Energy release distribution method, device and system for high-capacity flexible dc converter valve sub-module

Abstract

The application discloses an energy release distribution method, device and system for a large-capacity flexible DC converter valve sub-module, and specifically comprises the following steps: firstly, based on identification of the structure design of the large-capacity flexible DC converter valve sub-module, anti-current weak points in a simulation identification loop are identified; then, one or more energy release paths are added in the identified anti-current weak point area to form a target energy release path; finally, the energy generated by the current in the large-capacity flexible DC converter valve sub-module is reasonably distributed and released through the target energy release path, so that effective energy release distribution is realized. The method can effectively reduce the damage of short-circuit faults to the system by optimizing the energy release path, meanwhile, the high protection cost is avoided, and therefore the operation reliability and maintenance convenience of the large-capacity flexible DC converter valve sub-module are improved.

Description

Technical Field

[0001] This invention belongs to the field of energy technology, and in particular relates to a method, device and system for energy release and distribution of a large-capacity flexible DC converter valve submodule. Background Technology

[0002] To reduce unit cost, improve transmission efficiency, enhance grid operation economy, reduce transmission corridor occupancy, and increase equipment utilization, flexible DC converter valves will be developed towards higher voltage levels and larger transmission capacities. With the continuous increase in voltage levels and transmission capacity, flexible DC transmission systems are gradually becoming one of the main technical means for large-scale long-distance power transmission of new energy sources and grid connection of offshore wind power. However, with the increase in capacitance and voltage levels, explosion-proof energy increases significantly, potentially causing huge impacts during short-circuit discharge. Therefore, destructive testing has become a key technical challenge in the development of high-voltage / large-capacity flexible DC converter valves, posing a significant challenge to the explosion-proof performance design of the modules.

[0003] Current technologies typically address destructive testing by increasing physical protection measures, such as adding more and stronger protective barriers. While this approach can reduce the impact of short-circuit current on the module by thickening and reinforcing the protective barriers, it also significantly increases manufacturing costs. Furthermore, existing physical protection measures are often insufficient for large-capacity flexible DC converter valves facing extreme conditions of high energy release.

[0004] Specifically, the existing solutions have the following problems:

[0005] (1) High protection cost: Existing technologies rely too much on physical protection and structural strength improvement, which significantly increases the manufacturing cost of converter valve submodules, especially in large-capacity systems, where high-strength protective materials and complex mechanical structure designs are required.

[0006] (2) Limited response capability: Under high-current discharge conditions, existing technologies still face the limits of their protective capabilities. Although mechanical protection can mitigate the damage caused by faults, it cannot effectively channel fault energy, thus failing to provide complete protection.

[0007] (3) Difficult to maintain: The mechanical protection design of the sub-module is complex, which increases the difficulty of system maintenance and repair, and is not conducive to the reliability guarantee and fault handling in long-term operation.

[0008] (4) Limited energy release path: Existing designs have not fully considered the energy release problem during explosion protection. The energy release path is single and limited, resulting in short-circuit current concentrated in local areas, which increases the risk of damage.

[0009] Therefore, the main drawback of existing technologies lies in their over-reliance on physical protection and the lack of optimization of system design from the perspective of energy release, which leads to high protection costs, serious failure consequences and complex maintenance problems. Summary of the Invention

[0010] The technical problem to be solved by this invention is to address the aforementioned shortcomings of the prior art by proposing an energy release and distribution method, apparatus, and system for a large-capacity flexible DC converter valve submodule. This method, by optimizing the energy release path, can effectively reduce the damage to the system caused by short-circuit faults, while avoiding high protection costs, thereby improving the operational reliability and maintenance convenience of the large-capacity flexible DC converter valve submodule.

[0011] In a first aspect, the present invention provides an energy release and distribution method for a large-capacity flexible DC converter valve submodule, the method comprising the following steps:

[0012] Step S1: Obtain the structural design of the high-capacity flexible DC converter valve submodule and identify the weak points in the circuit's resistance to current through simulation;

[0013] Step S2: Add one or more energy release paths in the area where the current-resistant weak point is located to obtain the target energy release path;

[0014] Step S3: Through the target energy release path, the energy generated by the current in the large-capacity flexible DC converter valve submodule is distributed and released to complete the energy release distribution for the large-capacity flexible DC converter valve submodule.

[0015] Furthermore, the weak points in the current resistance of the high-capacity flexible DC converter valve submodule in step S1 were obtained through simulation modeling.

[0016] Step S1 specifically includes the following steps:

[0017] Step S11: Obtain the structural design model of the large-capacity flexible DC converter valve submodule;

[0018] Step S12: Analyze the initial energy release path of the large-capacity flexible DC converter valve submodule;

[0019] Step S13: Based on the structural design model and circuit discharge path of the large-capacity flexible DC converter valve submodule, a simulation initial model of the initial energy release path is constructed using circuit simulation software;

[0020] Step S14: Set the component parameters of electrical characteristics in the initial simulation model to obtain the first simulation model;

[0021] Step S15: Using the first simulation model, simulate the current resistance weakness of the large-capacity flexible DC converter valve submodule to obtain the current resistance weakness in the large-capacity flexible DC converter valve submodule.

[0022] Furthermore, the simulation model was constructed using ANSYS and Psim software.

[0023] Further, step S2 specifically includes the following steps:

[0024] Step S21: Based on the structural design of the large-capacity flexible DC converter valve submodule, determine the location of the current-resistant weak point; and analyze the current characteristics of the current-resistant weak point under different operating conditions.

[0025] Step S22: Based on the current characteristics and the location of the current-resistant weak point, construct a second simulation model including one or more additional corresponding energy release paths;

[0026] The energy release path includes path elements and path topology;

[0027] The path elements are resistors, and / or capacitors, and / or inductors, and / or diodes, and / or switching elements, and / or connectors, and / or water-cooled plates;

[0028] The path topology includes the connection relationships and connection methods of path elements;

[0029] Step S23: Based on the second simulation model, analyze the energy release path under different operating conditions and evaluate its improvement effect on current resistance;

[0030] If the improvement effect meets the design requirements, then the corresponding energy release path is determined as the simulated energy release path.

[0031] Step S24: According to the simulated energy release path, connect the path elements according to the path topology to obtain the target energy release path.

[0032] Furthermore, in step S3, the energy generated by the current in the large-capacity flexible DC converter valve submodule is distributed and released through the target energy release path, specifically including the following steps:

[0033] Step S31: Based on various parameters of the large-capacity flexible DC converter valve submodule, construct a third simulation model; and evaluate the explosion-proof performance of the large-capacity flexible DC converter valve submodule according to the changes in electrical and mechanical performance parameters in the large-capacity flexible DC converter valve submodule.

[0034] The electrical and mechanical performance parameters include current, and / or, electrodynamic force, and / or, stray inductance, and / or, deformation;

[0035] Step S32: Based on the explosion-proof performance of the large-capacity flexible DC converter valve submodule, the large-capacity flexible DC converter valve submodule is simulated under different operating scenarios using the third simulation model to obtain simulation analysis results;

[0036] Step S33: Based on the simulation analysis results, by comparing different energy transfer methods, adjust the energy release path and ratio to obtain the target energy allocation scheme;

[0037] The energy transfer methods include consuming energy through parallel or series resistors, and / or storing energy through capacitors, and / or transferring energy through inductors, and / or increasing the loop path;

[0038] Step S34: Release the energy of the large-capacity flexible DC converter valve submodule according to the target energy distribution scheme.

[0039] In a second aspect, the present invention provides an energy release and distribution device for a large-capacity flexible DC converter valve submodule, the device comprising:

[0040] The acquisition unit is used to acquire the structural design of the high-capacity flexible DC converter valve submodule and identify the weak points in the circuit that are resistant to current through simulation.

[0041] The design unit, connected to the acquisition unit, is used to add one or more energy release paths in the area where the current-resistant weak point is located, to obtain the target energy release path.

[0042] The distribution unit, connected to the design unit, is used to distribute and release the energy generated by the current in the large-capacity flexible DC converter valve submodule through the target energy release path, so as to complete the energy release distribution for the large-capacity flexible DC converter valve submodule.

[0043] Furthermore, the acquisition unit includes:

[0044] The acquisition module is used to acquire the structural design model of the high-capacity flexible DC converter valve submodule.

[0045] An analysis module, connected to the acquisition module, is used to analyze the initial energy release path of the large-capacity flexible DC converter valve submodule;

[0046] The first construction module, connected to the analysis module, is used to construct an initial simulation model of the initial energy release path based on the structural design model and circuit discharge path of the large-capacity flexible DC converter valve submodule, using circuit simulation software.

[0047] The setting module, connected to the first construction module, is used to set the component parameters of electrical characteristics in the initial simulation model to obtain the first simulation model;

[0048] The first simulation module, connected to the setting module, is used to simulate the current-resistance weakness points of the large-capacity flexible DC converter valve submodule through the first simulation model, thereby obtaining the current-resistance weakness points in the large-capacity flexible DC converter valve submodule.

[0049] Furthermore, the design unit includes:

[0050] The analysis module is used to determine the location of the current-resistant weak point based on the structural design of the large-capacity flexible DC converter valve submodule; and to analyze the current characteristics of the current-resistant weak point under different operating conditions.

[0051] The second construction module, connected to the analysis module, is used to construct a second simulation model, including one or more new corresponding energy release paths, based on the current characteristics and the location of the current resistance weakness.

[0052] The energy release path includes path elements and path topology;

[0053] The path element is a resistor, and / or a capacitor, and / or an inductor, and / or a diode, and / or a switching element, and / or an element that adds a loop path;

[0054] The path topology includes the connection relationships and connection methods of path elements;

[0055] The first evaluation module, connected to the second construction module, is used to analyze the energy release path under different operating conditions based on the second simulation model, and evaluate its improvement effect on current resistance.

[0056] If the improvement effect meets the design requirements, then the corresponding energy release path is determined as the simulated energy release path.

[0057] A connection module, connected to the first evaluation module, is used to connect the path elements according to the path topology based on the simulated energy release path to obtain the target energy release path.

[0058] Furthermore, the allocation unit includes:

[0059] The processing module is used to construct a third simulation model based on various parameters of the large-capacity flexible DC converter valve submodule; and to evaluate the explosion-proof performance of the large-capacity flexible DC converter valve submodule based on the changes in electrical and mechanical performance parameters in the large-capacity flexible DC converter valve submodule.

[0060] The electrical and mechanical performance parameters include current, and / or, electrodynamic force, and / or, stray inductance, and / or, deformation;

[0061] The second simulation module, connected to the processing module, is used to simulate the large-capacity flexible DC converter valve submodule under different operating scenarios based on the explosion-proof performance of the large-capacity flexible DC converter valve submodule, and obtain simulation analysis results.

[0062] An adjustment module, connected to the second simulation module, is used to adjust the energy release path and ratio based on the simulation analysis results and by comparing different energy transfer methods, in order to obtain a target energy allocation scheme.

[0063] The energy transfer methods include consuming energy through parallel or series resistors, and / or storing energy through capacitors, and / or transferring energy through inductors;

[0064] The release module, connected to the adjustment module, is used to release the energy of the large-capacity flexible DC converter valve submodule according to the target energy distribution scheme.

[0065] Thirdly, the present invention provides a flexible DC transmission system, the system comprising:

[0066] High-capacity flexible DC converter valve submodule;

[0067] The energy release and distribution device for the large-capacity flexible DC converter valve submodule described in the second aspect is connected to the large-capacity flexible DC converter valve submodule and is used to optimize energy distribution and release to ensure normal system operation.

[0068] This invention optimizes the energy release path, effectively reducing the damage to the system caused by short-circuit faults while avoiding high protection costs, thereby improving the operational reliability and maintenance convenience of the large-capacity flexible DC converter valve submodule. Specific beneficial effects are as follows:

[0069] 1. Reduced failure risk: This invention, through an optimized energy release path, can quickly disperse and release the energy generated by various faults (including short circuits), reduce the impact of fault current on key system components, and thus reduce the probability of system failure.

[0070] 2. Improved fault tolerance: Even in the event of a short-circuit fault, the system can control the impact of the fault through an effective energy release path, preventing the fault from escalating further and improving the system's fault tolerance.

[0071] 3. Stable system operation: By rationally allocating energy release, this invention ensures stable operation of the system under various working conditions, reduces instability caused by energy fluctuations, and improves the overall reliability of the system.

[0072] 4. Extend equipment life: This invention, through optimized energy release paths, can reduce the burden on equipment under fault conditions, reduce equipment stress and wear, thereby extending equipment life and reducing the frequency of equipment replacement and maintenance.

[0073] 5. Reduced need for protective equipment: This invention can effectively reduce the damage of faults to the system, reduce the need for expensive protective equipment (such as short circuit and overcurrent protection devices, fuses, etc.), and save system construction and maintenance costs.

[0074] 6. Convenient maintenance operation: The optimized energy release path of this invention makes it easier to locate and repair the system when a fault occurs, thereby improving maintenance convenience and reducing maintenance time and labor costs.

[0075] 7. Enhanced fault tolerance of submodules: This invention can enhance the fault tolerance of submodules, reduce downtime, improve system stability, and ensure long-term stable operation. Attached Figure Description

[0076] Figure 1 This is a schematic diagram of an energy release and distribution method for a large-capacity flexible DC converter valve submodule in an embodiment of the present invention;

[0077] Figure 2 This is a schematic diagram of the valve string connection structure in an embodiment of the present invention;

[0078] Figure 3 This is a schematic diagram of the topology connection in an embodiment of the present invention;

[0079] Figure 4 This is a schematic diagram of the discharge current path from D1 to T2 in an embodiment of the present invention;

[0080] Figure 5 This is a schematic diagram of the discharge current path of D3-T4 in an embodiment of the present invention;

[0081] Figure 6 This is a schematic diagram of the discharge current path from T1 to T2 in an embodiment of the present invention;

[0082] Figure 7 This is a schematic diagram of the discharge current path from T3 to T4 in an embodiment of the present invention;

[0083] Figure 8 This is a schematic diagram of the discharge circuit inductor simulation model in an embodiment of the present invention;

[0084] Figure 9This is a schematic diagram of the parallel copper busbars sharing the current in an embodiment of the present invention;

[0085] Figure 10 This is a comparative schematic diagram of the present invention with and without a busbar in an embodiment of the present invention;

[0086] Figure 11 This is a schematic diagram of an energy release and distribution device for a large-capacity flexible DC converter valve submodule in an embodiment of the present invention;

[0087] In the attached figures, the reference numerals are: 10, acquisition unit; 20, design unit; 30, allocation unit. Detailed Implementation

[0088] To enable those skilled in the art to better understand the technical solution of the present invention, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0089] It is understood that the specific embodiments and accompanying drawings described herein are merely for explaining the invention and are not intended to limit the invention.

[0090] It is understood that, without conflict, the various embodiments and features in the embodiments of the present invention can be combined with each other.

[0091] It is understood that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, while the parts unrelated to the present invention are not shown in the drawings.

[0092] It is understood that each unit or module involved in the embodiments of the present invention may correspond to only one entity structure, or may be composed of multiple entity structures, or multiple units or modules may be integrated into one entity structure.

[0093] It is understood that, without conflict, the functions and steps marked in the flowcharts and block diagrams of this invention may occur in a different order than that marked in the accompanying drawings.

[0094] It is understood that the flowcharts and block diagrams of this invention illustrate the possible architecture, functions, and operations of systems, apparatuses, devices, and methods according to various embodiments of this invention. Each block in the flowchart or block diagram may represent a unit, module, program segment, or code, containing executable instructions for implementing the specified function. Furthermore, each block or combination of blocks in the block diagram and flowchart can be implemented using a hardware-based system to achieve the specified function, or using a combination of hardware and computer instructions.

[0095] It is understood that the units and modules involved in the embodiments of the present invention can be implemented by software or by hardware. For example, the units and modules can be located in a processor.

[0096] Example 1:

[0097] This embodiment presents an energy release and distribution method for a large-capacity flexible DC converter valve submodule, which has broad application prospects in several important fields. In large-scale wind and solar grid integration, this method can effectively cope with instantaneous short circuits and current surges, ensuring power balance and stability. In DC power supply systems in urban centers, it optimizes system design, enhances shock resistance, reduces the risk of power outages, and improves user experience. Furthermore, in marine renewable energy projects, this method ensures reliable operation of the converter valve under extreme environments. In electric vehicle charging stations, it helps optimize discharge paths, improving the safety and reliability of charging piles. In power-intensive heavy industries, it reduces the impact of short-circuit currents on equipment, thereby minimizing downtime losses. In high-voltage DC transmission systems, it improves system stability and efficiency, becoming a key supporting technology for future power grids. Simultaneously, in smart distribution networks, optimized energy management schemes can support dynamic response, improving the intelligence and automation level of the entire distribution system.

[0098] like Figure 1 As shown, this embodiment provides an energy release and distribution method for a large-capacity flexible DC converter valve submodule, the method comprising the following steps:

[0099] Step S1: Obtain the structural design of the high-capacity flexible DC converter valve submodule and identify the weak points in the circuit's resistance to current through simulation.

[0100] As a specific implementation method, the weak point in the current resistance of the large-capacity flexible DC converter valve submodule in step S1 is obtained through simulation model;

[0101] Step S1 specifically includes the following steps:

[0102] Step S11: Obtain the structural design model of the large-capacity flexible DC converter valve submodule;

[0103] Step S12: Analyze the initial energy release path of the large-capacity flexible DC converter valve submodule;

[0104] Step S13: Based on the structural design model and circuit discharge path of the large-capacity flexible DC converter valve submodule, a simulation initial model of the initial energy release path is constructed using circuit simulation software;

[0105] Step S14: Set the component parameters of electrical characteristics in the initial simulation model to obtain the first simulation model;

[0106] Step S15: Using the first simulation model, simulate the current resistance weakness of the large-capacity flexible DC converter valve submodule to obtain the current resistance weakness in the large-capacity flexible DC converter valve submodule.

[0107] The simulation model in this embodiment was built using ANSYS and Psim software. These tools (ANSYS and Psim) possess powerful electrical, thermal, and mechanical simulation capabilities, enabling users to comprehensively analyze and evaluate the performance of large-capacity flexible DC converter valve submodules. ANSYS software can simulate current flow, thermal management, and the stability and reliability of materials under various operating conditions; while Psim software focuses on the dynamic simulation of power electronics and electrical systems, enabling real-time analysis and optimization of complex circuits. By using these simulation tools individually or in combination, the performance optimization design of energy release and distribution methods can be effectively supported, and the system response under fault conditions can be studied in depth, providing reliable theoretical basis and technical support for practical applications.

[0108] Step S2: Based on the structural design of the large-capacity flexible DC converter valve submodule, one or more energy release paths are added in the area where the current resistance is weak to obtain the target energy release path.

[0109] As a specific implementation method, step S2 specifically includes the following steps:

[0110] Step S21: Based on the structural design of the large-capacity flexible DC converter valve submodule, determine the location of the current-resistant weak point; and analyze the current characteristics of the current-resistant weak point under different operating conditions.

[0111] In the structural design of high-capacity flexible DC converter valve submodules, critical locations with weak current resistance include electrical contact points (such as solder joints and bolt connections), bends in conductor paths, heat dissipation structures, interfaces of insulating materials, and the mounting location of current transformers. Furthermore, the connection areas between the printed circuit board (PCB) and other modules, the locations of power switching devices (such as IGBTs and MOSFETs), and the placement of overcurrent protection devices are also potentially critical areas with weak current resistance. Therefore, designing and optimizing these locations can effectively improve the current carrying capacity and overall reliability of the converter valve submodule.

[0112] Step S22: Based on the current characteristics and the location of the current-resistant weak point, construct a second simulation model including one or more newly added corresponding energy release paths; the energy release path includes path components and path topology; the path components are resistors, and / or capacitors, and / or inductors, and / or diodes, and / or switching elements, and / or connectors, and / or water-cooled plates; the path topology includes the connection relationship and connection method of the path components.

[0113] Step S23: Based on the second simulation model, analyze the energy release path under different operating conditions and evaluate its improvement effect on current resistance;

[0114] If the improvement effect meets the design requirements, then the corresponding energy release path is determined as the simulated energy release path.

[0115] Step S24: According to the simulated energy release path, connect the path elements according to the path topology to obtain the target energy release path.

[0116] Step S3: Through the target energy release path, the energy generated by the current in the large-capacity flexible DC converter valve submodule is distributed and released to complete the energy release distribution for the large-capacity flexible DC converter valve submodule.

[0117] As a specific implementation method, step S3 involves distributing and releasing the energy generated by the current in the large-capacity flexible DC converter valve submodule through the target energy release path, specifically including the following steps:

[0118] Step S31: Based on various parameters of the large-capacity flexible DC converter valve submodule, construct a third simulation model; and evaluate the explosion-proof performance of the large-capacity flexible DC converter valve submodule according to the changes in electrical and mechanical performance parameters in the large-capacity flexible DC converter valve submodule.

[0119] The electrical and mechanical performance parameters include current, and / or, electrodynamic force, and / or, stray inductance, and / or, deformation;

[0120] Step S32: Based on the explosion-proof performance of the large-capacity flexible DC converter valve submodule, the large-capacity flexible DC converter valve submodule is simulated under different operating scenarios using the third simulation model to obtain simulation analysis results;

[0121] Step S33: Based on the simulation analysis results, by comparing different energy transfer methods, adjust the energy release path and ratio to obtain the target energy allocation scheme;

[0122] The energy transfer methods include consuming energy through parallel or series resistors, and / or storing energy through capacitors, and / or transferring energy through inductors, and / or increasing the loop path;

[0123] Step S34: Release the energy of the large-capacity flexible DC converter valve submodule according to the target energy distribution scheme.

[0124] The first, second, and third simulation models can be different types of simulation systems or multiple modules within the same simulation software. In actual simulation processes, users typically use an integrated simulation software (what designers call a "simulation model"), which is internally divided into multiple specialized modules. Each module performs in-depth analysis and calculations for specific functions or parameters, thereby achieving more comprehensive and accurate simulation results. This flexible modular design enables the simulation software to handle various complex analytical needs, supporting designers in conducting thorough simulations and verifications in different scenarios. This integrated approach not only improves simulation efficiency but also enhances the interoperability between different modules, making the overall simulation process smoother and more efficient.

[0125] This embodiment first identifies the weak points in the current resistance of the large-capacity flexible DC converter valve submodule; then, based on the structural design of the module, one or more energy release paths are added to the identified weak point areas to form target energy release paths; finally, through the target energy release paths, the energy generated by the current in the large-capacity flexible DC converter valve submodule is rationally distributed and released, thereby achieving effective energy release and distribution. It mainly includes the following three parts:

[0126] (1) Design of energy release paths: In the design process of the converter valve submodule in this embodiment, the weak points of the structural design are analyzed, and multiple energy release paths are added at the weak points to allow the current to be dispersed through different release channels when a fault occurs, so as to avoid excessive energy concentration. These release paths include the reasonable planning of the internal circuit and the reasonable layout of the module space.

[0127] (2) Energy Distribution and Release Control Strategy: This embodiment adopts a simulation-based energy distribution control algorithm. By simulating and analyzing the explosion-proof parameters such as current, electrodynamic force, stray inductance, and deformation of each submodule, the energy release path and ratio are rationally designed to ensure that the system can balance the energy release burden on each path. Simulation calculations help determine the optimal impedance matching and release load for each path.

[0128] (3) Low-cost protection design: This embodiment reduces the requirements for mechanical protection by increasing the release path, reducing the thickness or number of protective baffles, and optimizing the connection structure of sub-modules, thereby significantly reducing the overall protection cost of the system. At the same time, the new design improves the system's maintenance and operation convenience.

[0129] In practical implementation, this embodiment can employ a valve string structure. For example... Figure 2As shown, the parallel connection of the upper and lower connecting bars of AC1 and AC2, as well as the negative connecting bar, in the valve string structure is an effective design strategy. By achieving multi-path current diversion, this design can effectively reduce local current and electrodynamic stress, thereby significantly reducing the impact on a single connecting bar. This not only improves the safety and stability of the equipment under explosion-proof conditions but also enhances its operability and reliability. Therefore, to improve system safety, this structure adopts a parallel design of the upper and lower connecting bars of AC1, the upper and lower connecting bars of AC2, and the negative connecting bar. This design has the following advantages:

[0130] 1. Parallel splitting of energy release

[0131] By using parallel connection, the current released during explosion-proof energy release can be distributed through multiple paths. This design ensures that, in the event of discharge or short circuit, the current does not concentrate on a single connector but is evenly distributed across multiple parallel paths. This dispersion effectively reduces the current load on a single connector.

[0132] 2. Reduce local current and electrodynamic stress

[0133] When current flows through multiple parallel paths, the intensity of the local current decreases significantly; this is technically known as the current shunting effect. Furthermore, the electro-stress also decreases. Electro-stress is the effect of the electric field induced by the current; excessive electro-stress can lead to fatigue or damage to the connector material. Through parallel design, the reduction of electro-stress helps extend the service life of the connector and reduces the potential risk of failure.

[0134] 3. Reduce impact on individual connecting rows.

[0135] In explosion-proof conditions, the instantaneous release of energy can cause the equipment to suffer a large current surge. By connecting AC1, AC2, and the negative terminal in parallel, the design effectively prevents surges caused by a concentration of instantaneous current on a single terminal. This redundancy design ensures that, under certain circumstances, no connection path will fail due to excessive current, thereby enhancing the safety of the entire system.

[0136] 4. Enhance system reliability

[0137] Connecting the AC1 and AC2 upper and lower connecting blocks and the negative connecting block in parallel not only enhances the system's resistance to short circuits and overloads but also significantly improves system reliability. It provides a more stable current management scheme in extreme operating conditions or unexpected events, ensuring safe system operation.

[0138] Figure 3This is a topology diagram showing the specific location of the AC branch. It mainly includes: a full-bridge topology, consisting of upper and lower half-bridges composed of four main switches (T1, T2, T3, T4) and corresponding diodes (D1, D2, D3, D4); and AC parallel rows, designed in parallel to ensure that discharge energy is effectively distributed among multiple paths.

[0139] During the charging process of the capacitor through the upper diode, if the lower diode conducts or breaks down due to overvoltage, the upper diode may be damaged during reverse recovery, forming a DT circuit discharge. For example... Figure 4 and Figure 5 As shown, the discharge paths indicated by arrows illustrate the current shunting process of the D1-T2 and D3-T4 circuits. Furthermore, the figure emphasizes the shunting effect, demonstrating the importance of distributing current stress across multiple connectors through multiple release paths to prevent excessive impact on a single connector.

[0140] Figure 4 A schematic diagram of the discharge current path from D1 to T2 is shown. In the full-bridge topology, when the capacitor is charged through D1, the lower diode T2 conducts or breaks down due to overvoltage. After the upper diode is damaged by reverse recovery, it forms a short-circuit discharge loop with T2. The current flows from the positive terminal of the capacitor through D1, then through the AC busbar to T2, and then through the negative busbar to collect at the negative terminal of the capacitor.

[0141] Figure 5 The diagram illustrates the discharge current path from D3 to T4. When the capacitor is charged through D3, the lower diode T4 conducts or breaks down due to overvoltage. After the upper diode fails due to reverse recovery, it forms a short-circuit discharge loop with T4. The current flows from the positive terminal of the capacitor through D3, is shunt to T4 via the AC busbar, and then converges to the negative terminal of the capacitor via the negative busbar.

[0142] During the charging process of the capacitor through the upper diode, if the lower diode conducts or breaks down due to overvoltage, it may also damage the upper IGBT, resulting in a short circuit discharge in the TT circuit. For example... Figure 6 and Figure 7 As shown, the discharge paths indicated by arrows illustrate the current shunting process in the T1-T2 and T3-T4 discharge circuits.

[0143] Specifically Figure 6 The diagram illustrates the discharge current path from T1 to T2. When the capacitor is charged through D1, if the lower transistor T2 is turned on or experiences overvoltage breakdown, the damage to the lower transistor will cause damage to the upper transistor of T1, thus forming a short-circuit discharge loop with T2. At this time, the current flows out from the positive terminal of the capacitor, through T1, then through the AC busbar to T2, and finally through the negative busbar to the negative terminal of the capacitor.

[0144] Figure 7This illustrates the discharge current path from T3 to T4. When the capacitor is charged through D3, if the lower transistor T4 is turned on or experiences overvoltage breakdown, the damage to the lower transistor will cause damage to the upper transistor of T3, forming a short-circuit discharge loop with T4. In this case, the current flows out from the positive terminal of the capacitor, through T3, then through the AC busbar to T4, and finally collects at the negative terminal of the capacitor through the negative busbar.

[0145] Figure 8 This is a schematic diagram of the inductor simulation model of the discharge circuit. The simulation model includes the layout of the inductor components and their connection to the discharge path. This model is used to analyze the current flow characteristics during the discharge process. The inductor components play a role in storing magnetic energy and smoothing current fluctuations, reducing the impact of instantaneous current on the circuit.

[0146] In the specific design of the converter valve submodule, the magnitude of the discharge current is a crucial factor affecting explosion-proof testing. Excessive discharge current not only increases the destructive force of the explosion but also places greater protective pressure on the valve string structure. Therefore, based on the structural protection capacity of the valve string, the acceptable discharge limit current is estimated. Taking into account both the discharge current and the turn-off spike caused by stray inductance during converter circuit shutdown, the stray inductance is controlled below 140nH using ANSYS simulation software. This balances electrical performance with explosion-proof performance.

[0147] Furthermore, designing for electrical stress dispersion is also crucial. While avoiding high protection costs, optimizing energy release paths effectively reduces the damage caused by short-circuit faults to the system, thereby improving the overall operational reliability and maintenance convenience of the converter valve. Specifically, the inductance design of the discharge current path can achieve effective energy distribution, diverting the energy released by the submodule capacitor during a short circuit into multiple different paths, reducing the concentration of local current and electrical stress, thus mitigating the impact on individual parts and optimizing the overall protection effect of the system. For example... Figure 9 As shown, using parallel copper busbars to share the current can effectively reduce the risks caused by current concentration. Furthermore, Figure 9 The exhibition also showcased the application of high-strength pressure plates to further enhance the system's protective capabilities.

[0148] By using a simulation-based energy distribution control algorithm, parameters such as short-circuit shoot-through, electrodynamic force, stray inductance, and deformation of each submodule are analyzed. This allows for the rational design of the energy release sequence and proportion, ensuring a balanced energy release burden across all paths. Simulation calculations help determine the optimal impedance matching and load release for each path. Analysis of the parameter values ​​in the figure and table below shows that by increasing the number of shunt buses (from one AC bus to two AC buses), the single-point strength can be reduced, deformation can be halved, and the electrodynamic force of the AC bus can be reduced from 550kN to 240kN, while the stress-deformation can be reduced from 4.77mm to 2.44mm. Figure 10 As shown, the left side shows the effect of having only one AC row, while the right side shows the effect of having two AC rows.

[0149] This embodiment effectively reduces the damage to the system caused by short-circuit faults by optimizing the energy release path and avoids high protection costs, thereby improving the operational reliability and maintenance convenience of the large-capacity flexible DC converter valve submodule. While ensuring system reliability, it significantly reduces the difficulty and cost of overall protection, improving the system's economy and maintenance convenience. Specifically, this is reflected in the following:

[0150] This embodiment addresses the protection problem of existing large-capacity flexible DC converter valve submodules in explosion-proof testing, proposing a novel protection method based on energy release and distribution. Through the rational distribution of energy during short-circuit faults and the optimized design of the release path, this embodiment not only improves the overall protection effect of the system but also demonstrates several significant technical advantages. Specifically:

[0151] (1) Improved flow path capacity

[0152] By increasing and optimizing energy release paths, this embodiment effectively disperses the concentrated flow of short-circuit current within the submodule, avoiding the situation in existing technologies where current flows through a single channel, thereby reducing the burden on individual current paths. This design makes the electrodynamic force, current density, and heat more uniform in each path, improving the overall withstand capability of the converter valve system and reducing the risk of local overload and damage. Compared with traditional methods that rely on increasing the strength or number of protective baffles, this embodiment achieves more efficient energy conduction by optimizing energy release paths, avoiding excessive impact of short-circuit current on individual components and reducing the risk of submodule deformation due to excessive electrodynamic force.

[0153] (2) Improved stability of the pressure string structure

[0154] In large-capacity flexible DC converter valves, the key to explosion-proof testing lies in the stability of the valve string structure. In existing technologies, the concentrated release of current often leads to uneven stress on the pressure string structure, resulting in mechanical deformation or module failure. This embodiment, however, uses simulation calculations to analyze the current, electrodynamic forces, and deformation characteristics of each path in detail, and optimizes the design to ensure the rational distribution of energy across different channels. This method significantly improves the stability of the pressure string structure, reduces the impact of unbalanced electrical stress between sub-modules, and lowers the mechanical stress caused by module interactions. Compared to existing technologies, this embodiment not only enhances the deformation resistance of the pressure string structure under fault conditions and ensures the stability of the valve string structure, but also reduces the risk of local faults spreading to other modules, thereby improving the overall reliability of the system.

[0155] (3) Reduction in protection costs and complexity

[0156] By rationally designing the energy release path, this embodiment reduces reliance on physical protective facilities (such as protective baffles and connectors). Existing technologies typically enhance the system's resistance to short-circuit faults by increasing the thickness and strength of protective baffles, which undoubtedly increases production costs and maintenance difficulty. In contrast, the optimized design of this embodiment reduces the requirement for mechanical protection strength, specifically in the following ways:

[0157] a) The thickness of the protective baffle is reduced, thereby lowering material costs;

[0158] b) The design of the submodule connectors is simplified, reducing the complexity of system manufacturing and installation.

[0159] Example 2:

[0160] like Figure 11 As shown, this embodiment provides an energy release and distribution device for a large-capacity flexible DC converter valve submodule, the device comprising:

[0161] Acquisition unit 10 is used to acquire the structural design of the large-capacity flexible DC converter valve submodule and identify the weak points in the circuit that are resistant to current through simulation.

[0162] Design unit 20, connected to acquisition unit 10, is used to add one or more energy release paths in the area where the current-resistant weak point is located, to obtain the target energy release path;

[0163] The distribution unit 30, connected to the design unit 20, is used to distribute and release the energy generated by the current in the large-capacity flexible DC converter valve submodule through the target energy release path, so as to complete the energy release distribution for the large-capacity flexible DC converter valve submodule.

[0164] As one specific implementation, the acquisition unit 10 includes:

[0165] The acquisition module is used to acquire the structural design model of the high-capacity flexible DC converter valve submodule.

[0166] An analysis module, connected to the acquisition module, is used to analyze the initial energy release path of the large-capacity flexible DC converter valve submodule;

[0167] The first construction module, connected to the analysis module, is used to construct an initial simulation model of the initial energy release path based on the structural design model and circuit discharge path of the large-capacity flexible DC converter valve submodule, using circuit simulation software.

[0168] The setting module, connected to the first construction module, is used to set the component parameters of electrical characteristics in the initial simulation model to obtain the first simulation model;

[0169] The first simulation module, connected to the setting module, is used to simulate the current-resistance weakness points of the large-capacity flexible DC converter valve submodule through the first simulation model, thereby obtaining the current-resistance weakness points in the large-capacity flexible DC converter valve submodule.

[0170] As one specific implementation method, design unit 20 includes:

[0171] The analysis module is used to determine the location of the current-resistant weak point based on the structural design of the large-capacity flexible DC converter valve submodule; and to analyze the current characteristics of the current-resistant weak point under different operating conditions.

[0172] The second construction module, connected to the analysis module, is used to construct a second simulation model, including one or more new corresponding energy release paths, based on the current characteristics and the location of the current resistance weakness.

[0173] The energy release path includes path elements and path topology;

[0174] The path element is a resistor, and / or a capacitor, and / or an inductor, and / or a diode, and / or a switching element, and / or an element that adds a loop path;

[0175] The path topology includes the connection relationships and connection methods of path elements;

[0176] The first evaluation module, connected to the second construction module, is used to analyze the energy release path under different operating conditions based on the second simulation model, and evaluate its improvement effect on current resistance.

[0177] If the improvement effect meets the design requirements, then the corresponding energy release path is determined as the simulated energy release path.

[0178] A connection module, connected to the first evaluation module, is used to connect the path elements according to the path topology based on the simulated energy release path to obtain the target energy release path.

[0179] As one specific implementation, the allocation unit 30 includes:

[0180] The processing module is used to construct a third simulation model based on various parameters of the large-capacity flexible DC converter valve submodule; and to evaluate the explosion-proof performance of the large-capacity flexible DC converter valve submodule based on the changes in electrical and mechanical performance parameters in the large-capacity flexible DC converter valve submodule.

[0181] The electrical and mechanical performance parameters include current, and / or, electrodynamic force, and / or, stray inductance, and / or, deformation;

[0182] The second simulation module, connected to the processing module, is used to simulate the large-capacity flexible DC converter valve submodule under different operating scenarios based on the explosion-proof performance of the large-capacity flexible DC converter valve submodule, and obtain simulation analysis results.

[0183] An adjustment module, connected to the second simulation module, is used to adjust the energy release path and ratio based on the simulation analysis results and by comparing different energy transfer methods, in order to obtain a target energy allocation scheme.

[0184] The energy transfer methods include consuming energy through parallel or series resistors, and / or storing energy through capacitors, and / or transferring energy through inductors;

[0185] The release module, connected to the adjustment module, is used to release the energy of the large-capacity flexible DC converter valve submodule according to the target energy distribution scheme.

[0186] The apparatus of this embodiment is capable of performing the method in Embodiment 1.

[0187] Example 3:

[0188] This embodiment provides a flexible DC transmission system, the system comprising:

[0189] High-capacity flexible DC converter valve submodule;

[0190] The energy release and distribution device for the large-capacity flexible DC converter valve submodule described in Example 2 is connected to the large-capacity flexible DC converter valve submodule and is used to optimize energy distribution and release to ensure normal system operation.

[0191] This embodiment provides a flexible DC transmission system, consisting of a high-capacity flexible DC converter valve submodule and a corresponding energy release and distribution device. The system is designed to ensure that the converter valve submodule can release energy through one or more alternative paths in the event of a short-circuit fault, thereby withstanding extremely large current surges. This invention guarantees the series stability of the valve assembly, the integrity of the water circuit (or water cooling system), and the short-circuit conduction state of the ports, thus not affecting the normal operation of the system.

[0192] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for energy release and distribution in a large-capacity flexible DC converter valve submodule, characterized in that, The method includes the following steps: Step S1: Obtain the structural design of the high-capacity flexible DC converter valve submodule and identify the weak points in the circuit's resistance to current through simulation; Step S2: Add one or more energy release paths in the area where the current-resistant weak point is located to obtain the target energy release path; Step S3: Through the target energy release path, the energy generated by the current in the large-capacity flexible DC converter valve submodule is distributed and released to complete the energy release distribution for the large-capacity flexible DC converter valve submodule.

2. The energy release and distribution method for a large-capacity flexible DC converter valve submodule according to claim 1, characterized in that, The weak points in the current resistance of the high-capacity flexible DC converter valve submodule in step S1 were obtained through simulation modeling. Step S1 specifically includes the following steps: Step S11: Obtain the structural design model of the large-capacity flexible DC converter valve submodule; Step S12: Analyze the initial energy release path of the large-capacity flexible DC converter valve submodule; Step S13: Based on the structural design model and circuit discharge path of the large-capacity flexible DC converter valve submodule, a simulation initial model of the initial energy release path is constructed using circuit simulation software; Step S14: Set the component parameters of electrical characteristics in the initial simulation model to obtain the first simulation model; Step S15: Using the first simulation model, simulate the current resistance weakness of the large-capacity flexible DC converter valve submodule to obtain the current resistance weakness in the large-capacity flexible DC converter valve submodule.

3. The energy release and distribution method for a large-capacity flexible DC converter valve submodule according to claim 2, characterized in that, The simulation model was built using ANSYS and Psim software.

4. The energy release and distribution method for a large-capacity flexible DC converter valve submodule according to claim 1, characterized in that, Step S2 specifically includes the following steps: Step S21: Based on the structural design of the large-capacity flexible DC converter valve submodule, determine the location of the current-resistant weak point; and analyze the current characteristics of the current-resistant weak point under different operating conditions. Step S22: Based on the current characteristics and the location of the current-resistant weak point, construct a second simulation model including one or more additional corresponding energy release paths; The energy release path includes path elements and path topology; The path elements are resistors, and / or capacitors, and / or inductors, and / or diodes, and / or switching elements, and / or connectors, and / or water-cooled plates; The path topology includes the connection relationships and connection methods of path elements; Step S23: Based on the second simulation model, analyze the energy release path under different operating conditions and evaluate its improvement effect on current resistance; If the improvement effect meets the design requirements, then the corresponding energy release path is determined as the simulated energy release path. Step S24: According to the simulated energy release path, connect the path elements according to the path topology to obtain the target energy release path.

5. The energy release and distribution method for a large-capacity flexible DC converter valve submodule according to any one of claims 1 to 4, characterized in that, In step S3, the energy generated by the current in the large-capacity flexible DC converter valve submodule is distributed and released through the target energy release path, specifically including the following steps: Step S31: Based on various parameters of the large-capacity flexible DC converter valve submodule, construct a third simulation model; and evaluate the explosion-proof performance of the large-capacity flexible DC converter valve submodule according to the changes in electrical and mechanical performance parameters in the large-capacity flexible DC converter valve submodule. The electrical and mechanical performance parameters include current, and / or, electrodynamic force, and / or, stray inductance, and / or, deformation; Step S32: Based on the explosion-proof performance of the large-capacity flexible DC converter valve submodule, the large-capacity flexible DC converter valve submodule is simulated under different operating scenarios using the third simulation model to obtain simulation analysis results; Step S33: Based on the simulation analysis results, by comparing different energy transfer methods, adjust the energy release path and ratio to obtain the target energy allocation scheme; The energy transfer methods include consuming energy through parallel or series resistors, and / or storing energy through capacitors, and / or transferring energy through inductors, and / or increasing the loop path; Step S34: Release the energy of the large-capacity flexible DC converter valve submodule according to the target energy distribution scheme.

6. An energy release and distribution device for a large-capacity flexible DC converter valve submodule, characterized in that, The device includes: The acquisition unit is used to acquire the structural design of the high-capacity flexible DC converter valve submodule and identify the weak points in the circuit that are resistant to current through simulation. The design unit, connected to the acquisition unit, is used to add one or more energy release paths in the area where the current-resistant weak point is located, to obtain the target energy release path. The distribution unit, connected to the design unit, is used to distribute and release the energy generated by the current in the large-capacity flexible DC converter valve submodule through the target energy release path, so as to complete the energy release distribution for the large-capacity flexible DC converter valve submodule.

7. The energy release and distribution device for a large-capacity flexible DC converter valve submodule according to claim 6, characterized in that, The acquisition unit includes: The acquisition module is used to acquire the structural design model of the high-capacity flexible DC converter valve submodule. An analysis module, connected to the acquisition module, is used to analyze the initial energy release path of the large-capacity flexible DC converter valve submodule; The first construction module, connected to the analysis module, is used to construct an initial simulation model of the initial energy release path based on the structural design model and circuit discharge path of the large-capacity flexible DC converter valve submodule, using circuit simulation software. The setting module, connected to the first construction module, is used to set the component parameters of electrical characteristics in the initial simulation model to obtain the first simulation model; The first simulation module, connected to the setting module, is used to simulate the current-resistance weakness points of the large-capacity flexible DC converter valve submodule through the first simulation model, thereby obtaining the current-resistance weakness points in the large-capacity flexible DC converter valve submodule.

8. The energy release and distribution device for a large-capacity flexible DC converter valve submodule according to claim 6, characterized in that, The design unit includes: The analysis module is used to determine the location of the current-resistant weak point based on the structural design of the large-capacity flexible DC converter valve submodule; and to analyze the current characteristics of the current-resistant weak point under different operating conditions. The second construction module, connected to the analysis module, is used to construct a second simulation model, including one or more new corresponding energy release paths, based on the current characteristics and the location of the current resistance weakness. The energy release path includes path elements and path topology; The path element is a resistor, and / or a capacitor, and / or an inductor, and / or a diode, and / or a switching element; The path topology includes the connection relationships and connection methods of path elements; The first evaluation module, connected to the second construction module, is used to analyze the energy release path under different operating conditions based on the second simulation model, and evaluate its improvement effect on current resistance. If the improvement effect meets the design requirements, then the corresponding energy release path is determined as the simulated energy release path. A connection module, connected to the first evaluation module, is used to connect the path elements according to the path topology based on the simulated energy release path to obtain the target energy release path.

9. The energy release and distribution device for a large-capacity flexible DC converter valve submodule according to any one of claims 6 to 8, characterized in that, The allocation unit includes: The processing module is used to construct a third simulation model based on various parameters of the large-capacity flexible DC converter valve submodule; and to evaluate the explosion-proof performance of the large-capacity flexible DC converter valve submodule based on the changes in electrical and mechanical performance parameters in the large-capacity flexible DC converter valve submodule. The electrical and mechanical performance parameters include current, and / or, electrodynamic force, and / or, stray inductance, and / or, deformation; The second simulation module, connected to the processing module, is used to simulate the large-capacity flexible DC converter valve submodule under different operating scenarios based on the explosion-proof performance of the large-capacity flexible DC converter valve submodule, and obtain simulation analysis results. An adjustment module, connected to the second simulation module, is used to adjust the energy release path and ratio based on the simulation analysis results and by comparing different energy transfer methods, in order to obtain a target energy allocation scheme. The energy transfer methods include consuming energy through parallel or series resistors, and / or storing energy through capacitors, and / or transferring energy through inductors, and / or increasing the loop path; The release module, connected to the adjustment module, is used to release the energy of the large-capacity flexible DC converter valve submodule according to the target energy distribution scheme.

10. A flexible DC transmission system, characterized in that, The system includes: High-capacity flexible DC converter valve submodule; The energy release and distribution device for a large-capacity flexible DC converter valve submodule according to any one of claims 6 to 9, wherein the device is connected to the large-capacity flexible DC converter valve submodule and is used to optimize energy distribution and release to ensure normal system operation.

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