Reactive power configuration method and system for converter stations in multi-terminal high-voltage direct-current transmission project

Abstract

The invention discloses a reactive power configuration method and system for converter stations in a multi-terminal high-voltage direct-current power transmission project. The reactive power configuration method comprises the following steps: constructing a high-voltage direct-current power transmission system single line diagram in a target power transmission project; determining a rated trigger angle and a rated turn-off angle of the inverter side; processing the rated trigger angle and the rated turn-off angle to obtain reactive power consumption of the converter; processing the constructed high-voltage direct-current transmission impedance model to obtain a full-band harmonic impedance curve; processing the rated turn-off angle and the current value obtained by real-time detection to obtain harmonic current; determining a minimum filter group number based on the harmonic voltage distortion rate; and inputting the reactive power consumption of the converter, the minimum filter group number and the reactive power capacity of the high-voltage direct-current power transmission system into a pre-constructed inductive reactive power capacity relational expression, and determining an inductive reactive power capacity configuration scheme. According to the method provided by the embodiment of the invention, the high-voltage direct-current power transmission system in the high-voltage direct-current power transmission project is reasonably configured, so that the operation performance of the direct-current system is optimal.

Description

Technical Field

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

[0002] The HVDC transmission project is an important way for the optimal allocation of energy resources in China, and the HVDC system has been widely applied in scenarios such as new energy grid connection and cross-regional power transmission.

[0003] However, the traditional HVDC transmission project is based on the thyristor-based LCC (Line commutation converter) commutation technology. During the LCC commutation period, the thyristor requires the AC bus to provide sufficient voltage to ensure the successful transfer of current to the next phase. However, the LCC continuously consumes a large amount of reactive power during operation, especially during the commutation process, the reactive power demand suddenly increases. If the capacity of the reactive power compensation equipment configured is insufficient, it will lead to voltage fluctuations or even sudden drops in the converter bus voltage.

[0004] Therefore, how to perform reasonable reactive power configuration to optimize the operation 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 a converter station in a multi-terminal HVDC transmission project to solve the problem of unreasonable reactive power configuration, which in turn leads to voltage fluctuations in the converter bus, so as to achieve reasonable reactive power configuration and optimize the operation 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 HVDC transmission project, including: Constructing a single-line diagram of the HVDC transmission system in the target transmission project; Determining the rated firing angle of 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 HVDC transmission system, and determining the rated turn-off angle of 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 HVDC transmission system; Processing the rated firing angle and the rated turn-off angle by using the converter reactive power compensation technology to obtain the converter reactive power consumption; Processing the constructed HVDC transmission impedance model by using the frequency-domain scanning method to obtain the full-frequency harmonic impedance curve, where the HVDC transmission impedance model is obtained based on the harmonic frequencies of the grid elements in the single-line diagram of the HVDC transmission system; Processing the rated turn-off angle and the current value obtained by real-time detection to obtain the harmonic current; Determine the minimum number of filter groups of the converter station based on the harmonic voltage distortion rate obtained from the harmonic current and the full-band harmonic impedance curve; Input the reactive power consumption of the converter, the minimum number of filter groups of the converter station, and the reactive power capacity of the HVDC transmission system into a pre-constructed relational expression of inductive reactive power capacity to obtain the inductive reactive power capacity, and execute the inductive reactive power capacity configuration plan determined by the inductive reactive power capacity.

[0007] As one of the preferred solutions, the construction process of the single-line diagram of the HVDC transmission system includes: Obtain the component information of the HVDC transmission system; Generate a descriptive expression of the topological relationship of the single-line diagram of the HVDC transmission system based on the obtained component information of the HVDC transmission system; Generate topological relationship information of the single-line diagram of the HVDC transmission system based on the real-time descriptive expression of the topological relationship of the single-line diagram of the HVDC transmission system, and generate a single-line diagram of the HVDC transmission system based on the topological relationship information of the single-line diagram of the HVDC transmission system.

[0008] As one of the preferred solutions, the determination process of the rated firing angle includes: Determine the rated voltage of the rectifier-side bus in the single-line diagram of the HVDC transmission system 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 HVDC transmission system, and determine the rated voltage of the inverter-side bus 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 HVDC transmission system; Determine the transformation ratio based on the rated voltage of the rectifier-side bus and the rated voltage of the inverter-side bus; Process the rated voltage of the rectifier-side bus, the transformation ratio, and the real-time voltage of the HVDC transmission system using the inverse trigonometric function to obtain the rated firing angle.

[0009] As one of the preferred solutions, the determination process of the rated extinction angle includes: Obtain the short-circuit capacity in the HVDC transmission system in real time; Determine the initial extinction 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 HVDC transmission system; Correct the initial extinction angle using the short-circuit capacity to obtain the rated extinction angle of the inverter side.

[0010] As one of the preferred solutions, the processing of the rated extinction angle and the current value obtained by real-time detection to obtain the harmonic current includes: Obtain the current value passing through the converter station in real time; Perform a fast Fourier transform on the current value to obtain the harmonic amplitude and phase; Perform converter harmonic modeling on the rated turn-off angle, the harmonic amplitude, and the phase to obtain the theoretical harmonic current amplitude; Obtain the background harmonic spectrum of the high-voltage DC transmission system when the converter is out of service; Perform dynamic superposition on the theoretical harmonic current amplitude and the background harmonic spectrum to obtain the harmonic current.

[0011] As one of the preferred solutions, determining the minimum number of filter groups of the converter station includes the following steps: Determine the theoretical minimum number of filter groups based on the harmonic voltage distortion rate; Process the theoretical minimum number of filter groups using the N-1 criterion to obtain the minimum number of filter groups of the converter station.

[0012] As one of the preferred solutions, after obtaining the full-band harmonic impedance curve, the reactive power configuration method for the converter station in the multi-terminal high-voltage DC transmission project further includes: Inject a harmonic test signal into the rectifier-side bus of the high-voltage DC transmission system; Based on the harmonic test signal and the voltage of the rectifier-side bus, obtain the voltage-current spectrum; Input the voltage-current spectrum into the least squares optimization algorithm to correct the full-band harmonic impedance curve.

[0013] As one of the preferred solutions, after the reactive power capacity configuration plan determined by the inductive reactive power capacity, the reactive power configuration method for the converter station in the multi-terminal high-voltage DC transmission project further includes: Process the rated trigger angle to obtain the maximum capacitive reactive power consumption of the converter station; Based on the AC voltage fluctuation range limit of the converter station determined according to the obtained AC voltage level, obtain the capacitive reactive power group capacity; Based on the maximum capacitive reactive power consumption and the capacitive reactive power group capacity, obtain the capacitive reactive power capacity; Determine the capacitive reactive power capacity configuration plan from the capacitive reactive power capacity.

[0014] As one of the preferred solutions, after determining the capacitive reactive power capacity configuration plan, the reactive power configuration method for the converter station in the multi-terminal high-voltage DC transmission project further includes: When the power of the high-voltage DC transmission system reaches the first threshold, execute the inductive reactive power capacity configuration plan; When the power of the high-voltage DC transmission system reaches the second threshold, execute the capacitive reactive power capacity configuration plan.

[0015] Another embodiment of the present invention provides a reactive power configuration system for a converter station in a multi-terminal high-voltage direct current (HVDC) transmission project, including: A construction module for constructing a single-line diagram of the HVDC transmission system in the target transmission project; A calculation module for determining the rated firing angle of 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 HVDC transmission system, and determining the rated turn-off angle of 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 HVDC transmission system; A processing module for processing the rated firing angle and the rated turn-off angle by using the converter reactive power compensation technology to obtain the converter reactive power consumption; A harmonic impedance module for processing the constructed HVDC transmission impedance model by using the frequency-domain scanning method to obtain a full-frequency band harmonic impedance curve, wherein the HVDC transmission impedance model is obtained based on the harmonic frequencies of the grid components in the single-line diagram of the HVDC transmission system; A harmonic current module for processing the rated turn-off angle and the current value obtained by real-time detection to obtain harmonic current; A determination module for determining the minimum number of filter groups of the converter station based on the harmonic voltage distortion rate obtained from the harmonic current and the full-frequency band harmonic impedance curve; An execution module for inputting the converter reactive power consumption, the minimum number of filter groups of the converter station, and the reactive power capacity of the HVDC transmission system into a pre-constructed inductive reactive power capacity relationship formula to obtain the inductive reactive power capacity, and executing the inductive reactive power capacity configuration scheme determined by the inductive reactive power capacity.

[0016] Compared with the prior art, the beneficial effects of the embodiments of the present invention are at least one of the following: The present invention provides a method for reactive power configuration of a converter station in a multi-terminal high-voltage direct current (HVDC) transmission project. The method includes: constructing a single-line diagram of the HVDC transmission system in the target transmission project; determining the rated firing angle of 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 HVDC transmission system, and determining the rated turn-off angle of 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 HVDC transmission system; using the converter reactive power compensation technology to process the rated firing angle and the rated turn-off angle to obtain the converter reactive power consumption; using the frequency-domain scanning method to process the constructed HVDC transmission impedance model to obtain the full-frequency harmonic impedance curve, where the HVDC transmission impedance model is obtained based on the harmonic frequencies of the grid components in the single-line diagram of the HVDC transmission system; processing the rated turn-off angle and the current value obtained by real-time detection to obtain the harmonic current; determining the minimum number of filter groups of the converter station based on the harmonic voltage distortion rate obtained from the harmonic current and the full-frequency harmonic impedance curve; inputting the converter reactive power consumption, the minimum number of filter groups of the converter station, and the reactive power capacity of the HVDC transmission system into a pre-constructed inductive reactive power capacity relationship formula to obtain the inductive reactive power capacity, and executing the inductive reactive power capacity configuration scheme determined by the inductive reactive power capacity. Compared with the prior art, the present invention rationally configures the HVDC transmission system in the HVDC transmission project, processes from the aspects of reactive power consumption and harmonics, so that the operation performance of the DC system reaches the optimal state. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic flowchart of a method for reactive power configuration of a converter station in a multi-terminal HVDC transmission project according to one embodiment of the present invention; Figure 2 is a schematic structural diagram of a reactive power configuration system of a converter station in a multi-terminal HVDC transmission project according to one embodiment of the present invention.

[0018] REFERENCE SIGNS: 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 OF THE EMBODIMENTS

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. 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 those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0020] In the description of this application, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", "third", etc. may explicitly or implicitly include one or more of such features. In the description of this application, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0021] In the description of this application, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components. The terms "vertical", "horizontal", "left", "right", "upper", "lower" and similar expressions used herein are only for the purpose of illustration and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation on the present invention. The term "and / or" used herein includes any and all combinations of one or more of the 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.

[0022] In the description of this application, it should be noted that unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by those skilled in the technical field to which this invention belongs. The terms used in the specification of this invention are only for the purpose of describing specific embodiments and are not intended to limit this invention. 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.

[0023] High-voltage direct current (HVDC) transmission projects are an important way for the optimal allocation of energy resources in China. HVDC systems have wide applications in scenarios such as new energy grid connection and cross-regional power transmission.

[0024] However, traditional HVDC projects are based on thyristor-based line commutation converter (LCC) commutation technology. During the commutation of LCC, thyristors require the AC bus to provide sufficient voltage to ensure the successful transfer of current to the next phase. However, LCC continuously consumes a large amount of reactive power during operation, especially during the commutation process when the reactive power demand suddenly increases. If the capacity of the reactive power compensation equipment configured is insufficient, it will cause voltage fluctuations or even sudden drops in the commutation bus voltage.

[0025] To this end, an embodiment of the present invention provides a method for reactive power configuration of a converter station in a multi-terminal high-voltage direct current (HVDC) transmission project. Specifically, please refer to Figure 1 , Figure 1 which shows a schematic flowchart of the method for reactive power configuration of a converter station in a multi-terminal HVDC transmission project according to one embodiment of the present invention. The method includes: S1: Construct a single-line diagram of the HVDC transmission system in the target transmission project; S2: Determine the rated firing angle of 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 HVDC transmission system, and determine the rated turn-off angle of 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 HVDC transmission system; S3: Use the converter reactive power compensation technology to process the rated firing angle and the rated turn-off angle to obtain the converter reactive power consumption; S4: Use the frequency-domain scanning method to process the constructed HVDC transmission impedance model to obtain the full-band harmonic impedance curve, where the HVDC transmission impedance model is obtained based on the harmonic frequencies of the grid components in the single-line diagram of the HVDC transmission system; S5: Process the rated turn-off angle and the current value obtained by real-time detection to obtain the harmonic current; S6: Determine the minimum number of filter groups of the converter station based on the harmonic voltage distortion rate obtained from the harmonic current and the full-band harmonic impedance curve; S7: Input the converter reactive power consumption, the minimum number of filter groups of the converter station, and the reactive power capacity of the HVDC transmission system into a pre-constructed inductive reactive power capacity relationship formula to obtain the inductive reactive power capacity, and execute the inductive reactive power capacity configuration scheme determined by the inductive reactive power capacity.

[0026] In step S1, the construction process of the single-line diagram of the HVDC transmission system in the target transmission project includes: Obtain the component information of the HVDC transmission system, where the component information includes the node information, switch information, connected equipment information and equipment type information, and the HVDC transmission line path information in the HVDC transmission system; generate a single-line diagram topology relationship description expression of the HVDC transmission system based on the obtained component information of the HVDC transmission system; generate the single-line diagram topology relationship information of the HVDC transmission system based on the single-line diagram topology relationship description expression of the HVDC transmission system, and generate the single-line diagram of the HVDC transmission system based on the single-line diagram topology relationship information of the HVDC transmission system.

[0027] Specifically, the node information includes the AC busbar of the converter station, the access point of the AC power grid, the DC busbar of the converter station, and the endpoints of the DC line. The switching devices include AC circuit breakers, DC circuit breakers, and disconnectors. The above data is sourced from the technical parameter tables provided by equipment manufacturers, standardized databases, and geographic information systems.

[0028] Based on graph theory algorithms, the system is abstracted as a graph, where nodes represent busbars or connection points, and edges represent lines or equipment.

[0029] In step S2, 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 HVDC transmission system, the rated firing angle on the rectifier side is determined, and 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 HVDC transmission system, the rated turn-off angle on the inverter side is determined.

[0030] The process of determining the rated firing angle includes determining the rated voltage of the rectifier-side busbar in the single-line diagram of the HVDC transmission system based on the number of converter stations on the rectifier side and the number of converter stations on the inverter side, and determining the rated voltage of the inverter-side busbar 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 HVDC transmission system; determining the transformation ratio based on the rated voltage of the rectifier-side busbar and the rated voltage of the inverter-side busbar.

[0031] Using the inverse trigonometric function to process the rated voltage of the rectifier-side busbar, the transformation ratio, and the real-time voltage of the HVDC transmission system to obtain the rated firing angle.

[0032] Specifically: Among them, is the rated firing angle, is the rated voltage of the rectifier-side busbar, is the transformation ratio, is the real-time voltage of the HVDC transmission system.

[0033] The process of determining the rated turn-off angle includes obtaining the short-circuit capacity in the HVDC transmission system in real time; determining the 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 HVDC transmission system.

[0034] The formula for the initial turn-off angle is: Among them, 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. Among them, 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.

[0035] Use the short-circuit capacity to correct the initial turn-off angle to obtain the rated turn-off angle of the inverter side.

[0036] Among them, the short-circuit capacity represents the current-carrying capacity of the AC system during a fault, which directly affects the voltage stability of 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: Among them, is the short-circuit current, is the short-circuit capacity.

[0037] The correction process is as follows: If the short-circuit capacity decreases, increase the initial turn-off angle to compensate for the loss of commutation time. Among them, is the rated turn-off angle.

[0038] In step S3, use the converter reactive power compensation technology to process the rated firing angle and the rated turn-off angle to obtain the reactive power consumption of the converter.

[0039] In this embodiment, the rated firing angle and the rated turn-off angle can be processed through a static var compensator to obtain the reactive power consumption of the converter.

[0040] After the static var compensator provides reactive power support, the converter does not need to increase the firing angle to absorb additional reactive power, thus allowing a smaller firing angle and reducing the reactive power consumption of the converter itself.

[0041] Preferably, the voltage fluctuation can also be compensated in real time through a static synchronous compensator, allowing the converter to operate at a better firing angle and turn-off angle.

[0042] In step S4, use the frequency-domain scanning method to process the constructed HVDC transmission impedance model to obtain the full-band harmonic impedance curve. Among them, the HVDC transmission impedance model is obtained based on the harmonic frequencies of the grid components in the single-line diagram of the HVDC transmission system.

[0043] The frequency-domain scanning method is a method for analyzing the system characteristics in the frequency domain. For the HVDC system, its harmonic impedance characteristics change with the frequency. Through the frequency-domain scanning method, by changing the frequency parameters and observing the system response, the harmonic impedance information of the system at different frequencies can be comprehensively obtained, thus drawing the full-band harmonic impedance curve.

[0044] The high-voltage DC transmission impedance model constructs an accurate model based on the harmonic frequencies of power grid components in the single-line diagram of the HVDC system, providing an accurate model basis for frequency-domain scanning and can also be called the component frequency-varying model. The single-line diagram clarifies the topological structure and component composition of the system, and the high-voltage DC transmission impedance model can reflect the electrical characteristics of components at different frequencies, making the construction of the harmonic impedance model more in line with the actual situation.

[0045] Specifically, through the frequency-domain scanning method, combined with the accurate high-voltage DC transmission impedance model, the full-frequency band harmonic impedance curve of the HVDC system can be efficiently obtained.

[0046] After obtaining the full-frequency band harmonic impedance curve, in the rectifier-side bus of the high-voltage DC transmission system, a harmonic test signal is injected. By injecting harmonic signals with specific frequencies and amplitudes, the harmonic response of the system can be excited, thereby obtaining the harmonic characteristic information of the system; based on the harmonic test signal and the voltage of the rectifier-side bus, a voltage-current spectrum is obtained, which reflects the voltage-current relationship of the system at different frequencies and provides a data basis for subsequent impedance correction; the voltage-current spectrum is input into the least squares optimization algorithm to correct the full-frequency band harmonic impedance curve. The least squares optimization algorithm is a commonly used data fitting and optimization method. Inputting the voltage-current spectrum into this algorithm can establish an optimization model for harmonic impedance, and by minimizing the error function, the full-frequency band harmonic impedance curve is corrected to make it more in line with the actual situation.

[0047] In step S5, the rated turn-off angle and the current value obtained by real-time detection are processed to obtain harmonic current.

[0048] Specifically, the current value passing through the converter station is obtained in real time; the current value is subjected to a fast Fourier transform to obtain the harmonic amplitude and phase; the converter harmonic modeling is performed on the rated turn-off angle, the harmonic amplitude, and the phase to obtain the theoretical harmonic current amplitude; the background harmonic spectrum of the high-voltage DC transmission system when the converter is out of service is obtained; the theoretical harmonic current amplitude and the background harmonic spectrum are dynamically superimposed to obtain the harmonic current.

[0049] Among them, performing a fast Fourier transform (FFT) on the current value of the converter station obtained in real time is an effective harmonic analysis method. The fast Fourier transform can convert the time-domain current signal to the frequency domain, thereby obtaining the amplitude and phase information of each harmonic, providing basic data for subsequent harmonic modeling.

[0050] Converter harmonic modeling is carried out using the rated turn-off angle, harmonic amplitude and phase, which is in line with the physical mechanism of converter harmonic generation. By establishing the model, the theoretical harmonic current amplitude can be calculated. Dynamically superimposing the theoretical harmonic current amplitude and the background harmonic spectrum takes into account the background harmonic factors in the system other than the harmonics generated by the converter itself, making the finally obtained harmonic current more in line with the actual situation.

[0051] Based on the harmonic voltage distortion rate obtained from the harmonic current and the full-band harmonic impedance curve, determine the minimum number of filter groups of the converter station.

[0052] Specifically, determine the theoretical minimum number of filter groups based on the harmonic voltage distortion rate; use the N-1 criterion to process the theoretical minimum number of filter groups to obtain the minimum number of filter groups of the converter station.

[0053] The N-1 criterion means that in a power system under normal operating conditions, any component fails or is disconnected due to a fault, and the power system should be able to maintain stable operation and normal power supply, other components are not overloaded, and the voltage and frequency are within the allowable range.

[0054] Input the reactive power consumption of the converter, the minimum number of filter groups of the converter station, and the reactive power capacity of the high-voltage direct current transmission system into the pre-constructed inductive reactive power capacity relationship formula to obtain the inductive reactive power capacity, and execute the inductive reactive power capacity configuration scheme determined by the inductive reactive power capacity.

[0055] After obtaining the inductive reactive power capacity configuration scheme determined by the inductive reactive power capacity, the reactive power configuration method for 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 according to the AC voltage fluctuation range limit of the converter station determined by the obtained AC voltage level; based on the maximum capacitive reactive power consumption and the capacitive reactive power group capacity, obtain the capacitive reactive power capacity; determine the capacitive reactive power capacity configuration scheme from the capacitive reactive power capacity.

[0056] When the power of the high-voltage direct current transmission system reaches the first threshold, execute the inductive reactive power capacity configuration scheme; When the power of the high-voltage direct current transmission system reaches the second threshold, execute the capacitive reactive power capacity configuration scheme.

[0057] Preferably, the first threshold is greater than 0.1 per unit value and less than 1 per unit value, and the second threshold is greater than or equal to 1 per unit value.

[0058] An 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. Specifically, please refer to Figure 2 , Figure 2The figure shows a schematic structural diagram of a reactive power configuration system of a converter station in a multi-terminal high-voltage DC transmission project in one embodiment of the present invention. The system includes: A construction module 11 for constructing a single-line diagram of a high-voltage DC transmission system in a target transmission project; A calculation module 12 for determining the rated firing angle of 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 DC transmission system, and determining the rated turn-off angle of 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 DC transmission system; A processing module 13 for processing the rated firing angle and the rated turn-off angle by using the converter reactive power compensation technology to obtain the converter reactive power consumption; A harmonic impedance module 14 for processing the constructed high-voltage DC transmission impedance model by using the frequency-domain scanning method to obtain a full-band harmonic impedance curve, wherein the high-voltage DC transmission impedance model is obtained based on the harmonic frequencies of the grid components in the single-line diagram of the high-voltage DC transmission system; A harmonic current module 15 for processing the rated turn-off angle and the current value obtained by real-time detection to obtain harmonic current; A determination module 16 for determining the minimum number of filter groups of the converter station based on the harmonic voltage distortion rate obtained from the harmonic current and the full-band harmonic impedance curve; An execution module 17 for inputting the converter reactive power consumption, the minimum number of filter groups of the converter station, and the reactive power capacity of the high-voltage DC transmission system into a pre-constructed inductive reactive power capacity relation formula to obtain the inductive reactive power capacity, and executing the inductive reactive power capacity configuration scheme determined by the inductive reactive power capacity.

[0059] Compared with the prior art, the beneficial effects of the embodiments of the present invention are at least one of the following: The present invention provides a method for reactive power configuration of a converter station in a multi-terminal high-voltage direct current (HVDC) transmission project. The method includes: constructing a single-line diagram of the HVDC transmission system in the target transmission project; determining the rated firing angle of 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 HVDC transmission system, and determining the rated turn-off angle of 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 HVDC transmission system; using the reactive power compensation technology of the converter to process the rated firing angle and the rated turn-off angle to obtain the reactive power consumption of the converter; using the frequency-domain scanning method to process the constructed HVDC transmission impedance model to obtain the full-frequency harmonic impedance curve, where the HVDC transmission impedance model is obtained based on the harmonic frequencies of the grid components in the single-line diagram of the HVDC transmission system; processing the rated turn-off angle and the current value obtained by real-time detection to obtain the harmonic current; determining the minimum number of filter groups of the converter station based on the harmonic voltage distortion rate obtained from the harmonic current and the full-frequency harmonic impedance curve; inputting the reactive power consumption of the converter, the minimum number of filter groups of the converter station, and the reactive power capacity of the HVDC transmission system into a pre-constructed inductive reactive power capacity relational expression to obtain the inductive reactive power capacity, and executing the inductive reactive power capacity configuration scheme determined by the inductive reactive power capacity. Compared with the prior art, the present invention rationally configures the HVDC transmission system in the HVDC transmission project, processes the reactive power consumption and harmonics, and optimizes the operation performance of the DC system.

[0060] The above embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the appended claims.

Claims

1. A reactive power configuration method for a converter station in a multi-terminal HVDC transmission project, characterized in that, Including: Construct a single-line diagram of the high-voltage direct current (HVDC) transmission system in the target transmission project; Determine the rated firing angle of 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 HVDC transmission system, and determine the rated turn-off angle of 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 HVDC transmission system; Use the converter reactive power compensation technology to process the rated firing angle and the rated turn-off angle to obtain the converter reactive power consumption; Use the frequency-domain scanning method to process the constructed HVDC transmission impedance model to obtain the full-frequency harmonic impedance curve, where the HVDC transmission impedance model is obtained based on the harmonic frequencies of the grid components in the single-line diagram of the HVDC transmission system; Process the rated turn-off angle and the current value obtained by real-time detection to obtain harmonic current; Determine the minimum number of filter groups of the converter station based on the harmonic voltage distortion rate obtained from the harmonic current and the full-frequency harmonic impedance curve; Input the converter reactive power consumption, the minimum number of filter groups of the converter station, and the reactive power capacity of the HVDC transmission system into a pre-constructed inductive reactive power capacity relationship formula to obtain the inductive reactive power capacity, and execute the inductive reactive power capacity configuration plan determined by the inductive reactive power capacity.

2. The reactive power configuration method for a converter station in a multi-terminal HVDC transmission project according to claim 1, characterized in that, The construction process of the single-line diagram of the HVDC transmission system includes: Obtain the component information of the HVDC transmission system; Generate a single-line diagram topology relationship description expression of the HVDC transmission system based on the obtained component information of the HVDC transmission system; Generate the single-line diagram topology relationship information of the HVDC transmission system based on the single-line diagram topology relationship description expression of the HVDC transmission system, and generate the single-line diagram of the HVDC transmission system based on the single-line diagram topology relationship information of the HVDC transmission system.

3. The reactive power configuration method for a converter station in a multi-terminal HVDC transmission project as claimed in claim 1, wherein, The determination process of the rated firing angle includes: Determine the rated voltage of the rectifier side bus in the single-line diagram of the HVDC transmission system 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 HVDC transmission system, and determine the rated voltage of the inverter side bus 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 HVDC transmission system; Determine the transformation ratio based on the rated voltage of the rectifier side bus and the rated voltage of the inverter side bus; Use the inverse trigonometric function to process the rated voltage of the rectifier side bus, the transformation ratio, and the real-time voltage of the HVDC transmission system to obtain the rated firing angle.

4. The reactive power configuration method of the converter station in the multi-terminal HVDC transmission project according to claim 3, wherein, The determination process of the rated turn-off angle includes: Real-time obtain the short-circuit capacity in the HVDC transmission system; Determine the 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 HVDC transmission system; Use the short-circuit capacity to correct the initial turn-off angle to obtain the rated turn-off angle of the inverter side.

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

6. The reactive power configuration method for a converter station in a multi-terminal HVDC transmission project as claimed in claim 1, wherein The determining the minimum number of filter groups of the converter station includes: Determine the theoretical minimum number of filter groups based on the harmonic voltage distortion rate; Process the theoretical minimum number of filter groups 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 as described in claim 1, characterized in that, After obtaining the full-frequency harmonic impedance curve, the reactive power configuration method for the converter station in the multi-terminal HVDC transmission project further includes: Inject a harmonic test signal into the rectifier-side bus of the HVDC transmission system; Obtain the voltage-current spectrum based on the harmonic test signal and the voltage of the rectifier-side bus; Input the voltage-current spectrum into the least squares optimization algorithm to correct the full-frequency harmonic impedance curve.

8. The reactive power configuration method for a converter station in a multi-terminal HVDC transmission project as described in claim 1, wherein After obtaining the reactive power capacity configuration plan determined by the inductive reactive power capacity, the reactive power configuration method for the converter station in the multi-terminal HVDC transmission project further includes: Process the rated trigger angle to obtain the maximum capacitive reactive power consumption of the converter station; Obtain the capacitive reactive power group capacity according to the AC voltage fluctuation range limit of the converter station determined by the obtained AC voltage level; Based on the maximum capacitive reactive power consumption and the capacitive reactive power group capacity, obtain the capacitive reactive power capacity; Determine the capacitive reactive power capacity configuration plan from the capacitive reactive power capacity.

9. The reactive power configuration method for a converter station in a multi-terminal HVDC transmission project as described in claim 8, characterized in that After determining the capacitive reactive power capacity configuration plan, the reactive power configuration method for the converter station in the multi-terminal HVDC transmission project further includes: When the power of the HVDC transmission system reaches the first threshold, execute the inductive reactive power capacity configuration plan; When the power of the HVDC transmission system reaches the second threshold, execute the capacitive reactive power capacity configuration plan.

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

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