Magnet power supply system of Tokamak device

Abstract

The invention relates to the technical field of magnet power supply systems, and discloses a magnet power supply system of a Tokamak device, which comprises a magnet power supply topology of a rechargeable battery, the magnet power supply topology of the rechargeable battery is formed by connecting at least one rechargeable battery pack in series with an H-bridge converter to form a basic module, and the H-bridge converter adopts a controllable semiconductor switch, such as an IGBT (Insulated Gate Bipolar Translator). A four-quadrant operation function is realized, and at least one basic module is connected in series and in parallel to form a rated current value corresponding to each magnet; the plurality of basic modules are connected in series to form a basic unit, and then the plurality of basic units are connected in parallel to form a magnet power supply. According to the invention, the magnet power supply adopts a modular design similar to the technology; large-current output is realized through parallel connection, and high-voltage output of different voltage levels is realized through series connection. Component types are greatly reduced, modular maintenance and operation are realized, and system complexity and operation and maintenance difficulty are greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of magnet power supply systems, and in particular to a magnet power supply system for a tokamak device. Background Art

[0002] The magnetic confinement fusion reactor generates fusion energy by driving the plasma current through a magnet power supply and an auxiliary heating system. The most advanced ITER (International Thermonuclear Experimental Reactor) fusion reactor power supply system has a high peak power operation and requires a large-capacity pulse substation. The superconducting magnet power supply of existing fusion devices mostly adopts a phase-controlled rectifier topology. The auxiliary heating high-voltage power supply has problems such as large heat loss and device voltage limitation. In addition, when facing a power grid failure, the lack of energy storage devices in the high-power converter can easily lead to experiment suspension and equipment damage. With the development of rechargeable battery technology, its performance can meet the needs of fusion reactor power systems.

[0003] For example, the ITER power grid has a short-circuit capacity of 10GVA, a 400kVac substation with a pulse capacity of 500MVA, a steady-state substation capacity of 120MVA, and a total capacity of 620MVA; the total capacity of the high-power four-quadrant converter is 2.2GVA. When the fusion reactor is started, the transient power demand reaches 1000MVA. It is the largest dedicated substation and converter in current scientific research equipment. The magnet power supply reactive power demand of the fusion reactor requires the substation to match the 750MVar reactive compensation and filtering device, making the entire distribution system occupy about 70,000m 2 .

[0004] The greater the fusion power of a fusion reactor, the greater the power of the magnet and auxiliary heating, which requires a larger power supply. Fusion reactor power generation must not only meet its own needs, but also be able to be transmitted to the power grid. Therefore, its power generation must be greater than its own power consumption. For example, EU DEMO will demonstrate a fusion power of 2GW after 2050, generating 500MW of electric power, which is approximately equal to the capacity of the ITER substation. Its magnet and auxiliary heating system capacity is greater than that of ITER. The fusion reactor itself has such a huge power demand that it is still a long way to go for the fusion reactor to be connected to the grid for power generation.

[0005] In the process of studying complex physical systems, each subsystem is interconnected and precisely coordinated, requiring stable power supply. If there is a lightning strike or a power grid failure, the entire distribution network will lose power temporarily. Even if the control system has UPS support, the high-power converter does not have similar energy storage devices to provide power, resulting in abnormal termination of the experimental device, which causes irreversible damage to some core components or causes significant financial losses. This is an unavoidable problem in the current scientific research process.

[0006] To this end, the present invention proposes a magnet power supply system for a Tokamak device. Summary of the invention

[0007] An object of the present invention is to provide a magnet power supply system for a Tokamak device, so as to solve at least one technical problem raised in the background technology.

[0008] An embodiment of the present application provides a magnet power supply system for a tokamak device, including a magnet power supply topology of a rechargeable battery, wherein the magnet power supply topology of the rechargeable battery is composed of at least one rechargeable battery pack connected in series with an H-bridge converter to form a basic module, the H-bridge converter adopts a controllable semiconductor switch, such as an IGBT, to achieve a four-quadrant operation function, and at least one of the basic modules is connected in series and in parallel to form a rated current value corresponding to each magnet; multiple basic modules can be connected in series to form a basic unit, and multiple basic units can be connected in parallel to form a magnet power supply.

[0009] Furthermore, the rechargeable battery pack is composed of a plurality of battery cells connected in series, and the battery cells are selected to have a preset discharge capacity. Battery packs with voltage levels from hundreds of volts to thousands of volts are generated by connecting different numbers of battery cells in series to meet the voltage requirements of different magnet power sources.

[0010] Furthermore, the magnet power supply system also includes a control module, which is topologically connected to the magnet power supply of the rechargeable battery to realize the conversion of electric energy and the four-quadrant operation control of the magnet power supply system, ensuring that the magnet current and voltage can be adjusted as needed under different working conditions to control the plasma configuration.

[0011] Furthermore, it also includes a safety monitoring and emergency handling module for monitoring the battery status in the rechargeable battery pack, and performing real-time detection, analysis and early warning of electrical abuse through the battery management system.

[0012] Furthermore, it also includes a power grid connection interface, which is equipped with an intelligent switching device. When the external power grid is normal, it chooses whether to obtain electricity from the power grid as needed. When the power grid fluctuates or there is a short-term power outage, it automatically cuts off the connection with the power grid. It is independently powered by a rechargeable battery pack, and the power grid connection interface has an electromagnetic compatibility design to reduce electromagnetic interference.

[0013] Furthermore, the magnet power supply system can be applied to tokamak devices with different fusion power scales. By adjusting the number of rechargeable battery packs and the series and parallel combinations of H-bridge converters, the power requirements of different magnets and auxiliary heating systems can be adapted, so that the fusion reactor device can be transformed from high-energy consumption operation to one that can achieve net power output.

[0014] Compared with the prior art, the technical solution of this application has the following beneficial effects:

[0015] The magnet power supply of this application adopts a modular design of similar technology. High voltage output of different voltage levels is achieved through series connection, and high current output is achieved through parallel connection. The number of component types is greatly reduced, and modular maintenance and operation are carried out, which greatly reduces the complexity of the system and the difficulty of operation and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0017] Figure 1 This is a topological schematic diagram of a magnet power supply system of a tokamak device of the present invention. DETAILED DESCRIPTION

[0018] See also Figure 1 , N and M are identifiers, x is a natural number, and 1≤x, y is a natural number, and 1≤y, the present invention provides a technical solution: a magnet power supply system of a tokamak device, including a magnet power supply topology of a rechargeable battery, the magnet power supply topology of the rechargeable battery is composed of at least one rechargeable battery pack connected in series with an H-bridge converter to form a basic module, the H-bridge converter adopts a controllable semiconductor switch, such as IGBT, to achieve a four-quadrant operation function, at least one of the basic modules is connected in series and in parallel to form a rated current value corresponding to each magnet; multiple basic modules can be connected in series to form a basic unit, and multiple basic units can be connected in parallel to form a magnet power supply.

[0019] In a specific embodiment of the present invention, the rechargeable battery pack is composed of a plurality of battery cells connected in series. The battery cells are selected to have a preset discharge capacity. Battery packs with voltage levels from hundreds to thousands of volts are generated by connecting different numbers of battery cells in series to meet the voltage requirements of different magnet power sources.

[0020] In a specific embodiment of the present invention, the magnet power supply system also includes a control module, which is topologically connected to the magnet power supply of the rechargeable battery to realize the conversion of electric energy and the four-quadrant operation control of the magnet power supply system, ensuring that the magnet current and voltage can be adjusted as needed under different working conditions to control the plasma configuration.

[0021] In a specific embodiment of the present invention, a safety monitoring and emergency processing module is also included to monitor the battery status in the rechargeable battery pack and perform real-time detection, analysis and early warning of electrical abuse through a battery management system.

[0022] In a specific embodiment of the present invention, it also includes a grid connection interface, which is provided with an intelligent switching device. When the external grid is normal, it selects whether to obtain electric energy from the grid as needed, and automatically cuts off the connection with the grid when the grid fluctuates or there is a short-term power outage. The grid connection interface is independently powered by a rechargeable battery pack, and the grid connection interface has an electromagnetic compatibility design to reduce electromagnetic interference.

[0023] In a specific embodiment of the present invention, the magnet power supply system can be applied to tokamak devices of different fusion power scales. By adjusting the number of rechargeable battery packs and the series and parallel combinations of H-bridge converters, the power requirements of different magnets and auxiliary heating systems can be adapted, so that the tokamak device can be transformed from high-energy consumption operation to one that can achieve net power output.

[0024] The present invention is specifically:

[0025] The current technological development of rechargeable batteries has greatly improved the power density and energy density. For example, the energy storage density of commercial lithium-ion batteries is 250Wh / kg, the output current of a single cell is greater than 300Ah, and a single battery pack is 2kV. For pulse operation of more than a minute level and discharge of more than 3C, a single battery pack can achieve a pulse output of 2kV 900A. For 100kA-level power supplies, the demand can be met by connecting battery packs in parallel.

[0026] The energy capacity required for the tokamak superconducting magnet is too large, and conventional UPS cannot achieve this function, and the mechanical energy storage capacity is insufficient. The technical parameters of rechargeable batteries are already suitable for the maximum power load requirements of fusion power sources from milliseconds to hours. For example, lithium-ion batteries can be cycled 6,000 times, meeting the total duration of ITER of 6,000 hours. Lithium-ion energy storage far exceeds magnet energy storage, and there is no resistance loss on the converter and grid lines. The energy utilization efficiency is better than that of traditional converter structures, and the capacity of the grid can be greatly reduced.

[0027] Upgrading from a 4-quadrant traditional converter structure to a lithium-ion battery power supply can simplify the converter structure. New topologies such as Figure 1 As shown: A lithium-ion battery pack is connected in series with an H-bridge to form a basic module. The rated voltage of the battery pack is E. For example, E can be set to 1.35 kVdc, which is similar to the voltage of the ITER magnet power module. The output current is 3C I0. Multiple modules are connected in parallel to form the rated current value of each coil I rate , the number of modules in parallel N = I rate / I0. The H-bridge uses controllable semiconductor switches, such as IGBT, so that a 4-quadrant operation function can be achieved with an H-bridge converter, and zero crossing can be smoothed. When high output voltage is required, the modules can be connected in series to reach the rated voltage, and then in parallel to generate the rated current. Analysis and design of power supply parameters:

[0028] The energy storage of lithium-ion batteries is much greater than that of coils, and can be used for a long time after a single charge. For example, a set of 1.35k 22.7kAh lithium batteries has an energy storage of 89.4GJ, which is greater than the energy storage of all magnet coils. For example, using a commercial product 166Ah NCM battery cell, 3C discharge, that is, the output current is 498A; the rated current capacity of the lithium battery pack is equal to 1 / 3 of the magnet current. Multiple cells in series generate 0.9 ～ The battery pack has a voltage level of 1.35kV. The battery pack and the H-bridge form a power module with the same structure. Multiple modules are connected in parallel to form the power supply for all magnets.

[0029] Each battery pack is electrically independent of each other and connected in parallel through an H bridge. In the initial state, the charger charges all modules of a set of power supplies in parallel at the same time, so the voltage of each power module is the same in the initial state. The battery pack is composed of hundreds of cells in series, and the difference in internal resistance can be adjusted during the production stage so that the overall internal resistance of each battery pack is within the allowable range. The internal resistance voltage of the battery pack accounts for about 2-3% of the battery voltage, and the lead resistance is much smaller than this value and can be ignored. In addition, lithium batteries are energy storage components, and SOC is related to voltage. If the output current of one of the modules is too large, more energy will be consumed, which makes the voltage of the battery pack lower than that of other modules, reducing the current, thereby achieving current balancing in each branch, and the principle of current balancing during the charging process is the same. Therefore, the current balancing of this solution can be solved by its own internal resistance. Even if the current of one of the modules is too large, the consistency of the output current of each module can be adjusted by changing the number of module cells during the debugging stage.

[0030] The reason why the magnet power supply capacity is huge is the demand for plasma control. The lithium battery power supply can provide rated power at the minute level, and the power supply can be disconnected from the power grid. The power loss of the entire power supply is only the ohmic heat loss and the energy coupled to the plasma by the magnetic field. The energy coupled to the plasma current by the ohmic coil is very small, concentrated in the plasma climbing stage, and the flat top stage is mainly the energy injected into the plasma by the auxiliary heating system. Therefore, the lithium battery capacity does not take into account the coupling loss of the ohmic field coil.

[0031] The maximum ohmic heat loss of ITER's total magnet power supply is its bus resistance. Calculated according to the maximum current, the maximum total power is about 41MW. When operating at a duty cycle of 0.25, the charger power is 1 / 3 of the heat loss power, that is, the total charger power is 41 / 3 = 13.7MW. If the fusion reactor runs continuously for 24 hours, the lithium battery power supply can be designed as an online charging mode, using a high-voltage isolation charger to charge each magnet power supply independently, and the maximum charging power is 41MW. The maximum power of ITER's magnet power supply exceeds 600MW. After using lithium batteries for power supply, the power demand of the power grid is reduced by more than 10 times.

[0032] The power supply capacity of the ITER substation using lithium battery power is shown in Table 1; it drops from 620MW in the current topology to 219MW. If ITER is to operate fusion power generation 24 hours a day in the future and auxiliary heating is only used for ignition, the power supply capacity is 173.8MW.

[0033] According to this grid capacity, the new topology eliminates ITER's 400kVac high-voltage grid, 1000MVAr reactive power, and filtering problems, and only 110kVac substation capacity is required.

[0034] Table 1 Capacity of ITER substation using rechargeable battery power supply

[0035]

[0036] Lithium battery fires are mainly caused by thermal runaway. There are three reasons for thermal runaway: mechanical abuse, electrical abuse and temperature abuse. For power battery packs, only electrical abuse is considered. There are three factors of electrical abuse: overcharging, overdischarging and internal short circuit. Overcharging and overdischarging are controlled by the battery management system (BMS) to make the battery state of charge (SOC) operate within the range of 1% to 99%. Under normal conditions, the battery pack voltage is detected to determine the power, thereby avoiding the uncertainty caused by the load SOC algorithm. The charging voltage is lower than the maximum operating voltage, and the discharge voltage is higher than the minimum operating voltage. For example, a 5% margin is reserved. If the internal short circuit is caused by a manufacturing defect, it can be found by factory inspection. If it gradually develops into an internal short circuit during use, heat and gas will be generated inside the battery, causing the battery cell to heat up and expand. Through temperature and shell deformation detection, it can be handled in time to avoid fire. Since battery thermal runaway is a slow-developing process, it can be judged in advance and handled in time using existing technical conditions. The specific method is to develop and design a BMS system for power supply to detect, analyze and warn of various status information of the battery pack to ensure that the battery pack is removed before the battery cell safety valve opens.

[0037] If the fault continues to develop, the safety valve of the battery cell will open and burn. Water spraying is required to extinguish the fire, and the exhaust system should work at the same time to prevent the accumulation of combustible gas and explosion. For fires in ultra-high voltage power supplies, lithium iron phosphate batteries can be considered to increase safety performance and reduce fire risks. Develop automatic dismantling robots to complete the automatic dismantling of faulty modules to ensure that the faulty modules can still be solved when personnel are prohibited from approaching. At the same time, automatic inspection robots can be developed with temperature, gas and smoke detection functions to provide early warning and reduce fire risks.

[0038] ITER magnet power supply adopts 20th century topology, requiring large-capacity power grid, and large-capacity reactive power compensation and filtering devices. More than 40 years have passed, and the progress of rechargeable battery technology in the electrical field has brought innovation to the topology of power supply systems in the fusion field. This application analyzes and designs the new lithium battery structure power supply of the superconducting magnet power supply system. The new topology has huge advantages: 1) The magnet power supply adopts a modular design of similar technology, and achieves large current output through parallel connection. 2) The number of components is greatly reduced, and modular maintenance and operation greatly reduce the complexity and difficulty of operation and maintenance. 3) The area occupied by the distribution system (including reactive power compensation and filtering devices) is reduced by 10 times compared with ITER, the distribution network voltage is reduced from 400kVac to 110kVac, and the grid capacity is also reduced by more than 1 times; 4) The lithium-ion power supply can also realize the net power input of the 2GW fusion power of the next-generation DEMO into the power grid, solving the problem that the power generation of the next-generation fusion reactor in the current design is lower than its own consumption, and accelerating the arrival of commercial fusion reactors.

[0039] The above is only a preferred specific implementation of the present invention; however, the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solution and its improved conception within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A magnet power supply system for a tokamak device, characterized in that: A magnet power supply topology including a rechargeable battery, wherein the magnet power supply topology includes at least one rechargeable battery pack connected in series with an H-bridge converter to form a basic module, the H-bridge converter uses a controllable semiconductor switch, at least one of the basic modules is connected in series and in parallel to form a rated current value corresponding to each magnet; a plurality of the basic modules can be connected in series to form a basic unit, and a plurality of the basic units can be connected in parallel to form a magnet power supply.

2. The magnet power supply system of a tokamak device according to claim 1, characterized in that: The rechargeable battery pack is composed of a plurality of battery cells connected in series. The battery cells are selected to have a preset discharge capacity. Battery packs with voltage levels ranging from several hundred to several kilovolts are generated by connecting different numbers of battery cells in series to meet the voltage requirements of different magnet power sources.

3. The magnet power supply system of a tokamak device according to claim 1, characterized in that: The magnet power supply system also includes a control module, which is topologically connected to the magnet power supply of the rechargeable battery to realize the conversion of electric energy and the four-quadrant operation control of the magnet power supply system, ensuring that the magnet current and voltage can be adjusted as needed under different working conditions to control the plasma configuration.

4. The magnet power supply system of a tokamak device according to claim 1, characterized in that: It also includes a safety monitoring and emergency handling module for monitoring the battery status in the rechargeable battery pack and performing real-time detection, analysis and early warning of electrical abuse through the battery management system.

5. The magnet power supply system of a tokamak device according to claim 1, characterized in that: It also includes a grid connection interface, which is equipped with an intelligent switching device. When the external grid is normal, it chooses whether to obtain electricity from the grid as needed. When the grid fluctuates or there is a short-term power outage, the connection with the grid is automatically cut off. The grid connection interface is independently powered by a rechargeable battery pack, and the grid connection interface has an electromagnetic compatibility design to reduce electromagnetic interference.

6. The magnet power supply system of a tokamak device according to claim 5, characterized in that: The magnet power supply system can be applied to tokamak devices of different fusion power scales. By adjusting the number of rechargeable battery packs and the parallel and series combinations of H-bridge converters, the power requirements of different magnet systems can be adapted, so that the fusion reactor device can be transformed from high-energy consumption operation to one that can achieve net power output.

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