A reactive power configuration method and system for converter stations in multi-terminal high-voltage direct current transmission projects

Abstract

The present invention discloses a method and system for reactive power configuration of a converter station in a multi-terminal HVDC transmission project, comprising: constructing a single-line diagram of the HVDC transmission system in the target transmission project; determining the rated trigger angle and the rated cut-off angle of the inverter side; processing the rated trigger angle and the rated cut-off angle to obtain the reactive power consumption of the converter; processing the constructed HVDC transmission impedance model to obtain a full-band harmonic impedance curve; processing the rated cut-off angle and the current value obtained by real-time detection to obtain the harmonic current; determining the minimum number of filter groups based on the harmonic voltage distortion rate; and inputting the reactive power consumption of the converter, the minimum number of filter groups, and the reactive capacity of the HVDC transmission system into a pre-constructed inductive reactive capacity relationship to determine the inductive reactive capacity configuration scheme. The method provided in the embodiment of the present invention optimizes the operating performance of the DC system by rationally configuring the HVDC transmission system in the HVDC transmission project.

Description

Technical Field

[0001] The present invention relates to the field of electric power technology, and in particular to a reactive power configuration method and system for a converter station in a multi-terminal high-voltage direct current (HVDC) power transmission project. Background Art

[0002] High-voltage direct current (HVDC) transmission projects are an important way to optimize the allocation of energy resources in my country. High-voltage direct current (HVDC) transmission systems are widely used in scenarios such as new energy grid connection and cross-regional power transmission.

[0003] However, traditional DC transmission projects rely on thyristor-based LCC (Line Commutation Converter) commutation technology. During LCC commutation, the thyristors require sufficient voltage from the AC bus to ensure successful current transfer to the next phase. However, LCCs continuously consume large amounts of reactive power during operation, especially during commutation when reactive power demand surges. Insufficient reactive power compensation equipment can cause the commutation bus voltage to fluctuate or even plummet.

[0004] Therefore, how to reasonably configure reactive power to optimize the operating performance of the DC system has become a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0005] The present invention provides a reactive power configuration method and system for converter stations in a multi-terminal high-voltage direct current (HVDC) power transmission project, to solve the problem of irrational reactive power configuration, which in turn leads to voltage fluctuations in the commutation busbar, thereby achieving reasonable reactive power configuration and optimizing the operating performance of the DC system.

[0006] To solve the above technical problems, an embodiment of the present invention provides a reactive power configuration method for a converter station in a multi-terminal high-voltage direct current (HVDC) power transmission project, comprising:

[0007] Construct a single-line diagram of the HVDC transmission system in the target transmission project;

[0008] determining a rated trigger angle on the rectifier side based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the HVDC transmission system single-line diagram, and determining a rated turn-off angle on the inverter side based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the HVDC transmission system single-line diagram;

[0009] Processing the rated trigger angle and the rated cut-off angle using a converter reactive power compensation technology to obtain converter reactive power consumption;

[0010] Processing the constructed HVDC transmission impedance model using a frequency domain scanning method to obtain a full-band harmonic impedance curve, wherein the HVDC transmission impedance model is obtained based on the harmonic frequencies of the grid components in the HVDC transmission system single-line diagram;

[0011] Processing the rated turn-off angle and the current value obtained by real-time detection to obtain harmonic current;

[0012] determining a minimum number of filter groups of the converter station based on a harmonic voltage distortion rate obtained from the harmonic current and the full-band harmonic impedance curve;

[0013] The reactive power consumption of the converter, the minimum number of filter groups of the converter station, and the reactive capacity of the high-voltage direct current transmission system are input into a pre-established inductive reactive capacity relationship to obtain the inductive reactive capacity, and an inductive reactive capacity configuration scheme determined by the inductive reactive capacity is executed.

[0014] As one preferred solution, the process of constructing the single-line diagram of the HVDC transmission system includes:

[0015] Obtain component information of HVDC transmission system;

[0016] generating a topological relationship description expression of a single-line diagram of the high-voltage direct current transmission system based on the acquired component information of the high-voltage direct current transmission system;

[0017] Based on a real-time HVDC system single-line diagram topology relationship description expression, topology relationship information of the HVDC system single-line diagram is generated; based on the HVDC system single-line diagram topology relationship information, a HVDC system single-line diagram is generated.

[0018] As one preferred solution, the process of determining the rated firing angle includes:

[0019] determining a rated voltage of a busbar on the rectifier side of the HVDC transmission system one-line diagram based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the HVDC transmission system one-line diagram, and determining a rated voltage of a busbar on the inverter side based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the HVDC transmission system one-line diagram;

[0020] determining a transformation ratio value based on the rated voltage of the rectifier-side bus and the rated voltage of the inverter-side bus;

[0021] The rated voltage of the rectifier-side bus, the transformation ratio, and the real-time voltage of the high-voltage direct current transmission system are processed using an inverse trigonometric function to obtain the rated trigger angle.

[0022] As one preferred solution, the process of determining the rated turn-off angle includes:

[0023] obtaining the short-circuit capacity of the HVDC transmission system in real time;

[0024] Determining an initial turn-off angle based on the number of converter stations on the rectifier side, the number of converter stations on the inverter side, and the transformation ratio in the single-line diagram of the high-voltage direct current transmission system;

[0025] The initial turn-off angle is corrected using the short-circuit capacity to obtain a rated turn-off angle on the inverter side.

[0026] As one preferred solution, the processing of the rated turn-off angle and the current value obtained by real-time detection to obtain the harmonic current includes:

[0027] acquiring a current value passing through the converter station in real time;

[0028] Performing a fast Fourier transform on the current value to obtain harmonic amplitude and phase;

[0029] Performing converter harmonic modeling on the rated turn-off angle, the harmonic amplitude, and the phase to obtain a theoretical harmonic current amplitude;

[0030] Obtaining a background harmonic spectrum of the HVDC transmission system when the converter is out of service;

[0031] The theoretical harmonic current amplitude and the background harmonic spectrum are dynamically superimposed to obtain the harmonic current.

[0032] As one preferred solution, the process of determining the minimum number of filter groups of the converter station includes:

[0033] Determining a theoretical minimum number of filter groups based on the harmonic voltage distortion rate;

[0034] The theoretical minimum number of filter groups is processed using the N-1 criterion to obtain the minimum number of filter groups of the converter station.

[0035] As one preferred solution, after obtaining the full-band harmonic impedance curve, the reactive power configuration method of the converter station in the multi-terminal HVDC transmission project further includes:

[0036] injecting a harmonic test signal into a rectifier-side busbar of the high-voltage direct current transmission system;

[0037] Obtaining a voltage-current spectrum based on the harmonic test signal and the voltage of the rectifier-side bus;

[0038] The voltage-current spectrum is input into a least square optimization algorithm to modify the full-band harmonic impedance curve.

[0039] As one preferred solution, after the inductive reactive capacity configuration solution is determined by the inductive reactive capacity, the reactive power configuration method of the converter station in the multi-terminal HVDC power transmission project further includes:

[0040] Processing the rated trigger angle to obtain the maximum capacitive reactive power consumption of the converter station;

[0041] Obtaining the capacitive reactive power group capacity based on the AC voltage fluctuation range limit of the converter station determined according to the acquired AC voltage level;

[0042] Obtaining capacitive reactive capacity based on the maximum capacitive reactive consumption and the capacitive reactive group capacity;

[0043] A capacitive reactive capacity configuration scheme is determined according to the capacitive reactive capacity.

[0044] As one preferred solution, after determining the capacitive reactive capacity configuration solution, the reactive power configuration method for a converter station in a multi-terminal HVDC power transmission project further includes:

[0045] When the power of the high-voltage direct current transmission system reaches a first threshold, executing the inductive reactive capacity configuration scheme;

[0046] When the power of the high-voltage direct current transmission system reaches a second threshold, the capacitive reactive capacity configuration scheme is executed.

[0047] Another embodiment of the present invention provides a reactive power configuration system for a converter station in a multi-terminal high-voltage direct current transmission project, comprising:

[0048] A construction module for constructing a single-line diagram of a high-voltage direct current transmission system in a target transmission project;

[0049] a calculation module, configured to determine a rated trigger angle on the rectifier side based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the HVDC transmission system single-line diagram, and determine a rated turn-off angle on the inverter side based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the HVDC transmission system single-line diagram;

[0050] a processing module, configured to process the rated trigger angle and the rated cut-off angle using a converter reactive power compensation technology to obtain converter reactive power consumption;

[0051] a harmonic impedance module for processing the constructed HVDC impedance model using a frequency domain scanning method to obtain a full-band harmonic impedance curve, wherein the HVDC impedance model is obtained based on the harmonic frequencies of the grid components in the HVDC system single-line diagram;

[0052] A harmonic current module is used to process the rated cut-off angle and the current value obtained by real-time detection to obtain a harmonic current;

[0053] a determination module, configured to determine a minimum number of filter groups of the converter station based on a harmonic voltage distortion rate obtained from the harmonic current and the full-band harmonic impedance curve;

[0054] an execution module, configured to input the reactive power consumption of the converter, the minimum number of filter groups of the converter station, and the reactive capacity of the HVDC transmission system into a pre-established inductive reactive capacity relationship equation to obtain the inductive reactive capacity, and execute an inductive reactive capacity configuration scheme determined by the inductive reactive capacity.

[0055] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0056] The present invention provides a reactive power configuration method for converter stations in a multi-terminal high-voltage direct current (HVDC) power transmission project. The method comprises: constructing a single-line diagram of a high-voltage direct current (HVDC) power transmission system in a target power transmission project; determining a rated trigger angle on the rectifier side based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the single-line diagram of the high-voltage direct current (HVDC) power transmission system; determining a rated cut-off angle on the inverter side based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the single-line diagram of the high-voltage direct current (HVDC) power transmission system; processing the rated trigger angle and the rated cut-off angle using a converter reactive power compensation technology to obtain converter reactive power consumption; processing the constructed high-voltage direct current (HVDC) power transmission impedance model using a frequency domain scanning method to obtain A full-band harmonic impedance curve, wherein the HVDC transmission impedance model is obtained based on the harmonic frequencies of the grid components in the HVDC transmission system single-line diagram; the rated shut-off angle and the current value obtained by real-time detection are processed to obtain harmonic current; the minimum number of filter groups of the converter station is determined based on the harmonic current and the harmonic voltage distortion rate obtained from the full-band harmonic impedance curve; the converter reactive power consumption, the minimum number of filter groups of the converter station, and the reactive capacity of the HVDC transmission system are input into a pre-constructed inductive reactive capacity relationship to obtain the inductive reactive capacity, and the inductive reactive capacity configuration scheme determined by the inductive reactive capacity is executed. Compared with the existing technology, the present invention optimizes the operating performance of the DC system by rationally configuring the HVDC transmission system in the HVDC transmission project and processing reactive power consumption and harmonics. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a flow chart of a reactive power configuration method of a converter station in a multi-terminal high-voltage direct current transmission project in one embodiment of the present invention;

[0058] Figure 2 The present invention is a schematic structural diagram of a reactive power configuration system of a converter station in a multi-terminal high-voltage direct current transmission project in one embodiment of the present invention.

[0059] Reference numerals:

[0060] Among them, 11, construction module; 12, calculation module; 13, processing module; 14, harmonic impedance module; 15, harmonic current module; 16, determination module; 17, execution module. DETAILED DESCRIPTION

[0061] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0062] In the description of this application, the terms "first," "second," "third," etc. are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first," "second," "third," etc. may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0063] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be a communication between the two components. The terms "vertical", "horizontal", "left", "right", "up", "down" and similar expressions used herein are for illustrative purposes only, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0064] In the description of this application, it should be noted that, unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by those skilled in the art. The terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. Those skilled in the art will understand the specific meanings of the above terms in this application in specific circumstances.

[0065] High-voltage direct current (HVDC) transmission projects are an important way to optimize the allocation of energy resources in my country. High-voltage direct current (HVDC) transmission systems are widely used in scenarios such as new energy grid connection and cross-regional power transmission.

[0066] However, traditional DC transmission projects rely on thyristor-based LCC (Line Commutation Converter) commutation technology. During LCC commutation, the thyristors require sufficient voltage from the AC bus to ensure successful current transfer to the next phase. However, LCCs continuously consume large amounts of reactive power during operation, especially during commutation when reactive power demand surges. Insufficient reactive power compensation equipment can cause the commutation bus voltage to fluctuate or even plummet.

[0067] To this end, an embodiment of the present invention provides a reactive power configuration method for a converter station in a multi-terminal HVDC transmission project. For details, see Figure 1 , Figure 1 The figure shows a flow chart of a reactive power configuration method for a converter station in a multi-terminal HVDC transmission project according to one embodiment of the present invention. The method includes:

[0068] S1: Construct the single line diagram of the HVDC transmission system in the target transmission project;

[0069] S2: determining a rated trigger angle on the rectifier side based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the HVDC transmission system single-line diagram, and determining a rated turn-off angle on the inverter side based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the HVDC transmission system single-line diagram;

[0070] S3: Processing the rated trigger angle and the rated turn-off angle using a converter reactive power compensation technology to obtain converter reactive power consumption;

[0071] S4: Processing the constructed HVDC transmission impedance model using a frequency domain scanning method to obtain a full-band harmonic impedance curve, wherein the HVDC transmission impedance model is obtained based on the harmonic frequencies of the grid components in the HVDC transmission system single-line diagram;

[0072] S5: Processing the rated turn-off angle and the current value obtained by real-time detection to obtain a harmonic current;

[0073] S6: Determining a minimum number of filter groups of the converter station based on a harmonic voltage distortion rate obtained from the harmonic current and the full-band harmonic impedance curve;

[0074] S7: Inputting the reactive power consumption of the converter, the minimum number of filter groups of the converter station, and the reactive capacity of the HVDC transmission system into a pre-established inductive reactive capacity relationship to obtain the inductive reactive capacity, and executing the inductive reactive capacity configuration scheme determined by the inductive reactive capacity.

[0075] In step S1, the process of constructing a single-line diagram of the HVDC transmission system in the target transmission project includes:

[0076] Acquiring component information of a high-voltage direct current (HVDC) transmission system, the component information including node information, switch information, connected device information and device type information, and HVDC transmission line path information in the HVDC transmission system; generating a topological relationship description expression for a single-line diagram of the HVDC transmission system based on the acquired component information of the HVDC transmission system; generating topological relationship information for the single-line diagram of the HVDC transmission system based on the topological relationship description expression for the single-line diagram of the HVDC transmission system; and generating a single-line diagram of the HVDC transmission system based on the topological relationship information for the single-line diagram of the HVDC transmission system.

[0077] Specifically, node information includes the converter station AC busbar, AC grid access point, converter station DC busbar, and DC line endpoints. Switchgear includes AC circuit breakers, DC circuit breakers, and disconnectors. This data is sourced from technical parameter sheets provided by equipment manufacturers, standardized databases, and geographic information systems.

[0078] Based on graph theory algorithms, the system is abstracted into a graph, where nodes represent buses or connection points and edges represent lines or devices.

[0079] In step S2, a rated trigger angle on the rectifier side is determined based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the HVDC transmission system single-line diagram, and a rated turn-off angle on the inverter side is determined based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the HVDC transmission system single-line diagram.

[0080] The process of determining the rated firing angle includes determining the rated voltage of a busbar on the rectifier side of the HVDC transmission system single-line diagram based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the HVDC transmission system single-line diagram; determining the rated voltage of a busbar on the inverter side based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the HVDC transmission system single-line diagram; and determining a transformation ratio value based on the rated voltage of the busbar on the rectifier side and the rated voltage of the busbar on the inverter side.

[0081] The rated voltage of the rectifier-side bus, the transformation ratio, and the real-time voltage of the high-voltage direct current transmission system are processed using an inverse trigonometric function to obtain the rated trigger angle.

[0082] Specifically:

[0083]

[0084] in, is the rated firing angle, is the rated voltage of the rectifier-side busbar, is the variable ratio, is the real-time voltage of the HVDC transmission system.

[0085] The process of determining the rated shutdown angle includes obtaining the short-circuit capacity in the high-voltage direct current transmission system in real time; and determining the initial shutdown angle based on the number of converter stations on the rectifier side, the number of converter stations on the inverter side, and the transformation ratio value in the single-line diagram of the high-voltage direct current transmission system.

[0086] The formula for the initial turn-off angle is:

[0087]

[0088] in, is the current value passing through the converter station, is the initial turn-off angle, is the total equivalent commutation reactance of the converter valve group, where the total equivalent commutation reactance of the converter valve group is determined by the number of converter stations on the rectifier side and the inverter side.

[0089] The initial turn-off angle is corrected using the short-circuit capacity to obtain a rated turn-off angle on the inverter side.

[0090] The short-circuit capacity represents the current carrying capacity of the AC system during a fault, which directly affects the voltage stability during the commutation process. The short-circuit capacity can be obtained through a power system dynamic monitoring device (such as a PMU) or a simulation model. Its calculation formula is as follows:

[0091]

[0092] in, is the short-circuit current, is the short-circuit capacity.

[0093] The correction process is as follows:

[0094]

[0095] If the short-circuit capacity decreases, the initial turn-off angle is increased to compensate for the commutation time loss, where: is the rated turn-off angle.

[0096] In step S3, the rated trigger angle and the rated turn-off angle are processed using a converter reactive power compensation technology to obtain converter reactive power consumption.

[0097] In this embodiment, the rated trigger angle and the rated turn-off angle may be processed by a static VAR compensator to obtain the reactive power consumption of the converter.

[0098] After the static VAR compensator provides reactive support, the converter does not need to absorb additional reactive power by increasing the firing angle, thereby allowing a smaller firing angle and reducing the converter's own reactive power consumption.

[0099] Preferably, the voltage fluctuation can also be compensated in real time by a static synchronous compensator, allowing the converter to operate at a more optimal trigger angle and turn-off angle.

[0100] In step S4, the constructed HVDC transmission impedance model is processed using a frequency domain scanning method to obtain a full-band harmonic impedance curve, wherein the HVDC transmission impedance model is obtained based on the harmonic frequencies of the grid components in the HVDC transmission system single-line diagram.

[0101] The frequency domain scanning method is a method for analyzing system characteristics within the frequency domain. For HVDC systems, their harmonic impedance characteristics will change with frequency. By changing the frequency parameters and observing the system response, the frequency domain scanning method can fully obtain the system's harmonic impedance information at different frequencies, thereby drawing a full-frequency harmonic impedance curve.

[0102] The HVDC impedance model is a precise model constructed based on the harmonic frequencies of grid components in the HVDC system one-line diagram. This provides an accurate model foundation for frequency domain scanning and is also known as a component frequency-dependent model. The one-line diagram defines the system topology and component composition, while the HVDC impedance model reflects the electrical characteristics of components at different frequencies, making the construction of the harmonic impedance model more realistic.

[0103] Specifically, the full-band harmonic impedance curve of the HVDC system can be efficiently obtained through the frequency domain scanning method combined with an accurate high-voltage direct current transmission impedance model.

[0104] After obtaining the full-band harmonic impedance curve, a harmonic test signal is injected into the rectifier-side busbar of the HVDC transmission system. By injecting a harmonic signal of a specific frequency and amplitude, the system's harmonic response can be stimulated, thereby obtaining the system's harmonic characteristic information. Based on the harmonic test signal and the voltage of the rectifier-side busbar, a voltage-current spectrum is obtained. This spectrum reflects the relationship between the system's voltage and current at different frequencies, providing a data basis for subsequent impedance correction. The voltage-current spectrum is input into a least squares optimization algorithm to correct the full-band harmonic impedance curve. The least squares optimization algorithm is a commonly used data fitting and optimization method. By inputting the voltage-current spectrum into the algorithm, an optimization model for harmonic impedance can be established. By minimizing the error function, the full-band harmonic impedance curve can be corrected to make it more consistent with actual conditions.

[0105] In step S5, the rated turn-off angle and the current value obtained by real-time detection are processed to obtain harmonic current.

[0106] Specifically, the current value passing through the converter station is obtained in real time; the current value is fast Fourier transformed to obtain the harmonic amplitude and phase; the converter harmonic modeling is performed on the rated shutdown angle, the harmonic amplitude and the phase to obtain the theoretical harmonic current amplitude; the background harmonic spectrum of the high-voltage direct current transmission system when the converter is shut down is obtained; the theoretical harmonic current amplitude and the background harmonic spectrum are dynamically superimposed to obtain the harmonic current.

[0107] Among them, fast Fourier transform (FFT) of the real-time current value of the converter station is an effective harmonic analysis method. Fast Fourier transform can convert the time domain current signal into the frequency domain, thereby obtaining the amplitude and phase information of each harmonic, providing basic data for subsequent harmonic modeling.

[0108] Using the rated shutdown angle, harmonic amplitude, and phase to model converter harmonics conforms to the physical mechanism of converter harmonic generation. This model allows the calculation of theoretical harmonic current amplitudes. Dynamically superimposing the theoretical harmonic current amplitudes with the background harmonic spectrum takes into account background harmonics in the system, in addition to those generated by the converter itself. This results in a harmonic current that is more consistent with actual conditions.

[0109] The minimum number of filter groups of the converter station is determined based on the harmonic voltage distortion rate obtained from the harmonic current and the full-band harmonic impedance curve.

[0110] Specifically, the theoretical minimum number of filter groups is determined based on the harmonic voltage distortion rate; the theoretical minimum number of filter groups is processed using the N-1 criterion to obtain the minimum number of filter groups of the converter station.

[0111] The N-1 criterion means that under normal operating conditions, if any component in the power system is free of faults or disconnected due to a fault, the power system should be able to maintain stable operation and normal power supply, other components should not be overloaded, and the voltage and frequency should be within the allowable range.

[0112] The reactive power consumption of the converter, the minimum number of filter groups of the converter station, and the reactive capacity of the high-voltage direct current transmission system are input into a pre-established inductive reactive capacity relationship to obtain the inductive reactive capacity, and an inductive reactive capacity configuration scheme determined by the inductive reactive capacity is executed.

[0113] After obtaining the inductive reactive capacity configuration scheme determined by the inductive reactive capacity, the reactive power configuration method of the converter station in the multi-terminal high-voltage direct current transmission project further includes: processing the rated trigger angle to obtain the maximum capacitive reactive power consumption of the converter station; obtaining the capacitive reactive power group capacity based on the AC voltage fluctuation range limit of the converter station determined according to the acquired AC voltage level; obtaining the capacitive reactive power capacity based on the maximum capacitive reactive power consumption and the capacitive reactive power group capacity; and determining the capacitive reactive power configuration scheme based on the capacitive reactive power capacity.

[0114] When the power of the high-voltage direct current transmission system reaches a first threshold, executing the inductive reactive capacity configuration scheme;

[0115] When the power of the high-voltage direct current transmission system reaches a second threshold, the capacitive reactive capacity configuration scheme is executed.

[0116] Preferably, the first threshold is greater than 0.1 per unit and less than 1 per unit, and the second threshold is greater than or equal to 1 per unit.

[0117] An embodiment of the present invention provides a reactive power configuration system for a converter station in a multi-terminal HVDC transmission project. Figure 2 , Figure 2 FIG2 is a schematic structural diagram of a reactive power configuration system for a converter station in a multi-terminal HVDC transmission project according to one embodiment of the present invention. The system includes:

[0118] A construction module 11 is used to construct a single-line diagram of a high-voltage direct current transmission system in a target power transmission project;

[0119] a calculation module 12, configured to determine a rated trigger angle on the rectifier side based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the HVDC transmission system single-line diagram, and determine a rated turn-off angle on the inverter side based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the HVDC transmission system single-line diagram;

[0120] A processing module 13 is configured to process the rated trigger angle and the rated cut-off angle using a converter reactive power compensation technology to obtain converter reactive power consumption;

[0121] a harmonic impedance module 14 for processing the constructed HVDC transmission impedance model using a frequency domain scanning method to obtain a full-band harmonic impedance curve, wherein the HVDC transmission impedance model is obtained based on the harmonic frequencies of the grid components in the HVDC transmission system single-line diagram;

[0122] The harmonic current module 15 is used to process the rated cut-off angle and the current value obtained by real-time detection to obtain a harmonic current;

[0123] a determination module 16, configured to determine a minimum number of filter groups of the converter station based on a harmonic voltage distortion rate obtained from the harmonic current and the full-band harmonic impedance curve;

[0124] The execution module 17 is configured to input the reactive power consumption of the converter, the minimum number of filter groups of the converter station, and the reactive capacity of the HVDC transmission system into a pre-established inductive reactive capacity relationship to obtain the inductive reactive capacity, and execute the inductive reactive capacity configuration scheme determined by the inductive reactive capacity.

[0125] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0126] The present invention provides a reactive power configuration method for converter stations in a multi-terminal high-voltage direct current (HVDC) power transmission project. The method comprises: constructing a single-line diagram of a high-voltage direct current (HVDC) power transmission system in a target power transmission project; determining a rated trigger angle on the rectifier side based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the single-line diagram of the high-voltage direct current (HVDC) power transmission system; determining a rated cut-off angle on the inverter side based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the single-line diagram of the high-voltage direct current (HVDC) power transmission system; processing the rated trigger angle and the rated cut-off angle using a converter reactive power compensation technology to obtain converter reactive power consumption; processing the constructed high-voltage direct current (HVDC) power transmission impedance model using a frequency domain scanning method to obtain A full-band harmonic impedance curve, wherein the HVDC transmission impedance model is obtained based on the harmonic frequencies of the grid components in the HVDC transmission system single-line diagram; the rated shut-off angle and the current value obtained by real-time detection are processed to obtain harmonic current; the minimum number of filter groups of the converter station is determined based on the harmonic current and the harmonic voltage distortion rate obtained from the full-band harmonic impedance curve; the converter reactive power consumption, the minimum number of filter groups of the converter station, and the reactive capacity of the HVDC transmission system are input into a pre-constructed inductive reactive capacity relationship to obtain the inductive reactive capacity, and the inductive reactive capacity configuration scheme determined by the inductive reactive capacity is executed. Compared with the existing technology, the present invention optimizes the operating performance of the DC system by rationally configuring the HVDC transmission system in the HVDC transmission project and processing reactive power consumption and harmonics.

[0127] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A reactive power configuration method for a converter station in a multi-terminal high-voltage direct current transmission project, characterized in that: include: Construct a single-line diagram of the HVDC transmission system in the target transmission project; determining a rated trigger angle on the rectifier side based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the HVDC transmission system single-line diagram, and determining a rated turn-off angle on the inverter side based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the HVDC transmission system single-line diagram; Processing the rated trigger angle and the rated cut-off angle using a converter reactive power compensation technology to obtain converter reactive power consumption; Processing the constructed HVDC transmission impedance model using a frequency domain scanning method to obtain a full-band harmonic impedance curve, wherein the HVDC transmission impedance model is obtained based on the harmonic frequencies of the grid components in the HVDC transmission system single-line diagram; Processing the rated turn-off angle and the current value obtained by real-time detection to obtain harmonic current; determining a minimum number of filter groups of the converter station based on a harmonic voltage distortion rate obtained from the harmonic current and the full-band harmonic impedance curve; The reactive power consumption of the converter, the minimum number of filter groups of the converter station, and the reactive capacity of the high-voltage direct current transmission system are input into a pre-established inductive reactive capacity relationship to obtain the inductive reactive capacity, and an inductive reactive capacity configuration scheme determined by the inductive reactive capacity is executed.

2. The reactive power configuration method for a converter station in a multi-terminal HVDC power transmission project according to claim 1, characterized in that: The process of constructing the single-line diagram of the HVDC transmission system includes: Obtain component information of HVDC transmission system; generating a topological relationship description expression of a single-line diagram of the high-voltage direct current transmission system based on the acquired component information of the high-voltage direct current transmission system; Based on the HVDC system single-line diagram topology relationship description expression, the HVDC system single-line diagram topology relationship information is generated, and based on the HVDC system single-line diagram topology relationship information, the HVDC system single-line diagram is generated.

3. The reactive power configuration method for a converter station in a multi-terminal HVDC transmission project according to claim 1, characterized in that: The process of determining the rated firing angle includes: determining a rated voltage of a busbar on the rectifier side of the HVDC transmission system one-line diagram based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the HVDC transmission system one-line diagram, and determining a rated voltage of a busbar on the inverter side based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the HVDC transmission system one-line diagram; determining a transformation ratio value based on the rated voltage of the rectifier-side bus and the rated voltage of the inverter-side bus; The rated voltage of the rectifier-side bus, the transformation ratio, and the real-time voltage of the high-voltage direct current transmission system are processed using an inverse trigonometric function to obtain the rated trigger angle.

4. The reactive power configuration method for a converter station in a multi-terminal HVDC transmission project according to claim 3, characterized in that: The process of determining the rated turn-off angle includes: obtaining the short-circuit capacity of the HVDC transmission system in real time; Determining an initial turn-off angle based on the number of converter stations on the rectifier side, the number of converter stations on the inverter side, and the transformation ratio in the single-line diagram of the high-voltage direct current transmission system; The initial turn-off angle is corrected using the short-circuit capacity to obtain a rated turn-off angle on the inverter side.

5. The reactive power configuration method for a converter station in a multi-terminal HVDC power transmission project according to claim 1, characterized in that: The step of processing the rated turn-off angle and the current value obtained by real-time detection to obtain the harmonic current includes: acquiring a current value passing through the converter station in real time; Performing a fast Fourier transform on the current value to obtain harmonic amplitude and phase; Performing converter harmonic modeling on the rated turn-off angle, the harmonic amplitude, and the phase to obtain a theoretical harmonic current amplitude; Obtaining a background harmonic spectrum of the HVDC transmission system when the converter is out of service; The theoretical harmonic current amplitude and the background harmonic spectrum are dynamically superimposed to obtain the harmonic current.

6. The reactive power configuration method for a converter station in a multi-terminal HVDC transmission project according to claim 1, characterized in that: The process of determining the minimum number of filter groups of the converter station includes: Determining a theoretical minimum number of filter groups based on the harmonic voltage distortion rate; The theoretical minimum number of filter groups is processed using the N-1 criterion to obtain the minimum number of filter groups of the converter station.

7. The reactive power configuration method for a converter station in a multi-terminal HVDC transmission project according to claim 1, characterized in that: After obtaining the full-band harmonic impedance curve, the reactive power configuration method of the converter station in the multi-terminal HVDC transmission project further includes: injecting a harmonic test signal into a rectifier-side busbar of the high-voltage direct current transmission system; Obtaining a voltage-current spectrum based on the harmonic test signal and the voltage of the rectifier-side bus; The voltage-current spectrum is input into a least square optimization algorithm to modify the full-band harmonic impedance curve.

8. The reactive power configuration method for a converter station in a multi-terminal HVDC power transmission project according to claim 1, characterized in that: After obtaining the inductive reactive capacity configuration scheme determined by the inductive reactive capacity, the reactive power configuration method of the converter station in the multi-terminal HVDC power transmission project further includes: Processing the rated trigger angle to obtain the maximum capacitive reactive power consumption of the converter station; Obtaining the capacitive reactive power group capacity based on the AC voltage fluctuation range limit of the converter station determined according to the acquired AC voltage level; Obtaining capacitive reactive capacity based on the maximum capacitive reactive consumption and the capacitive reactive group capacity; A capacitive reactive capacity configuration scheme is determined according to the capacitive reactive capacity.

9. The reactive power configuration method for a converter station in a multi-terminal HVDC power transmission project according to claim 8, characterized in that: After determining the capacitive reactive capacity configuration scheme, the reactive power configuration method of the converter station in the multi-terminal HVDC transmission project further includes: When the power of the high-voltage direct current transmission system reaches a first threshold, executing the inductive reactive capacity configuration scheme; When the power of the high-voltage direct current transmission system reaches a second threshold, the capacitive reactive capacity configuration scheme is executed.

10. A reactive power configuration system for a converter station in a multi-terminal high-voltage direct current transmission project, characterized in that: include: A construction module for constructing a single-line diagram of a high-voltage direct current transmission system in a target transmission project; a calculation module, configured to determine a rated trigger angle on the rectifier side based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the HVDC transmission system single-line diagram, and determine a rated turn-off angle on the inverter side based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side in the HVDC transmission system single-line diagram; a processing module, configured to process the rated trigger angle and the rated cut-off angle using a converter reactive power compensation technology to obtain converter reactive power consumption; a harmonic impedance module for processing the constructed HVDC impedance model using a frequency domain scanning method to obtain a full-band harmonic impedance curve, wherein the HVDC impedance model is obtained based on the harmonic frequencies of the grid components in the HVDC system single-line diagram; A harmonic current module is used to process the rated cut-off angle and the current value obtained by real-time detection to obtain a harmonic current; a determination module, configured to determine a minimum number of filter groups of the converter station based on a harmonic voltage distortion rate obtained from the harmonic current and the full-band harmonic impedance curve; An execution module is configured to input the reactive power consumption of the converter, the minimum number of filter groups of the converter station, and the reactive capacity of the HVDC transmission system into a pre-established inductive reactive capacity relationship to obtain the inductive reactive capacity, and execute an inductive reactive capacity configuration scheme determined by the inductive reactive capacity.

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