Method and device for voltage instability suppression of flexible dc transmission system based on dc voltage divider

Abstract

The embodiment of the application provides a flexible direct current power transmission system voltage instability suppression method and device based on a direct current voltage divider, which comprises the following steps: collecting original voltage after the direct current voltage divider and before the introduction of a control link in the flexible direct current power transmission system; performing parameter estimation according to the original voltage to generate a voltage division ratio parameter; performing voltage correction modeling according to the voltage division ratio parameter to generate a voltage correction module; and performing voltage correction on the original voltage through the voltage correction module to generate a corrected control voltage. Since the original voltage is input into the voltage correction module for parameter adjustment, when the original voltage passes through the voltage correction module, the dynamic correction relationship between the voltage division ratios is achieved, so that the measurement value of the voltage is more accurate, and the problem caused by the abnormal increase of the direct current voltage is avoided. In this way, the linear increase of the direct current side voltage caused by the damage of the voltage divider can be effectively reduced, and the safety and stability of the flexible direct current power transmission system can be improved.

Description

Technical Field

[0001] This invention relates to the field of flexible DC transmission technology, and in particular to a method and apparatus for suppressing voltage instability in a flexible DC transmission system based on a DC voltage divider. Background Technology

[0002] In flexible DC transmission systems, the failure of a single unit in the DC voltage divider can affect the transmission characteristics of the secondary system, posing a risk of instability in the DC side voltage of the flexible DC transmission converter station under a closed-loop control strategy. The DC voltage divider is used to measure the DC voltage of the entire power grid and is one of the essential key devices in a flexible DC power grid. Its measurement results are used in the control system of the flexible transmission system. If the DC voltage divider fails, it can easily cause abnormal measured voltage, i.e., the actual output voltage in the system does not match the measured voltage value. Under the control of flexible DC transmission, especially under constant voltage control, this affects the normal operation of the system. Furthermore, the failure of a single component in the voltage divider in the flexible DC system can amplify the fault, forming a positive feedback loop that can cause neutral bus and pole bus faults, directly affecting the reliability of the DC power grid operation. Summary of the Invention

[0003] One object of the present invention is to provide a method and apparatus for suppressing voltage instability in a flexible DC transmission system based on a DC voltage divider, so as to solve at least one of the aforementioned problems.

[0004] To achieve the above objectives, this invention discloses a method for suppressing voltage instability in a flexible DC transmission system based on a DC voltage divider, comprising: The original voltage in the flexible DC transmission system after passing through the DC voltage divider and before being introduced into the control loop is collected. Based on the original voltage, parameter estimation is performed to generate the voltage divider ratio parameter; Based on the voltage division ratio parameters, voltage correction modeling is performed to generate a voltage correction module; The voltage correction module corrects the original voltage to generate a corrected control voltage.

[0005] As an embodiment of the present invention, the above method for estimating parameters based on the original voltage to generate voltage divider ratio parameters includes: estimating parameters based on the original voltage using the obtained voltage divider parameters and voltage divider properties to generate voltage divider ratio parameters.

[0006] As an embodiment of the present invention, the above method for voltage correction modeling based on the voltage division ratio parameter to generate a voltage correction module includes: estimating the pole bus voltage and neutral bus voltage based on the voltage division ratio parameter; deriving a linear relationship expression for the pole bus voltage and neutral bus voltage based on the pole bus voltage and neutral bus voltage; performing voltage amplitude analysis on the linear relationship expression under different voltage division ratios to obtain the latest expression in the frequency domain; converting the latest expression in the frequency domain into a time domain expression; and generating a voltage correction module based on the standard radiation system represented by the time domain expression.

[0007] As an embodiment of the present invention, the expressions for the pole bus voltage and neutral bus voltage estimated based on the voltage division ratio parameter in the above method are as follows: ; ; The linear relationship between the pole bus voltage and the neutral bus voltage is expressed as follows: ; In the above formula: , ; in C For DC-side filter capacitors, L For line inductance, U dcref This is the reference value for outer loop DC voltage control. U dc This is the actual value of the outer loop voltage. U dcP1 and U dcN1 These are the pole bus voltage and neutral bus voltage at the location of the voltage divider measurement point, respectively. k 1 is U dcP1 The ratio of the secondary value of the voltage divider multiplied by the fixed transformation ratio to the actual value. k 2 is U dcN1 The ratio of the secondary value of the voltage divider multiplied by the fixed transformation ratio to the actual value. I sdref This is the reference value for the inner loop current. k vp This refers to the proportional coefficient of the outer loop PI control link. k vi is the integral coefficient of the PI control loop, and s is the Laplace operator.

[0008] As an embodiment of the present invention, the above method performs voltage amplitude analysis on the linear relationship expression under different voltage division ratios to obtain the latest expression in the frequency domain: ; In the formula U dcH This is the amplitude voltage of the positive pole bus when the voltage divider at the positive pole bus fails.

[0009] As an embodiment of the present invention, the above method uses the voltage correction module to perform voltage correction on the original voltage to generate a corrected control voltage, including: inputting the original voltage into the voltage correction module for parameter adjustment, outputting the corrected control voltage, and completing the control voltage amplitude correction.

[0010] Another aspect of the present invention discloses a voltage instability suppression device for a flexible DC transmission system based on a DC voltage divider. The device includes: a voltage acquisition unit for acquiring the original voltage in the flexible DC transmission system after passing through the DC voltage divider and before being introduced into the control loop; a parameter estimation unit for estimating parameters based on the original voltage to generate a voltage division ratio parameter; a correction modeling unit for performing voltage correction modeling based on the voltage division ratio parameter to generate a voltage correction module; and a voltage correction unit for correcting the original voltage through the voltage correction module to generate a corrected control voltage.

[0011] As an embodiment of the present invention, the above-mentioned parameter estimation unit is specifically used to perform parameter estimation based on the original voltage by acquiring the voltage divider parameters and voltage divider properties, and generate voltage division ratio parameters.

[0012] As an embodiment of the present invention, the above-mentioned correction modeling unit is specifically used for: estimating the pole bus voltage and neutral bus voltage based on the voltage division ratio parameter; deriving a linear relationship based on the pole bus voltage and neutral bus voltage to obtain a linear relationship expression between the pole bus voltage and neutral bus voltage; performing voltage amplitude analysis on the linear relationship expression under different voltage division ratios to obtain the latest expression in the frequency domain; converting the latest expression in the frequency domain into a time domain expression, and generating a voltage correction module based on the standard radiation system represented by the time domain expression.

[0013] As an embodiment of the present invention, the voltage correction unit is specifically used to input the original voltage into the voltage correction module for parameter adjustment, output the corrected control voltage, and complete the control voltage amplitude correction.

[0014] The present invention also discloses a computer-readable medium having a computer program stored thereon, which, when executed by a processor, implements the method described above.

[0015] The present invention also discloses a computer device, including a memory and a processor, wherein the memory is used to store information including program instructions, and the processor is used to control the execution of the program instructions, wherein the processor executes the program to implement the method described above.

[0016] The present invention also discloses a computer program product, including a computer program / instruction, which, when executed by a processor, implements the method described above.

[0017] As described above, the voltage instability suppression method and apparatus for flexible DC transmission systems based on DC voltage dividers provided by this invention collects the original voltage in the flexible DC transmission system after passing through the DC voltage divider and before being introduced into the control loop; performs parameter estimation based on the original voltage to generate voltage division ratio parameters; performs voltage correction modeling based on the voltage division ratio parameters to generate a voltage correction module; and performs voltage correction on the original voltage through the voltage correction module. It is evident that because the original voltage is input to the voltage correction module and its parameters are adjusted, when the original voltage passes through this voltage correction module, the dynamic correction relationship between the voltage division ratios makes the voltage measurement more accurate and avoids problems caused by abnormal increases in DC voltage. This effectively reduces the linear increase in DC side voltage caused by voltage divider damage, contributing to improved safety and stability of the flexible DC transmission system. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A flowchart illustrating a method for suppressing voltage instability in a flexible DC transmission system based on a DC voltage divider, provided in an embodiment of the present invention; Figure 2 A flowchart illustrating another method for suppressing voltage instability in a flexible DC transmission system based on a DC voltage divider, provided in an embodiment of the present invention; Figure 3 A flowchart of the voltage correction module provided in an embodiment of the present invention; Figure 4 An improved control loop for a flexible DC transmission system is provided in this embodiment of the invention. Figure 5 This is a schematic diagram of a DC voltage anomaly in a primitive flexible DC transmission system provided in an embodiment of the present invention; Figure 6A schematic diagram of an improved flexible DC transmission system for DC voltage suppression provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of a voltage instability suppression device for a flexible DC transmission system based on a DC voltage divider, provided in an embodiment of the present invention. Figure 8 This is a schematic diagram of the structure of a computer device provided in an embodiment of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that the voltage instability suppression method and device for flexible DC transmission systems based on DC voltage dividers disclosed in this application can be used in the field of artificial intelligence technology, or in any field other than artificial intelligence technology. The application field of the voltage instability suppression method and device for flexible DC transmission systems based on DC voltage dividers disclosed in this application is not limited.

[0022] To facilitate understanding of the technical solution provided in this application, the relevant content of the technical solution will be explained below. Flexible DC transmission systems are characterized by flexible control and good power quality, offering significant advantages in areas such as asynchronous interconnection of AC power grids and offshore wind power transmission. DC voltage dividers are used to measure the DC voltage of the entire power grid and are one of the essential key devices in flexible DC power grids; their measurement results are used in the control system of flexible transmission. If a DC voltage divider malfunctions, it can easily cause abnormal measured voltage, forming a positive feedback loop and leading to an abnormal increase in DC-side voltage.

[0023] The following uses a voltage instability suppression device for a flexible DC transmission system based on a DC voltage divider as an example to illustrate the implementation process of the voltage instability suppression method for a flexible DC transmission system based on a DC voltage divider provided in this embodiment of the invention. It is understood that the execution entity of the voltage instability suppression method for a flexible DC transmission system based on a DC voltage divider provided in this embodiment of the invention includes, but is not limited to, a voltage instability suppression device for a flexible DC transmission system based on a DC voltage divider.

[0024] Figure 1 A flowchart illustrating a voltage instability suppression method for a flexible DC transmission system based on a DC voltage divider, as provided in this embodiment of the invention, is shown below. Figure 1 As shown, the method includes: Step S101: Collect the original voltage in the flexible DC transmission system after passing through the DC voltage divider and before being introduced into the control loop.

[0025] Step S102: Estimate parameters based on the original voltage to generate voltage divider ratio parameters.

[0026] Step S103: Perform voltage correction modeling based on the voltage division ratio parameters to generate a voltage correction module.

[0027] Step S104: The original voltage is corrected by the voltage correction module to generate a corrected control voltage.

[0028] This invention provides a method and apparatus for suppressing voltage instability in flexible DC transmission systems based on DC voltage dividers. The method involves acquiring the original voltage in the flexible DC transmission system after passing through the DC voltage divider and before being introduced into the control loop; estimating parameters based on the original voltage to generate voltage division ratio parameters; performing voltage correction modeling based on the voltage division ratio parameters to generate a voltage correction module; and correcting the original voltage using the voltage correction module. As can be seen, this invention adjusts the parameters of the voltage correction module when the original voltage passes through it. Due to the dynamic correction relationship between the voltage division ratios, the measured voltage value is more accurate, and problems caused by abnormal increases in DC voltage are avoided. This effectively reduces the linear increase in DC-side voltage caused by voltage divider failure, contributing to improved safety and stability of the flexible DC transmission system.

[0029] Figure 2 This is a flowchart illustrating another method for suppressing voltage instability in a flexible DC transmission system based on a DC voltage divider, provided by an embodiment of the present invention. In this embodiment, each step is performed by a flexible DC transmission system voltage instability suppression device based on a DC voltage divider. Figure 2 As shown, the method includes: Step S201: Collect the original voltage in the flexible DC transmission system after passing through the DC voltage divider and before being introduced into the control loop.

[0030] In this embodiment of the invention, the secondary cable typically refers to the cable connecting the primary side of the high-voltage equipment to the secondary side of the control or protection device. These cables may transmit low-voltage signals or voltage signals that have been stepped down.

[0031] Specifically, a resistive-capacitive DC voltage divider is used to detect the original voltage flowing through the secondary cable and before it is introduced into the control circuit.

[0032] Step S202: Based on the obtained voltage divider parameters and voltage divider properties, perform parameter estimation according to the original voltage to generate voltage division ratio parameters.

[0033] The voltage divider parameters here may include the high-voltage arm parameters and low-voltage arm parameters of the DC voltage divider. In this embodiment of the invention, the high-voltage arm and low-voltage arm parameters of the DC voltage divider can be obtained through pre-detection. The voltage divider attributes are intrinsic parameter properties, including but not limited to conductor material, quantity and arrangement, diameter and length. These attributes can be pre-stored in a relevant database and retrieved when needed, for example, by associating and retrieving them from the database through identifiers such as the specific model of the voltage divider.

[0034] In this embodiment of the invention, the estimation method can be selected from existing estimation methods according to actual needs, such as Kalman filtering, least squares method, neural networks, etc. This embodiment of the invention does not limit this selection. Taking least squares method as an example: The voltage divider parameters are the high-voltage arm resistance and the low-voltage arm resistance, and it is assumed that the high-voltage arm resistance R1 and the low-voltage arm resistance R2 of the voltage divider are known. Considering the voltage divider properties, such as conductor material, quantity and arrangement, diameter, and length, these properties will affect the actual voltage division ratio of the voltage divider. In this embodiment, the ideal voltage division ratio can be corrected based on the voltage divider properties, assuming a correction factor of [missing value]. α It can be a value calculated based on the properties of the voltage divider, or it may require experimental determination.

[0035] Assuming the DC voltage divider is an ideal linear voltage divider with a division ratio of k, then the original voltage... U raw With actual DC voltage U dc The relationship between them can be represented as: U raw =α (R2 / (R1 + R2)) U dc ; make k = α (R2 / (R1 + R2)) ,but: U raw = k U dc .

[0036] collection N Group original voltage U raw ( i ) and the corresponding actual DC voltage U dc ( i ) data.

[0037] Solving for the optimal solution using the least squares method k value: k = Σ[ U raw ( i ) U dc ( i )] / Σ[ U dc ( i ) 2 ].

[0038] The final result k The value is the estimated voltage divider ratio parameter, which includes information about the voltage divider parameters, voltage divider properties, and measurement data.

[0039] Step S203: Perform voltage correction modeling based on the voltage division ratio parameters to generate a voltage correction module.

[0040] Preferred, such as Figure 3 This step, as shown, further includes the following sub-steps: Step S2031: Estimate the pole bus voltage and neutral bus voltage based on the voltage division ratio parameters.

[0041] The expressions for the pole bus voltage and neutral bus voltage obtained based on the voltage divider ratio parameter estimation are as follows: ; ; in C For DC-side filter capacitors, L For line inductance, U dcref This is the reference value for outer loop DC voltage control. U dc This is the actual value of the outer loop voltage. U dcP1 and U dcN1 These are the pole bus voltage and neutral bus voltage at the location of the voltage divider measurement point, respectively. k 1 and k 2 represents the partial pressure ratio parameter, where k 1 is U dcP1 The ratio of the secondary value of the voltage divider multiplied by the fixed transformation ratio to the actual value. k 2 is U dcN1 The ratio of the secondary value of the voltage divider multiplied by the fixed transformation ratio to the actual value. I sdref This is the reference value for the inner loop current.k vp This refers to the proportional coefficient of the outer loop PI control link. k vi is the integral coefficient of the PI control loop, and s is the Laplace operator.

[0042] Step S2032: Based on the linear relationship between the pole bus voltage and the neutral bus voltage, derive the linear relationship expression between the pole bus voltage and the neutral bus voltage.

[0043] The linear relationship between the pole bus voltage and the neutral bus voltage is expressed as follows: ; In the above formula: , .

[0044] This expression describes the dynamic relationship between the pole bus voltage and the neutral bus voltage in a flexible DC transmission system, reflecting the system's operating characteristics under control.

[0045] Step S2033: Perform voltage amplitude analysis on the linear relationship expression under different voltage division ratios to obtain the latest expression in the frequency domain.

[0046] The goal of this step is to analyze the impact of different voltage division ratios on the system voltage amplitude and obtain an expression describing this impact in the frequency domain. By analyzing the linear relationship expression, the frequency response characteristics of the system under different voltage division ratios can be obtained. Specifically, the latest expression is as follows: ; In the formula U dcH This is the amplitude voltage of the positive pole bus when the voltage divider at the positive pole bus fails.

[0047] Step S2034: Convert the latest expression in the frequency domain into a time domain expression, and generate a voltage correction module based on the standard radiation system represented by the time domain expression.

[0048] In this embodiment, the obtained time-domain expression is a standard affine system, and the specific expression is as follows:

[0049] in: .

[0050] This embodiment converts the frequency domain expression into a time domain expression, which provides a more intuitive description of the system's dynamic behavior in the time domain. Since the obtained time domain expression is a standard affine system, a standard affine system model can be constructed based on it. This model is used to describe the voltage dynamic characteristics in flexible DC transmission systems. The final voltage correction module is based on this affine system model, and it can make corresponding control adjustments according to changes in the voltage divider ratio parameter, thereby achieving more accurate voltage correction.

[0051] Furthermore, by placing the voltage correction module in the system's control loop, an improved control loop for the flexible DC transmission system can be constructed.

[0052] Step S204: Input the original voltage into the voltage correction module for parameter adjustment, and output the corrected control voltage to complete the control voltage amplitude correction.

[0053] In this embodiment of the invention, the parameters of the original voltage input voltage correction module are adjusted. When the original voltage passes through this voltage correction module, the dynamic correction relationship between the voltage divider ratios makes the voltage measurement more accurate and avoids problems caused by abnormal increases in DC voltage. This effectively reduces the linear increase in DC side voltage caused by voltage divider damage, and helps improve the safety and stability of the flexible DC transmission system.

[0054] Figure 4 An improved control loop for a flexible DC transmission system is provided in an embodiment of the present invention, such as... Figure 4 As shown, the control loop of the flexible DC converter station mainly adopts a dual closed-loop control strategy with an inner current loop and an outer voltage loop. This application mainly studies the impact of DC voltage divider failure on the DC-side voltage of the MMC-HVDC converter, and the DC-side voltage mainly acts on the outer voltage loop. The inner loop current is considered as an ideal state, so the modeling mainly considers the impact of DC voltage on the stability of the outer voltage loop and the DC-side voltage. The overall structure diagram of the flexible DC system, including the control loop, is shown below. Figure 3 As shown, the bridge arm inductors and resistors are omitted. Arm is the bridge arm submodule, C is the DC-side filter capacitor, and L is the line inductance. U dcref This is the reference value for outer loop DC voltage control. U dc This is the actual value of the outer loop voltage. U cq It is the grounding point voltage. U dcP1 and U dcN1 These are the pole bus voltage and neutral bus voltage at the location of the voltage divider measurement point, respectively. U dcP For voltageU dcP1 The measured value, U dcN1 For voltage U dcN The measured value, and satisfying U dcP = k 1 U dcP1 , U dcN = k 2 U dcN1 . k 1 for U dcP1 The ratio of the secondary value of the voltage divider multiplied by the fixed transformation ratio to the actual value. k 2 for U dcN1 The ratio of the secondary value of the voltage divider multiplied by the fixed transformation ratio to the actual value. I L This refers to the current flowing from the converter into the DC load. I sdref为 Inner loop current reference value, G vpi For the outer ring PI Control links.

[0055] The advantage of this dual-loop control strategy is that it can simultaneously and quickly respond to voltage changes (through the outer loop) and current changes (through the inner loop), thus providing good steady-state and dynamic performance. Furthermore, by introducing a voltage divider model, the dynamic effects of the voltage divider can be considered in the control loop, further improving the overall performance and stability of the system.

[0056] In practical applications, Figure 5 A schematic diagram of the DC voltage of a primitive flexible DC transmission system provided in an embodiment of the present invention is shown below. Figure 5 As shown, the horizontal axis represents time in seconds (s), the vertical axis represents voltage in kilovolts (kV), and n represents the number of damaged DC voltage divider units. Figure 4 As shown, with the increase of damaged units, the divergent rise in voltage becomes increasingly obvious. Figure 6 A voltage diagram illustrating an improved flexible DC transmission system for DC voltage suppression, provided as an embodiment of the present invention, is shown below. Figure 6 As shown, the horizontal axis represents time, in seconds (s); the vertical axis represents voltage, in kilovolts (kV). Figure 6As shown, after adding the voltage correction module constructed in this application, the voltage fluctuation is smaller over time, eliminating the adverse effects of abnormal voltage rise caused by damage to a certain unit of the voltage divider, preventing the cause of abnormal DC voltage in the system due to damage to the voltage divider, and ensuring the steady-state operation of the system.

[0057] It is worth noting that the acquisition, storage, use, and processing of data in the technical solution of this application all comply with relevant laws and regulations. The user information in the embodiments of this application was obtained through legal and compliant means, and the acquisition, storage, use, and processing of user information have been authorized and agreed upon by the client.

[0058] It is worth noting that the information collected in this application is information and data authorized by the user or fully authorized by all parties, and the collection, storage, use, processing, transmission, provision, disclosure and application of the relevant data all comply with the relevant laws, regulations and standards of the relevant countries and regions, necessary confidentiality measures have been taken, and they do not violate public order and good morals. Corresponding operation portals are provided for users to choose to authorize or refuse.

[0059] It is worth noting that the technical solution provided in this application provides users with a corresponding operation entry point, allowing users to choose to agree to or reject the automated decision-making result; if the user chooses to reject, the process will proceed to the expert decision-making process.

[0060] Figure 7 This is a schematic diagram of a voltage instability suppression device for a flexible DC transmission system based on a DC voltage divider, provided in an embodiment of the present invention. The device includes: a voltage acquisition unit 710, a parameter estimation unit 720, a correction modeling unit 730, and a voltage correction unit 740, which are connected sequentially. The voltage acquisition unit 710 is used to acquire the original voltage in the flexible DC transmission system after passing through the DC voltage divider and before being introduced into the control loop.

[0061] The parameter estimation unit 720 is used to estimate parameters based on the original voltage and generate voltage division ratio parameters.

[0062] The correction modeling unit 730 is used to perform voltage correction modeling based on the voltage division ratio parameters and generate a voltage correction module.

[0063] The voltage correction unit 740 is used to correct the original voltage through the voltage correction module to generate a corrected control voltage.

[0064] Preferably, the parameter estimation unit 720 is specifically used to perform parameter estimation based on the original voltage using the acquired voltage divider parameters and voltage divider attributes, and generate voltage division ratio parameters.

[0065] Preferably, the above-mentioned correction modeling unit 730 is specifically used for: estimating the pole bus voltage and neutral bus voltage based on the voltage division ratio parameter; deriving a linear relationship based on the pole bus voltage and neutral bus voltage to obtain a linear relationship expression for the pole bus voltage and neutral bus voltage; performing voltage amplitude analysis on the linear relationship expression under different voltage division ratios to obtain the latest expression in the frequency domain; converting the latest expression in the frequency domain into a time domain expression, and generating a voltage correction module based on the standard radiation system represented by the time domain expression.

[0066] Preferably, the voltage correction unit 740 is specifically used to input the original voltage into the voltage correction module for parameter adjustment, output the corrected control voltage, and complete the control voltage amplitude correction.

[0067] For a detailed description of each of the above units, please refer to the corresponding descriptions in the foregoing method embodiments, which will not be repeated here.

[0068] As described above, the voltage instability suppression device for flexible DC transmission systems based on a DC voltage divider provided by this invention collects the original voltage in the flexible DC transmission system after passing through the DC voltage divider and before being introduced into the control loop; it estimates parameters based on the original voltage to generate voltage division ratio parameters; it models voltage correction based on the voltage division ratio parameters to generate a voltage correction module; and it corrects the original voltage through the voltage correction module. It is evident that because the original voltage is input to the voltage correction module, the parameters are adjusted. When the original voltage passes through this voltage correction module, the dynamic correction relationship between the voltage division ratios makes the voltage measurement more accurate and avoids problems caused by abnormal increases in DC voltage. This effectively reduces the linear increase in DC side voltage caused by voltage divider damage, contributing to improved safety and stability of the flexible DC transmission system.

[0069] The systems, devices, modules, or units described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer device, specifically, a computer device can be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smartphone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or any combination of these devices.

[0070] This invention provides a computer device, including a memory and a processor. The memory stores information including program instructions, and the processor controls the execution of the program instructions. When the program instructions are loaded and executed by the processor, they implement the steps of the above-described embodiment of the DC voltage suppression method for flexible DC transmission systems based on voltage dividers. For a detailed description, please refer to the above-described embodiment of the DC voltage suppression method for flexible DC transmission systems based on voltage dividers.

[0071] The following is for reference. Figure 8 It shows a schematic diagram of the structure of a computer device 600 suitable for implementing the embodiments of this application.

[0072] like Figure 8 As shown, the computer device 600 includes a central processing unit (CPU) 601, which can perform various appropriate tasks and processes based on programs stored in read-only memory (ROM) 602 or programs loaded from storage section 608 into random access memory (RAM) 603. The RAM 603 also stores various programs and data required for the operation of the computer device 600. The CPU 601, ROM 602, and RAM 603 are interconnected via a bus 604. An input / output (I / O) interface 605 is also connected to the bus 604.

[0073] The following components are connected to I / O interface 605: an input section 606 including a keyboard, mouse, etc.; an output section 607 including a cathode ray tube (CRT), liquid crystal feedback (LCD), etc., and a speaker, etc.; a storage section 608 including a hard disk, etc.; and a communication section 609 including a network interface card such as a LAN card, modem, etc. The communication section 609 performs communication processing via a network such as the Internet. A drive 610 is also connected to I / O interface 605 as needed. A removable medium 611, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on drive 610 as needed so that computer programs read from it can be installed in storage section 608 as needed.

[0074] In particular, according to embodiments of the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program tangibly embodied on a machine-readable medium, the computer program including program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via communication section 609, and / or installed from removable medium 611.

[0075] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0076] For ease of description, the above devices are described separately by function as various units. Of course, in implementing this application, the functions of each unit can be implemented in one or more software and / or hardware.

[0077] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0078] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0079] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0080] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0081] The acquisition, storage, use, and processing of data in this application all comply with the relevant provisions of national laws and regulations.

[0082] It should be noted that in the embodiments of this application, certain software, components, models and other existing solutions in the industry may be mentioned. These should be regarded as exemplary and are only intended to illustrate the feasibility of implementing the technical solution of this application. However, it does not mean that the applicant has used or necessarily used the solution.

[0083] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0084] This application can be described in the general context of computer-executable instructions, such as program modules, that are executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform a specific task or implement a specific abstract data type. This application can also be practiced in distributed computing environments where tasks are performed by remote processing devices connected via a communication network. In distributed computing environments, program modules can reside in local and remote computer storage media, including storage devices.

[0085] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0086] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for suppressing voltage instability in a flexible DC transmission system based on a DC voltage divider, characterized in that, The method includes: The original voltage in the flexible DC transmission system after passing through the DC voltage divider and before being introduced into the control loop is collected. Based on the original voltage, parameter estimation is performed to generate the voltage divider ratio parameter; Based on the voltage division ratio parameters, voltage correction modeling is performed to generate a voltage correction module; The voltage correction module corrects the original voltage to generate a corrected control voltage.

2. The method for suppressing voltage instability in a flexible DC transmission system based on a DC voltage divider according to claim 1, characterized in that, The step of estimating parameters based on the original voltage to generate the voltage divider ratio parameters includes: By obtaining the voltage divider parameters and attributes, the voltage divider ratio parameters are generated based on the original voltage and parameter estimation.

3. The method for suppressing voltage instability in a flexible DC transmission system based on a DC voltage divider according to claim 1, characterized in that, The step of performing voltage correction modeling based on the voltage division ratio parameters to generate a voltage correction module includes: The pole bus voltage and neutral bus voltage are estimated based on the voltage division ratio parameters. Based on the linear relationship between the pole bus voltage and the neutral bus voltage, the linear relationship expression between the pole bus voltage and the neutral bus voltage is derived. The voltage amplitude of the linear relationship expression under different voltage division ratios is analyzed to obtain the latest expression in the frequency domain; The latest expression in the frequency domain is converted into a time domain expression, and a voltage correction module is generated based on the standard radiation system represented by the time domain expression.

4. The method for suppressing voltage instability in a flexible DC transmission system based on a DC voltage divider according to claim 3, characterized in that, The expressions for the pole bus voltage and neutral bus voltage estimated based on the voltage division ratio parameters are as follows: ； ； The linear relationship between the pole bus voltage and the neutral bus voltage is expressed as follows: ； In the above formula: ， ； in C For DC-side filter capacitors, L For line inductance, U dcref This is the reference value for outer loop DC voltage control. U dc This is the actual value of the outer loop voltage. U dcP1 and U dcN1 These are the pole bus voltage and neutral bus voltage at the location of the voltage divider measurement point, respectively. k 1 is U dcP1 The ratio of the secondary value of the voltage divider multiplied by the fixed transformation ratio to the actual value. k 2 is U dcN1 The ratio of the secondary value of the voltage divider multiplied by the fixed transformation ratio to the actual value. I sdref This is the reference value for the inner loop current. k vp This refers to the proportional coefficient of the outer loop PI control link. k vi is the integral coefficient of the PI control loop, and s is the Laplace operator.

5. The method for suppressing voltage instability in a flexible DC transmission system based on a DC voltage divider according to claim 4, characterized in that, By performing voltage amplitude analysis on the linear relationship expression under different voltage division ratios, the latest expression in the frequency domain is obtained as follows: ； In the formula U dcH This is the amplitude voltage of the positive pole bus when the voltage divider at the positive pole bus fails.

6. The method for suppressing voltage instability in a flexible DC transmission system based on a DC voltage divider according to claim 1, characterized in that, The step of correcting the original voltage using the voltage correction module to generate a corrected control voltage includes: The original voltage is input into the voltage correction module for parameter adjustment, and the corrected control voltage is output to complete the control voltage amplitude correction.

7. A voltage instability suppression device for a flexible DC transmission system based on a DC voltage divider, characterized in that, The device includes: The voltage acquisition unit is used to acquire the original voltage in the flexible DC transmission system after passing through the DC voltage divider and before being introduced into the control loop. A parameter estimation unit is used to estimate parameters based on the original voltage and generate voltage division ratio parameters. The voltage correction modeling unit is used to perform voltage correction modeling based on the voltage division ratio parameters and generate a voltage correction module. The voltage correction unit is used to correct the original voltage through the voltage correction module to generate a corrected control voltage.

8. The voltage instability suppression device for flexible DC transmission systems based on a DC voltage divider according to claim 7, characterized in that, The parameter estimation unit is specifically used to estimate parameters based on the original voltage using the acquired voltage divider parameters and voltage divider properties, and generate voltage division ratio parameters.

9. The voltage instability suppression device for flexible DC transmission systems based on a DC voltage divider according to claim 7, characterized in that, The correction modeling unit is specifically used for: estimating the pole bus voltage and neutral bus voltage based on the voltage divider ratio parameter; and deriving a linear relationship expression for the pole bus voltage and neutral bus voltage based on the pole bus voltage and neutral bus voltage. The voltage amplitude of the linear relationship expression under different voltage division ratios is analyzed to obtain the latest expression in the frequency domain; The latest expression in the frequency domain is converted into a time domain expression, and a voltage correction module is generated based on the standard radiation system represented by the time domain expression.

10. The voltage instability suppression device for flexible DC transmission systems based on a DC voltage divider according to claim 7, characterized in that, The voltage correction unit is specifically used to input the original voltage into the voltage correction module for parameter adjustment, and output the corrected control voltage to complete the control voltage amplitude correction.

11. A computer-readable medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the voltage instability suppression method for flexible DC transmission systems based on DC voltage dividers as described in any one of claims 1 to 6.

12. A computer device comprising a memory and a processor, the memory for storing information including program instructions, and the processor for controlling the execution of the program instructions, characterized in that, When the program instructions are loaded and executed by the processor, they implement the voltage instability suppression method for flexible DC transmission systems based on DC voltage dividers as described in any one of claims 1 to 6.

13. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the voltage instability suppression method for flexible DC transmission systems based on DC voltage dividers as described in any one of claims 1 to 6.

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