Control method and device of power transmission system, equipment and storage medium

Abstract

The invention discloses a control method, device and equipment of a power transmission system and a storage medium, which are applied to a target power transmission system formed by a converter transformer, and comprise the following steps: acquiring power data of an alternating current system in the target power transmission system; inputting the power data into a flexible direct current transmission equivalent model to obtain converter transformer parameters; the converter transformer parameters are input into a vector solving model to be processed, the converter transformer magnetic flux is obtained, the vector solving model is screened and confirmed from a first vector solving model, a second vector solving model and a third vector solving model, and the converter transformer magnetic flux is obtained. The screening confirmation process is configured to analyze an electromotive force change result of each vector solving model under a corresponding vector relation graph; generating a converter transformer control signal based on the contrastive analysis result of the converter transformer magnetic flux; and sending the converter transformer control signal to the corresponding converter transformer.

Description

Technical Field

[0001] This invention relates to the field of power transmission system technology, and in particular to a control method for power transmission systems. Background Technology

[0002] In flexible DC transmission systems, converter transformers are indispensable core equipment. Their functions encompass multiple dimensions, including electrical isolation, voltage matching, harmonic suppression, and fault protection, directly impacting the safety, economy, and reliability of the flexible DC system. In scenarios such as AC / DC interconnection and renewable energy grid integration, converter transformers connect AC / DC systems, achieving efficient energy conversion and transmission. They are a key guarantee supporting the development of modern power systems towards high-proportion renewable energy and highly flexible regulation.

[0003] In existing technologies, the power transmission control strategy of flexible DC transmission systems focuses on single-threaded command transmission. For example, the most basic mode is that the master station of the flexible DC transmission system has a fixed DC voltage, and the slave station transmits active power according to the command. However, the working performance of the converter transformer directly affects the transmission effect during the transmission process. The existing single-threaded command transmission method does not take this into account. That is, the working state of the converter transformer is fixed, which leads to problems such as limited dynamic adjustment capability of the system, increased risk of equipment overload, and accumulation of power transmission deviation. Summary of the Invention

[0004] This invention provides a control method, device, equipment, and storage medium for a power transmission system to solve the technical problem of fixed operating state of converter transformers in the prior art, so as to realize dynamic adjustment of converter transformers and improve their operating capacity.

[0005] To address the aforementioned technical problems, embodiments of the present invention provide a control method for a power transmission system, applied to a target power transmission system composed of converter transformers, the method comprising:

[0006] Acquire the power data of the AC system in the target power transmission system;

[0007] The power data is input into the equivalent model of flexible DC transmission to obtain the converter transformer parameters;

[0008] The parameters of the converter transformer are input into a vector solution model for processing to obtain the magnetic flux of the converter transformer. The vector solution model is selected and confirmed from the first vector solution model, the second vector solution model and the third vector solution model. The selection and confirmation process is configured to analyze the electromotive force change results of each vector solution model under the corresponding vector relationship diagram.

[0009] Based on the comparative analysis results of the magnetic flux of the converter transformer, a control signal for the converter transformer is generated;

[0010] The control signal of the converter transformer is sent to the corresponding converter transformer.

[0011] As a preferred embodiment, the converter transformer control signal includes at least reactive power boundary information;

[0012] The generation of converter transformer control signals based on the comparative analysis results of the converter transformer's magnetic flux includes:

[0013] The reactive power of the AC system is set according to the voltage of the AC system.

[0014] The voltage and the reactive power are input into the vector solution model to obtain the magnetic flux to be screened. If the magnetic flux to be screened exceeds the magnetic flux of the converter transformer, the reactive power is confirmed as the control signal of the converter transformer.

[0015] As a preferred embodiment, the processing procedure of the first vector solution model includes at least the following:

[0016] Based on the principle of circuit vectors, a first vector relationship diagram is constructed, and based on the first vector relationship diagram, the first electromotive force change data corresponding to the grid-side port of the converter transformer is obtained. The first vector relationship diagram reflects the relationship between active power and inductive reactive power.

[0017] As a preferred embodiment, the processing steps of the second vector solution model include at least:

[0018] Based on the principle of circuit vectors, a second vector relationship diagram is constructed, and based on the second vector relationship diagram, the second electromotive force change data corresponding to the grid-side port of the converter transformer is obtained. The second vector relationship diagram reflects the relationship between active power and capacitive reactive power.

[0019] As a preferred embodiment, the processing procedure of the third adequate solution model includes at least the following:

[0020] Based on the principle of circuit vectors, a third vector relationship diagram is constructed, and based on the third vector relationship diagram, the third electromotive force change data corresponding to the grid-side port of the converter transformer is obtained. The third vector relationship diagram reflects the state in which the AC system only generates capacitive reactive power.

[0021] As a preferred embodiment, the process of determining the vector relationship diagram includes at least the following:

[0022] Based on the filtering of the first, second, and third electromotive force change data, a selected vector relationship diagram is determined, wherein the vector relationship diagram is a first vector relationship diagram, a second vector relationship diagram, or a third vector relationship diagram.

[0023] As a preferred embodiment, the flexible DC transmission equivalent model includes at least a first-level equivalent model, a second-level equivalent model, and a third-level equivalent model;

[0024] The process of inputting the power data into the equivalent model of flexible DC transmission to obtain the converter transformer parameters includes at least the following:

[0025] The power data is input into the first-level equivalent model to obtain the equivalent voltage data and phase angle difference data of the converter valve;

[0026] The equivalent voltage data of the converter valve and the phase angle difference data are input into the second-level equivalent model to obtain the valve-side voltage data and valve-side current data of the converter transformer.

[0027] The valve-side voltage data and valve-side current data of the converter transformer are input into the three-level equivalent model to obtain the grid-side current and the angle data between the grid-side voltage and current.

[0028] Another embodiment of the present invention provides a control device for a power transmission system, applied to a target power transmission system composed of converter transformers, the device comprising:

[0029] The acquisition module is used to acquire power data of the AC system in the target power transmission system;

[0030] The preprocessing module is used to input the power data into the equivalent model of flexible DC transmission to obtain the converter transformer parameters;

[0031] The running module is used to input the parameters of the converter transformer into the vector solution model for processing to obtain the magnetic flux of the converter transformer. The vector solution model is selected and confirmed from the first vector solution model, the second vector solution model and the third vector solution model. The selection and confirmation process is configured to analyze the electromotive force change results of each vector solution model under the corresponding vector relationship diagram.

[0032] The analysis module is used to generate converter transformer control signals based on the vector solution model;

[0033] The control module is used to send the control signal of the converter transformer to the corresponding converter transformer.

[0034] Another embodiment of the present invention provides a control device for a power transmission system, including 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 a power transmission system control method as described above.

[0035] In another embodiment of the present invention, a computer-readable storage medium is provided, the computer-readable storage medium storing a computer program, wherein when the device containing the computer-readable storage medium executes the computer program, it implements a control method for a power transmission system as described above.

[0036] Compared with the prior art, the beneficial effects of the embodiments of the present invention are at least one of the following:

[0037] Overcoming the technical barrier of relying solely on a single thread for instruction transmission in existing technologies, a feedback correction method was conceived and combined with the working performance characteristics of the converter transformer, thereby realizing feedback correction of the working state of the converter transformer.

[0038] This scheme establishes a control method for the power transmission system. Building upon the single-threaded command transmission of the power transmission control strategy, it adds control signals for the operating status of the converter transformer, thereby improving the dynamic adjustment capability of the converter transformer during operation. This mechanism ensures the safe operation of the converter transformer and avoids risks such as core saturation due to excessive magnetic flux.

[0039] This scheme utilizes an equivalent model for flexible DC transmission to convert core parameters such as active power and reactive power of the AC system into the calculation of the inter-terminal voltage of the converter transformer. This provides intuitive and quantifiable basic parameters for subsequent flux analysis, solving the problem that the state of the converter transformer is difficult to directly evaluate under different power transmission scenarios. Combined with vector relationship diagrams under different operating conditions, it fully considers the flux changes under different operating modes, accurately reflects the dynamic trend of flux changes, and avoids calculation deviations caused by ignoring key parameters.

[0040] This scheme utilizes reactive power boundary control to control the operating capacity boundary of the converter transformer, providing executable instructions for the scheduling and operation of the DC system, and improving the operational reliability and efficiency of the entire flexible DC project. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the control method of a power transmission system in one embodiment of the present invention;

[0042] Figure 2 This is a conceptual diagram of the equivalent model of flexible DC transmission in one embodiment of the present invention;

[0043] Figure 3 This is a simplified circuit diagram of the flexible DC system of the converter transformer core in one embodiment of the present invention;

[0044] Figure 4 This is a vector diagram of active and inductive reactive power emitted by an AC system in one embodiment of the present invention;

[0045] Figure 5This is a vector diagram of active and capacitive reactive power emitted by an AC system in one embodiment of the present invention;

[0046] Figure 6 In one embodiment of the present invention, the AC system only emits a capacitive reactive power vector diagram;

[0047] Figure 7 This is a schematic diagram of the control device structure of a power transmission system in one embodiment of the present invention;

[0048] Figure 8 This is a schematic diagram of the control equipment structure of a power transmission system in one embodiment of the present invention;

[0049] Figure label:

[0050] Among them, 11. Acquisition module, 12. Preprocessing module, 13. Execution module, 14. Parsing module, 15. Control module, 21. Processor, and 22. Memory. Detailed Implementation

[0051] 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. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0052] In the description of this application, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0053] In the description of this application, it should be noted that, unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing specific embodiments only and is not intended to limit the invention. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0054] It is important to note that converter transformers are indispensable core equipment in flexible DC transmission systems. Their functions encompass multiple dimensions, including electrical isolation, voltage matching, harmonic suppression, and fault protection, directly impacting the safety, economy, and reliability of the flexible DC system. In scenarios such as AC / DC interconnection and renewable energy grid integration, converter transformers achieve efficient energy conversion and transmission by connecting AC / DC systems. The actual flux capacity of the converter transformer directly affects its ability to handle the current power transmission, thus limiting the reactive power output of the DC system. This is a crucial guarantee for supporting the development of modern power systems towards high-proportion renewable energy and highly flexible control. In existing technologies, the transmission control strategy of flexible DC transmission systems focuses on single-threaded command transmission. For example, the most basic mode is that the master station of the flexible DC transmission system has a fixed DC voltage, and the slave stations transmit active power according to commands. However, the operating performance of the converter transformer directly affects the transmission effect during transmission. Existing single-threaded command transmission methods do not consider this, meaning the operating state of the converter transformer is fixed, leading to problems such as limited system dynamic adjustment capabilities, increased equipment overload risk, and accumulated power transmission deviations.

[0055] One embodiment of the present invention provides a control method for a power transmission system, applied to a target power transmission system composed of converter transformers. For details, please refer to [link to relevant documentation]. Figure 1 , Figure 1 The diagram shown illustrates a control method for a power transmission system according to one embodiment of the present invention. The method includes steps S1 to S5:

[0056] S1. Obtain the power data of the AC system in the target power transmission system;

[0057] S2. Input the power data into the equivalent model of flexible DC transmission to obtain the converter transformer parameters;

[0058] S3. Input the parameters of the converter transformer into the vector solution model for processing to obtain the magnetic flux of the converter transformer. The vector solution model is selected and confirmed from the first vector solution model, the second vector solution model and the third vector solution model. The selection and confirmation process is configured to analyze the electromotive force change results of each vector solution model under the corresponding vector relationship diagram.

[0059] S4. Based on the comparative analysis results of the magnetic flux of the converter transformer, generate the converter transformer control signal;

[0060] S5. Send the control signal of the converter transformer to the corresponding converter transformer.

[0061] In the above embodiments, a control method for a power transmission system is applied to a target power transmission system composed of converter transformers. Specifically, the overall architecture of the power transmission system includes at least: a DC side module, an AC side module, and a converter module, etc., wherein the converter module is connected to the DC side module on one side and the AC side module on the other side. Preferably, the DC side module includes DC transmission lines and DC filters, etc., the AC side module includes AC transmission lines and AC filters, etc., and the converter module includes converters and converter transformers, etc.

[0062] Further, in step S1, the power data of the AC system in the target power transmission system is acquired. Specifically, the power data includes at least the power supply voltage U. S DC active power P, reactive power Q, and equivalent inductance X.

[0063] Furthermore, in step S2, the equivalent model for flexible DC transmission can be found in [reference needed]. Figure 2 , Figure 2 The diagram shown is a conceptual representation of an equivalent model for flexible DC transmission in one embodiment of the present invention. The equivalent model includes a first-level equivalent model, a second-level equivalent model, and a third-level equivalent model. Specifically, the first-level equivalent model processes the DC active power P and reactive power Q to obtain the equivalent voltage U of the converter valve. C The relevant processing steps for the phase angle difference δ are shown in formulas (1) to (4):

[0064]

[0065] Where P is DC active power; Q is reactive power; U S U is the power supply voltage; C δ is the equivalent voltage of the converter valve; X is the phase angle difference; L is the equivalent inductance; δ is the phase angle difference; X is the equivalent inductance; L is the equivalent voltage of the converter valve. tr For commutation, the equivalent inductance is used; U dc is the DC voltage; M is the modulation ratio.

[0066] The second-level equivalent model uses the equivalent voltage U of the converter valve C The phase angle difference δ is processed to obtain the valve-side voltage and valve-side current of the converter transformer. The relevant processing procedures are shown in formulas (5)-(8):

[0067]

[0068] Where TC is the current converter transformer gear; Δη is the converter transformer step size; U SN ′ The rated voltage on the converter transformer valve side; U SN Rated voltage of the AC system; M N The rated modulation ratio; U S U is the actual AC voltage;S ′ I represents the actual AC voltage on the valve side. ac For alternating current flowing through the grid side; N norm The rated transformer ratio is denoted by P; the active power transmitted at the grid-side reference PCC point is denoted by Q; and the reactive power transmitted at the grid-side reference PCC point is denoted by U. pcc The AC voltage at the grid-side reference PCC point.

[0069] The third-level equivalent model processes the valve-side voltage and valve-side current of the converter transformer to obtain the grid-side current and the angle between them and the grid-side voltage and current. The relevant processing procedures are shown in formulas (9)-(10):

[0070]

[0071] Among them, I SC U is the grid-side current; θ is the angle between the grid-side voltage and current; P is the active power transmitted at the grid-side reference PCC point; Q is the reactive power transmitted at the grid-side reference PCC point; U S This represents the actual AC voltage on the grid side.

[0072] Furthermore, in step S3, the magnetic flux calculation of the converter transformer model is related to the converter transformer voltage and the core cross-sectional area. With a fixed cross-sectional area, excessive magnetic flux will lead to core saturation. For a simplified circuit of the converter transformer core's flexible DC system, please refer to [link to relevant documentation]. Figure 3 , Figure 3 The diagram shown is a simplified circuit diagram of the flexible DC system of a converter transformer core according to one embodiment of the present invention. In the converter transformer, when the primary winding is connected to the power supply, under the action of AC voltage, the primary winding generates magnetic flux current and magnetomotive force, which establishes alternating magnetic flux in the core. Based on the law of electromagnetic induction, the alternating magnetic flux in the iron core will generate a self-induced electromotive force E1 across the primary winding and a mutual-induced electromotive force E2 across the secondary winding. However, due to the resistance and leakage reactance of the primary and secondary windings in actual transformers, and the losses in the iron core, leakage flux will also exist.

[0073] The processing procedures for E1 and E2 are shown in formula (11):

[0074]

[0075] In this embodiment, the electromotive force E is used to calculate the electromotive forces E1 and E2; f is the system frequency; E1 is the primary port voltage of the converter transformer; and N is the number of turns of the converter transformer coil. For commutation, the magnetic flux is changed.

[0076] at this time

[0077]

[0078] Therefore, the magnitude of magnetic flux essentially reflects the magnitude of electromotive force. The following establishes a vector solution model under different operating conditions, and analyzes the trend of electromotive force E1 under different operating conditions through the vector solution model. Specifically, the different operating conditions mainly include active and inductive reactive power generated by the AC system, active and capacitive reactive power generated by the AC system, and capacitive reactive power generated by the AC system.

[0079] When the resistance of the converter transformer is close to its inductance, i.e., R≈ωL, the amplitude of the voltage E1 at the primary winding port of the converter transformer is approximately equal to U. S Typically, the resistance of the converter transformer is much smaller than its inductive reactance, i.e., R << ωL. Preferably, when the AC system generates both active and inductive reactive power, see [link to relevant documentation]. Figure 4 , Figure 4 This diagram illustrates the active and inductive reactive power vector diagrams generated by an AC system in one embodiment of the present invention. In this case, the reactive power Q generated by the AC system to the DC system is negative, and the angle θ represents the grid-side current I. SC Lagging AC system voltage U S Then, the grid-side current generates a voltage drop across the resistor and inductor of the converter transformer, U RS The voltage drop across resistor Rs is related to I. SC In phase, U SC For current I SC The voltage drop generated across the commutator transformer leakage reactance, and I SC Forming a 90-degree angle, U LR For the voltage drop across the resistor U RS With leakage resistance voltage drop U SC The phasor result is shown in equation (13).

[0080]

[0081] Furthermore, the converter transformer side port voltage E1 is:

[0082]

[0083] When the resistance of the commutator is much smaller than the inductive reactance, the amplitude of E1 is less than U. S .

[0084] Similarly, when an AC system generates active power and capacitive reactive power, please refer to the specific details. Figure 5 , Figure 5 This diagram shows the active and capacitive reactive power vector diagrams of an AC system in one embodiment of the present invention. In this case, the reactive power Q emitted by the AC system to the DC system is positive, and the angle θ represents the grid-side current I. SC Advanced AC system voltage U SThen, the grid-side current generates a voltage drop across the resistor and inductor of the converter transformer, U RS The voltage drop across resistor Rs is related to I. SC In phase, U SC For current I SC The voltage drop generated across the commutator transformer leakage reactance, and I SC Forming a 90-degree angle, U LR For the voltage drop across the resistor U RS With leakage resistance voltage drop U SC The phasor results show that when the resistance of the converter transformer is much smaller than its inductive reactance, E1 in U S The projection of the direction is greater than U S An increase in E1 indicates that the corresponding magnetic flux will also increase, meaning that the magnetic flux is increasing.

[0085] Similarly, when an AC system emits capacitive reactive power, see the details below. Figure 6 , Figure 6 The diagram shown illustrates an AC system that only emits capacitive reactive power vector diagrams in one embodiment of the present invention. In this case, the reactive power Q emitted by the AC system to the DC system is positive, and the angle θ represents the grid-side current I. SC Advanced AC system voltage U S 90°, then the grid-side current generates a voltage drop across the resistor and inductor of the converter transformer, U RS The voltage drop across resistor Rs is related to I. SC In phase, U SC For current I SC The voltage drop generated across the commutator transformer leakage reactance, and I SC Forming a 90-degree angle, U LR For the voltage drop across the resistor U RS With leakage resistance voltage drop U SC The phasor results.

[0086] Preferably, based on the vector solution model analysis, when the equivalent resistance of the converter transformer is much smaller than the inductive impedance, and the AC system only generates capacitive reactive power, the magnetic flux of the converter transformer is at its maximum. Therefore, in the subsequent calculation of magnetic flux, the conclusion relying on the phasor method only needs to traverse the case where the AC system only generates capacitive reactive power, that is, when the DC active power is 0, the corresponding magnetic flux is at its maximum. Therefore, for each calculation case, it is only necessary to set P=0, and then continuously traverse the reactive power Q and different AC system voltages U. S The magnitude of this value allows us to find the boundary of the magnetic flux limit, significantly reducing computational speed. Specifically, let the rated magnetic flux of the converter be... To add magnetic flux during actual operation; the short-circuit impedance is d. x Rated AC system voltage U SN Rated capacity S; Load loss P under rated capacity S The current communication system unit is U.S Given the reactive power Q of the AC system output, the flux of the converter transformer is calculated based on the above known conditions. The calculation of the maximum flux is shown in formula (15).

[0087]

[0088] In actual operating conditions, the magnitude of the magnetic flux to be considered should fully take into account the influence of the main magnetic flux and leakage flux on the basis of the rated magnetic flux, that is, the influence of copper loss Ur% and iron loss Ux% under different loads.

[0089] The copper loss ratio is shown in formula (16):

[0090]

[0091] The iron loss ratio is shown in formula (17):

[0092]

[0093] Where M is the leakage flux coupling coefficient. The magnitude of the coupling coefficient directly affects the energy transfer effect of the system and intuitively reflects the tightness of energy or signal transfer between two coils (or circuits, magnetic field systems). Its value range is usually between 0 and 1. When the coupling coefficient is close to 1, it indicates that the magnetic field coupling between the two coils is extremely tight, and most of the magnetic flux can pass from one coil to the other, and the energy or signal transfer efficiency is extremely high.

[0094] The main magnetic flux increase coefficient K1 is shown in formula (18):

[0095]

[0096] The leakage flux increase coefficient K2 is shown in formula (19):

[0097]

[0098] The largest leakage flux equal to the initial leakage flux The maximum value at a certain moment, considering the coupling coefficient, is obtained as follows:

[0099]

[0100] The maximum principal magnetic flux is equal to the maximum value of the initial principal magnetic flux at a certain moment:

[0101]

[0102] in, and The initial input parameters are the initial leakage flux and the main flux, respectively; θ is the angle between the grid-side voltage and current.

[0103] Total magnetic flux increase Considering the actual AC voltage level, as shown in formula (22):

[0104]

[0105] Further, in step S4, the converter transformer control signal includes at least the reactive power boundary. Specifically, the reactive power output of the AC system under different AC system conditions is set, while the active power is 0. The reactive power result is limited, and the AC system voltage is set in a step size of no more than 1%, as shown in Table 1 below. This is input into the vector solution model selected in step S3 to obtain the flux to be screened. When the flux of the converter transformer exceeds the flux to be screened, the flux to be screened is the flux limit value Blimit considered in the design of the converter transformer. When the flux reaches Blimit under different combinations of reactive power Q and AC system voltage Uac, the reactive power at this time can be considered as the reactive power boundary of the AC system. This boundary value is the control signal of the converter transformer, which is also the boundary of the subsequent DC system operation and scheduling command.

[0106] Table 1. Summary of calculations under different reactive power and AC system voltages (format)

[0107] Uac1 Uac2 Uac3 Q1 Q2 Q3

[0108] Taking the Gansu-Zhejiang project as an example, the AC system voltage at the sending end of this DC transmission project is 750kV, with a rated voltage of ±800kV, a rated current of 5000A, and a transmission capacity of 8000MW.

[0109] The calculation results for different AC system voltages are as follows:

[0110] 1) 790kV, P=0, Q=4049Mvar

[0111]

[0112]

[0113] 2) 785kV, P=0, Q=4049Mvar

[0114]

[0115] 3) 780kV, P=0, Q=4049Mvar

[0116]

[0117] 4) 775kV, P=0, Q=4049Mvar

[0118]

[0119] Based on this result, the commutator flux is calculated as shown in Table 2 below.

[0120] Table 2 Comparison of magnetic flux magnitudes under different active power conditions

[0121] Uac / kV 775 780 785 790 P = 8000MW, Q = 4090Mvar 1.965T 1.978T 1.99T 2.003T P = 0 MW, Q = 4090 Mvar 1.971T 1.984T 1.996T 2.009T

[0122] When an AC system outputs different active and reactive power, it is found that when the active power is equal to 0, the magnetic flux is greater when the reactive power is the same.

[0123] Table 3 Comparison of magnetic flux magnitudes under different capacitive unenergized forces.

[0124] Uac / kV 775 780 785 790 P = 0 MW, Q = 4090 Mvar 1.971T 1.984T 1.996T 2.009T P = 0MW, Q = 3782Mvar 1.956T 1.969T 1.981T 1.994T P = 0 MW, Q = 2200 Mvar 1.881T 1.894T 1.906T 1.918T

[0125] Furthermore, when the converter flux is limited to 1.92T, the maximum reactive power allowed by the AC system is 2200Mvar.

[0126] Furthermore, in step S5, the converter transformer control signal includes at least a reactive power boundary. The converter transformer control signal is sent to the corresponding converter transformer. Specifically, after generating the converter transformer control signal, to ensure the accuracy and real-time performance of the signal during transmission and to avoid control command failure due to delay or interference, the converter transformer control signal is transmitted through internal system lines. Preferably, the internal system lines can be high-speed optical fiber communication links or Ethernet. To ensure the integrity and effectiveness of the transmitted control signal, the converter transformer signal receiving end processes the received converter transformer control signal and transmits the processed converter transformer control signal to the converter transformer, thereby achieving precise control of the converter transformer's operating status.

[0127] Another embodiment of the present invention provides a control device for a power transmission system. For details, please refer to [link to relevant documentation]. Figure 7 , Figure 7 The diagram shown illustrates the structure of a control device for a power transmission system according to one embodiment of the present invention. The device includes:

[0128] The acquisition module is used to acquire power data of the AC system in the target power transmission system;

[0129] The preprocessing module is used to input the power data into the equivalent model of flexible DC transmission to obtain the converter transformer parameters;

[0130] The running module is used to input the parameters of the converter transformer into the vector solution model for processing to obtain the magnetic flux of the converter transformer. The vector solution model is selected and confirmed from the first vector solution model, the second vector solution model and the third vector solution model. The selection and confirmation process is configured to analyze the electromotive force change results of each vector solution model under the corresponding vector relationship diagram.

[0131] The analysis module is used to generate converter transformer control signals based on the vector solution model;

[0132] The control module is used to send the control signal of the converter transformer to the corresponding converter transformer.

[0133] See Figure 8 , Figure 8 The diagram illustrates the structure of a control device for a power transmission system according to one embodiment of the present invention. The control device 20 for a power transmission system provided in this embodiment includes a processor 21, a memory 22, and a computer program stored in the memory 22 and configured to be executed by the processor 21. When the processor 21 executes the computer program, it implements the steps described in the above embodiment of the control method for a power transmission system. Figure 1 Steps S1 to S6 as described above.

[0134] If the integrated module of the control device 20 for the power transmission system is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments 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, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0135] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0136] Accordingly, embodiments of the present invention provide a computer-readable storage medium comprising a stored computer program, wherein, when the computer program is executed, it controls the device containing the computer-readable storage medium to perform steps in a control method for a power transmission system as described in the above embodiments, for example... Figure 1 Steps S1 to S6 as described above.

[0137] Compared with the prior art, the beneficial effects of the embodiments of the present invention are at least one of the following:

[0138] (1) It overcomes the technical barrier of relying on a single thread for instruction transmission in the existing technology. It is conceived through feedback correction method and combined with the working performance characteristics of converter transformer, thereby realizing feedback correction of the working state of converter transformer.

[0139] (2) This scheme establishes a control method for the power transmission system. Based on the single-threaded instruction transmission of the power transmission control strategy, it adds control signals for the operating status of the converter transformer, thereby improving the dynamic adjustment capability of the converter transformer during operation. This mechanism ensures the safe operation of the converter transformer and avoids risks such as core saturation due to excessive magnetic flux.

[0140] (3) This scheme uses the equivalent model of flexible DC transmission to convert the core parameters such as active power and reactive power of the AC system into the calculation of the voltage between the terminals of the converter transformer, which provides intuitive and quantifiable basic parameters for subsequent magnetic flux analysis and solves the problem that the state of the converter transformer is difficult to evaluate directly under different power transmission scenarios. Combined with the vector relationship diagram under different operating conditions, the magnetic flux change under different operating modes is fully considered, which can accurately reflect the dynamic change trend of magnetic flux and avoid calculation deviation caused by ignoring key parameters.

[0141] (4) This scheme utilizes the reactive power boundary to control the operating capacity boundary of the converter transformer, providing an executable instruction basis for the scheduling and operation of the DC system, and improving the operational reliability and efficiency of the entire flexible DC project.

[0142] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A control method for a power transmission system, characterized in that, The method, applied to a target power transmission system consisting of converter transformers, includes: Acquire the power data of the AC system in the target power transmission system; The power data is input into the equivalent model of flexible DC transmission to obtain the converter transformer parameters; The parameters of the converter transformer are input into a vector solution model for processing to obtain the magnetic flux of the converter transformer. The vector solution model is selected and confirmed from the first vector solution model, the second vector solution model and the third vector solution model. The selection and confirmation process is configured to analyze the electromotive force change results of each vector solution model under the corresponding vector relationship diagram. Based on the comparative analysis results of the magnetic flux of the converter transformer, a control signal for the converter transformer is generated; The control signal of the converter transformer is sent to the corresponding converter transformer.

2. The control method for a power transmission system as described in claim 1, characterized in that, The converter transformer control signal includes at least reactive power boundary information; The generation of converter transformer control signals based on the comparative analysis results of the converter transformer's magnetic flux includes: The reactive power of the AC system is set according to the voltage of the AC system. The voltage and the reactive power are input into the vector solution model to obtain the magnetic flux to be screened. If the magnetic flux to be screened exceeds the magnetic flux of the converter transformer, the reactive power is confirmed as the control signal of the converter transformer.

3. The control method for a power transmission system as described in claim 1, characterized in that, The processing steps of the first vector solution model include at least: Based on the principle of circuit vectors, a first vector relationship diagram is constructed, and based on the first vector relationship diagram, the first electromotive force change data corresponding to the grid-side port of the converter transformer is obtained. The first vector relationship diagram reflects the relationship between active power and inductive reactive power.

4. The control method for a power transmission system as described in claim 1, characterized in that, The processing steps of the second vector solution model include at least the following: Based on the principle of circuit vectors, a second vector relationship diagram is constructed, and based on the second vector relationship diagram, the second electromotive force change data corresponding to the grid-side port of the converter transformer is obtained. The second vector relationship diagram reflects the relationship between active power and capacitive reactive power.

5. The control method for a power transmission system as described in claim 1, characterized in that, The processing steps of the third appropriate solution model include at least the following: Based on the principle of circuit vectors, a third vector relationship diagram is constructed, and based on the third vector relationship diagram, the third electromotive force change data corresponding to the grid-side port of the converter transformer is obtained. The third vector relationship diagram reflects the state in which the AC system only generates capacitive reactive power.

6. A control method for a power transmission system as described in any one of claims 3 to 5, characterized in that, The process of determining the vector relationship diagram includes at least the following: Based on the filtering of the first, second, and third electromotive force change data, a selected vector relationship diagram is determined, wherein the vector relationship diagram is a first vector relationship diagram, a second vector relationship diagram, or a third vector relationship diagram.

7. The control method for a power transmission system as described in claim 1, characterized in that, The equivalent model for flexible DC transmission includes at least a first-level equivalent model, a second-level equivalent model, and a third-level equivalent model; The process of inputting the power data into the equivalent model of flexible DC transmission to obtain the converter transformer parameters includes at least the following: The power data is input into the first-level equivalent model to obtain the equivalent voltage data and phase angle difference data of the converter valve; The equivalent voltage data of the converter valve and the phase angle difference data are input into the second-level equivalent model to obtain the valve-side voltage data and valve-side current data of the converter transformer. The valve-side voltage data and valve-side current data of the converter transformer are input into the three-level equivalent model to obtain the grid-side current and the angle data between the grid-side voltage and current.

8. A control device for a power transmission system, characterized in that, The device, applied to a target power transmission system consisting of converter transformers, comprises: The acquisition module is used to acquire power data of the AC system in the target power transmission system; The preprocessing module is used to input the power data into the equivalent model of flexible DC transmission to obtain the converter transformer parameters; The running module is used to input the parameters of the converter transformer into the vector solution model for processing to obtain the magnetic flux of the converter transformer. The vector solution model is selected and confirmed from the first vector solution model, the second vector solution model and the third vector solution model. The selection and confirmation process is configured to analyze the electromotive force change results of each vector solution model under the corresponding vector relationship diagram. The analysis module is used to generate converter transformer control signals based on the comparative analysis results of the magnetic flux of the converter transformer; The control module is used to send the control signal of the converter transformer to the corresponding converter transformer.

9. A control device for a power transmission system, characterized in that, It includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor, when executing the computer program, implements the control method for the power transmission system as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, wherein when the device containing the computer-readable storage medium executes the computer program, it implements the control method of the power transmission system as described in any one of claims 1 to 7.

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