Network construction control method and system for inhibiting asymmetric fault overvoltage

Abstract

The invention discloses a network construction control method and system for inhibiting asymmetric fault overvoltage, and the method comprises the steps: generating a network construction controller through a virtual synchronous generator, and enabling an output parameter of the network construction controller to be a duty ratio component of the network construction controller; a fan converter is connected into a power grid through a filter, the fan converter is additionally provided with a negative sequence voltage controller, and the output parameter of the negative sequence voltage controller is the duty ratio component of the negative sequence voltage controller; and superposing the duty ratio component of the network construction controller and the duty ratio component of the negative sequence voltage controller, and then outputting the superposed duty ratio component of the network construction controller and the negative sequence voltage controller to suppress the asymmetric fault overvoltage. According to the invention, on the basis of the internal overvoltage mechanism of the fan converter during the asymmetric fault, a negative sequence voltage control link is introduced, and network construction voltage control is matched, so that no negative sequence voltage during the asymmetric fault of the fan converter is ensured, and the generation of overvoltage is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of asymmetric fault overvoltage suppression, and more specifically, to a method and system for controlling a network for suppressing asymmetric fault overvoltage. Background Art

[0002] The proportion of renewable energy in the power system continues to rise, making renewable energy bases an important part of power generation. However, the temporary overvoltage problem during a fault is a key issue that limits the safe and stable operation of renewable energy units and power grids. Among them, the overvoltage caused by the reclosing of a single-phase instantaneous ground fault is a common temporary overvoltage fault in renewable energy stations. Suppressing the overvoltage generated during the reclosing process of a single-phase instantaneous ground fault is an important safety and stability issue.

[0003] Compared with the low inertia of grid-following control, grid-building control technology can build voltage with inertia, and has good adaptability and stability for weak and even extremely weak grids. It can autonomously and quickly build system voltage in weak grids, compensate for the inherent inertial damping characteristics of the system, and provide reliable voltage and frequency support for the system. Existing studies have shown that grid-building control has a beneficial effect on suppressing overvoltage (Shang Lei et al., Grid-building reactive compensation suppresses transient overvoltage at the sending end of renewable energy, Electric Power Engineering Technology, 43(2), 2024).

[0004] However, the overvoltage of the single-phase instantaneous ground fault reclosing switch is mainly generated in the period from the single-phase instantaneous ground fault to the reclosing switch. Due to the effect of the fault phase, there is a negative sequence in the AC voltage, and the negative sequence voltage is the main cause of the overvoltage. Although the grid control has a certain inhibitory effect on the overvoltage, due to the existence of negative sequence voltage, there will still be a single-phase instantaneous ground fault reclosing switch overvoltage.

[0005] Therefore, a technology is needed to suppress asymmetric fault overvoltage. Summary of the invention

[0006] The technical solution of the present invention provides a network control method and system for suppressing asymmetric fault overvoltage, so as to solve the problem of how to suppress asymmetric fault overvoltage.

[0007] In order to solve the above problems, the present invention provides a network control method for suppressing asymmetric fault overvoltage, the method comprising:

[0008] Generate a network controller through a virtual synchronous generator, wherein the output parameter of the network controller is a duty cycle component of the network controller;

[0009] The wind turbine converter is connected to the power grid through a filter, and a negative sequence voltage controller is added to the wind turbine converter, and the output parameter of the negative sequence voltage controller is a duty cycle component of the negative sequence voltage controller;

[0010] The duty cycle component of the network controller and the duty cycle component of the negative sequence voltage controller are superimposed and then outputted to suppress asymmetric fault overvoltage.

[0011] Preferably, the negative sequence voltage component v of the negative sequence voltage controller qn The calculation method is:

[0012]

[0013] Among them, LP is a low-pass filter, v αβ is the voltage vector at the AC busbar of the wind turbine converter in the two-phase stationary coordinate system, and the angle is the angle of the negative sequence voltage synchronous rotation coordinate system, and j is the imaginary axis in the complex plane.

[0014] Preferably, the negative sequence voltage reference value v of the negative sequence voltage controller is qrefn is 0.

[0015] Preferably, the negative-sequence voltage controller duty cycle component of the negative-sequence voltage controller is:

[0016]

[0017] Among them, k pn is the proportional link, k in is the integral link, ΔD q is the duty cycle component of the negative sequence voltage controller, and s is a complex variable in the complex plane.

[0018] Based on another aspect of the present invention, the present invention provides a network control system for suppressing asymmetric fault overvoltage, the system comprising:

[0019] A first control unit is used to generate a network controller through a virtual synchronous generator, wherein an output parameter of the network controller is a duty cycle component of the network controller;

[0020] A second control unit is used for connecting the wind turbine converter to the power grid through the filter, the wind turbine converter is added with a negative sequence voltage controller, and the output parameter of the negative sequence voltage controller is a duty cycle component of the negative sequence voltage controller;

[0021] The result unit is used to output the superposition of the duty cycle component of the network controller and the duty cycle component of the negative sequence voltage controller, so as to suppress the asymmetric fault overvoltage.

[0022] Preferably, the negative sequence voltage component v of the negative sequence voltage controller qn The calculation method is:

[0023]

[0024] Among them, LP is a low-pass filter, v αβ is the voltage vector at the AC busbar of the wind turbine converter in the two-phase stationary coordinate system, and the angle is the angle of the negative sequence voltage synchronous rotation coordinate system, and j is the imaginary axis in the complex plane.

[0025] Preferably, the negative sequence voltage reference value v of the negative sequence voltage controller is qrefn is 0.

[0026] Preferably, the negative-sequence voltage controller duty cycle component of the negative-sequence voltage controller is:

[0027]

[0028] Among them, k pn is the proportional link, k in is the integral link, ΔD q is the duty cycle component of the negative sequence voltage controller, and s is a complex variable in the complex plane.

[0029] Based on another aspect of the present invention, the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and the computer program is used to execute a network control method for suppressing asymmetric fault overvoltage.

[0030] Based on another aspect of the present invention, the present invention provides an electronic device, the electronic device comprising: a processor and a memory; wherein,

[0031] The memory is a memory for storing instructions executable by the processor;

[0032] The processor is used to read the executable instructions from the memory and execute the instructions to implement a network control method for suppressing asymmetric fault overvoltage.

[0033] The technical solution of the present invention provides a network control method and system for suppressing asymmetric fault overvoltage, wherein the method includes: generating a network controller through a virtual synchronous generator, the output parameter of the network controller is the duty cycle component of the network controller; the wind turbine converter is connected to the power grid through a filter, the wind turbine converter adds a negative sequence voltage controller, the output parameter of the negative sequence voltage controller is the duty cycle component of the negative sequence voltage controller; the duty cycle component of the network controller is superimposed with the duty cycle component of the negative sequence voltage controller and then output, so as to suppress the asymmetric fault overvoltage. The present invention is based on the inherent mechanism of overvoltage of the wind turbine converter during asymmetric faults, and by introducing a negative sequence voltage control link and cooperating with the network voltage control, it is ensured that the wind turbine converter has no negative sequence voltage during asymmetric faults, thereby avoiding the generation of overvoltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0035] Figure 1 A flow chart of a network control method for suppressing asymmetric fault overvoltage according to a preferred embodiment of the present invention;

[0036] Figure 2 A control logic diagram of a network control method for suppressing asymmetric fault overvoltage according to a preferred embodiment of the present invention;

[0037] Figure 3 A schematic diagram of the waveforms of AC voltage, positive sequence voltage and negative sequence voltage during an asymmetric fault according to a preferred embodiment of the present invention; and

[0038] Figure 4 The structure diagram of a network control system for suppressing asymmetric fault overvoltage according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0039] Now, exemplary embodiments of the present invention are described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0040] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0041] Figure 1 The present invention is a flowchart of a network control method for suppressing asymmetric fault overvoltage according to a preferred embodiment of the present invention.

[0042] The present invention is based on the inherent overvoltage mechanism of the wind turbine converter during an asymmetric fault. By introducing a negative sequence voltage control link and coordinating with the grid voltage control, it ensures that the wind turbine converter has no negative sequence voltage during an asymmetric fault, thereby avoiding the generation of overvoltage.

[0043] The method of the present invention can be applied to the design of a wind turbine controller to improve the reliable and stable operation capability of the wind turbine converter and the voltage recovery capability after the asymmetric fault is cleared.

[0044] like Figure 1As shown, the present invention provides a network control method for suppressing asymmetric fault overvoltage, the method comprising:

[0045] Step 101: Generate a network controller through a virtual synchronous generator, where an output parameter of the network controller is a duty cycle component of the network controller;

[0046] The wind turbine converter of the present invention is connected to the power grid through an L filter, and a virtual synchronous generator technology is used to realize network control to form a network controller. The output parameter of the network controller is the duty cycle component D d , D q .

[0047] Step 102: the wind turbine converter is connected to the grid through the filter, and a negative sequence voltage controller is added to the wind turbine converter, and the output parameter of the negative sequence voltage controller is a duty cycle component of the negative sequence voltage controller;

[0048] The wind turbine converter of the present invention adds a negative sequence voltage controller, and the duty cycle of the negative sequence voltage controller output is ΔD q .

[0049] Step 103: superimpose the duty cycle component of the network controller and the duty cycle component of the negative sequence voltage controller and output them to suppress the asymmetric fault overvoltage.

[0050] The duty cycle component ΔD output by the negative sequence voltage controller of the present invention is q The duty cycle component D output by the network controller q Overlay.

[0051] Preferably, the negative sequence voltage component v of the negative sequence voltage controller qn The calculation method is:

[0052]

[0053] Among them, LP is a low-pass filter, v αβ is the voltage vector at the AC busbar of the wind turbine converter in the two-phase stationary coordinate system, and the angle is the angle of the negative sequence voltage synchronous rotation coordinate system, and j is the imaginary axis in the complex plane.

[0054] The negative sequence voltage controller of the present invention, the negative sequence voltage component v qn The calculation method is:

[0055]

[0056] Among them, LP is a low-pass filter, v αβ is the voltage vector at the AC busbar of the wind turbine converter in the two-phase stationary coordinate system, and the angle is the negative sequence voltage synchronous rotation coordinate system angle.

[0057] Preferably, the negative sequence voltage reference value v of the negative sequence voltage controller is qrefn is 0.

[0058] The negative sequence voltage controller of the present invention, the negative sequence voltage reference value v qrefn The value of is 0.

[0059] Preferably, the negative sequence voltage controller duty cycle component of the negative sequence voltage controller is:

[0060]

[0061] Among them, k pn is the proportional link, k in is the integral link, ΔD q is the duty cycle component of the negative sequence voltage controller, and s is a complex variable in the complex plane.

[0062] The negative sequence voltage controller of the present invention has a duty cycle component ΔD q The specific calculation formula of and is:

[0063]

[0064] Among them, k pn is the proportional link, k in For the points segment.

[0065] When the present invention operates normally, the AC bus voltage of the fan converter is symmetrical, the negative sequence voltage component is 0, and the negative sequence controller output is 0.

[0066] During a single-phase instantaneous grounding fault, the AC bus voltage of the fan converter is asymmetric, the negative sequence voltage component is not 0, and overvoltage suppression is achieved through a negative sequence voltage controller.

[0067] The present invention is based on the inherent overvoltage mechanism of the wind turbine converter during an asymmetric fault. By introducing a negative sequence voltage control link and coordinating with the grid voltage control, it ensures that the wind turbine converter has no negative sequence voltage during an asymmetric fault, thereby avoiding the generation of overvoltage.

[0068] The method of the present invention can be applied to the design of a wind turbine controller to improve the reliable and stable operation capability of the wind turbine converter and the voltage recovery capability after the asymmetric fault is cleared.

[0069] The present invention discloses a network control method for suppressing asymmetric fault overvoltage, which specifically includes the following process:

[0070] The wind turbine converter is connected to the grid through the L filter, and the virtual synchronous generator technology is used to realize the grid control to form a grid controller. The output parameter of the grid controller is the duty cycle component D d , D q.

[0071] The wind turbine converter adds a negative sequence voltage controller, and the duty cycle of the negative sequence voltage controller output is ΔD q .like Figure 2 shown.

[0072] The duty cycle component ΔD of the negative sequence voltage controller output q The duty cycle component D output by the network controller q Overlay.

[0073] The negative sequence voltage controller of the present invention, the negative sequence voltage component v qn The calculation method is:

[0074]

[0075] Where LP is a low-pass filter, v αβ is the voltage vector at the AC busbar of the wind turbine converter in the two-phase stationary coordinate system, and the angle is the negative sequence voltage synchronous rotation coordinate system angle.

[0076] The negative sequence voltage controller of the present invention, the negative sequence voltage reference value v qrefn The value of is 0.

[0077] The negative sequence voltage controller of the present invention has a duty cycle component ΔD q The specific calculation formula of and is:

[0078]

[0079] In the formula, k pn is the proportional link, k in For the points segment.

[0080] The present invention Figure 3 The fault logic is as follows: a phase A grounding fault occurs at 0.1s, the phase A circuit breaker on the fault side trips at 0.15s, the phase A circuit breaker on the opposite side trips at 0.152s, the phase A circuit breaker on the fault side recloses at 0.65s, and the phase A circuit breaker on the opposite side recloses at 0.653s.

[0081] When the present invention is in normal operation, as described above Figure 3 At 0.1s before the fault, the AC bus voltage of the wind turbine converter is symmetrical and the negative sequence voltage component is 0.

[0082] During a single-phase instantaneous ground fault, the present invention, as described above, Figure 3 During the period of 0.1s-0.65s, the AC bus voltage of the wind turbine converter is asymmetric and has a negative sequence voltage component.

[0083] The network control method for suppressing asymmetric fault overvoltage proposed in the present invention suppresses negative sequence voltage through a negative sequence voltage controller, thereby eliminating overvoltage during reclosing of a single-phase instantaneous grounding fault.

[0084] Figure 4 The structure diagram of a network control system for suppressing asymmetric fault overvoltage according to a preferred embodiment of the present invention.

[0085] like Figure 4 As shown, the present invention provides a network control system for suppressing asymmetric fault overvoltage, the system comprising:

[0086] A first control unit 401 is used to generate a network controller through a virtual synchronous generator, and the output parameter of the network controller is a duty cycle component of the network controller;

[0087] A second control unit 402 is used for connecting the wind turbine converter to the power grid through the filter, and the wind turbine converter adds a negative sequence voltage controller, and the output parameter of the negative sequence voltage controller is a duty cycle component of the negative sequence voltage controller;

[0088] Preferably, the negative sequence voltage component v of the negative sequence voltage controller qn The calculation method is:

[0089]

[0090] Among them, LP is a low-pass filter, v αβ is the voltage vector at the AC busbar of the wind turbine converter in the two-phase stationary coordinate system, and the angle is the angle of the negative sequence voltage synchronous rotation coordinate system, and j is the imaginary axis in the complex plane.

[0091] Preferably, the negative sequence voltage reference value v of the negative sequence voltage controller is qrefn is 0.

[0092] Preferably, the negative sequence voltage controller duty cycle component of the negative sequence voltage controller is:

[0093]

[0094] Among them, k pn is the proportional link, k in is the integral link, ΔD q is the duty cycle component of the negative sequence voltage controller, and s is a complex variable in the complex plane.

[0095] The result unit 403 is used to output the superposition of the duty cycle component of the network controller and the duty cycle component of the negative sequence voltage controller, so as to suppress the asymmetric fault overvoltage.

[0096] A network control system for suppressing asymmetric fault overvoltage in a preferred embodiment of the present invention corresponds to a network control method for suppressing asymmetric fault overvoltage in a preferred embodiment of the present invention, and will not be described in detail here.

[0097] The present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and the computer program is used to execute a network control method for suppressing asymmetric fault overvoltage.

[0098] The present invention provides an electronic device, the electronic device comprising: a processor and a memory; wherein:

[0099] Memory, a memory for storing processor executable instructions;

[0100] The processor is used for reading executable instructions from a memory and executing the instructions to implement a network control method for suppressing asymmetric fault overvoltage.

[0101] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. The schemes in the embodiments of the present invention may be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0102] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0103] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0104] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0105] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0106] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

[0107] The invention has been described above with reference to a few embodiments. However, it is readily apparent to a person skilled in the art that other embodiments than the ones disclosed above are equally within the scope of the invention, as defined by the appended patent claims.

[0108] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / / the [means, component, etc.]" are to be openly interpreted as at least one instance of a means, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not necessarily have to be performed in the exact order disclosed, unless explicitly stated otherwise.

Claims

1. A network control method for suppressing asymmetric fault overvoltage, the method comprising: Generate a network controller through a virtual synchronous generator, wherein the output parameter of the network controller is a duty cycle component of the network controller; The wind turbine converter is connected to the power grid through a filter, and a negative sequence voltage controller is added to the wind turbine converter, and the output parameter of the negative sequence voltage controller is a duty cycle component of the negative sequence voltage controller; The duty cycle component of the network controller and the duty cycle component of the negative sequence voltage controller are superimposed and then outputted to suppress asymmetric fault overvoltage.

2. The method according to claim 1, wherein the negative sequence voltage component v of the negative sequence voltage controller qn The calculation method is: in, LP is a low-pass filter, v αβ is the voltage vector at the AC busbar of the wind turbine converter in the two-phase stationary coordinate system, and the angle is the angle of the negative sequence voltage synchronous rotation coordinate system, and j is the imaginary axis in the complex plane.

3. The method according to claim 2, wherein the negative sequence voltage reference value v of the negative sequence voltage controller is qrefn is 0.

4. The method according to claim 3, wherein the negative sequence voltage controller duty cycle component of the negative sequence voltage controller is: in, k pn is the proportional link, k in is the integral link, ΔD q is the duty cycle component of the negative sequence voltage controller, and s is a complex variable in the complex plane.

5. A network control system for suppressing asymmetric fault overvoltage, the system comprising: A first control unit is used to generate a network controller through a virtual synchronous generator, wherein an output parameter of the network controller is a duty cycle component of the network controller; A second control unit is used for connecting the wind turbine converter to the power grid through a filter, wherein the wind turbine converter is added with a negative sequence voltage controller, and the output parameter of the negative sequence voltage controller is a duty cycle component of the negative sequence voltage controller; The result unit is used to output the superposition of the duty cycle component of the network controller and the duty cycle component of the negative sequence voltage controller, so as to suppress the asymmetric fault overvoltage.

6. The system according to claim 5, wherein the negative sequence voltage component v of the negative sequence voltage controller qn The calculation method is: in, LP is a low-pass filter, v αβ is the voltage vector at the AC busbar of the wind turbine converter in the two-phase stationary coordinate system, and the angle is the angle of the negative sequence voltage synchronous rotation coordinate system, and j is the imaginary axis in the complex plane.

7. The system according to claim 6, wherein the negative sequence voltage reference value v of the negative sequence voltage controller is qrefn is 0.

8. The system according to claim 7, wherein the negative sequence voltage controller duty cycle component of the negative sequence voltage controller is: in, k pn is the proportional link, k in is the integral link, ΔD q is the duty cycle component of the negative sequence voltage controller, and s is a complex variable in the complex plane.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and the computer program is used to execute the method according to any one of claims 1 to 4.

10. An electronic device, characterized in that: The electronic device comprises: a processor and a memory; wherein, The memory is a memory for storing instructions executable by the processor; The processor is configured to read the executable instructions from the memory and execute the instructions to implement the method according to any one of claims 1 to 4.

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