming normal operation.

[0054] In one embodiment of this application, it further includes: When the grid-connected converter is in droop control mode, obtain droop control information; Based on the droop control information, a PWM modulation signal is obtained.

[0055] In one embodiment of this application, obtaining the PWM modulation signal based on the droop control information includes: The droop control information includes: active droop coefficient, reactive droop coefficient, rated active power, rated reactive power, rated voltage amplitude, and rated voltage angular frequency. Based on the active power droop coefficient, the reactive power droop coefficient, the rated value of active power, the rated value of reactive power, the rated value of voltage amplitude, and the rated value of voltage angular frequency, the voltage reference amplitude and phase reference value at the PCC point are obtained. The PWM modulation signal is obtained based on the voltage reference amplitude and the phase reference value.

[0056] In one embodiment of this application, obtaining the current loop reference value based on the maximum current amplitude and the output value of the voltage loop includes: When the current loop reference value is less than or equal to the maximum current amplitude, the current loop output value is equal to the current loop reference value; When the current loop reference value is greater than the maximum current amplitude, the d-axis component of the current loop reference value is the maximum current amplitude, and the q-axis component is 0. In the fault current limiting mode, the integral coefficient of the voltage loop PI controller is 0.

[0057] The functions of each module in each device in the embodiments of this application can be found in the corresponding descriptions in the above methods, and will not be repeated here.

[0058] Figure 6 A structural block diagram of an electronic device according to an embodiment of this application is shown. Figure 6 As shown, the electronic device includes a memory 410 and a processor 420. The memory 410 stores instructions that can be executed on the processor 420. When the processor 420 executes the instructions, it implements the regulation method of the grid converter in the above embodiment. The number of memories 410 and processors 420 can be one or more. This electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present application described and / or claimed herein.

[0059] The electronic device may also include a communication interface 430 for communicating with external devices and exchanging data. The devices are interconnected using different buses and can be mounted on a common motherboard or otherwise as needed. The processor 420 can process instructions executed within the electronic device, including instructions stored in or on memory to display graphical information of a GUI on an external input / output device (such as a display device coupled to the interface). In other embodiments, multiple processors and / or multiple buses can be used with multiple memories and multiple memory modules, if desired. Similarly, multiple electronic devices can be connected, each providing some of the necessary operations (e.g., as a server array, a group of blade servers, or a multiprocessor system). The bus can be divided into address buses, data buses, control buses, etc. For ease of illustration, Figure 6 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0060] Optionally, in a specific implementation, if the memory 410, processor 420 and communication interface 430 are integrated on a single chip, the memory 410, processor 420 and communication interface 430 can communicate with each other through an internal interface.

[0061] It should be understood that the aforementioned processor can be a Central Processing Unit (CPU), or other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. General-purpose processors can be microprocessors or any conventional processor. It is worth noting that the processor can be a processor supporting Advanced Reduced Instruction Set Machines (ARM) architecture.

[0062] This application provides a computer-readable storage medium (such as the memory 410 described above) that stores computer instructions, which, when executed by a processor, implement the method provided in this application.

[0063] Optionally, memory 410 may include a program storage area and a data storage area, wherein the program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the electronic device, etc. Furthermore, memory 410 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, memory 410 may optionally include memory remotely located relative to processor 420, and these remote memories can be connected to the electronic device 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.

[0064] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0065] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0066] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more (two or more) executable instructions for implementing a particular logical function or process. Furthermore, the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functionality involved.

[0067] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus or device (such as a computer-based system, a processor-included system or other system that can fetch and execute instructions from, an instruction execution system, apparatus or device).

[0068] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. All or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware, the program being stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiments.

[0069] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. This storage medium can be a read-only memory, a disk, or an optical disk, etc.

[0070] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in this application, and these should all be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for regulating a grid-connected converter, characterized in that, include: In the event of a network failure in the grid converter, the grid converter switches from droop control mode to fault current limiting mode. When the grid converter network is in fault current limiting mode, the control of the voltage loop of the grid converter network fails, and the maximum current amplitude allowed to flow through the grid converter and the output value of the voltage loop are determined. The current loop reference value is obtained based on the maximum current amplitude and the output value of the voltage loop.

2. The method according to claim 1, characterized in that, Also includes: When the grid-connected converter is in droop control mode, obtain droop control information; Based on the droop control information, a PWM modulation signal is obtained.

3. The method according to claim 2, characterized in that, Based on the droop control information, the PWM modulation signal is obtained as follows: The droop control information includes: active droop coefficient, reactive droop coefficient, rated active power, rated reactive power, rated voltage amplitude, and rated voltage angular frequency. Based on the active power droop coefficient, the reactive power droop coefficient, the rated value of active power, the rated value of reactive power, the rated value of voltage amplitude, and the rated value of voltage angular frequency, the voltage reference amplitude and phase reference value at the PCC point are obtained. The PWM modulation signal is obtained based on the voltage reference amplitude and the phase reference value.

4. The method according to claim 1, characterized in that, Based on the maximum current amplitude and the output value of the voltage loop, the current loop reference values ​​are obtained as follows: When the current loop reference value is less than or equal to the maximum current amplitude, the current loop output value is equal to the current loop reference value; When the current loop reference value is greater than the maximum current amplitude, the d-axis component of the current loop reference value is the maximum current amplitude, and the q-axis component is 0. In the fault current limiting mode, the integral coefficient of the voltage loop PI controller is 0.

5. A regulating system for a grid converter, characterized in that, include: The switching module is used to switch the grid converter from droop control mode to fault current limiting mode in the event of a network failure in the grid converter. The determination module is used to determine the maximum allowable current amplitude and voltage loop output value of the grid converter when the grid converter network is in fault current limiting mode and the voltage loop control of the grid converter network fails. The module is used to obtain a current loop reference value based on the maximum current amplitude and the output value of the voltage loop.

6. The regulation system for the grid converter according to claim 5, characterized in that, Also includes: When the grid-connected converter is in droop control mode, obtain droop control information; Based on the droop control information, a PWM modulation signal is obtained.

7. The regulating system for a grid converter according to claim 6, characterized in that, Based on the droop control information, the PWM modulation signal is obtained as follows: The droop control information includes: active droop coefficient, reactive droop coefficient, rated active power, rated reactive power, rated voltage amplitude, and rated voltage angular frequency. Based on the active power droop coefficient, the reactive power droop coefficient, the rated value of active power, the rated value of reactive power, the rated value of voltage amplitude, and the rated value of voltage angular frequency, the voltage reference amplitude and phase reference value at the PCC point are obtained. The PWM modulation signal is obtained based on the voltage reference amplitude and the phase reference value.

8. The regulation system for a grid converter according to claim 5, characterized in that, The process of obtaining the current loop reference value based on the maximum current amplitude and the voltage loop output value includes: When the current loop reference value is less than or equal to the maximum current amplitude, the current loop output value is equal to the current loop reference value; When the current loop reference value is greater than the maximum current amplitude, the d-axis component of the current loop reference value is the maximum current amplitude, and the q-axis component is 0. In the fault current limiting mode, the integral coefficient of the voltage loop PI controller is 0.

9. An electronic device, characterized in that, include: At least one processor; And a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method of any one of claims 1-4.

10. A computer-readable storage medium storing computer instructions that, when executed by a processor, implement the method as described in any one of claims 1-4.

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