Flexible direct current converter valve side rated voltage configuration method and device, terminal equipment and storage medium

Abstract

The invention discloses a flexible direct current converter valve side rated voltage configuration method and device, terminal equipment and a storage medium, and belongs to the field of power systems. Constructing a boundary valve side operating voltage set taking the ratio of the valve side rated voltage to the direct current side rated voltage as a variable, and further constructing a third harmonic modulation degree set taking the ratio as a variable; according to the third harmonic modulation degree set, constructing a function relational expression between the maximum third harmonic modulation degree in the third harmonic modulation degree set and the ratio; according to the function relational expression, calculating the value of the ratio when the maximum third harmonic modulation degree is the minimum value, and taking the value as a target ratio; calculating a target valve side rated voltage value according to the target ratio and the direct current side rated voltage; and configuring the valve side rated voltage of the flexible DC converter according to the target valve side rated voltage value. The technical vacancy of valve side rated voltage configuration in the prior art is filled.

Description

Technical Field

[0001] This invention relates to the field of power systems, and more particularly to a method, apparatus, terminal equipment, and storage medium for configuring the rated voltage on the valve side of a flexible DC converter. Background Technology

[0002] In recent years, flexible DC transmission technology has developed rapidly. Modular multilevel converters (MMCs) have become the mainstream technology due to their excellent harmonic characteristics, low switching losses, and ease of voltage level expansion. With the surge in demand for high-capacity, long-distance power transmission in the global energy transition, low-cost, lightweight flexible DC transmission technology has become a key direction for industry exploration.

[0003] The multilevel-DC-link converter (MDC) is a novel flexible DC-DC converter topology. During operation, the MDC constructs a multilevel sinusoidal half-wave voltage using a multilevel DC link. This voltage is then flipped half-cycle by the commutating H-bridge at the zero-crossing point to achieve an alternating voltage output. The MDC offers output voltage waveform quality equivalent to that of the multilevel converter (MMC), while reducing the number of module capacitors and power devices, resulting in significant economic and lightweight advantages.

[0004] The AC and DC side voltages of the converter control unit (MCU) have a fixed proportional relationship. To achieve decoupling of the AC and DC side voltages, a third harmonic modulation wave needs to be added to the AC voltage modulation wave of the MDC. The setting of the AC valve-side voltage rating affects the magnitude of the third harmonic modulation wave, and thus affects the harmonic level on the converter valve side. Therefore, designing a reasonable valve-side rated voltage to minimize the third harmonic is crucial for MDC parameter design. However, there is currently no direct method to guide the design of the valve-side rated voltage. Summary of the Invention

[0005] This invention provides a method, apparatus, terminal equipment, and storage medium for configuring the valve-side rated voltage of a flexible DC converter, which can fill the technical gap in the prior art for configuring the valve-side rated voltage.

[0006] An embodiment of the present invention provides a method for configuring the rated voltage on the valve side of a flexible DC converter, comprising:

[0007] Obtain the DC-side rated voltage, valve-side equivalent impedance, and boundary power set of the flexible DC converter; wherein, the boundary power set includes a first boundary power set, a second boundary power set, a third boundary power set, a fourth boundary power set, a fifth boundary power set, and a sixth boundary power set; the first boundary power set includes the maximum positive active power and the maximum inductive reactive power under the maximum positive active power; the second boundary power set includes the maximum positive active power and the maximum capacitive reactive power under the maximum positive active power; the third boundary power set includes the maximum negative active power and the maximum inductive reactive power under the maximum negative active power; the fourth boundary power set includes the maximum negative active power and the maximum capacitive reactive power under the maximum negative active power; the fifth boundary power set includes zero active power and the maximum inductive reactive power under zero active power; the sixth boundary power set includes zero active power and the maximum capacitive reactive power under zero active power.

[0008] Based on the DC-side rated voltage, the valve-side equivalent impedance, and the boundary power set, a boundary valve-side operating voltage set is constructed with the ratio of the valve-side rated voltage to the DC-side rated voltage as the variable.

[0009] Based on the DC side rated voltage and the boundary valve side operating voltage set, a third harmonic modulation set with the ratio as a variable is constructed;

[0010] Based on the third harmonic modulation set, construct a functional relationship between the largest third harmonic modulation set and the ratio;

[0011] Based on the functional relationship, calculate the value of the ratio when the maximum third harmonic modulation index takes the minimum value, and use it as the target ratio.

[0012] Calculate the target valve-side rated voltage value based on the target ratio and the DC-side rated voltage;

[0013] Configure the valve-side rated voltage of the flexible DC converter according to the target valve-side rated voltage value.

[0014] Furthermore, the expression for the boundary power set is:

[0015] S={(P1,Q1),(P2,Q2),(P3,Q3),(P4,Q4),(P5,Q5),(P6,Q6)};

[0016] P1 = P2 = P p ;

[0017] Q1 = Q pL ;

[0018] Q2 = Q pC ;

[0019] P3 = P4 = P n ;

[0020] Q3 = Q nL ;

[0021] Q4 = Q nC ;

[0022] P5 = P6 = 0;

[0023] Q5 = Q 0L ;

[0024] Q6 = Q 0C ;

[0025] In the formula, S represents the boundary power set; P p Q represents the maximum positive active power; pL Q represents the maximum inductive reactive power under the maximum positive active power; pC P represents the maximum capacitive reactive power under the maximum positive active power. n Q represents the maximum negative active power; nL Q represents the maximum inductive reactive power under the condition of maximum negative active power; nC Q represents the maximum capacitive reactive power under the maximum negative active power; 0L Q represents the maximum inductive reactive power at zero active power; 0C This represents the maximum capacitive reactive power at zero active power.

[0026] Furthermore, the expression for the operating voltage set on the boundary valve side is:

[0027]

[0028] In the formula, m represents the ratio of the valve-side rated voltage to the DC-side rated voltage; V(m) represents the boundary valve-side operating voltage set when the ratio of the valve-side rated voltage to the DC-side rated voltage is m; U i U represents the i-th boundary valve-side operating voltage in the boundary valve-side operating voltage set when the ratio of the valve-side rated voltage to the DC-side rated voltage is m; DN X represents the rated voltage on the DC side; X represents the equivalent impedance on the valve side.

[0029] Furthermore, the expression for the third harmonic modulation set is:

[0030]

[0031] In the formula, V3(m) represents the third harmonic modulation set when the ratio of the valve-side rated voltage to the DC-side rated voltage is m; U 3,i(m) represents the i-th third harmonic modulation index in the third harmonic modulation index set when the ratio of the valve-side rated voltage to the DC-side rated voltage is m.

[0032] Furthermore, the functional relationship between the largest third harmonic modulation index in the third harmonic modulation index set and the ratio is expressed as follows:

[0033] V 3,max (m) = max(V3(m));

[0034] In the formula, V 3,max (m) represents the maximum third harmonic modulation index in the third harmonic modulation index set when the ratio of the valve-side rated voltage to the DC-side rated voltage is m.

[0035] Furthermore, the formula for calculating the rated voltage value on the target valve side is as follows:

[0036] m0 = argmin m V 3,max (m);

[0037] In the formula, m0 represents the target valve-side rated voltage value.

[0038] Furthermore, the valve-side equivalent impedance is the AC equivalent impedance of the flexible DC converter referred to the valve side;

[0039] The equivalent impedance on the valve side is the transformer short-circuit impedance and the equivalent impedance at the connection point from the transformer to the AC system.

[0040] Another embodiment of the present invention provides a valve-side rated voltage configuration device for a flexible DC converter, comprising: a data acquisition module, a data analysis module, and a configuration module;

[0041] The data acquisition module is used to acquire the DC-side rated voltage, valve-side equivalent impedance, and boundary power set of the flexible DC converter; wherein, the boundary power set includes a first boundary power set, a second boundary power set, a third boundary power set, a fourth boundary power set, a fifth boundary power set, and a sixth boundary power set; the first boundary power set includes the maximum positive active power and the maximum inductive reactive power under the maximum positive active power; the second boundary power set includes the maximum positive active power and the maximum capacitive reactive power under the maximum positive active power; the third boundary power set includes the maximum negative active power and the maximum inductive reactive power under the maximum negative active power; the fourth boundary power set includes the maximum negative active power and the maximum capacitive reactive power under the maximum negative active power; the fifth boundary power set includes zero active power and the maximum inductive reactive power under zero active power; the sixth boundary power set includes zero active power and the maximum capacitive reactive power under zero active power.

[0042] The data analysis module is used to construct a boundary valve-side operating voltage set with the ratio of the valve-side rated voltage to the DC-side rated voltage as a variable, based on the DC-side rated voltage, the valve-side equivalent impedance, and the boundary power set; construct a third harmonic modulation index set with the ratio as a variable, based on the DC-side rated voltage and the boundary valve-side operating voltage set; construct a functional relationship between the largest third harmonic modulation index in the third harmonic modulation index set and the ratio, based on the third harmonic modulation index set; calculate the value of the ratio when the largest third harmonic modulation index takes its minimum value, based on the functional relationship, as the target ratio; and calculate the target valve-side rated voltage value based on the target ratio and the DC-side rated voltage.

[0043] The configuration module is used to configure the valve-side rated voltage of the flexible DC converter according to the target valve-side rated voltage value.

[0044] Another embodiment of the present invention provides a terminal device, including: a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein when the processor executes the computer program, it implements the steps of the flexible DC converter valve-side rated voltage configuration method of the present invention.

[0045] Another embodiment of the present invention also provides a computer-readable storage medium item, including: a stored computer program, which, when the computer program is running, controls the device where the computer-readable storage medium is located to perform steps such as the valve-side rated voltage configuration method for flexible DC converter of the present invention.

[0046] The following benefits can be obtained by implementing the present invention:

[0047] This invention calculates the valve-side rated voltage based on the DC-side rated voltage, valve-side equivalent impedance, and boundary power set, and provides a method for configuring the valve-side rated voltage of a flexible DC converter. This fills the technical gap in the prior art for configuring the valve-side rated voltage. Moreover, this invention can minimize the third harmonic of the converter under the designed valve-side rated voltage, thereby improving the operating performance of the flexible DC converter. Attached Figure Description

[0048] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0049] Figure 1 This is a schematic flowchart of a method for configuring the rated voltage on the valve side of a flexible DC converter according to an embodiment of the present invention;

[0050] Figure 2 This is a topology diagram of a novel flexible DC-DC converter.

[0051] Figure 3 This is a schematic diagram of the operating principle of a new type of flexible DC converter;

[0052] Figure 4 This is a schematic diagram of the structure of a valve-side rated voltage configuration device for a flexible DC converter according to an embodiment of the present invention. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the term "comprising" and any variations thereof in the specification, claims and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0055] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order, or primary and secondary relationship of the indicated technical features.

[0056] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0057] See Figure 1 To fill the technical gap in the prior art regarding valve-side rated voltage configuration, an embodiment of the present invention provides a method for configuring the valve-side rated voltage of a flexible DC converter, comprising:

[0058] S1. Obtain the DC-side rated voltage, valve-side equivalent impedance, and boundary power set of the flexible DC converter; wherein, the boundary power set includes a first boundary power set, a second boundary power set, a third boundary power set, a fourth boundary power set, a fifth boundary power set, and a sixth boundary power set; the first boundary power set includes the maximum positive active power and the maximum inductive reactive power under the maximum positive active power; the second boundary power set includes the maximum positive active power and the maximum capacitive reactive power under the maximum positive active power; the third boundary power set includes the maximum negative active power and the maximum inductive reactive power under the maximum negative active power; the fourth boundary power set includes the maximum negative active power and the maximum capacitive reactive power under the maximum negative active power; the fifth boundary power set includes zero active power and the maximum inductive reactive power under zero active power; the sixth boundary power set includes zero active power and the maximum capacitive reactive power under zero active power.

[0059] Please refer to Figure 2 This is a topology diagram of a novel flexible DC-DC converter, consisting of three single-phase converters. Each single-phase converter includes a multi-level DC link and a commutating H-bridge. The multi-level DC link is constructed by cascading multiple half-bridge or full-bridge power modules to generate the DC port voltage of the single-phase converter. The commutating H-bridge is a single-phase four-arm topology, with each arm consisting of multiple power devices directly connected in series to adapt to high-voltage applications. The three single-phase converters are connected in series on the DC side, and the AC side is connected to the AC grid via three single-phase converter transformers.

[0060] Please refer to Figure 3 This is a schematic diagram of the operating principle of a novel flexible DC-DC converter. During operation and control, the MDC constructs a multi-level sinusoidal half-wave voltage using a multi-level DC link. The commutating H-bridge performs a half-cycle flip at the voltage zero-crossing point to achieve alternating voltage output. This significantly reduces the series voltage equalization problem of the H-bridge components, making this topology feasible in high-voltage power transmission. The MDC has output voltage waveform quality equivalent to that of the MMC, while reducing the number of module capacitors and power devices, resulting in significant economic and lightweight advantages.

[0061] It should be noted that the technical problem this invention aims to solve is how to configure the valve-side rated voltage of a flexible DC-DC converter. In the parameter design of an MDC, the valve-side rated voltage is a crucial parameter. Since the AC valve-side voltage of an MDC is a half-cycle flip of a sinusoidal half-wave voltage constructed from three multi-level DC links, and the DC voltage of the MDC is formed by the superposition of the sinusoidal half-wave voltages of three multi-level DC links, there is a fixed proportional relationship between the AC and DC side voltages of the MDC. When AC voltage fluctuations or power output changes cause AC voltage changes, a third harmonic modulation wave needs to be added to the AC voltage modulation wave of the MDC to prevent the DC side voltage from changing accordingly. The third harmonic modulation wave ultimately manifests as an adjustment amount in the MDC DC voltage, thereby achieving decoupling of the AC and DC side voltages. The setting of the AC valve-side rated voltage affects the magnitude of the third harmonic modulation wave, and thus affects the harmonic level on the converter valve side. Therefore, designing a reasonable valve-side rated voltage to minimize the third harmonic is key to the parameter design of the MDC.

[0062] This invention is mainly applied to multilevel DC-DC converters (MDCs). The principle is as follows: the rated voltage on the valve side is designed based on the rated voltage on the DC side of the MDC, the power operating range on the AC side, and the equivalent impedance on the valve side, so that the third harmonic of the converter under the rated voltage on the valve side reaches the minimum level, thereby improving the operating performance of the MDC.

[0063] In step S1, the boundary points of the AC side power operating range are obtained, including the maximum positive active power, the maximum negative active power, the maximum inductive reactive power under the maximum positive active power, the maximum capacitive reactive power under the maximum positive active power, the maximum inductive reactive power under the maximum negative active power, the maximum capacitive reactive power under the maximum negative active power, the maximum inductive reactive power under zero active power, and the maximum capacitive reactive power under zero active power, forming a boundary power set. The boundary power set includes a total of six boundary power groups, each consisting of a set of corresponding active and reactive power.

[0064] In a preferred embodiment, the expression for the boundary power set is:

[0065] S={(P1,Q1),(P2,Q2),(P3,Q3),(P4,Q4),(P5,Q5),(P6,Q6)};

[0066] P1 = P2 = P p ;

[0067] Q1 = Q pL ;

[0068] Q2 = Q pC ;

[0069] P3 = P4 = Pn ;

[0070] Q3 = Q nL ;

[0071] Q4 = Q nC ;

[0072] P5 = P6 = 0;

[0073] Q5 = Q 0L ;

[0074] Q6 = Q 0C ;

[0075] In the formula, S represents the boundary power set; P p Q represents the maximum positive active power; pL Q represents the maximum inductive reactive power under the maximum positive active power; pC P represents the maximum capacitive reactive power under the maximum positive active power. n Q represents the maximum negative active power; nL Q represents the maximum inductive reactive power under the condition of maximum negative active power; nC Q represents the maximum capacitive reactive power under the maximum negative active power; 0L Q represents the maximum inductive reactive power at zero active power; 0C This represents the maximum capacitive reactive power at zero active power.

[0076] In a preferred embodiment, the valve-side equivalent impedance is the AC equivalent impedance of the flexible DC converter referred to the valve side;

[0077] The equivalent impedance on the valve side is the transformer short-circuit impedance and the equivalent impedance at the connection point from the transformer to the AC system.

[0078] S2. Based on the DC-side rated voltage, the valve-side equivalent impedance, and the boundary power set, construct a boundary valve-side operating voltage set with the ratio of the valve-side rated voltage to the DC-side rated voltage as the variable.

[0079] In a preferred embodiment, the expression for the boundary valve-side operating voltage set is:

[0080]

[0081] In the formula, m represents the ratio of the valve-side rated voltage to the DC-side rated voltage; V(m) represents the boundary valve-side operating voltage set when the ratio of the valve-side rated voltage to the DC-side rated voltage is m; U i U represents the i-th boundary valve-side operating voltage in the boundary valve-side operating voltage set when the ratio of the valve-side rated voltage to the DC-side rated voltage is m; DNX represents the rated voltage on the DC side; X represents the equivalent impedance on the valve side.

[0082] In this embodiment, the boundary valve-side operating voltage corresponding to each boundary power group is calculated based on the DC-side rated voltage, the valve-side equivalent impedance, and the boundary power group set, thus forming the boundary valve-side operating voltage set.

[0083] S3. Based on the DC side rated voltage and the boundary valve side operating voltage set, construct a third harmonic modulation set with the ratio as the variable.

[0084] In a preferred embodiment, the expression for the third harmonic modulation set is:

[0085]

[0086] In the formula, V3(m) represents the third harmonic modulation set when the ratio of the valve-side rated voltage to the DC-side rated voltage is m; U 3,i (m) represents the i-th third harmonic modulation index in the third harmonic modulation index set when the ratio of the valve-side rated voltage to the DC-side rated voltage is m.

[0087] In this embodiment, the third harmonic modulation index corresponding to each boundary valve side operating voltage is calculated based on the DC side rated voltage and the boundary valve side operating voltage set, thus forming a third harmonic modulation index set.

[0088] S4. Based on the third harmonic modulation set, construct a functional relationship between the largest third harmonic modulation value in the third harmonic modulation set and the ratio.

[0089] In a preferred embodiment, the functional relationship between the largest third harmonic modulation index in the third harmonic modulation index set and the ratio is expressed as follows:

[0090] V 3,max (m) = max(V3(m));

[0091] In the formula, V 3,max (m) represents the maximum third harmonic modulation index in the third harmonic modulation index set when the ratio of the valve-side rated voltage to the DC-side rated voltage is m.

[0092] S5. Based on the aforementioned functional relationship, calculate the value of the ratio when the maximum third harmonic modulation index reaches its minimum value, and use this value as the target ratio.

[0093] In a preferred embodiment, the formula for calculating the target valve-side rated voltage value is as follows:

[0094] m0 = argmin m V 3,max (m);

[0095] In the formula, m0 represents the target valve-side rated voltage value.

[0096] In this embodiment, a theoretical analytical method is used to obtain V. 3,max Find the minimum extreme point of (m) and obtain the value of m0 corresponding to the minimum extreme point.

[0097] In another embodiment, drawing V is used. 3,max By finding the minimum value position through the relationship curve between (m) and m0, the m0 value corresponding to the minimum value position is obtained.

[0098] S6. Calculate the target valve-side rated voltage value based on the target ratio and the DC-side rated voltage. In step S6, the formula for calculating the target valve-side rated voltage value is:

[0099] U vN =m0·U DN ;

[0100] In the formula, U vN This indicates the rated voltage value on the target valve side.

[0101] S7. Configure the valve-side rated voltage of the flexible DC converter according to the target valve-side rated voltage value.

[0102] In step S7, the valve-side rated voltage of the flexible DC converter is set to the target valve-side rated voltage value. Under the target valve-side rated voltage value, the third harmonic modulation amplitude required to maintain the DC-side voltage at the rated value during MDC operation will always be at its minimum compared to other valve-side voltage values, thereby minimizing the harmonic components of the converter.

[0103] After configuring the valve-side rated voltage, the design of the remaining main circuit parameters of the MDC is then carried out.

[0104] It should be noted that this invention calculates the valve-side rated voltage based on the DC-side rated voltage, the valve-side equivalent impedance, and the boundary power set, and provides a method for configuring the valve-side rated voltage of a flexible DC converter. This fills the technical gap in the prior art for configuring the valve-side rated voltage. Moreover, this invention can minimize the third harmonic of the converter under the designed valve-side rated voltage, thereby improving the operating performance of the flexible DC converter.

[0105] like Figure 2 As shown, based on the above-described method embodiments, an embodiment of the present invention provides a valve-side rated voltage configuration device for a flexible DC converter, comprising: a data acquisition module, a data analysis module, and a configuration module;

[0106] The data acquisition module is used to acquire the DC-side rated voltage, valve-side equivalent impedance, and boundary power set of the flexible DC converter; wherein, the boundary power set includes a first boundary power set, a second boundary power set, a third boundary power set, a fourth boundary power set, a fifth boundary power set, and a sixth boundary power set; the first boundary power set includes the maximum positive active power and the maximum inductive reactive power under the maximum positive active power; the second boundary power set includes the maximum positive active power and the maximum capacitive reactive power under the maximum positive active power; the third boundary power set includes the maximum negative active power and the maximum inductive reactive power under the maximum negative active power; the fourth boundary power set includes the maximum negative active power and the maximum capacitive reactive power under the maximum negative active power; the fifth boundary power set includes zero active power and the maximum inductive reactive power under zero active power; the sixth boundary power set includes zero active power and the maximum capacitive reactive power under zero active power.

[0107] The data analysis module is used to construct a boundary valve-side operating voltage set with the ratio of the valve-side rated voltage to the DC-side rated voltage as a variable, based on the DC-side rated voltage, the valve-side equivalent impedance, and the boundary power set; construct a third harmonic modulation index set with the ratio as a variable, based on the DC-side rated voltage and the boundary valve-side operating voltage set; construct a functional relationship between the largest third harmonic modulation index in the third harmonic modulation index set and the ratio, based on the third harmonic modulation index set; calculate the value of the ratio when the largest third harmonic modulation index takes its minimum value, based on the functional relationship, as the target ratio; and calculate the target valve-side rated voltage value based on the target ratio and the DC-side rated voltage.

[0108] The configuration module is used to configure the valve-side rated voltage of the flexible DC converter according to the target valve-side rated voltage value.

[0109] It is understood that the above-described device embodiments correspond to the method embodiments of the present invention, and can implement the method for configuring the valve-side rated voltage of a flexible DC converter provided by any of the above-described method embodiments of the present invention.

[0110] It should be noted that the device embodiments described above are merely illustrative, and some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the device embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can specifically be implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without any creative effort.

[0111] Based on the above-described method embodiments, another embodiment of the present invention provides a terminal device, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the flexible DC converter valve-side rated voltage configuration method of any embodiment of the present invention.

[0112] For example, in this embodiment, the computer program can be divided into one or more modules, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in the terminal device.

[0113] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0114] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the terminal device, connecting all parts of the terminal device via various interfaces and lines.

[0115] Based on the above-described method embodiments, another embodiment of the present invention provides a computer-readable storage medium including a stored computer program, wherein, when the computer program is executed, it controls the device where the computer-readable storage medium is located to execute the flexible DC converter valve-side rated voltage configuration method described in any of the above-described method embodiments of the present invention.

[0116] The modules / units integrated in the device / terminal equipment, if implemented as software functional units and sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.

[0117] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for configuring the rated voltage on the valve side of a flexible DC converter, characterized in that, include: Obtain the DC-side rated voltage, valve-side equivalent impedance, and boundary power set of the flexible DC converter; wherein, the boundary power set includes a first boundary power set, a second boundary power set, a third boundary power set, a fourth boundary power set, a fifth boundary power set, and a sixth boundary power set; the first boundary power set includes the maximum positive active power and the maximum inductive reactive power under the maximum positive active power; the second boundary power set includes the maximum positive active power and the maximum capacitive reactive power under the maximum positive active power; the third boundary power set includes the maximum negative active power and the maximum inductive reactive power under the maximum negative active power; the fourth boundary power set includes the maximum negative active power and the maximum capacitive reactive power under the maximum negative active power; the fifth boundary power set includes zero active power and the maximum inductive reactive power under zero active power; the sixth boundary power set includes zero active power and the maximum capacitive reactive power under zero active power. Based on the DC-side rated voltage, valve-side equivalent impedance, and boundary power set, a boundary valve-side operating voltage set is constructed with the ratio of the valve-side rated voltage to the DC-side rated voltage as the variable. Based on the DC-side rated voltage and the boundary valve-side operating voltage set, a third harmonic modulation set is constructed with the ratio as a variable; Based on the third harmonic modulation set, construct a functional relationship between the largest third harmonic modulation set and the ratio; Based on the functional relationship, calculate the value of the ratio when the maximum third harmonic modulation index takes the minimum value, and use it as the target ratio. Calculate the target valve-side rated voltage value based on the target ratio and the DC-side rated voltage; Configure the valve-side rated voltage of the flexible DC converter according to the target valve-side rated voltage value.

2. The method for configuring the rated voltage on the valve side of a flexible DC converter as described in claim 1, characterized in that, The expression for the boundary power set is: S={(P1,Q1),(P2,Q2),(P3,Q3),(P4,Q4),(P5,Q5),(P6,Q6)}; P1=P2=P p ; Q1=Q pL ; Q2=Q pC ; P3=P4=P n ; Q3=Q nL ; Q4=Q nC ; P5 = P6 = 0; Q5=Q 0L ; Q6=Q 0C ; In the formula, S represents the boundary power set; P p Q represents the maximum positive active power; pL Q represents the maximum inductive reactive power under the maximum positive active power; pC P represents the maximum capacitive reactive power under the maximum positive active power. n Q represents the maximum negative active power; nL Q represents the maximum inductive reactive power under the condition of maximum negative active power; nC Q represents the maximum capacitive reactive power under the maximum negative active power; 0L Q represents the maximum inductive reactive power at zero active power; 0C This represents the maximum capacitive reactive power at zero active power.

3. The method for configuring the rated voltage on the valve side of a flexible DC converter as described in claim 2, characterized in that, The expression for the operating voltage set on the boundary valve side is: In the formula, m represents the ratio of the valve-side rated voltage to the DC-side rated voltage; V(m) represents the boundary valve-side operating voltage set when the ratio of the valve-side rated voltage to the DC-side rated voltage is m; U i U represents the i-th boundary valve-side operating voltage in the boundary valve-side operating voltage set when the ratio of the valve-side rated voltage to the DC-side rated voltage is m; DN X represents the rated voltage on the DC side; X represents the equivalent impedance on the valve side.

4. The method for configuring the rated voltage on the valve side of a flexible DC converter as described in claim 3, characterized in that, The expression for the third harmonic modulation set is: In the formula, V3(m) represents the third harmonic modulation set when the ratio of the valve-side rated voltage to the DC-side rated voltage is m; U 3,i (m) represents the i-th third harmonic modulation index in the third harmonic modulation index set when the ratio of the valve-side rated voltage to the DC-side rated voltage is m.

5. The method for configuring the rated voltage on the valve side of a flexible DC converter as described in claim 4, characterized in that, The functional relationship between the largest third harmonic modulation index in the third harmonic modulation index set and the ratio is expressed as follows: V 3,max (m)=max(V3(m)); In the formula, V 3,max (m) represents the maximum third harmonic modulation index in the third harmonic modulation index set when the ratio of the valve-side rated voltage to the DC-side rated voltage is m.

6. The method for configuring the rated voltage on the valve side of a flexible DC converter as described in claim 5, characterized in that, The formula for calculating the rated voltage value of the target valve side is: m0=argmin m V 3,max (m); In the formula, m0 represents the target valve-side rated voltage value.

7. The method for configuring the rated voltage on the valve side of a flexible DC converter as described in claim 1, characterized in that, The valve-side equivalent impedance is the AC equivalent impedance of the flexible DC converter referred to the valve side. The equivalent impedance on the valve side is the transformer short-circuit impedance and the equivalent impedance at the connection point from the transformer to the AC system.

8. A device for configuring the rated voltage on the valve side of a flexible DC converter, characterized in that, include: Data acquisition module, data analysis module, and configuration module; The data acquisition module is used to acquire the DC-side rated voltage, valve-side equivalent impedance, and boundary power set of the flexible DC converter; wherein, the boundary power set includes a first boundary power set, a second boundary power set, a third boundary power set, a fourth boundary power set, a fifth boundary power set, and a sixth boundary power set; the first boundary power set includes the maximum positive active power and the maximum inductive reactive power under the maximum positive active power; the second boundary power set includes the maximum positive active power and the maximum capacitive reactive power under the maximum positive active power; the third boundary power set includes the maximum negative active power and the maximum inductive reactive power under the maximum negative active power; the fourth boundary power set includes the maximum negative active power and the maximum capacitive reactive power under the maximum negative active power; the fifth boundary power set includes zero active power and the maximum inductive reactive power under zero active power; the sixth boundary power set includes zero active power and the maximum capacitive reactive power under zero active power. The data analysis module is used to construct a boundary valve-side operating voltage set with the ratio of the valve-side rated voltage to the DC-side rated voltage as a variable, based on the DC-side rated voltage, valve-side equivalent impedance, and boundary power set; construct a third harmonic modulation index set with the ratio as a variable, based on the DC-side rated voltage and the boundary valve-side operating voltage set; construct a functional relationship between the largest third harmonic modulation index in the third harmonic modulation index set and the ratio, based on the third harmonic modulation index set; calculate the value of the ratio when the largest third harmonic modulation index takes its minimum value, based on the functional relationship, as the target ratio; and calculate the target valve-side rated voltage value based on the target ratio and the DC-side rated voltage. The configuration module is used to configure the valve-side rated voltage of the flexible DC converter according to the target valve-side rated voltage value.

9. A terminal device, characterized in that, The device includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein, when the processor executes the computer program, it implements the valve-side rated voltage configuration method for a flexible DC converter as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, include: A stored computer program, wherein, when the computer program is executed, it controls the device containing the computer-readable storage medium to perform the valve-side rated voltage configuration method for a flexible DC converter as described in any one of claims 1-7.

Images