Converter multi-parallel harmonic interaction analysis method, device, equipment and medium

Abstract

The invention belongs to the technical field of electric power, and provides a converter multi-machine parallel harmonic interaction analysis method, device and equipment and a medium, and the method comprises the steps: determining the network side output current of a converter; determining the source current small semaphore of the converter and the output admittance of the converter according to the grid-side output current; determining the source current disturbance of the converter according to the source current small semaphore, and further calculating the PCC node voltage of the common grid-connected point of the target power grid system; determining an interaction factor of harmonic admittance of the converter according to the PCC node voltage of the common grid-connected point and the grid-side output current; determining a harmonic amplification critical condition by adopting a peak criterion according to the interaction factor of harmonic admittance; and determining a harmonic interaction analysis result of the converter in the target power grid system according to the harmonic amplification critical condition, and executing control processing according to the harmonic interaction analysis result. The method has the beneficial effects that the accuracy of harmonic analysis is improved, and the accuracy of subsequent control processing is improved.

Description

Technical Field

[0001] This invention relates to the field of power technology, and in particular to a method, apparatus, equipment, and medium for harmonic interaction analysis of multiple parallel converters. Background Technology

[0002] With the increasing penetration of renewable energy, converters are being used more and more widely in the power grid. The harmonic interaction problem when multiple converters are running in parallel has become a key factor restricting system performance.

[0003] Existing analytical methods mainly focus on judging system stability, such as the Nyquist criterion based on impedance ratio and eigenvalue analysis. However, they are difficult to quantify the amplification conditions of harmonic interaction and lack analytical accuracy under multiple influencing factors (such as control parameters, grid impedance, and number of parallel units), resulting in inaccurate subsequent processing such as fault analysis and harmonic control. Summary of the Invention

[0004] Aimed at solving at least one of the technical problems existing in the prior art, the present invention provides a method, apparatus, equipment and medium for harmonic interaction analysis of multiple parallel converters, which improves the accuracy of harmonic interaction analysis and subsequent harmonic control accuracy of multiple parallel converters.

[0005] One aspect of the present invention provides a method for harmonic interaction analysis of multiple parallel converters, comprising:

[0006] The grid-side output current of the converter is determined based on the power control loop reference voltage of the converter and the voltage input at the common grid connection point, wherein multiple converters are connected in parallel to form the target power grid system;

[0007] Determine the source current small-signal quantity and the output admittance of the converter based on the grid-side output current.

[0008] The source current disturbance of the converter is determined based on the small signal quantity of the source current. Based on the source current disturbance of the converter, the output admittance of the converter and the voltage given disturbance of the target power grid system, the PCC node voltage of the common grid connection point of the target power grid system is calculated.

[0009] The interaction factor of the harmonic admittance of the converter is determined based on the PCC node voltage and grid-side output current at the common grid connection point. The interaction factor includes the mutual interaction factor and the self-interaction factor.

[0010] The critical condition for harmonic amplification is determined by the peak criterion based on the interaction factor of harmonic admittance.

[0011] The harmonic interaction analysis results of the converter in the target power grid system are determined based on the harmonic amplification critical condition, and control processing is performed based on the harmonic interaction analysis results.

[0012] According to the aforementioned method for harmonic interaction analysis of multi-machine parallel converters, the grid-side output current of the converter is determined based on the power control loop reference voltage and the voltage input at the common grid connection point, including:

[0013] The grid-side output current The calculation formula is:

[0014]

[0015]

[0016]

[0017] in, Indicates relative to the grid-side output current Reference admittance, Indicates relative to the grid-side output current 's output admittance' This is the reference voltage for the power control loop. The voltage input at the common grid connection point. The impedance of the filter capacitor is... For the grid-side filter inductor impedance, Let the voltage outer loop transfer function be... It is the transfer function in the inner current loop that uses the reference current of the voltage loop as the input. In the inner current loop, the sampled capacitor voltage is used as the transfer function of the input quantity.

[0018] According to the aforementioned method for analyzing harmonic interactions in a multi-machine parallel converter, determining the source current small-signal quantity and the output admittance of the converter based on the grid-side output current includes:

[0019] Will Represented as source current small-signal quantity , will be expressed as the output admittance of the converter, where Indicates relative to the grid-side output current Reference admittance, Indicates relative to the grid-side output current 's output admittance' This is the reference voltage for the power control loop. This refers to the voltage input at the common grid connection point.

[0020] According to the aforementioned method for harmonic interaction analysis of multi-machine parallel converters, the source current disturbance of the converter is determined based on the small-signal quantity of the source current. Based on the source current disturbance, output admittance, and voltage setpoint disturbance of the converter, the PCC node voltage of the target power grid system's common grid connection point is calculated, including:

[0021] Using the small-signal source current as the source current disturbance, the PCC node voltage at the common grid connection point of the target power grid system with multiple converters connected in parallel is calculated using the node voltage method. The calculation formula is as follows:

[0022]

[0023] in, The voltage of the PCC node at the common grid connection point. The total number of converters connected in parallel in the target power grid system. Indicates the first Source current disturbance of the converter. Indicates the first The output admittance of the converter The admittance of the target power grid system, Provide a voltage disturbance for the target power grid system.

[0024] According to the aforementioned method for harmonic interaction analysis of multi-machine parallel converters, the interaction factor for determining the harmonic admittance of the converter based on the PCC node voltage at the common grid connection point and the grid-side output current includes:

[0025] Calculate the output admittance of the converter :

[0026]

[0027] in This refers to the grid-side output current of the converter. The voltage of the PCC node at the common grid connection point;

[0028] Based on the converter's output admittance The sum of the output admittances of all converters in the target power grid system and the power grid admittance are used to calculate the admittance ratio.

[0029] The harmonic admittance interaction factor and harmonic admittance self-interaction factor of the converter are determined based on the admittance ratio, where the harmonic admittance interaction factor is... The calculation formula is:

[0030]

[0031] Harmonic admittance interaction factor Indicates the first The extent to which the converter is affected by disturbances from other converters or the power grid, among which For grid admittance;

[0032] Harmonic admittance self-interaction factor The calculation formula is:

[0033]

[0034] Among them, harmonic admittance self-interaction factor Indicates the first The degree to which the converter is affected by its own disturbances. For the first Taiwan converter output admittance, For the first Current disturbance on the output admittance of the converter. For the total current disturbance of the target power grid system, It is the sum of the output admittances of all converters in the target power grid system.

[0035] According to the aforementioned method for harmonic interaction analysis of multi-machine parallel converters, the critical condition for harmonic amplification is determined using a peak criterion based on the interaction factor of harmonic admittance, including:

[0036] The interaction factor is expressed as a function of the admittance ratio:

[0037]

[0038] The admittance ratio function of the mutual interaction factor and the self-interaction factor is obtained as follows:

[0039]

[0040]

[0041] Determine the gain margin of the admittance ratio based on the Nyquist stability criterion. and phase margin According to the magnitude margin and phase margin The critical conditions for harmonic amplification are determined, including the mutual amplification condition and the self-mutual amplification condition. The mutual amplification condition is as follows: and Interaction factors peak Self-interactive amplification condition is Non-infinite and Self-interaction factor peak .

[0042] According to the aforementioned method for harmonic interaction analysis of multi-machine parallel converters, the harmonic interaction analysis results of the converters in the target power grid system are determined based on the harmonic amplification critical condition, and control processing is performed based on the harmonic interaction analysis results, including:

[0043] The harmonic interaction analysis results include harmonic amplification and harmonic attenuation. Based on the harmonic interaction analysis results, control parameters are adjusted to maintain the harmonics of the target power grid system within a preset value.

[0044] Another aspect of the present invention provides a converter multi-machine parallel harmonic interactive analysis device, comprising:

[0045] The first module is used to determine the grid-side output current of the converter based on the power control loop reference voltage and the voltage input of the common grid connection point, wherein multiple converters are connected to the target grid system in parallel.

[0046] The second module is used to determine the source current small-signal quantity and output admittance of the converter based on the grid-side output current.

[0047] The third module is used to determine the source current disturbance of the converter based on the small signal quantity of the source current, and to calculate the PCC node voltage of the common grid connection point of the target power grid system based on the source current disturbance, output admittance and voltage setpoint disturbance of the converter.

[0048] The fourth module is used to determine the interaction factor of the converter's harmonic admittance based on the PCC node voltage and grid-side output current at the common grid connection point. The interaction factor includes mutual interaction factor and self-interaction factor.

[0049] The fifth module is used to determine the critical conditions for harmonic amplification based on the peak criterion using the interaction factor of harmonic admittance.

[0050] The sixth module is used to determine the harmonic interaction analysis results of the converter in the target power grid system based on the harmonic amplification critical condition, and to perform control processing based on the harmonic interaction analysis results.

[0051] Another aspect of the present invention provides an electronic device, including a processor and a memory;

[0052] The memory is used to store programs;

[0053] The processor executes the program to implement the method as described above.

[0054] This invention also discloses a computer-readable storage medium storing a program that is executed by a processor using the methods described above.

[0055] The beneficial effects of this invention are as follows: By using the harmonic admittance interaction factor and the self-interaction factor, the influence of self-disturbance and mutual disturbance on harmonic interaction is clearly distinguished, achieving a refined analysis of the interaction mechanism; the quantitative conditions for harmonic interaction amplification are determined based on the peak criterion, and the critical conditions for harmonic amplification are used to determine whether harmonics are amplified and the degree of amplification, providing a clear boundary basis for system parameter design; by using voltage-given disturbances and small-signal quantities of source currents that cause grid disturbances, the effect of dual disturbances on harmonic interaction in actual operation is more realistically reflected, improving the accuracy of harmonic analysis and the accuracy of subsequent control processing. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of the structure of a multi-machine parallel power grid system for converters according to an embodiment of the present invention.

[0057] Figure 2 This is a schematic diagram of the harmonic interaction analysis process for multi-machine parallel converters according to an embodiment of the present invention.

[0058] Figure 3 This is a block diagram of the loop control structure of a grid-type converter circuit according to an embodiment of the present invention.

[0059] Figure 4 This is a circuit diagram of a single inverter according to an embodiment of the present invention.

[0060] Figure 5 This is a schematic diagram of a grid-connected system with three converters according to an embodiment of the present invention.

[0061] Figure 6 This is an analysis diagram of the impact of parallel converter systems with different grid configurations on harmonic interaction in an embodiment of the present invention. (a) is a diagram showing the variation of the Nyquist curve of the open-loop transfer function of the system when the grid impedance changes, and (b) is a diagram showing the variation of the harmonic amplification factor and impedance.

[0062] Figure 7 This is a schematic diagram of a converter multi-machine parallel harmonic interactive analysis device according to an embodiment of the present invention. Detailed Implementation

[0063] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings. Throughout the description, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. In the following description, suffixes such as "module," "part," or "unit" used to denote elements are used only for the purpose of illustrative purposes and have no inherent meaning. Therefore, "module," "part," or "unit" can be used interchangeably. In this subsequent description, the consecutive reference numerals for method steps are for ease of review and understanding. Adjusting the order of implementation of the steps, considering the overall technical solution of the present invention and the logical relationships between the steps, will not affect the technical effects achieved by the present invention. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0064] refer to Figure 1 , Figure 1 This is a schematic diagram of a multi-machine parallel grid system structure of converters according to an embodiment of the present invention. It includes N grid-type converters. The grid-type converters 1-N are connected to the grid system in parallel. The outputs of the N converters are fed into the grid system through a common grid connection point. The grid system has corresponding grid admittance.

[0065] In some practical examples, the converter is a grid-type converter, but the converter can also be an inverter, rectifier, etc.

[0066] refer to Figure 2 , Figure 2 This is a schematic diagram of the multi-machine parallel harmonic interaction analysis process of the converter according to an embodiment of the present invention, which includes, but is not limited to, steps S100~S600:

[0067] S100 determines the grid-side output current of the converter based on the power control loop reference voltage and the voltage input at the common grid connection point, wherein multiple converters are connected in parallel to form the target power grid system.

[0068] In some embodiments, such as Figure 3 The diagram shown illustrates the circuit loop control structure of a grid-connected converter. Considering the combined effects of a given disturbance and grid disturbance, a small-signal model of a single converter is established, and the grid-side output current of the grid-connected converter is... As an output quantity, the grid-side output current The calculation formula is:

[0069]

[0070]

[0071]

[0072] for Figure 2 and grid-side output current, of which Indicates relative to the grid-side output current Reference admittance, Indicates relative to the grid-side output current 's output admittance' This is the reference voltage for the power control loop. The voltage input at the common grid connection point. The impedance of the filter capacitor is... For the grid-side filter inductor impedance, Let the voltage outer loop transfer function be... It is the transfer function in the inner current loop that uses the reference current of the voltage loop as the input. In the inner current loop, the sampled capacitor voltage is used as the transfer function of the input quantity. For grid-side output current, The transfer function of the delay element, Let be the transfer function of the inner current loop. The reference current comes from the voltage link. For the inverter-side filter inductor impedance, DC input voltage, For the converter-side inductor current, The collected capacitor voltage. It is a voltage-modulated signal.

[0073] S200 determines the source current small-signal quantity and output admittance of the converter based on the grid-side output current.

[0074] In some embodiments, Represented as source current small-signal quantity , will be expressed as the output admittance of the converter, where Indicates relative to the grid-side output current Reference admittance, Indicates relative to the grid-side output current 's output admittance' This is the reference voltage for the power control loop. This refers to the voltage input at the common grid connection point.

[0075] In some embodiments, reference Figure 4 The circuit diagram shown is for a single inverter, where the inverter is a type of converter. Therefore, for a single inverter, its source current has a small signal quantity. and output admittance Represented as:

[0076]

[0077] in, For reference admittance, The output admittance of the inverter. Figure 4 In This refers to the node voltage of the common node PCC.

[0078] S300 determines the source current disturbance of the converter based on the small signal quantity of the source current, and calculates the PCC node voltage of the common grid connection point of the target power grid system based on the source current disturbance of the converter, the output admittance of the converter and the voltage given disturbance of the target power grid system.

[0079] In some embodiments, such as Figure 5 The schematic diagram of the grid-connected system with three converters shown illustrates the target power grid system composed of three converters (inverters), including the corresponding branches. In a multi-converter grid-connected system, the node voltage of the common node PCC is calculated using a small-signal source current as the source current disturbance. The node voltage method is used to calculate the PCC node voltage of the common grid connection point of multiple converters in the target power grid system. The calculation formula is as follows:

[0080]

[0081] in, The voltage of the PCC node at the common grid connection point. The total number of converters connected in parallel in the target power grid system. Indicates the first Source current disturbance of the converter. Indicates the first The output admittance of the converter The admittance of the target power grid system, Provide a voltage disturbance for the target power grid system.

[0082] S400 determines the interaction factor of the converter's harmonic admittance based on the PCC node voltage and grid-side output current at the common grid connection point. The interaction factor includes mutual interaction factor and self-interaction factor.

[0083] In some embodiments, for a power grid system with multiple converters connected in parallel, the output admittance of each converter is:

[0084]

[0085] in This refers to the grid-side output current of the converter. This refers to the node voltage of the common node PCC.

[0086] In some embodiments, the admittance ratio is calculated as the harmonic admittance interaction factor and the harmonic admittance self-interaction factor, wherein the harmonic admittance interaction factor is... The calculation formula is:

[0087]

[0088] Harmonic admittance interaction factor Indicates the first The extent to which the converter is affected by disturbances from other converters or the power grid, among which For the grid admittance (of the target power grid system), and Indicates the serial number of the converter in the target power grid system;

[0089] Harmonic admittance self-interaction factor The calculation formula is:

[0090]

[0091] Among them, harmonic admittance self-interaction factor Indicates the first The degree to which the converter is affected by its own disturbances. For the first Taiwan converter output admittance, For the first Current disturbance on the output admittance of the converter. For the total current disturbance of the target power grid system, It is the sum of the output admittances of all converters in the target power grid system.

[0092] Combination Figure 5 The diagram shown is of a grid-connected system with three converters. Figure 5 Interaction factor of mid-harmonic admittance The specific expression is as follows:

[0093]

[0094] It is understood that the harmonic admittance interaction factor and harmonic admittance self-interaction factor in the embodiments of the present invention are used to distinguish between the disturbance of a single converter itself and the disturbance between multiple converters. The disturbance of a single converter itself is determined by the harmonic admittance self-interaction factor, while the disturbance between multiple converters is determined by the harmonic admittance interaction factor.

[0095] In some embodiments, the harmonic amplification or attenuation of a target power grid system can be determined by the harmonic admittance interaction factor and the harmonic admittance self-interaction factor. At times, mutual interference leads to harmonic amplification; when At times, mutual interference leads to harmonic attenuation; when At that time, self-disruption leads to harmonic amplification; when At that time, self-disruption leads to harmonic attenuation.

[0096] S500 uses the peak criterion to determine the critical condition for harmonic amplification based on the interaction factor of harmonic admittance.

[0097] In some embodiments, the interaction factor is expressed as a function of the admittance ratio. :

[0098]

[0099] The admittance ratio function of the mutual interaction factor and the self-interaction factor is obtained as follows:

[0100]

[0101]

[0102] Determine the gain margin of the admittance ratio based on the Nyquist stability criterion. and phase margin According to the magnitude margin and phase margin The critical conditions for harmonic amplification are determined, including the mutual amplification condition and the self-mutual amplification condition. It is a function of the admittance ratio. Let be the admittance ratio function of the interaction factor. Let be the admittance ratio function of the self-interaction factor, and when the interaction amplification condition is and Interaction factors peak Self-interactive amplification condition is Non-infinite and At that time, self-interaction factor peak .

[0103] refer to Figure 6 This diagram illustrates the impact of parallel grid-connected converter systems with different grid configurations on harmonic interaction. Simulations verify the harmonic interaction characteristics of parallel grid-connected converter systems under varying grid impedance conditions. Taking a parallel system of two different grid-connected inverters as an example, the harmonic characteristics of each inverter's output branch are analyzed in detail. Simulation selection... =0.1mH is used as the baseline condition. Figure 6 (a) illustrates the variation of the Nyquist curve of the system's open-loop transfer function as the grid impedance changes, showing that under different... At the given values ​​(0.1mH, 0.5mH, 1mH), the phase margin of the system interaction factor remains below 60°, and harmonic current amplification occurs in specific frequency bands (around 1600Hz, 455Hz, and 336Hz, respectively). It is noteworthy that as the grid impedance increases, the peak frequency of harmonic amplification decreases. Figure 6 (b) It can be seen that the harmonic amplification factor increases significantly with increasing impedance.

[0104] S600 determines the harmonic interaction analysis results of the converter in the target power grid system based on the harmonic amplification critical condition, and performs control processing based on the harmonic interaction analysis results.

[0105] In some embodiments, the harmonic interaction analysis results include harmonic amplification and harmonic attenuation. Based on the harmonic interaction analysis results, control parameters are adjusted to maintain the harmonics of the target power grid system within a preset value.

[0106] It is understood that the harmonic interaction analysis results of the embodiments of the present invention are based on the critical condition of harmonic amplification, which can obtain more accurate analysis results. Therefore, subsequent control processing can achieve better results, such as analyzing the impact of harmonics on system performance, harmonic suppression, and dynamic control.

[0107] Figure 7 This is a schematic diagram of a converter multi-machine parallel harmonic interactive analysis device according to an embodiment of the present invention. The device includes a first module 710, a second module 720, a third module 730, a fourth module 740, a fifth module 750, and a sixth module 760.

[0108] The system comprises six modules: First, determining the grid-side output current of the converter based on the power control loop reference voltage and the voltage input at the common grid connection point (PCC). Multiple converters are connected to the target grid system in parallel. Second, determining the source current small-signal quantity and output admittance of the converter based on the grid-side output current. Third, determining the source current disturbance of the converter based on the source current small-signal quantity, and calculating the PCC node voltage at the common grid connection point based on the source current disturbance, output admittance, and voltage input disturbance. Fourth, determining the harmonic admittance interaction factor of the converter based on the PCC node voltage at the common grid connection point and the grid-side output current. This interaction factor includes mutual interaction factors and self-interaction factors. Fifth, determining the harmonic amplification critical condition using a peak criterion based on the harmonic admittance interaction factor. Sixth, determining the harmonic interaction analysis results of the converters in the target grid system based on the harmonic amplification critical condition, and executing control processing based on the harmonic interaction analysis results.

[0109] For example, with the cooperation of the first to sixth modules in the device, the embodiment device can implement any of the aforementioned multi-converter parallel harmonic interaction analysis methods, namely, determining the grid-side output current of the converter based on the power control loop reference voltage of the converter and the voltage input of the common grid connection point, wherein multiple converters are connected in parallel to form the target power grid system; determining the source current small-signal quantity and output admittance of the converter based on the grid-side output current; determining the source current disturbance of the converter based on the source current small-signal quantity; calculating the PCC node voltage of the common grid connection point of the target power grid system based on the source current disturbance, the output admittance of the converter, and the voltage given disturbance of the target power grid system; determining the interaction factor of the harmonic admittance of the converter based on the PCC node voltage of the common grid connection point and the grid-side output current, wherein the interaction factor includes mutual interaction factor and self-interaction factor; determining the harmonic amplification critical condition based on the peak criterion of the harmonic admittance interaction factor; determining the harmonic interaction analysis result of the converter in the target power grid system based on the harmonic amplification critical condition; and performing control processing based on the harmonic interaction analysis result. The beneficial effects of this invention are as follows: By using the harmonic admittance interaction factor and the self-interaction factor, the influence of self-disturbance and mutual disturbance on harmonic interaction is clearly distinguished, achieving a refined analysis of the interaction mechanism; the quantitative conditions for harmonic interaction amplification are determined based on the peak criterion, and the critical conditions for harmonic amplification are used to determine whether harmonics are amplified and the degree of amplification, providing a clear boundary basis for system parameter design; by using voltage-given disturbances and small-signal quantities of source currents that cause grid disturbances, the effect of dual disturbances on harmonic interaction in actual operation is more realistically reflected, improving the accuracy of harmonic analysis and the accuracy of subsequent control processing.

[0110] This invention also provides an electronic device, which includes a processor and a memory;

[0111] The memory stores the program;

[0112] The processor executes a program to perform the aforementioned converter multi-machine parallel harmonic interactive analysis method; the electronic device has the function of carrying and running the software system for converter multi-machine parallel harmonic interactive analysis provided in the embodiments of the present invention, such as a personal computer, minicomputer, mainframe, workstation, network or distributed computing environment, standalone or integrated computer platform, or communicating with charged particle tools or other imaging devices, etc.

[0113] This invention also provides a computer-readable storage medium storing a program that is executed by a processor to implement the multi-machine parallel harmonic interactive analysis method for converters as described above.

[0114] In some alternative embodiments, the functions / operations mentioned in the block diagrams may not occur in the order shown in the operation diagrams. For example, depending on the functions / operations involved, two consecutively shown blocks may actually be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order. Furthermore, the embodiments presented and described in the flowcharts of this invention are provided by way of example to provide a more comprehensive understanding of the technology. The disclosed methods are not limited to the operations and logic flows presented in the embodiments of this invention. Alternative embodiments are contemplated, in which the order of various operations is changed and sub-operations described as part of a larger operation are executed independently.

[0115] This invention also discloses a computer program product or computer program, which includes computer instructions stored in a computer-readable storage medium. A processor of a computer device can read the computer instructions from the computer-readable storage medium and execute the computer instructions, causing the computer device to perform the aforementioned converter multi-machine parallel harmonic interactive analysis method.

[0116] Furthermore, although the invention has been described in the context of functional modules, it should be understood that, unless otherwise stated, one or more of the described functions and / or features may be integrated into a single physical device and / or software module, or one or more functions and / or features may be implemented in a separate physical device or software module. It is also understood that a detailed discussion of the actual implementation of each module is unnecessary for understanding the invention. Rather, considering the properties, functions, and internal relationships of the various functional modules in the apparatus disclosed in the embodiments of the invention, the actual implementation of the module will be understood within the scope of conventional skill of an engineer. Therefore, those skilled in the art can implement the invention as set forth in the claims using ordinary techniques without excessive experimentation. It is also understood that the specific concepts disclosed are merely illustrative and are not intended to limit the scope of the invention, which is determined by the full scope of the appended claims and their equivalents.

[0117] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0118] 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). For the purposes of this specification, "computer-readable medium" can be any means that can include, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0119] More specific examples of computer-readable media (a non-exhaustive list) include: electrical connections (electronic devices) having one or more wires, portable computer disk drives (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0120] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0121] In the description of this specification, 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 the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0122] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

[0123] The above is a detailed description of the preferred embodiments of the present invention, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A method for harmonic interaction analysis of multi-machine parallel converters, characterized in that, include: The grid-side output current of the converter is determined based on the power control loop reference voltage of the converter and the voltage input at the common grid connection point, wherein multiple converters are connected in parallel to form the target power grid system; Determine the source current small-signal quantity and the output admittance of the converter based on the grid-side output current. The source current disturbance of the converter is determined based on the small signal quantity of the source current. Based on the source current disturbance of the converter, the output admittance of the converter and the voltage given disturbance of the target power grid system, the PCC node voltage of the common grid connection point of the target power grid system is calculated. The interaction factor of the harmonic admittance of the converter is determined based on the PCC node voltage and grid-side output current at the common grid connection point. The interaction factor includes the mutual interaction factor and the self-interaction factor. The critical condition for harmonic amplification is determined by the peak criterion based on the interaction factor of harmonic admittance. The harmonic interaction analysis results of the converter in the target power grid system are determined based on the harmonic amplification critical condition, and control processing is performed based on the harmonic interaction analysis results.

2. The method for harmonic interaction analysis of multi-machine parallel converters according to claim 1, characterized in that, The determination of the grid-side output current of the converter based on the power control loop reference voltage and the voltage input at the common grid connection point includes: The grid-side output current The calculation formula is: ； ； ； in, Indicates relative to the grid-side output current Reference admittance, Indicates relative to the grid-side output current 's output admittance' This is the reference voltage for the power control loop. The voltage input at the common grid connection point. The impedance of the filter capacitor is... For the grid-side filter inductor impedance, Let the voltage outer loop transfer function be... It is the transfer function in the inner current loop that uses the reference current of the voltage loop as the input. In the inner current loop, the sampled capacitor voltage is used as the transfer function of the input quantity.

3. The method for harmonic interaction analysis of multi-machine parallel converters according to claim 1, characterized in that, The determination of the source current small-signal quantity and the output admittance of the converter based on the grid-side output current includes: Will Represented as source current small-signal quantity , will be expressed as the output admittance of the converter, where Indicates relative to the grid-side output current Reference admittance, Indicates relative to the grid-side output current 's output admittance' This is the reference voltage for the power control loop. This refers to the voltage input at the common grid connection point.

4. The method for harmonic interaction analysis of multi-machine parallel converters according to claim 1, characterized in that, The process of determining the source current disturbance of the converter based on the small-signal quantity of the source current, and calculating the PCC node voltage of the target power grid system's common grid connection point based on the converter's source current disturbance, output admittance, and voltage setpoint disturbance, includes: Using the small-signal source current as the source current disturbance, the PCC node voltage at the common grid connection point of the target power grid system with multiple converters connected in parallel is calculated using the node voltage method. The calculation formula is as follows: ； in, The voltage of the PCC node at the common grid connection point. The total number of converters connected in parallel in the target power grid system. Indicates the first Source current disturbance of the converter. Indicates the first The output admittance of the converter The admittance of the target power grid system, Provide a voltage disturbance for the target power grid system.

5. The method for harmonic interaction analysis of multi-machine parallel converters according to claim 1, characterized in that, The interaction factor for determining the harmonic admittance of the converter based on the PCC node voltage and grid-side output current at the common grid connection point includes: Calculate the output admittance of the converter : ； in This refers to the grid-side output current of the converter. The voltage of the PCC node at the common grid connection point; Based on the converter's output admittance The sum of the output admittances of all converters in the target power grid system and the power grid admittance are used to calculate the admittance ratio. The harmonic admittance interaction factor and harmonic admittance self-interaction factor of the converter are determined based on the admittance ratio, where the harmonic admittance interaction factor is... The calculation formula is: ； Harmonic admittance interaction factor Indicates the first The extent to which the converter is affected by disturbances from other converters or the power grid, among which For grid admittance; Harmonic admittance self-interaction factor The calculation formula is: ； Among them, harmonic admittance self-interaction factor Indicates the first The degree to which the converter is affected by its own disturbances. For the first Taiwan converter output admittance, For the first Current disturbance on the output admittance of the converter. For the total current disturbance of the target power grid system, It is the sum of the output admittances of all converters in the target power grid system.

6. The method for harmonic interaction analysis of multi-machine parallel converters according to claim 5, characterized in that, The determination of the critical condition for harmonic amplification using the peak criterion based on the interaction factor of harmonic admittance includes: The interaction factor is expressed as a function of the admittance ratio: ； The admittance ratio function of the mutual interaction factor and the self-interaction factor is obtained as follows: ； ； Determine the gain margin of the admittance ratio based on the Nyquist stability criterion. and phase margin According to the magnitude margin and phase margin The critical conditions for harmonic amplification are determined, including the mutual amplification condition and the self-mutual amplification condition. The mutual amplification condition is as follows: and Interaction factors peak Self-interactive amplification condition is Non-infinite and Self-interaction factor peak .

7. The method for harmonic interaction analysis of multi-machine parallel converters according to claim 6, characterized in that, The process of determining the harmonic interaction analysis results of the converter in the target power grid system based on the harmonic amplification critical condition, and executing control processing based on the harmonic interaction analysis results, includes: The harmonic interaction analysis results include harmonic amplification and harmonic attenuation. Based on the harmonic interaction analysis results, control parameters are adjusted to maintain the harmonics of the target power grid system within a preset value.

8. A converter multi-machine parallel harmonic interactive analysis device, characterized in that, include: The first module is used to determine the grid-side output current of the converter based on the power control loop reference voltage and the voltage input of the common grid connection point, wherein multiple converters are connected to the target grid system in parallel. The second module is used to determine the source current small-signal quantity and output admittance of the converter based on the grid-side output current. The third module is used to determine the source current disturbance of the converter based on the small signal quantity of the source current, and to calculate the PCC node voltage of the common grid connection point of the target power grid system based on the source current disturbance, output admittance and voltage setpoint disturbance of the converter. The fourth module is used to determine the interaction factor of the converter's harmonic admittance based on the PCC node voltage and grid-side output current at the common grid connection point. The interaction factor includes mutual interaction factor and self-interaction factor. The fifth module is used to determine the critical conditions for harmonic amplification based on the peak criterion using the interaction factor of harmonic admittance. The sixth module is used to determine the harmonic interaction analysis results of the converter in the target power grid system based on the harmonic amplification critical condition, and to perform control processing based on the harmonic interaction analysis results.

9. An electronic device, characterized in that, Including the processor and memory; The memory is used to store programs; The processor executes the program to implement the converter multi-machine parallel harmonic interactive analysis method as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The storage medium stores a program, which is executed by a processor to implement the converter multi-machine parallel harmonic interactive analysis method as described in any one of claims 1-7.

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