Flexible low-frequency converter valve section twin trawling test system and operation control method

Abstract

The invention provides a flexible low-frequency converter valve section twin-dragging test system and an operation control method, and relates to the technical field of power electronic application, and the system comprises an accompanying test valve section and a tested valve section, and the accompanying test valve section and the tested valve section are connected in parallel; wherein the accompanying test valve section operates as a voltage source, comprises a plurality of power sub-modules and is used for providing an alternating current voltage at least comprising a first frequency and an alternating current voltage at a second frequency, and the first frequency is not equal to the second frequency; the tested valve section comprises a plurality of test valve sections, and each test valve section further comprises a plurality of power submodules. The operation control method comprises the steps of starting power supply charging in a starting stage, and supplementing loss by an energy supplementing power supply in the whole process; in a steady state, the capacitor voltage of the accompanying test valve section is not changed, double-frequency component power reverse transmission is realized based on energy conservation, and the current and the capacitor voltage of the tested valve section are regulated and controlled. According to the overall scheme, the flexible low-frequency converter valve section twin-drag test cost can be saved, the system stability is guaranteed, and the test effectiveness is improved.

Description

Technical Field

[0001] This invention relates to the field of power electronics application technology, and in particular to a flexible low-frequency converter valve section drag test system and operation control method. Background Technology

[0002] Flexible low-frequency transmission (FLFT) technology increases the line's capacitive reactance to ground by reducing the transmission frequency, thereby reducing capacitive current in the cable and improving transmission efficiency. Compared to power frequency AC transmission, it is more economical and efficient. Compared to high voltage direct current (HVDC) transmission, FLFT possesses the characteristics of AC transmission, such as electromagnetic induction transformation and zero-crossing current interruption. Therefore, FLFT has significant technical and economic advantages and a promising market prospect in scenarios such as offshore wind power transmission, renewable energy grid connection, and low-frequency grid construction.

[0003] M3C, with its advantages of low output harmonic content and high equivalent switching frequency, is currently the mainstream FLFT technology. In high-voltage, high-capacity flexible power transmission applications such as offshore wind power and new energy grid connection, M3C, similar to MMC, requires series submodules to increase the transmission voltage. However, as the transmission voltage level increases, the number of series submodules required increases proportionally, posing significant challenges to the production and testing of the entire valve.

[0004] Currently, it is possible to build a complete 9-arm flexible low-frequency power transmission simulation platform, simultaneously reducing operating voltage and transmission power, so that the entire system receives the same current stress as in actual engineering, and conduct valve-related tests. However, for converter manufacturers, building a complete dynamic simulation test platform requires many modules, occupies a large area, and has a high overall investment cost. Furthermore, the overall station control strategy is more complex, and the corresponding secondary system investment cost will also be higher.

[0005] In summary, there is an urgent need for a technical solution that can overcome the above-mentioned shortcomings, optimize hardware structure, and simplify test operation control strategies. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention proposes a flexible low-frequency converter valve section drag-out test system and its operation control method. This invention can be used to conduct steady-state tests on M3C power devices, saving on the cost of flexible low-frequency converter valve section drag-out testing, ensuring system stability, and improving test effectiveness.

[0007] In a first aspect of the present invention, a flexible low-frequency converter valve section counter-test system is proposed. The system includes: a test valve section and a valve section under test, wherein the test valve section and the valve section under test are connected in parallel; wherein...

[0008] The test valve section operates as a voltage source and includes multiple power sub-modules for providing AC voltages of at least a first frequency and a second frequency, wherein the first frequency is not equal to the second frequency.

[0009] The valve section under test includes multiple test valve sections, and each test valve section further includes multiple power submodules.

[0010] In one embodiment, the power submodule is an AC-DC conversion submodule, including an AC port and a DC port;

[0011] The AC ports corresponding to the multiple power sub-modules in the test valve section are connected in series in sequence.

[0012] The AC ports corresponding to the multiple power submodules in each of the test valve sections are connected in series sequentially.

[0013] In one embodiment, the power submodule is a full-bridge module, comprising four fully controlled power devices and a capacitor;

[0014] The four fully controlled power devices are divided into two groups, with two fully controlled power devices in each group connected in series. The two groups are connected in parallel, and the nodes of the parallel connection constitute the DC port of the power submodule.

[0015] The capacitor is connected in parallel to the DC port of the power submodule;

[0016] The midpoint of the two fully controlled power devices connected in series in each group constitutes the AC port of the power submodule.

[0017] In one embodiment, the system further includes: a startup power supply and a replenishment power supply; the startup power supply and the replenishment power supply are DC power supplies;

[0018] The starting power supply is connected in parallel with the AC port of the accompanying valve section;

[0019] The supplementary power supply is connected in parallel with the DC port of the test valve section.

[0020] In one embodiment, the system further includes: multiple reactor branches;

[0021] In this process, for each of the test valve sections, a reactor branch is connected in series to form multiple sets of branches; each set of test valve sections and reactor branches connected in series is further connected in parallel, and then connected in parallel with the accompanying test valve section.

[0022] In one embodiment, the system further includes a controller; wherein the controller controls the tested valve segment to output an AC current consisting of the superposition of the AC current of the first frequency and the AC current of the second frequency.

[0023] In one embodiment, the controller includes: a system controller and a valve controller;

[0024] The valve controller outputs a trigger signal for the IGBT within the converter valve section based on the input modulation wave.

[0025] The system controller uses the parameters required by the test as the input variable reference value and the modulation wave of the test valve section as the reference voltage. Based on the modulation wave of the test valve section, the amplitude and phase of the first and second frequency components of the modulation wave of the test valve section are controlled and adjusted according to the system operating parameter requirements, and the output is the modulation wave of the valve controller.

[0026] In one embodiment, the system controller constructs a transfer function of the system input and the second frequency component current of the valve under test, the average voltage of the capacitor of the valve under test submodule, and the DC current component of the valve under test. The system controller obtains the modulation wave parameters of the valve under test through a PI controller. The modulation wave parameters include the voltage phase of the first frequency component, the voltage phase of the second frequency component, and the DC voltage.

[0027] In one embodiment, the system controller performs parameter control based on energy balance and a PI controller, and the first frequency current component of the tested valve segment automatically forms a solution;

[0028] When it is necessary to adjust the first frequency current component of the valve under test, the first frequency current component of the valve under test is controlled in an open loop by adjusting the first frequency voltage amplitude component and the second frequency voltage amplitude component of the valve under test.

[0029] In a second aspect of the present invention, an operation control method for a flexible low-frequency converter valve section drag test is proposed, the method being executed based on a flexible low-frequency converter valve section drag test system; wherein, the method includes:

[0030] During the startup phase, the starting power supply charges the test valve section and the valve section under test. Once the preset operating conditions are met, the starting power supply is taken out of operation. During operation, the supplementary power supply remains in operation to compensate for system operating losses.

[0031] During the steady-state phase, the test valve section serves as a reference module, maintaining a constant average module capacitor voltage; the module capacitor voltage of the test valve section is controlled at the target value; based on energy conservation, the active power transmission corresponding to the first frequency component and the second frequency component is equal in magnitude and opposite in direction; between the test valve section and the test valve section, the active power transmitted from the test valve section to the test valve section through the second frequency component will be fed back from the test valve section to the test valve section through the first frequency component;

[0032] During the control phase, a modulation wave is generated by the controller to control the output of the tested valve segment to generate an AC current with the first frequency and the second frequency superimposed, while suppressing the DC current component.

[0033] The flexible low-frequency converter valve section drag test system and operation control method proposed in this invention uses the test valve section as a voltage source to output two AC voltages of different frequencies. The tested valve section contains multiple series power sub-modules and is equipped with reactor branches, which can simultaneously control power frequency and low frequency currents, eliminating complex and redundant test equipment, significantly reducing the construction cost of the test platform, and is effectively applicable to the steady-state test of M3C converter valve sections, meeting the steady-state test requirements of M3C power devices. During the operation control process, the starting power supply completes charging and then exits during the startup phase, while the supplementary power supply is fully engaged to compensate for system operating losses. In steady state, based on energy conservation, the active power of the two frequency components is transmitted in reverse between the test and tested valve sections. With the control structure composed of a system controller and a valve controller, the capacitor voltage of the tested valve section module can be accurately controlled at the target value, suppressing the DC current component and ensuring the stability of the current component of the tested valve section, thus ensuring stable system operation. This not only improves the effectiveness and reliability of the test, but also further optimizes the economy and stability of system operation. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the architecture of the flexible low-frequency converter valve section drag test system according to Embodiment 1 of the present invention.

[0036] Figure 2 This is a schematic diagram of the system architecture of a specific embodiment of the present invention.

[0037] Figure 3 This is a schematic diagram of the flexible low-frequency converter valve section drag test system architecture according to Embodiment 2 of the present invention.

[0038] Figure 4 This is a schematic diagram of the controller control logic of the flexible low-frequency converter valve section drag test system according to Embodiment 3 of the present invention.

[0039] Figure 5 This is a schematic diagram of the operation control method of a flexible low-frequency converter valve section drag test system according to an embodiment of the present invention. Detailed Implementation

[0040] The principles and spirit of the invention will now be described with reference to several exemplary embodiments. It should be understood that these embodiments are given merely to enable those skilled in the art to better understand and implement the invention, and are not intended to limit the scope of the invention in any way. Rather, these embodiments are provided to make this disclosure more thorough and complete, and to fully convey the scope of this disclosure to those skilled in the art.

[0041] Those skilled in the art will recognize that embodiments of the present invention can be implemented as a system, apparatus, device, method, or computer program product. Therefore, this disclosure can be specifically implemented in the following forms: entirely hardware, entirely software (including firmware, resident software, microcode, etc.), or a combination of hardware and software.

[0042] According to an embodiment of the present invention, a flexible low-frequency converter valve section drag test system and operation control method are proposed, which relates to the field of power electronics application technology.

[0043] The principles and spirit of the present invention will be explained in detail below with reference to several representative embodiments.

[0044] Example 1:

[0045] Figure 1 This is a schematic diagram of the flexible low-frequency converter valve section drag test system architecture according to Embodiment 1 of the present invention. Figure 1 As shown, the system includes:

[0046] The test valve section PS and the test valve section BS are connected in parallel.

[0047] The test valve section PS operates as a voltage source and includes P power sub-modules PV1-PVP, which are used to provide at least an AC voltage U1 with a first frequency and an AC voltage U2 with a second frequency, wherein the first frequency is not equal to the second frequency; P is a positive integer.

[0048] The test valve segment BS includes N test valve segments BS1-BSN, and each test valve segment BS1-BSN further includes M power sub-modules; N and M are positive integers.

[0049] For example, test valve section BS1 includes power submodules BS11-BS1M; test valve section BS2 includes power submodules BS21-BS2M; and test valve section BSN includes power submodules BSN1-BSNM.

[0050] In one embodiment, the power submodule is an AC-DC conversion submodule, including an AC port and a DC port;

[0051] The AC ports corresponding to the P power sub-modules PV1-PVP in the test valve section PS are connected in series in sequence.

[0052] The AC ports corresponding to the multiple power submodules in each of the test valve sections BS1-BSN are connected in series. That is, power submodules BS11-BS1M are connected in series to form the test valve section BS1, power submodules BS21-BS2M are connected in series to form the test valve section BS2, and power submodules BSN1-BSNM are connected in series to form the test valve section BSN.

[0053] In one embodiment, the power submodule is a full-bridge module, comprising four fully controlled power devices and a capacitor;

[0054] The four fully controlled power devices are divided into two groups, with two fully controlled power devices in each group connected in series. The two groups are connected in parallel, and the nodes of the parallel connection constitute the DC port of the power submodule.

[0055] The capacitor is connected in parallel to the DC port of the power submodule;

[0056] The midpoint of the two fully controlled power devices connected in series in each group constitutes the AC port of the power submodule.

[0057] In one embodiment, the system further includes: a startup power supply S1 and a replenishment power supply S2; the startup power supply S1 and the replenishment power supply S2 are DC power supplies;

[0058] The starting power supply S1 is connected in parallel with the AC port of the accompanying valve section PS;

[0059] The supplementary power supply S2 is connected in parallel with the DC port of the test valve section PS.

[0060] In one embodiment, the system further includes: multiple reactor branches L1-LN;

[0061] In this system, for each of the test valve sections BS1-BSN, a reactor branch is connected in series to form multiple sets of branches; that is, test valve section BS1 is connected in series with reactor branch L1; test valve section BS2 is connected in series with reactor branch L2; test valve section BSN is connected in series with reactor branch LN; each set of test valve sections and reactor branches connected in series is further connected in parallel, and then connected in parallel with the auxiliary test valve section PS to form a test system.

[0062] In one embodiment, reference Figure 2 This is a schematic diagram of the system architecture of a specific embodiment of the present invention. Figure 2 As shown, the system also includes a controller 100; wherein the controller 100 controls the tested valve segment to output an AC current that is the superposition of the AC current of the first frequency and the AC current of the second frequency.

[0063] Specifically, the controller 100 includes: a system controller 110 and a valve controller 120;

[0064] The valve controller 120 outputs a trigger signal for the IGBT in the converter valve section according to the input modulation wave.

[0065] The system controller 110 uses the parameters required by the test as the input variable reference value and the modulation wave of the test valve section as the reference voltage. Based on the modulation wave of the test valve section, the amplitude and phase of the first frequency component and the second frequency component of the modulation wave of the test valve section are controlled and adjusted according to the system operating parameter requirements, and the output is the modulation wave of the valve controller 120.

[0066] The system controller 110 constructs a transfer function of the system input and the second frequency component current of the valve section under test, the average voltage of the capacitor of the valve section submodule under test, and the DC current component of the valve section under test. It obtains the modulation wave parameters of the valve section under test through a PI controller. The modulation wave parameters include the voltage phase of the first frequency component, the voltage phase of the second frequency component, and the DC voltage.

[0067] The system controller 110 performs parameter control based on energy balance and PI controller, and the first frequency current component of the tested valve section automatically forms a solution.

[0068] When it is necessary to adjust the first frequency current component of the valve under test, the first frequency current component of the valve under test is controlled in an open loop by adjusting the first frequency voltage amplitude component and the second frequency voltage amplitude component of the valve under test.

[0069] Example 2:

[0070] Figure 3 This is a schematic diagram of the flexible low-frequency converter valve section drag test system architecture according to Embodiment 2 of the present invention. Figure 3 As shown, the system includes: a test valve section PS, a test valve section BS, a reactor branch L, a starting power supply S1, and a supplementary power supply S2.

[0071] In one embodiment, the test valve section PS is connected in series by P power submodule AC ports, which serves as a voltage source. The output voltage includes at least two frequencies, denoted as first frequency AC voltage U1 and second frequency AC voltage U2, and the first frequency is not equal to the second frequency.

[0072] The reactor branch L is connected in series with the parallel branch on one side of the test valve section and the valve section under test.

[0073] The starting power supply is connected in parallel with the AC output side of the test valve section. During the startup phase, the starting power supply charges both the test valve section and the valve section under test. Once the system operating conditions are met, the starting power supply is disconnected.

[0074] The supplementary power supply is connected in parallel with the capacitor of the test valve section module. Throughout the system's operation, the supplementary power supply remains operational to compensate for operational losses.

[0075] The reactor branch has only one reactor branch, and the valve section under test is formed by connecting all the AC ports of the power submodules in series. The reactor branch L, the valve section under test PS, and the valve section under test BS are connected in series end to end to form the test system.

[0076] Example 3:

[0077] Figure 4 This is a schematic diagram of the controller control logic of the flexible low-frequency converter valve section drag test system according to Embodiment 3 of the present invention. The example uses a first frequency of 50Hz and a second frequency of 20Hz.

[0078] like Figure 4 As shown, during operation, the system input conditions are determined according to the specific experimental requirements:

[0079] U PS_50 U PS_20 U BS_50 U BS_20 I 20_ref U c_BS-ref I DC_ref ;

[0080] in,

[0081] U PS_20 U PS_50 U BS_20 U BS_50 The effective voltage values ​​of the 20Hz component of the test valve section, the 50Hz component of the test valve section, the 20Hz component of the tested valve section, and the 50Hz component of the tested valve section.

[0082] I 20_ref : Reference value of the 20Hz current component of the valve section under test.

[0083] U c_BS-ref Reference value for capacitor voltage of the valve section module under test.

[0084] I DC_ref : Reference value of DC current component of the valve section under test.

[0085] U PS_50 U PS_20 U BS_50 U BS_20 Uc_BS-ref It depends on the number of sub-modules in the valve section under test, the required sub-module capacitor voltage, and the valve section output voltage. 20_ref I DC_ref Depending on the test current and its component values ​​in the valve section test requirements, I is typically... DC_ref It is 0.

[0086] Construct the system input and the 20Hz component of the current I20 in the tested valve section, and the capacitor voltage U of the tested valve section submodule. C_BS DC current component I of the tested valve section DC The transfer function of key electrical quantities is obtained through a PI controller, which acquires the BS modulation wave parameters: the voltage phase of the tested valve section at 20Hz. Voltage phase of the tested valve section at 50Hz DC voltage U of the tested valve section DC Based on energy balance and the above control, the effective current I at 50Hz in the tested valve section is... 50 Automatic solution generation, when a solution is needed for I 50 During adjustment, the voltage amplitude component of the 50Hz test valve section and the voltage amplitude of the 20Hz test valve section are adjusted to affect I. 50 Perform open-loop control.

[0087] The generated modulation wave serves as the input signal for the valve controller, controlling the trigger signal of the IGBTs within the converter valve section. The valve controller employs the nearest-level modulation method.

[0088] It should be noted that although several modules of the flexible low-frequency converter valve section towing test system have been mentioned in the detailed description above, this division is merely exemplary and not mandatory. In fact, according to embodiments of the present invention, the features and functions of two or more modules described above can be embodied in one module. Conversely, the features and functions of one module described above can be further divided and embodied by multiple modules.

[0089] Having described the apparatus according to exemplary embodiments of the present invention, the following references are made to... Figure 5 The operation control method of the flexible low-frequency converter valve section drag test system according to an exemplary embodiment of the present invention is introduced.

[0090] Figure 5 This is a schematic diagram of the operation control method of a flexible low-frequency converter valve section drag test system according to an embodiment of the present invention. Figure 5 As shown, the method includes:

[0091] S501, during the startup phase, the starting power supply charges the test valve section and the valve section under test. After the preset operating conditions are reached, the starting power supply is taken out of operation. During operation, the supplementary power supply remains in operation to compensate for system operating losses.

[0092] S502, in the steady-state phase, the test valve section serves as a reference module, maintaining a constant average module capacitor voltage; the module capacitor voltage of the test valve section is controlled at the target value; based on energy conservation, the active power transmission corresponding to the first frequency component and the second frequency component is equal in magnitude and opposite in direction; between the test valve section and the test valve section, the active power transmitted from the test valve section to the test valve section through the second frequency component will be fed back from the test valve section to the test valve section through the first frequency component;

[0093] S503, in the control phase, generates a modulation wave through the controller to control the output of the tested valve section to superimpose the first frequency and the second frequency of the AC current, while suppressing the DC current component.

[0094] In one embodiment, the flexible low-frequency converter valve section drag test system and operation control method proposed in this invention are applicable to scenarios including at least the steady-state test of the M3C converter valve section.

[0095] This invention enables equivalent testing of the valve section of the M3C converter based on the flexible high-voltage direct current transmission MMC in the form of valve sections (several series sub-modules composed of proportions), realizing the equivalent testing of the valve section of the M3C converter on a drag test platform.

[0096] During the startup phase, the starting power supply charges the test valve section and the valve section under test. Once the system operating conditions are met, the starting power supply is deactivated. Throughout the entire system operation, the supplementary power supply remains operational to compensate for operational losses.

[0097] After the system completes module pre-charging, it enters steady-state mode. The test valve section serves as a reference module, and the average module capacitor voltage remains constant. The system energy transmission loop consists of three parts: a first-frequency energy transmission loop, a second-frequency energy transmission loop, and the energy stored in the capacitor of the test valve section module. The capacitor of the test valve section module is controlled at the target value. Ignoring system losses (which have been compensated for by the energy replenishment module), based on energy conservation, for the valve section itself, the active power transmission of the first-frequency component is equal in magnitude and opposite in direction to the active power transmission of the second-frequency component. Between the test valve section and the valve section under test, the active power transmitted from the test valve section to the valve section under test via the second-frequency component is fed back from the valve section under test to the test valve section via the first-frequency component.

[0098] The controller controls the tested valve section to output an AC current consisting of the superposition of the first frequency AC current and the second frequency AC current. The basic control structure of the controller mainly consists of two parts: a system controller and a valve controller. The valve controller outputs the trigger signal of the IGBT in the controlled commutation valve section according to the input modulation wave.

[0099] The system controller uses the parameters required by the test as reference values ​​for the input variables, and its output is the modulated wave of the valve controller. The modulated wave u of the test valve section... ps (t) serves as the reference voltage, and the modulated wave u of the tested valve segment is... bs (t) in u ps Based on (t), and according to the system operating parameter requirements, the amplitude and phase of the first and second frequency components of the modulation wave of the tested valve section are controlled and adjusted. Simultaneously, considering the absence of a DC current component in the low-frequency converter valve, a DC current suppression controller is constructed.

[0100] The system controller constructs transfer functions for key electrical quantities such as the system input and the second frequency component current of the valve under test, the average voltage of the capacitors in the valve under test submodules, and the DC current component of the valve under test. It obtains the modulation wave parameters of the valve under test—the voltage phase of the first frequency component, the voltage phase of the second frequency component, and the DC voltage—through a PI controller. Based on energy balance and the above control, the first frequency current component of the valve under test automatically forms a solution. When adjustment of the first frequency current component is required, open-loop control of the first frequency current component is achieved by adjusting the amplitude components of the first and second frequency voltages of the valve under test.

[0101] It should be noted that although the operation of the method of the present invention has been described in a specific order in the above embodiments and figures, this does not require or imply that the operations must be performed in that specific order, or that all the operations shown must be performed to achieve the desired result. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps.

[0102] The flexible low-frequency converter valve section drag test system and operation control method proposed in this invention uses the test valve section as a voltage source to output two AC voltages of different frequencies. The tested valve section contains multiple series power sub-modules and is equipped with reactor branches, which can simultaneously control power frequency and low-frequency current, eliminating complex and redundant test equipment, significantly reducing the construction cost of the test platform, and is effectively applicable to the steady-state test of M3C converter valve sections, meeting the steady-state test requirements of M3C power devices. During the operation control process, the starting phase is completed by charging through the starting power supply and then withdrawn, while the replenishing power supply is continuously engaged in the compensation system. The system minimizes operating losses and, in steady state, achieves reverse transmission of active power of two frequency components between the test and under-test valve segments based on energy conservation. Combined with a control structure consisting of a system controller (including PI control and DC current suppression function, capable of precisely adjusting the modulation wave parameters of the under-test valve segment) and a valve controller (using the nearest-level modulation), it can accurately control the capacitor voltage of the under-test valve segment module to the target value, suppress the DC current component, ensure the stability of the current component in the under-test valve segment, and guarantee stable system operation. This not only improves the effectiveness and reliability of the test but also further optimizes the economy and stability of system operation.

[0103] The acquisition, storage, use, and processing of data in this application comply with relevant laws and regulations.

[0104] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, apparatus, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0105] This invention is described with reference to flowchart illustrations and / or block diagrams of methods and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0106] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0107] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0108] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A flexible low-frequency converter valve section drag test system, characterized in that, The system includes: a test valve section and a test valve section, wherein the test valve section and the test valve section are connected in parallel; wherein, The test valve section operates as a voltage source and includes multiple power sub-modules for providing AC voltages of at least a first frequency and a second frequency, wherein the first frequency is not equal to the second frequency. The valve section under test includes multiple test valve sections, and each test valve section further includes multiple power submodules.

2. The flexible low-frequency converter valve section drag test system according to claim 1, characterized in that, The power submodule is an AC-DC conversion submodule, including AC ports and DC ports; The AC ports corresponding to the multiple power sub-modules in the test valve section are connected in series in sequence. The AC ports corresponding to the multiple power submodules in each of the test valve sections are connected in series sequentially.

3. The flexible low-frequency converter valve section drag test system according to claim 2, characterized in that, The power submodule is a full-bridge module, comprising four fully controlled power devices and a capacitor; The four fully controlled power devices are divided into two groups, with two fully controlled power devices in each group connected in series. The two groups are connected in parallel, and the nodes of the parallel connection constitute the DC port of the power submodule. The capacitor is connected in parallel to the DC port of the power submodule; The midpoint of the two fully controlled power devices connected in series in each group constitutes the AC port of the power submodule.

4. The flexible low-frequency converter valve section drag test system according to claim 2, characterized in that, The system also includes: a startup power supply and a replenishment power supply; the startup power supply and the replenishment power supply are DC power supplies; The starting power supply is connected in parallel with the AC port of the accompanying valve section; The supplementary power supply is connected in parallel with the DC port of the test valve section.

5. The flexible low-frequency converter valve section drag test system according to claim 1, characterized in that, The system also includes: multiple reactor branches; In this process, for each of the test valve sections, a reactor branch is connected in series to form multiple sets of branches; each set of test valve sections and reactor branches connected in series is further connected in parallel, and then connected in parallel with the accompanying test valve section.

6. The flexible low-frequency converter valve section drag test system according to claim 1, characterized in that, The system also includes a controller; wherein the controller controls the tested valve segment to output an AC current that is the superposition of the AC current of the first frequency and the AC current of the second frequency.

7. The flexible low-frequency converter valve section drag test system according to claim 6, characterized in that, The controller includes: a system controller and a valve controller; The valve controller outputs a trigger signal for the IGBT within the converter valve section based on the input modulation wave. The system controller uses the parameters required by the test as the input variable reference value and the modulation wave of the test valve section as the reference voltage. Based on the modulation wave of the test valve section, the amplitude and phase of the first and second frequency components of the modulation wave of the test valve section are controlled and adjusted according to the system operating parameter requirements, and the output is the modulation wave of the valve controller.

8. The flexible low-frequency converter valve section drag test system according to claim 7, characterized in that, The system controller constructs a transfer function of the system input and the second frequency component current of the valve section under test, the average voltage of the capacitor of the valve section submodule under test, and the DC current component of the valve section under test. It obtains the modulation wave parameters of the valve section under test through the PI controller. The modulation wave parameters include the voltage phase of the first frequency component, the voltage phase of the second frequency component, and the DC voltage.

9. The flexible low-frequency converter valve section drag test system according to claim 8, characterized in that, The system controller performs parameter control based on energy balance and PI controller, and the first frequency current component of the tested valve section automatically forms a solution. When it is necessary to adjust the first frequency current component of the valve under test, the first frequency current component of the valve under test is controlled in an open loop by adjusting the first frequency voltage amplitude component and the second frequency voltage amplitude component of the valve under test.

10. A method for operation control during a drag test of a flexible low-frequency converter valve section, characterized in that, The method is performed on the towing test system based on the flexible low-frequency converter valve section according to any one of claims 1 to 9; wherein, the method includes: During the startup phase, the starting power supply charges the test valve section and the valve section under test. Once the preset operating conditions are met, the starting power supply is taken out of operation. During operation, the supplementary power supply remains in operation to compensate for system operating losses. During the steady-state phase, the test valve section serves as a reference module, maintaining a constant average module capacitor voltage; the module capacitor voltage of the test valve section is controlled at the target value; based on energy conservation, the active power transmission corresponding to the first frequency component and the second frequency component is equal in magnitude and opposite in direction; between the test valve section and the test valve section, the active power transmitted from the test valve section to the test valve section through the second frequency component will be fed back from the test valve section to the test valve section through the first frequency component; During the control phase, a modulation wave is generated by the controller to control the output of the tested valve segment to generate an AC current with the first frequency and the second frequency superimposed, while suppressing the DC current component.

Images