A sealed integrated high-voltage direct-current circuit breaker and a high-voltage direct-current power transmission system

Abstract

This application provides a sealed integrated high-voltage direct current (HVDC) circuit breaker and a HVDC transmission system, relating to the field of HVDC transmission technology. At least the fast-acting mechanical switch, reactor, high-speed closing switch, and surge arrester are each encapsulated in an independent sealed housing filled with insulating gas. This improves the insulation and sealing performance of each component, enhances their electromagnetic interference immunity, and mitigates the impact of environmental factors such as pollution, humidity, salt spray, and temperature differences. This also improves the insulation performance, breaking sensitivity, reliability, and service life of the HVDC circuit breaker components. By improving the insulation and sealing performance of the components, a compact and integrated design of all components is possible, thereby reducing the assembly difficulty and commissioning cycle of the HVDC circuit breaker, minimizing the footprint, and addressing the problems of high maintenance costs and low maintenance efficiency caused by dispersed components.

Description

Technical Field

[0001] This application relates to the field of high voltage direct current (HVDC) transmission technology, and more specifically, to a sealed integrated HVDC circuit breaker and a HVDC transmission system. Background Technology

[0002] The energy structure is rapidly shifting towards cleaner and lower-carbon energy sources, with wind power and solar power achieving large-scale centralized and distributed grid connection. Furthermore, with the continuous development of long-distance, inter-regional ultra-high-voltage direct current (UHVDC) transmission technology, the construction of flexible DC grids is entering a phase of accelerated development. UHVDC transmission technology, with its significant advantages such as large transmission capacity, low line loss, flexible control, and no synchronization stability issues, has become a core technological support for solving the current problem of reverse distribution of energy resources and load centers, and for improving the absorption capacity of new energy sources.

[0003] High-voltage direct current (HVDC) circuit breakers, as indispensable core protection and control equipment in DC transmission systems and DC grids, bear the critical responsibilities of long-term stable carrying of rated DC current during normal system operation, millisecond-level rapid interruption of short-circuit fault current under fault conditions, precise isolation of fault areas, prevention of fault propagation, and ensuring the safe and stable operation of non-faulty areas of the grid. Their breaking speed, reliability, environmental adaptability, and degree of integration directly determine the power supply reliability, operational safety, and engineering construction economy of DC transmission systems, making them one of the key pieces of equipment restricting the large-scale development of DC grids. However, the poor sealing performance of current HVDC circuit breakers not only affects the service life of the devices but also hinders the trend towards device integration. Summary of the Invention

[0004] In view of this, this application provides a sealed integrated high-voltage DC circuit breaker and a high-voltage DC transmission system, which effectively solves the existing technical problems, improves the insulation and sealing performance of each component in the high-voltage DC circuit breaker, ensures the long service life of the high-voltage DC circuit breaker, and is conducive to the development trend of high-voltage DC circuit breaker integration.

[0005] To achieve the above objectives, the technical solution provided in this application is as follows:

[0006] A sealed integrated high-voltage DC circuit breaker, the high-voltage DC circuit breaker comprising: a main current-carrying branch, a converter branch, and an energy absorption branch, wherein the main current-carrying branch, the converter branch, and the energy absorption branch are electrically connected in parallel;

[0007] When the main current-carrying branch includes at least one fast mechanical switch, and when the main current-carrying branch includes at least two fast mechanical switches, all the fast mechanical switches are connected in series.

[0008] The converter branch includes a reactor, a capacitor and at least one high-speed closing switch. When the converter branch includes at least two high-speed closing switches, all the high-speed closing switches are connected in series, and the reactor, the capacitor and the high-speed closing switch are connected in series.

[0009] When the energy absorption branch includes at least one surge arrester, and when the energy absorption branch includes at least two surge arresters, all surge arresters are connected in series.

[0010] Among the fast mechanical switch, the reactor, the capacitor, the high-speed closing switch, and the surge arrester, at least the fast mechanical switch, the reactor, the high-speed closing switch, and the surge arrester are respectively encapsulated in mutually independent sealed housings, and the sealed housings are filled with insulating gas.

[0011] Optionally, any one of the fast mechanical switch, the reactor, the capacitor, the high-speed closing switch, and the surge arrester may be encapsulated in an independent sealed housing, and the sealed housing may be filled with the insulating gas.

[0012] Optionally, the spacing between two adjacent sealing housings is 300-500 mm.

[0013] Optionally, the sealing housing may include a metal sealing housing or an alloy sealing housing.

[0014] Optionally, the insulating gas includes at least one of sulfur hexafluoride, nitrogen, perfluoroisobutyronitrile, and insulating air, wherein the dew point of the insulating air is not greater than -40°C.

[0015] Optionally, in at least one of the main flow branch, the converter branch, and the energy absorption branch, the sealed housings corresponding to the electrical connection components are connected by a closed busbar or a tubular busbar.

[0016] Optionally, the reactor and the capacitor are arranged adjacent to each other;

[0017] The fast mechanical switch and the high-speed closing switch are arranged along the adjacent structural direction surrounding the reactor and the capacitor.

[0018] Optionally, the surge arrester is adjacent to at least one of the reactor and the capacitor, and is disposed in the area surrounding the fast mechanical switch and the high-speed closing switch;

[0019] Alternatively, the surge arrester may be located on the side of the fast mechanical switch or the high-speed closing switch away from the adjacent structure of the reactor and the capacitor.

[0020] Optionally, the surge arrester includes a metal oxide surge arrester.

[0021] Based on the same inventive concept, this application also provides a high-voltage direct current transmission system, which includes the above-mentioned sealed integrated high-voltage direct current circuit breaker.

[0022] Compared with existing technologies, the technical solution provided in this application has at least the following advantages:

[0023] This application provides a sealed integrated high-voltage direct current (HVDC) circuit breaker and a HVDC transmission system. The HVDC circuit breaker includes a main current-carrying branch, a converter branch, and an energy absorption branch, wherein the main current-carrying branch, the converter branch, and the energy absorption branch are connected in parallel. The main current-carrying branch includes at least one fast-acting mechanical switch, and when the main current-carrying branch includes at least two fast-acting mechanical switches, all the fast-acting mechanical switches are connected in series. The converter branch includes a reactor, a capacitor, and at least one high-speed closing switch, and when the converter branch includes at least two high-speed closing switches... All the high-speed closing switches are connected in series, and the reactor, the capacitor, and the high-speed closing switch are connected in series; when the energy absorption branch includes at least one surge arrester, and when the energy absorption branch includes at least two surge arresters, all the surge arresters are connected in series; wherein, among the fast mechanical switch, the reactor, the capacitor, the high-speed closing switch, and the surge arrester, at least the fast mechanical switch, the reactor, the high-speed closing switch, and the surge arrester are respectively encapsulated in mutually independent sealed housings, and the sealed housings are filled with insulating gas.

[0024] As described above, the technical solution provided in this application encapsulates the fast mechanical switch, reactor, high-speed closing switch, and surge arrester in separate, sealed housings filled with insulating gas. This improves the insulation and sealing performance of each component in the high-voltage DC circuit breaker, thereby enhancing their electromagnetic interference resistance and mitigating their susceptibility to environmental factors such as pollution, humidity, salt spray, and temperature differences. It also improves the insulation performance, breaking sensitivity, reliability, and service life of the high-voltage DC circuit breaker components, meeting the stringent requirements of high-voltage DC transmission systems for rapid fault interruption. Furthermore, by improving the insulation and sealing performance of the components, it facilitates a compact and integrated design of all components in the high-voltage DC circuit breaker, reducing assembly difficulty and commissioning cycle, minimizing the footprint of the high-voltage DC circuit breaker, and addressing the issues of high maintenance costs and low maintenance efficiency caused by the dispersed nature of the components. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0026] Figure 1 A topology diagram of a sealed integrated high-voltage DC circuit breaker provided in this application embodiment;

[0027] Figure 2 A schematic diagram of a sealed integrated high-voltage DC circuit breaker provided in this application embodiment;

[0028] Figure 3 A schematic diagram of another sealed integrated high-voltage DC circuit breaker provided in this application embodiment.

[0029] Explanation of reference numerals in the attached figures:

[0030] 1. Surge arrester;

[0031] 2. Fast mechanical switches;

[0032] 3. Reactors;

[0033] 4 capacitors;

[0034] 5. High-speed closing switch. Detailed Implementation

[0035] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0036] As described in the background section, the current energy structure is rapidly shifting towards cleaner and lower-carbon energy sources, with wind power and photovoltaics achieving large-scale centralized and distributed grid connection. Furthermore, with the continuous development of long-distance, inter-regional ultra-high-voltage direct current (UHVDC) transmission technology, the construction of flexible DC grids is entering a phase of rapid acceleration. UHVDC transmission technology, with its significant advantages such as large transmission capacity, low line loss, flexible control, and no synchronization stability issues, has become a core technological support for solving the current problem of reverse distribution of energy resources and load centers, and for improving the absorption capacity of new energy sources.

[0037] High-voltage direct current (HVDC) circuit breakers, as indispensable core protection and control equipment in DC transmission systems and DC grids, bear the critical responsibilities of long-term stable carrying of rated DC current during normal system operation, millisecond-level rapid interruption of short-circuit fault current under fault conditions, precise isolation of fault areas, prevention of fault propagation, and ensuring the safe and stable operation of non-faulty areas of the grid. Their breaking speed, reliability, environmental adaptability, and degree of integration directly determine the power supply reliability, operational safety, and engineering construction economy of DC transmission systems, making them one of the key pieces of equipment restricting the large-scale development of DC grids. However, the poor sealing performance of current HVDC circuit breakers not only affects the service life of the devices but also hinders the trend towards device integration.

[0038] Specifically, existing high-voltage DC circuit breakers generally adopt a distributed, open, or platform-based layout, with their different components independently installed on outdoor platforms or in valve halls, connected by open rigid busbars. This layout presents significant technical problems: First, the components are directly exposed to the external environment, making them susceptible to pollution, humidity, salt spray, temperature differences, and other environmental factors. This also weakens their electromagnetic interference resistance, leading to a significant reduction in insulation and lifespan. Second, the open busbar connection results in large stray inductance, directly affecting the breaking speed and reliability of the high-voltage DC circuit breaker, making it difficult to meet the stringent requirements of high-voltage DC transmission systems for rapid fault interruption. Third, the open layout disperses the components, resulting in a large footprint, low space utilization, and difficulty in adapting to the miniaturized and compact construction needs of DC projects. It also increases the difficulty of component assembly and the commissioning cycle, leading to high maintenance costs and low maintenance efficiency due to the dispersed components.

[0039] Based on this, the present application provides a sealed integrated high-voltage DC circuit breaker and a high-voltage DC transmission system, which effectively solves the existing technical problems, improves the insulation and sealing of each component in the high-voltage DC circuit breaker, ensures the long service life of the high-voltage DC circuit breaker, and is conducive to the development trend of high-voltage DC circuit breaker integration.

[0040] To achieve the above objectives, the technical solutions provided in this application are as follows, in specific combination with... Figures 1 to 3 The technical solutions provided in the embodiments of this application will be described in detail.

[0041] Combination Figure 1 and Figure 2 As shown, Figure 1 A topology diagram of a sealed integrated high-voltage DC circuit breaker provided in this application embodiment. Figure 2This is a schematic diagram of a sealed integrated high-voltage DC circuit breaker provided in an embodiment of this application. The sealed integrated high-voltage DC circuit breaker provided in this embodiment can be a mechanical high-voltage DC circuit breaker. Mechanical high-voltage DC circuit breakers rely on mechanical switches in conjunction with an oscillating circuit to achieve forced zero-crossing interruption of DC current, possessing advantages such as low current loss, fast interruption speed, and high reliability. The high-voltage DC circuit breaker provided in this embodiment includes: a main current-carrying branch, a converter branch, and an energy absorption branch. The main current-carrying branch, the converter branch, and the energy absorption branch are connected in parallel, and are connected in parallel between the positive and negative buses in the high-voltage DC transmission system. The main current-carrying branch includes at least one fast mechanical switch 2. All fast mechanical switches 2 correspond to the identifier MS in the topology diagram. When the main current-carrying branch includes at least two fast mechanical switches 2, all fast mechanical switches 2 are connected in series, and the series connection of the fast mechanical switches 2 is connected between the positive and negative buses. The converter branch includes a reactor 3, a capacitor 4, and at least one high-speed closing switch 5. The reactor 3 corresponds to the symbol L in the topology diagram, the capacitor 4 corresponds to the symbol C, and all high-speed closing switches 5 correspond to the symbol K1. When the converter branch includes at least two high-speed closing switches 5, all high-speed closing switches 5 are connected in series. The reactor 3, the capacitor 4, and the high-speed closing switches 5 are also connected in series, and the series connection is between the positive and negative busbars. The energy absorption branch includes at least one surge arrester 1. All surge arresters 1 correspond to the symbol MOV in the topology diagram. When the energy absorption branch includes at least two surge arresters 1, all surge arresters 1 are connected in series, and the series connection is between the positive and negative busbars. Among the fast mechanical switch 2, the reactor 3, the capacitor 4, the high-speed closing switch 5, and the surge arrester 1, at least the fast mechanical switch 2, the reactor 3, the high-speed closing switch 5, and the surge arrester 1 are respectively encapsulated in mutually independent sealed housings, and the sealed housings are filled with insulating gas.

[0042] It should be noted that the high-voltage DC circuit breaker provided in this application embodiment is a core protection device for DC transmission systems and DC power grids. It is used to carry the rated DC current during normal system operation and to quickly interrupt the DC fault current when a fault occurs, isolating the fault area and ensuring the safe and stable operation of the system. The main current-carrying branch is composed of a fast mechanical switch 2 connected in series between the positive and negative busbars. It is the main current channel during normal system operation, carrying the rated DC current of the system, and undertaking the initial breaking action under fault conditions. The fast mechanical switch 2 has millisecond-level fast breaking capability, carrying the rated current during normal operation, and completing the breaking action after the current crosses zero under fault conditions, achieving electrical isolation. The converter branch consists of reactor 3, capacitor 4, and high-speed closing switch 5 connected in series. The series circuit is connected in parallel with the main current-carrying branch and is the core component for realizing DC current commutation. When a fault is triggered, the high-speed closing switch 5 closes, and the LC oscillation circuit composed of reactor 3 and capacitor 4 generates an oscillating current that is opposite to the current in the main current-carrying branch, quickly commutating the current in the main current-carrying branch to the energy absorption branch, realizing zero-current disconnection of the main switch. The high-speed closing switch 5 is the core control element of the converter branch, with microsecond-level fast closing capability. When a fault occurs, it quickly closes to trigger the LC oscillation circuit, providing the triggering conditions for the commutation process. The energy absorption branch is composed of surge arrester 1 connected in parallel to both ends of the main current-carrying branch. During the fault interruption process, it limits the overvoltage amplitude of the system, absorbs the fault energy of the system, and protects the main switch and other core components from electrical shock. Surge arrester 1 is the core component of the energy absorption branch. It has excellent nonlinear volt-ampere characteristics. It is in a high-resistance state during normal operation and quickly switches to a low-resistance state under overvoltage during a fault, dissipating fault energy and limiting overvoltage.

[0043] Understandably, the technical solution provided in this application encapsulates at least the fast mechanical switch 2, reactor 3, high-speed closing switch 5, and surge arrester 1 in independent sealed housings filled with insulating gas. This improves the insulation and sealing performance of each component in the high-voltage DC circuit breaker, completely isolating the fast mechanical switch 2, reactor 3, high-speed closing switch 5, and surge arrester 1 from the external environment. This enhances the components' resistance to electromagnetic interference, mitigates the impact of environmental factors such as pollution, humidity, salt spray, and temperature differences, and improves the insulation performance, breaking sensitivity, reliability, operational stability, and service life of the high-voltage DC circuit breaker, meeting the stringent requirements of high-voltage DC transmission systems for rapid fault interruption. Furthermore, by improving the insulation and sealing performance of the components, it facilitates a compact and integrated design of all components in the high-voltage DC circuit breaker, thereby reducing the assembly difficulty and commissioning cycle, minimizing the footprint of the high-voltage DC circuit breaker, and addressing the issues of high maintenance costs and low maintenance efficiency caused by the dispersed nature of the components. In addition, the surge arrester 1, fast mechanical switch 2, reactor 3, capacitor 4 and high-speed closing switch 5 in the high voltage DC circuit breaker can be repaired and faulty components can be replaced individually without disassembling the whole equipment, which further reduces the assembly difficulty and operation and maintenance efficiency.

[0044] Furthermore, in the embodiments of this application, any one of the fast mechanical switch 2, the reactor 3, the capacitor 4, the high-speed closing switch 5, and the surge arrester 1 is encapsulated in an independent sealed housing, and the sealed housing is filled with the insulating gas. That is, the technical solution provided in the embodiments of this application encapsulates the core functional components—surge arrester 1, fast mechanical switch 2, reactor 3, capacitor 4, and high-speed closing switch 5—independently in sealed housings, and fills the sealed housings with insulating gas to form an insulating environment, constituting a gas-insulated closed system. This further solves the technical problems of existing high-voltage DC circuit breakers, such as dispersed component layout, large footprint, poor sealing, weak electromagnetic interference resistance, difficult assembly, and high maintenance costs, thereby adapting to the miniaturized, high-reliability operation and construction requirements of high-voltage DC transmission systems.

[0045] In some embodiments, the spacing between two adjacent sealing housings provided in this application is 300-500 mm, thereby reducing the footprint of the high-voltage DC circuit breaker and lowering the assembly difficulty and subsequent maintenance costs. Furthermore, the sealing housings provided in this application include metal sealing housings or alloy sealing housings, which not only improve the sealing effect of the sealing housings but also enhance their mechanical strength and improve the reliability of the high-voltage DC circuit breaker. Optionally, the insulating gas provided in this application includes at least one of sulfur hexafluoride, nitrogen, perfluoroisobutyronitrile, and insulating air, wherein the dew point of the insulating air is not greater than -40°C. The insulating gas provided in this application can be a single gas or a mixture of gases; this application does not impose specific limitations on this. Additionally, the surge arrester 1 provided in this application includes a metal oxide surge arrester; this application does not impose specific limitations on this.

[0046] In some embodiments, in at least one of the main current-carrying branch, the converter branch, and the energy absorption branch, the sealed housings corresponding to the electrical connection components are connected via enclosed busbars or tubular busbars. That is, the sealed housings corresponding to different surge arresters 1 provided in this application embodiment can be connected via enclosed busbars or tubular busbars, and the sealed housing corresponding to surge arrester 1 can be connected to the sealed housings corresponding to other components via enclosed busbars or tubular busbars; the sealed housings corresponding to different fast mechanical switches 2 can be connected via enclosed busbars or tubular busbars, and the sealed housing corresponding to fast mechanical switches 2 can be connected to the sealed housings corresponding to other components via enclosed busbars or tubular busbars; the sealed housing corresponding to reactor 3 can be connected to the sealed housings corresponding to other components via enclosed busbars or tubular busbars; the sealed housing corresponding to capacitor 4... The sealed housing of the high-speed closing switch 5 can be connected to the sealed housings of other components via enclosed busbars or tubular busbars. The sealed housings of different high-speed closing switches 5 can also be connected via enclosed busbars or tubular busbars. This further reduces the overall size and footprint of the device, while also reducing stray inductance and current loss, improving the breaking speed and current reliability of the high-voltage DC circuit breaker, and adapting to the miniaturization and intensive construction requirements of high-voltage DC transmission systems. This solves the defects of existing technologies, such as dispersed layout and limited electrical performance. Optionally, the enclosed busbar provided in this embodiment can be a metal enclosed busbar or an alloy enclosed busbar. Alternatively, in at least one of the main flow branch, the converter branch, and the energy absorption branch provided in this application embodiment, the sealed housings corresponding to the electrical connection components are connected by cables, thereby improving layout flexibility; or, in the main flow branch, the converter branch, and the energy absorption branch provided in this application embodiment, the sealed housings corresponding to the electrical connection components in some branches are connected by cables, while the sealed housings corresponding to the electrical connection components in the remaining branches are connected by enclosed busbars or tubular busbars, thereby further improving layout flexibility. This application does not impose specific limitations on this.

[0047] The technical solution provided in this application embodiment includes a high-voltage direct current circuit breaker comprising a main current-carrying branch, a converter branch, and an energy absorption branch connected in parallel, strictly adhering to the classic topological logic of a mechanical high-voltage direct current circuit breaker. Simultaneously, the high-voltage direct current circuit breaker adopts a sealed integrated design, independently encapsulating the core functional components—such as the surge arrester 1, fast mechanical switch 2, reactor 3, capacitor 4, and high-speed closing switch 5—in a sealed housing. An insulating gas is filled within the sealed housing to form an insulating environment, constituting a gas-insulated closed system. This addresses the technical problems of existing high-voltage direct current circuit breakers, such as dispersed component layout, large footprint, poor sealing, weak electromagnetic interference resistance, difficult assembly, and high operation and maintenance costs. Therefore, it adapts to the miniaturized, high-reliability operation and construction requirements of high-voltage direct current transmission systems. The overall function of the high-voltage DC circuit breaker provided in this application is to stably carry the rated DC current during normal operation of the high-voltage DC transmission system, providing a reliable current path for DC power transmission; and to quickly and reliably interrupt the DC fault current when a short circuit or other fault occurs in the system, thereby limiting the overvoltage amplitude and absorbing fault energy to achieve electrical isolation between the fault area and the normal system, ensuring the safe and stable operation of the DC grid. At the same time, the technical solution provided in this application retains the core advantages of mechanical high-voltage DC circuit breakers, namely low current loss and stable breaking performance, resulting in a compact structure, high operational reliability, and convenient maintenance.

[0048] This embodiment uses surge arrester 1, fast mechanical switch 2, reactor 3, capacitor 4, and high-speed closing switch 5 as core functional components, and is equipped with metal or alloy sealed housings, insulating gas, and enclosed busbars or tubular busbars as auxiliary components to form a modular, integrated, and fully sealed high-voltage DC circuit breaker. Each core component forms three parallel branches according to its function: a main current-carrying branch, a converter branch, and an energy absorption branch. They are electrically interconnected through enclosed busbars or tubular busbars, strictly following the topological logic of mechanical high-voltage DC circuit breakers. The fast mechanical switch 2 is the only core component of the main current-carrying branch. Each fast mechanical switch 2 is independently encapsulated in its corresponding sealed housing. The sealed housing provides a sealed working environment for the fast mechanical switch 2. Its two ends serve as current inlet and outlet terminals, directly connected to the positive and negative busbars through bushings, becoming the main channel for current transmission during normal system operation, undertaking the task of carrying rated DC current, and simultaneously completing the initial breaking action under fault conditions. As the core component of the energy absorption branch, surge arrester 1 is also independently encapsulated in its corresponding sealed housing. The two ends of its sealed housing are connected in parallel to the two ends of the sealed housing of the corresponding fast mechanical switch 2 through a closed bus or tubular bus, forming an electrical parallel relationship with the fast mechanical switch 2. It plays a role in limiting overvoltage and absorbing fault energy during fault interruption, protecting each core component from electrical shock. The reactor 3, capacitor 4, and high-speed closing switch 5 are the core components of the converter branch. Each of them is independently encapsulated in its corresponding sealed housing. They can be connected in series in the order of high-speed closing switch 5, reactor 3, and capacitor 4 (without specific restrictions) through a closed bus or tubular bus to form a complete LC oscillating converter circuit. The entire converter branch after series connection is then connected in parallel at both ends of the sealed housing where the corresponding fast mechanical switch 2 is located through a closed bus or tubular bus. It forms an electrical parallel relationship with both the fast mechanical switch 2 and the surge arrester 1. Finally, they together constitute the core topology of a mechanical high-voltage DC circuit breaker with three branches connected in parallel: the main current-carrying branch, the converter branch, and the energy absorption branch.

[0049] In some embodiments, the sealing housings used to encapsulate the surge arrester 1, fast mechanical switch 2, reactor 3, capacitor 4, and high-speed closing switch 5 can all be customized structures adapted to the operating characteristics of each component. The sealing housings can be made of metal or alloy materials, providing excellent sealing performance and mechanical strength, effectively isolating the external environment from contact with the internal components, and providing a sealed space for the insulating gas inside. All sealing housings can be filled with insulating gases with excellent insulating properties, such as sulfur hexafluoride, replacing existing air insulation methods. This significantly improves the insulation performance between the components of the high-voltage DC circuit breaker, effectively reducing the installation spacing between components and providing a foundation for the compact design of the overall high-voltage DC circuit breaker structure. The connections between each sealed housing can be made using enclosed busbars or tubular busbars. These busbars are also sealed structures, achieving seamless sealing at the connection points with each sealed housing. This ensures the airtightness of the entire gas-insulated sealing system and prevents leakage of insulating gas from affecting the insulation performance of the components. At the same time, the connection method of enclosed busbars or tubular busbars significantly shortens the electrical connection distance between the core components, reduces stray inductance and current loss in the connection lines, improves the breaking speed and reliability of the high-voltage DC circuit breaker, and further optimizes the overall size of the device, achieving a compact layout.

[0050] In terms of functional allocation and coordinated operation of each core component, surge arrester 1, fast mechanical switch 2, reactor 3, capacitor 4, and high-speed closing switch 5 each perform their respective functions and cooperate precisely, strictly adhering to the breaking principle of mechanical high-voltage DC circuit breakers. Under the protection of a sealed integrated structure, they achieve efficient and reliable opening, closing, and fault interruption operations. Among them, fast mechanical switch 2 is the core current-carrying and breaking element of the entire high-voltage DC circuit breaker. Under normal operation, it is in a closed state, and the rated current of the DC transmission system flows through fast mechanical switch 2, providing the system with a low-loss and stable current path. Under fault conditions, after the current in the main current-carrying branch is forced to cross zero, fast mechanical switch 2 completes a rapid breaking action, achieving preliminary electrical isolation of the fault area. The sealed housing it is in effectively isolates external pollution, temperature and humidity changes, electromagnetic interference, and other factors, ensuring its operational accuracy and mechanical life. Surge arrester 1 possesses excellent nonlinear volt-ampere characteristics and is a key protective component during fault interruption. Under normal operation, when the system operating voltage is lower than its operating threshold, surge arrester 1 is in a high-resistance state with no current flowing through it, thus not affecting the normal operation of the system. During fault interruption, when the voltage across the high-voltage DC circuit breaker rises rapidly due to current commutation, surge arrester 1 quickly changes from a high-resistance state to a low-resistance state, guiding the fault current to its own branch. At the same time, it efficiently absorbs the fault energy stored in the DC grid, limiting the overvoltage amplitude to a safe range and protecting the fast mechanical switch 2, reactor 3, capacitor 4, and high-speed closing switch 5 from overvoltage breakdown damage.

[0051] The high-speed closing switch 5 is the core of the trigger control of the converter branch, with a microsecond-level ultra-fast closing capability. It is a key component in the start-up current commutation process. During normal operation, the high-speed closing switch 5 is in the open state, keeping the converter branch open and no current flowing through it. When the system detects a fault and issues an opening command, the high-speed closing switch 5 closes instantly, providing the closing condition for the LC oscillation circuit formed by the reactor 3 and the capacitor 4, triggering the commutation process. Reactor 3 and capacitor 4 serve as the core energy storage components of the LC oscillation circuit. Their parameters are precisely matched according to the interruption requirements of the high-voltage direct current transmission system. When the high-speed closing switch 5 is closed, the LC oscillation circuit formed by reactor 3 and capacitor 4 is immediately energized, generating a high-frequency oscillating current in the opposite direction to the fault current in the main current-carrying branch where the fast mechanical switch 2 is located. This reverse oscillating current rapidly superimposes with the fault current in the main branch, causing the contact current of the fast mechanical switch 2 to drop to zero in a very short time, achieving forced zero crossing of the current in the main current-carrying branch. This provides a key condition for the arc-free interruption of the fast mechanical switch 2, significantly improving the interruption reliability and interruption speed of the circuit breaker. Reactor 3 and capacitor 4 each have their own independent sealed housing, which can effectively isolate electromagnetic interference between them, ensuring the working stability of the LC oscillation circuit, ensuring precise control of the frequency and amplitude of the oscillation current, and ensuring the efficient completion of the commutation process.

[0052] The complete working process of the high-voltage DC circuit breaker provided in this application embodiment is divided into two core stages: normal operation and fault breaking. The states and actions of each core component under different operating conditions are strictly matched with the operating logic of the high-voltage DC circuit breaker. The sealed integrated structure only provides protection and connection for each component without changing its inherent action sequence and coordination accuracy, while providing a good environment for the reliable operation of each component. Under normal operation, the fast mechanical switch 2 is in the closed state, the high-speed closing switch 5 is in the open state, and the surge arrester 1 is in a high-resistance state because the system voltage has not reached the action threshold. At this time, the rated current of the high-voltage DC transmission system flows through the main current-carrying branch where the fast mechanical switch 2 is located. The converter branch is in the open state because the high-speed closing switch 5 is open, and the energy absorption branch has no current flowing through it because the surge arrester 1 has high resistance. The entire high-voltage DC circuit breaker only undertakes the rated current carrying function. All core components are in the fully protected environment of the sealed shell, and the stable operation is without mechanical action. The overall current loss of the equipment is low and the operation reliability is high.

[0053] Under fault interruption conditions, the entire process is divided into three continuous stages: commutation triggering, current commutation, and energy absorption and fault isolation. Each stage is seamlessly connected to achieve rapid and reliable interruption of the fault current. The first stage is commutation triggering. When a short-circuit fault occurs in the high-voltage direct current transmission system, the fault current rises rapidly. After the control system detects the fault signal through the detection device, it immediately issues an interruption command. After receiving the command, the high-speed closing switch 5 completes the closing action within microseconds, making the originally open commutation branch a closed loop. The LC oscillation circuit composed of reactor 3 and capacitor 4 is officially started. The second stage is current commutation. After the LC oscillation circuit is energized, a high-frequency oscillating current is rapidly generated that is opposite in direction to the fault current in the main current-carrying branch where the fast mechanical switch 2 is located. This reverse oscillating current is rapidly superimposed on the fault current in the main branch, causing the contact current of the fast mechanical switch 2 to drop to zero in a very short time, thus achieving forced zero crossing of the current in the main current-carrying branch. At this time, the fast mechanical switch 2 completes the rapid disconnection action under zero current conditions, completely commutating the fault current from the main current-carrying branch to the parallel commutation branch and energy absorption branch, thus completing the initial transfer of the fault current. The third stage is energy absorption and fault isolation. After the fast mechanical switch 2 is disconnected, the system fault current and the residual current of the LC oscillation circuit rapidly raise the voltage across the circuit breaker. When the voltage reaches the operating threshold of the surge arrester 1, the surge arrester 1 quickly switches to a low-resistance state, and all the fault current is transferred to the energy absorption branch where the surge arrester 1 is located. Subsequently, the surge arrester 1 efficiently absorbs the fault energy stored in the system, while strictly limiting the overvoltage amplitude across the high-voltage DC circuit breaker to prevent the core components from being subjected to overvoltage impact. After the surge arrester 1 has completely absorbed the fault energy, the system voltage gradually returns to the normal level, and no continuous current flows across the high-voltage DC circuit breaker. The entire fault breaking process is completed, and the fast mechanical switch 2 remains in the open state, achieving reliable electrical isolation between the fault area and the DC transmission system, ensuring the normal operation of the rest of the system.

[0054] The technical solution provided in this application, through the independent sealed encapsulation and integrated layout of the surge arrester 1, fast mechanical switch 2, reactor 3, capacitor 4, and high-speed closing switch 5, forms a sealed integrated structure with significant technical advantages. All structural designs revolve around the core components and the three-branch topology, without any additional redundant design. Firstly, the fully sealed housing and gas insulation design completely isolate all core components from the external environment, effectively avoiding the influence of external factors such as pollution, salt spray, temperature and humidity changes, and electromagnetic interference on the components. This significantly improves the environmental adaptability and anti-interference capability of the devices, extends their service life, and achieves the goal of maintenance-free operation. Secondly, the modular sealed encapsulation design allows each core component to be prefabricated, assembled, and debugged before leaving the factory. On-site assembly only requires connecting the sealed housings via enclosed busbars or tubular busbars, greatly simplifying the on-site assembly process, shortening the installation and commissioning cycle, and reducing on-site construction and commissioning costs. Third, the compact layout and short-distance connection of the enclosed busbar (or tubular busbar) significantly reduce the overall footprint and volume of the device, adapting to the miniaturized and intensive construction requirements of high-voltage direct current transmission systems. Simultaneously, the short-distance connection reduces stray inductance and current loss in the circuit, further improving the breaking speed, breaking reliability, and current carrying capacity of the high-voltage direct current circuit breaker. Fourth, the integrated design does not change the core topology and breaking principle of the high-voltage direct current circuit breaker, and is compatible with existing mature control logic and debugging methods. It does not require significant modifications to the control system of existing high-voltage direct current transmission systems, possessing strong practicality and promotional value, and can be directly applied to high-voltage direct current transmission systems, DC power grids, and other scenarios. Overall, the technical solution provided in this application, through structural innovation, effectively solves many technical pain points of existing structures while retaining the core advantages of mechanical high-voltage direct current circuit breakers, achieving a dual improvement in device performance and engineering adaptability, and possessing extremely high practical value.

[0055] refer to Figure 3 The diagram shows another sealed integrated high-voltage DC circuit breaker provided in this application embodiment. In this embodiment, the reactor 3 and the capacitor 4 can be arranged adjacent to each other; the fast mechanical switch 2 and the high-speed closing switch 5 are arranged along the adjacent structural direction surrounding the reactor 3 and the capacitor 4. The reactor 3 and the capacitor 4 are low-frequency maintenance components, while the fast mechanical switch 2 and the high-speed closing switch 5 are high-frequency maintenance components. The reactor 3 and the capacitor 4 are located in the internal area of ​​the high-voltage DC circuit breaker, while the fast mechanical switch 2 and the high-speed closing switch 5 are located in the peripheral area of ​​the high-voltage DC circuit breaker to facilitate maintenance of the high-voltage DC circuit breaker. Optionally, the surge arrester 1 provided in this embodiment is located on the side of the fast mechanical switch 2 or the high-speed closing switch 5 away from the adjacent structural direction of the reactor 3 and the capacitor 4; continuing as... Figure 3 As shown, in terms of spatial arrangement, the sealed housings of the core components provided in this application embodiment can be optimized according to the functional logic of the three branches. The sealed housings of the fast mechanical switch 2 and the surge arrester 1 can be arranged in parallel. The corresponding sealed housings of the high-speed closing switch 5, reactor 3, and capacitor 4 of the converter branch are arranged compactly along one side, and a safe distance that meets the insulation requirements is maintained between each sealed housing. This ensures the independent normal operation of each component and realizes the compact design of the overall structure of the high-voltage DC circuit breaker, significantly reducing the footprint of the device. Alternatively, the surge arrester 1 provided in this application embodiment may be adjacent to at least one of the reactor 3 and the capacitor 4, and may be located within the area surrounded by the fast mechanical switch 2 and the high-speed closing switch 5. This application does not impose specific limitations on this.

[0056] Based on the same inventive concept, this application also provides a high-voltage direct current transmission system, which includes the sealed integrated high-voltage direct current circuit breaker provided in any of the above embodiments.

[0057] In summary, this application provides a sealed integrated high-voltage direct current circuit breaker and a high-voltage direct current transmission system. The high-voltage direct current circuit breaker includes a main current-carrying branch, a converter branch, and an energy absorption branch, which are connected in parallel. The main current-carrying branch includes at least one fast mechanical switch, and when the main current-carrying branch includes at least two fast mechanical switches, all the fast mechanical switches are connected in series. The converter branch includes a reactor, a capacitor, and at least one high-speed closing switch, and the converter branch includes at least two high-speed closing switches. When closed, all the high-speed closing switches are connected in series, and the reactor, the capacitor, and the high-speed closing switch are also connected in series. When the energy absorption branch includes at least one surge arrester, and when the energy absorption branch includes at least two surge arresters, all the surge arresters are connected in series. Among the fast mechanical switch, the reactor, the capacitor, the high-speed closing switch, and the surge arrester, at least the fast mechanical switch, the reactor, the high-speed closing switch, and the surge arrester are respectively encapsulated in mutually independent sealed housings, and the sealed housings are filled with insulating gas. As can be seen from the above, the technical solution provided in this application encapsulates at least the fast mechanical switch, reactor, high-speed closing switch, and surge arrester in separate sealed housings filled with insulating gas. This improves the insulation and sealing performance of each component in the high-voltage DC circuit breaker, thereby enhancing the component's resistance to electromagnetic interference and mitigating its susceptibility to environmental factors such as pollution, humidity, salt spray, and temperature differences. It also improves the insulation performance, breaking sensitivity, reliability, and service life of the high-voltage DC circuit breaker components, meeting the stringent requirements of high-voltage DC transmission systems for rapid fault interruption. Furthermore, by improving the insulation and sealing performance of the components, it facilitates a compact and integrated design of all components in the high-voltage DC circuit breaker, reducing assembly difficulty and commissioning cycle, minimizing the footprint of the high-voltage DC circuit breaker, and addressing the issues of high maintenance costs and low maintenance efficiency caused by the dispersed nature of the components.

[0058] In the description of the embodiments of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and other terms indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0059] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of embodiments of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0060] In the embodiments of this application, unless otherwise explicitly specified and limited, terms such as "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0061] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0062] In the embodiments of this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0063] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A sealed integrated high-voltage DC circuit breaker, characterized by The high-voltage DC circuit breaker includes: a main current-carrying branch, a converter branch, and an energy absorption branch, wherein the main current-carrying branch, the converter branch, and the energy absorption branch are connected in parallel. When the main current-carrying branch includes at least one fast mechanical switch, and when the main current-carrying branch includes at least two fast mechanical switches, all the fast mechanical switches are connected in series. The converter branch includes a reactor, a capacitor and at least one high-speed closing switch. When the converter branch includes at least two high-speed closing switches, all the high-speed closing switches are connected in series, and the reactor, the capacitor and the high-speed closing switch are connected in series. When the energy absorption branch includes at least one surge arrester, and when the energy absorption branch includes at least two surge arresters, all surge arresters are connected in series. Among the fast mechanical switch, the reactor, the capacitor, the high-speed closing switch, and the surge arrester, at least the fast mechanical switch, the reactor, the high-speed closing switch, and the surge arrester are respectively encapsulated in mutually independent sealed housings, and the sealed housings are filled with insulating gas.

2. The sealed integrated HVDC circuit breaker according to claim 1, characterized in that The fast mechanical switch, the reactor, the capacitor, the high-speed closing switch, and the surge arrester are all encapsulated in independent sealed housings, and the sealed housings are filled with the insulating gas. 3.The sealed integrated HVDC circuit breaker according to claim 1, characterized in that, The distance between two adjacent sealing housings is 300-500 mm.

4. The sealed integrated high-voltage DC circuit breaker according to claim 1, characterized in that, The sealing housing includes a metal sealing housing or an alloy sealing housing.

5. The sealed integrated high-voltage DC circuit breaker according to claim 1, characterized in that, The insulating gas includes at least one of sulfur hexafluoride, nitrogen, perfluoroisobutyronitrile, and insulating air, wherein the dew point of the insulating air is not greater than -40°C.

6. The sealed integrated high-voltage DC circuit breaker according to claim 1, characterized in that, In at least one of the main flow branch, the converter branch, and the energy absorption branch, the sealed housings corresponding to the electrical connection components are connected by a closed busbar or a tubular busbar.

7. The sealed integrated high-voltage DC circuit breaker according to claim 1, characterized in that, The reactor and the capacitor are arranged adjacent to each other; The fast mechanical switch and the high-speed closing switch are arranged along the adjacent structural direction surrounding the reactor and the capacitor.

8. The sealed integrated high-voltage DC circuit breaker according to claim 7, characterized in that, The surge arrester is adjacent to at least one of the reactor and the capacitor, and is disposed in the area surrounding the fast mechanical switch and the high-speed closing switch; Alternatively, the surge arrester may be located on the side of the fast mechanical switch or the high-speed closing switch away from the adjacent structure of the reactor and the capacitor.

9. The sealed integrated high-voltage DC circuit breaker according to claim 1, characterized in that, The surge arrester includes a metal oxide surge arrester.

10. A high-voltage direct current transmission system, characterized in that, The high-voltage direct current transmission system includes the sealed integrated high-voltage direct current circuit breaker as described in any one of claims 1-9.

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