A high-capacity high-speed switch current limiting device

Abstract

The utility model relates to high -speed switch technical field, and disclose a kind of high-capacity high-speed switch current limiting device, applicable to 10.5kV industrial waste heat power generation system.The device includes outer cabinet, main loop component, current limiting component, control unit and maintenance isolation unit, main loop component realizes zero-loss power supply when normal operation by current-carrying bridge body, current limiting component adopts fuse and nonlinear resistance parallel structure, short-circuit current peak value can be quickly limited to below 40kA, control unit realizes millisecond level fault response by current transformer and electronic controller, maintenance isolation unit realizes on-line maintenance without shutdown by two groups of high-voltage disconnectors, line end pipe adopts epoxy resin insulating bushing and is equipped with sealing rubber ring, and insulation and dustproof performance are improved, the device solves the problem that traditional current limiting scheme is high in energy consumption, slow in response, difficult to maintain, significantly improves system safety and economy, applicable to short-circuit protection scene of small-capacity generator set direct connection 10kV system.

Description

Technical Field

[0001] This utility model relates to the field of high-speed switching technology, specifically a high-capacity high-speed switch current limiting device. Background Technology

[0002] During the operation of power systems, especially in waste heat power generation systems of industrial enterprises, the dangers of short-circuit current have always been a key issue threatening the safe and stable operation of the system. When a short-circuit fault occurs in a power system, the short-circuit current can often reach more than ten times the rated current or even higher. This current can cause severe impacts on core electrical equipment such as transformers, generators, circuit breakers, and transmission lines, and may lead to catastrophic accidents such as equipment winding deformation, insulation breakdown, or even fire.

[0003] Currently, in the industrial sector, a common method to limit short-circuit current is to connect a current-limiting reactor in series at the generator outlet. However, this technical solution has many insurmountable drawbacks: 1. Poor energy consumption and economy: The current-limiting reactor needs to be connected in series in the power supply circuit for a long time. Even if the system is operating normally, it will generate significant active and reactive power losses.

[0004] 2. Significant environmental and safety hazards: The air-core reactor generates a strong leakage magnetic field during operation, which damages the surrounding concrete structure and severely interferes with communication signals. In addition, the reactor body temperature rises significantly after long-term operation. For example, the temperature of the reactor's incoming and outgoing busbars in the company's system reaches as high as 125.3℃. High temperature will accelerate the aging of the reactor coil insulation, which can easily cause insulation breakdown, short circuit or fire. At the same time, it will cause high-temperature oxidation of the cable head lugs and increase the contact resistance, which will further lead to terminal burnout or cable head breakdown. In order to control the temperature of the reactor room, the air conditioner needs to run continuously for 24 hours, which increases energy consumption and cannot guarantee the cooling effect.

[0005] 3. Insufficient current limiting effect and maintainability: The reactance rate of conventional current limiting reactors is usually only 10%-15%, which cannot achieve deep limiting of short-circuit current. When the short-circuit current approaches or reaches the maximum breaking capacity of the vacuum circuit breaker (40kA), there is still a risk of circuit breaker failure. In addition, the reactor needs to be shut down for maintenance, which leads to unplanned shutdown of the generator set and affects the continuity of production.

[0006] Some solutions use ordinary high-speed switches in conjunction with reactors, but the response time of ordinary switches cannot meet the rapid interruption requirements in the initial stage of short-circuit current, which will still cause the peak short-circuit current to impact the equipment. At the same time, they lack an online maintenance structure, and the maintenance process still requires shutdown, which is difficult to adapt to the continuous operation requirements of industrial waste heat power generation systems. In order to solve the above problems, there is an urgent need for a large-capacity high-speed switch current limiting device that can take into account zero-loss operation, rapid current limiting, safety and reliability, and online maintenance, so as to solve the pain points of existing technologies. Therefore, we propose a large-capacity high-speed switch current limiting device. Utility Model Content

[0007] To address the shortcomings of existing technologies, this invention provides a high-capacity, high-speed switching current limiting device, which solves the aforementioned problems.

[0008] To achieve the above-mentioned objectives, this utility model provides the following technical solution: a high-capacity high-speed switch current limiting device, comprising an external cabinet, on both sides of which a generator input terminal and a generator output terminal are fixedly installed respectively. Each generator input terminal and generator output terminal consists of three sets, all integrated together via line end pipes. The ends of both sets of line end pipes penetrate the explosion-proof bridge cabinet and extend into the interior of the main circuit assembly. The main circuit assembly includes an explosion-proof bridge cabinet, a current-carrying bridge body, and a high-voltage vacuum circuit breaker. The input terminal of the high-voltage vacuum circuit breaker is electrically connected to the output terminal of the generator input terminal. The output terminal of the high-voltage vacuum circuit breaker is electrically connected to the input terminal of the explosion-proof bridge cabinet. The output terminal of the explosion-proof bridge cabinet is electrically connected to the input terminal of the current-carrying bridge body. The output terminal on the other side of the current-carrying bridge body is electrically connected to the input terminal of the generator output terminal.

[0009] Preferably, it further includes a current limiting component, which includes a fuse and a nonlinear resistor. One end of the fuse is connected in parallel with the input terminal of the current-carrying bridge, and the other end of the fuse is connected in parallel with the output terminal of the current-carrying bridge. The nonlinear resistor is connected in parallel with the fuse.

[0010] Preferably, it also includes two sets of high-voltage disconnect switches. One set of the high-voltage disconnect switches is installed between the high-voltage vacuum circuit breaker and the explosion bridge cabinet, and the other set of the high-voltage disconnect switches is connected in series between the current-carrying bridge body and the generator output terminal.

[0011] Preferably, it also includes a control unit, which includes a current transformer, an electronic controller, and a back-end transmission module. The current transformer is sleeved and installed on the line end pipe. The electronic controller and the back-end transmission module are both fixedly installed on the top of the current-carrying bridge and are electrically connected together. The electronic controller and the current transformer are also electrically connected together.

[0012] Preferably, the electronic controller has a built-in self-test module, which is used to detect the operating conditions of the electronic controller, the dedicated current transformer, and the explosion-proof bridge cabinet in real time.

[0013] Preferably, the line end tube is made of epoxy resin insulating sleeve material, and a sealing ring is provided at the penetration point between it and the explosion bridge cabinet to achieve insulation isolation and dustproof sealing between the main circuit components and the external cabinet.

[0014] Compared with the prior art, this utility model provides a high-capacity high-speed switching current limiting device, which has the following beneficial effects: 1. This high-capacity high-speed switch current limiting device uses epoxy resin insulating sleeves for the line end tubes. A sealing ring is provided at the penetration point between the sleeve and the explosion bridge cabinet. The epoxy resin material can withstand the insulation requirements of voltage levels of 10kV and above. The sealing ring can effectively prevent dust and moisture from entering. The double protection realizes reliable insulation isolation between the main circuit components and the external cabinet, reducing the risk of high voltage discharge.

[0015] 2. This high-capacity, high-speed switch current limiting device has a built-in self-test module in the electronic controller of the control unit, which can monitor the operating conditions of the electronic controller, current transformer and explosion bridge cabinet in real time. When an abnormality is detected in a component, an alarm is immediately triggered through the background transmission module with a response time of <0.1ms. This avoids protection delays or malfunctions caused by the failure of core components and improves the reliability of the device operation.

[0016] 3. This high-capacity high-speed switch current limiting device has a maintenance isolation unit containing two sets of high-voltage disconnect switches, which are connected in series between the high-voltage vacuum circuit breaker and the explosion bridge cabinet, and between the current-carrying bridge body and the generator output terminal, respectively. By disconnecting the vacuum circuit breaker and closing the disconnect switch, components such as the current-carrying bridge body can be isolated, enabling component replacement and maintenance without shutting down the generator set, thus reducing unplanned downtime. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of this utility model; Figure 2 This is a schematic diagram of the internal structure of the explosion-proof bridge cabinet of this utility model; Figure 3 This is a schematic diagram of the overall structure of this utility model.

[0018] In the diagram: 1. External cabinet; 2. Motor input terminal; 3. Motor output terminal; 4. Line terminal pipe; 5. Explosion bridge cabinet; 6. Current-carrying bridge body; 7. High-voltage vacuum circuit breaker; 8. Fuse; 9. Nonlinear resistor; 10. High-voltage disconnect switch; 11. Current transformer; 12. Electronic controller; 13. Backend transmission module. Detailed Implementation

[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0020] Please see Figure 1-3 A high-capacity, high-speed switching current limiting device includes an external cabinet 1. A generator input terminal 2 and a generator output terminal 3 are fixedly installed on both sides of the external cabinet 1. Each generator input terminal 2 and generator output terminal 3 consists of three sets, all integrated together via line end pipes 4. The ends of both sets of line end pipes 4 penetrate an explosion-proof bridge cabinet 5 and extend into the interior of a main circuit assembly. The main circuit assembly includes the explosion-proof bridge cabinet 5, a current-carrying bridge body 6, and a high-voltage vacuum circuit breaker 7. The input terminal of the high-voltage vacuum circuit breaker 7 is electrically connected to the output terminal of the generator input terminal 2. The output terminal of the high-voltage vacuum circuit breaker 7 is electrically connected to the input terminal of the explosion-proof bridge cabinet 5. The output terminal of the explosion-proof bridge cabinet 5 is electrically connected to the input terminal of the current-carrying bridge body 6. The output terminal on the other side of the current-carrying bridge body 6 is electrically connected to the input terminal of the generator output terminal 3.

[0021] Furthermore, the system also includes a current-limiting component, which comprises a fuse 8 and a nonlinear resistor 9. One end of the fuse 8 is connected in parallel with the input terminal of the current-carrying bridge 6, and the other end of the fuse 8 is connected in parallel with the output terminal of the current-carrying bridge 6. The nonlinear resistor 9 is connected in parallel with the fuse 8. During normal system operation, the main circuit current flows through the current-carrying bridge 6, and no current flows through the current-limiting component. When a short-circuit fault occurs in the system, the current-carrying bridge 6 is disconnected under the drive of the explosion-proof bridge cabinet 5, and the short-circuit current quickly switches to the current-limiting component branch. Fuse 8 melts within <0.5ms to interrupt the short-circuit current. At the same time, nonlinear resistor 9 absorbs the magnetic field energy generated during the breaking process of fuse 8, suppressing the generation of overvoltage. This can effectively avoid the active or reactive power loss caused by long-term series connection of traditional current-limiting reactors. In addition, nonlinear resistor 9 can control the overvoltage peak value below 45kV to prevent equipment insulation breakdown. The fast melting characteristic of fuse 8, combined with the current limiting effect, can limit the peak short-circuit current to below 40kA, which is compatible with the breaking capacity of high-voltage vacuum circuit breaker 7 and reduces the risk of circuit breaker breaking failure.

[0022] Furthermore, it also includes two sets of high-voltage disconnect switches 10. One set of high-voltage disconnect switches 10 is installed between the high-voltage vacuum circuit breaker 7 and the explosive bridge cabinet 5, and the other set of high-voltage disconnect switches 10 is connected in series between the current-carrying bridge body 6 and the generator output terminal 3. During normal system operation, both sets of high-voltage disconnect switches 10 are in the closed state, which does not affect the current flow in the main circuit. When maintenance is required on components such as the current-carrying bridge body 6 and the explosive bridge cabinet 5, the high-voltage vacuum circuit breaker 7 is first opened, and then the two sets of high-voltage disconnect switches 10 are closed to isolate the components to be maintained from the main circuit. At this time, temporary power can be supplied through the current-limiting component branch or switched to the emergency section to ensure that the generator set does not stop. This effectively solves the problem of the need to stop the machine for maintenance of traditional current-limiting devices, avoids production losses caused by unplanned shutdown of the generator set, realizes online maintenance, and improves the continuity of system operation. At the same time, the rated current of the high-voltage disconnect switch 10 is 3150A and the withstand voltage is 12kV, which is suitable for the overall operating conditions of the device and ensures electrical safety during the maintenance process.

[0023] Furthermore, it also includes a control unit, which comprises a current transformer 11, an electronic controller 12, and a backend transmission module 13. The current transformer 11 is sleeved and installed on the line end pipe 4. The electronic controller 12 and the backend transmission module 13 are both fixedly installed on the top of the current-carrying bridge body 6 and are electrically connected together. The electronic controller 12 is also electrically connected to the current transformer 11. During normal operation, the current transformer 11 collects the main circuit current signal in real time at a sampling rate of <1ms and transmits it to the electronic controller 12. The electronic controller 12 compares the collected current value with a preset short-circuit threshold. If the current does not exceed the threshold, the main circuit remains in normal condition. At the same time, the device's operating status is uploaded to the background monitoring system through the background transmission module 13. When the current exceeds the threshold, the electronic controller 12 sends a trigger command to the explosion bridge cabinet 5 within <0.1ms, driving the current-carrying bridge body 6 to disconnect. Compared with the response time of >10ms for ordinary high-speed switches, the total response time of this control unit is ≤1.2ms, which can intervene in the initial stage of short-circuit current rise, avoiding the impact of current peak on the equipment. The background transmission module 13 realizes remote monitoring without the need for on-site personnel. The high-precision sampling of the current transformer 11 ensures the accuracy of fault judgment and reduces the risk of malfunction.

[0024] Furthermore, the electronic controller 12 has a built-in self-test module, which is used to monitor the operating conditions of the electronic controller, the dedicated current transformer, and the explosion bridge cabinet in real time. During the operation of the device, the self-test module continuously monitors the status of the CPU and power module of the electronic controller 12, the sampling circuit of the current transformer 11, and the trigger circuit of the explosion bridge cabinet 5. If a component failure is detected, a fault signal is immediately generated and sent to the background monitoring system through the background transmission module 13, triggering an on-site alarm. This can detect potential faults in core components in advance and avoid short-circuit protection failure due to component failure. Compared with devices without self-test function, the fault diagnosis time can be shortened by more than 80%, the probability of sudden accidents can be reduced, and the reliability of device operation can be improved. It is especially suitable for the high requirements of industrial waste heat power generation systems for equipment stability.

[0025] Furthermore, the line end pipe 4 is made of epoxy resin insulating sleeve, and a sealing ring is provided at the penetration point between it and the explosion bridge cabinet 5. This is used to achieve insulation isolation and dustproof sealing between the main circuit components and the outer cabinet 1. During normal operation, the epoxy resin insulating sleeve can withstand a rated voltage of 10.5kV, preventing the high voltage of the main circuit from leaking to the cabinet body of the outer cabinet 1, ensuring that the cabinet body is not energized. The sealing ring fills the gap between the line end pipe 4 and the explosion bridge cabinet 5, preventing dust and moisture in the industrial environment from entering the interior of the main circuit components. This avoids the decrease in insulation performance caused by dust accumulation or the corrosion of metal parts caused by moisture. It effectively solves the problems of insufficient insulation and easy leakage in traditional devices, and the impact of dust and moisture on the life of components. The power frequency withstand voltage of the epoxy resin material is ≥42kV, which meets the insulation requirements of the 10.5kV system. The dustproof and waterproof rating of the sealing ring reaches IP30, which is suitable for the complex environment of the waste heat power generation workshop, extends the service life of the core components of the device, and reduces the frequency of maintenance. Example

[0026] Example 1: The external cabinet 1 provides an overall protective frame for the device. The generator input terminals 2 on both sides are connected to the outlet of the 30MW steam turbine generator set through the line terminal pipe 4. The generator output terminal 3 is connected to the 10kV working bus. During normal operation, the high-voltage vacuum circuit breaker 7 is closed, and the current forms the main circuit through the explosion bridge cabinet 5 and the current-carrying bridge body 6. The equivalent resistance of the current-carrying bridge body 6 is <0.01Ω, achieving zero-loss power supply. The current transformer 11 in the control unit samples the line current in real time. The electronic controller 12 compares the current value with the threshold. When a short circuit fault occurs, the current transformer 11 triggers the electronic controller 12 within 1ms. The latter sends a command to the explosion bridge cabinet 5 within 0.1ms. The current-carrying bridge body 6 is immediately disconnected, and the short circuit current switches to the branch of the fuse 8 and the nonlinear resistor 9. The fuse 8 blows within 0.5ms, limiting the current peak to below 40kA. Through a multi-level fast response mechanism, current limiting is completed before the short circuit current reaches its peak value, protecting the generator and circuit breaker from impact and adapting to industrial scenarios with high-frequency short circuit risks.

[0027] Example 2: The line terminal pipe 4 inside the external cabinet 1 uses epoxy resin sleeve, and the penetration point with the explosion bridge cabinet 5 is sealed with a rubber ring to achieve IP54 dustproof and waterproof rating. During maintenance, first disconnect the high-voltage vacuum circuit breaker 7, and then close the two sets of high-voltage disconnect switches 10 to isolate the explosion bridge cabinet 5 from the current-carrying bridge body 6 from the main circuit. At this time, the current can be temporarily supplied through the current limiting component. The self-test module of the electronic controller 12 monitors the isolation status in real time to ensure maintenance safety. After the maintenance is completed, disconnect the high-voltage disconnect switch 10 and close the high-voltage vacuum circuit breaker 7, and the device resumes normal operation. Through the modular isolation design, online maintenance of core components can be achieved, avoiding the problem of shutdown required for traditional reactor maintenance. At the same time, the combination of epoxy resin sleeve and sealing rubber ring improves the long-term operational stability of the device in dusty and high-temperature environments, and is suitable for high-pollution conditions such as silicon aluminothermic power generation.

[0028] External cabinet 1 is the integrated cabinet of the device. It adopts the improved structure of GGD type low voltage distribution cabinet and serves as the basic installation carrier of the entire device. The main circuit unit, current limiting unit and control unit are arranged in layers through metal partitions to provide mechanical support and electrical isolation space for each component.

[0029] Generator input terminal 2 consists of three sets of copper input busbars, installed on one side of the outer cabinet 1, used to connect to the output busbar of the 30MW steam turbine generator set and introduce the generator output current into the main circuit of the device.

[0030] Line end tube 4 is made of epoxy resin insulating sleeve and is sleeved on the outside of the main circuit copper busbar. The ends of both sets of line end tubes 4 penetrate the explosion bridge cabinet 5 to achieve insulation protection at a voltage level of 10.5kV, and at the same time play a mechanical fixing role for the internal copper busbar.

[0031] The explosion bridge cabinet 5 is a customized fast disconnection device connected in series between the high-voltage vacuum circuit breaker 7 and the current-carrying bridge body 6. It integrates an explosion-type disconnection mechanism. After receiving the command from the electronic controller 12, it can drive the current-carrying bridge body 6 to disconnect within 0.1ms, cutting off the main circuit current path.

[0032] High-voltage vacuum circuit breaker 7, model VS1-12 / 3150-40, has its input terminal electrically connected to the output terminal of generator input terminal 2 via a copper busbar, and its output terminal electrically connected to the input terminal of explosion bridge cabinet 5. It serves as a conventional on / off switch for the main circuit, with a rated breaking current of 40kA, and is used for switching circuits under normal operating conditions and interrupting initial fault current.

[0033] The current-carrying bridge 6 is a low-impedance silver-copper alloy conductive structure, installed in the middle layer inside the outer cabinet 1. Its input end is electrically connected to the output end of the explosion bridge cabinet 5, and its output end is electrically connected to the input end of the generator output end 3. During normal operation, it achieves zero-loss current carrying in the main circuit by approximating a wire. The top of the bridge is also fixedly installed with an electronic controller 12 and a background transmission module 13.

[0034] Generator output terminal 3 consists of three sets of copper outgoing lines, installed on the other side of the outer cabinet 1, used to connect to the 10kV working bus section and transmit the current processed by the device to the load side.

[0035] Fuse 8, model XRNT1-12 / 3150, is connected in parallel with the input terminal of the current-carrying bridge body 6 at one end and in parallel with the output terminal of the current-carrying bridge body 6 at the other end. It has a rated breaking capacity of 50kA and quickly melts to cut off the current in the current-limiting reactor branch during a short-circuit fault.

[0036] Nonlinear resistor 9 is a zinc oxide surge arrester, model HY5WZ-17 / 45, connected in parallel with fuse 8. It is used to absorb the magnetic field energy generated when fuse 8 interrupts the short-circuit current, limit the overvoltage peak value to ≤45kV, and protect the equipment insulation.

[0037] High-voltage disconnect switch 10, model GN22-10 / 3150, consists of two sets. One set is connected in series between the high-voltage vacuum circuit breaker 7 and the explosion bridge cabinet 5, and the other set is connected in series between the current-carrying bridge body 6 and the generator output terminal 3. The main circuit components are mechanically isolated through a rotary knife switch, which supports operation under load and isolates energized parts during equipment maintenance.

[0038] Current transformer 11, model LZZBJ9-10C, is mounted on the copper busbar of line terminal tube 4, with a transformation ratio of 3000 / 5. It is used to sample the main circuit current in real time and transmit the current signal to the electronic controller 12.

[0039] Electronic controller 12 is a customized intelligent control unit, which is fixedly installed on the top of the current-carrying bridge body 6. It has a built-in CPU and self-test module, and is electrically connected to the current transformer 11, the explosion bridge cabinet 5, and the background transmission module 13. It is used to receive current signals to determine whether short circuit protection is triggered, send action commands to the explosion bridge cabinet 5, and can also monitor the working conditions of itself, the current transformer 11, and the explosion bridge cabinet 5 in real time.

[0040] The background transmission module 13 adopts an RS485 communication module, which is fixedly installed on the top of the current-carrying bridge body 6 and electrically connected to the electronic controller 12. It is used to transmit the device's operating status to the background monitoring system to realize remote monitoring and alarm.

[0041] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-capacity high-speed switch current limiting device, comprising an external cabinet (1), wherein generator input terminals (2) and generator output terminals (3) are fixedly installed on both sides of the external cabinet (1), wherein there are three sets of generator input terminals (2) and generator output terminals (3), and they are all integrated together through line end pipes (4), wherein the ends of the two sets of line end pipes (4) penetrate through an explosion bridge cabinet (5) and extend into the interior of the main circuit assembly, characterized in that: The main circuit assembly includes an explosion bridge cabinet (5), a current-carrying bridge body (6), and a high-voltage vacuum circuit breaker (7). The input terminal of the high-voltage vacuum circuit breaker (7) is electrically connected to the output terminal of the generator input terminal (2). The output terminal of the high-voltage vacuum circuit breaker (7) is electrically connected to the input terminal of the explosion bridge cabinet (5). The output terminal of the explosion bridge cabinet (5) is electrically connected to the input terminal of the current-carrying bridge body (6). The output terminal on the other side of the current-carrying bridge body (6) is electrically connected to the input terminal of the generator output terminal (3). A current limiting component, comprising a fuse (8) and a nonlinear resistor (9), wherein one end of the fuse (8) is connected in parallel with the input terminal of the current-carrying bridge (6), and the other end of the fuse (8) is connected in parallel with the output terminal of the current-carrying bridge (6), and the nonlinear resistor (9) is connected in parallel with the fuse (8). It also includes two sets of high-voltage disconnect switches (10), one set of the high-voltage disconnect switches (10) is installed between the high-voltage vacuum circuit breaker (7) and the explosion bridge cabinet (5), and the other set of the high-voltage disconnect switches (10) is connected in series between the current-carrying bridge body (6) and the generator output terminal (3); It also includes a control unit, which includes a current transformer (11), an electronic controller (12) and a background transmission module (13). The current transformer (11) is sleeved and installed on the line end tube (4). The electronic controller (12) and the background transmission module (13) are both fixedly installed on the top of the current-carrying bridge body (6) and are electrically connected together. The electronic controller (12) and the current transformer (11) are electrically connected together. The electronic controller (12) has a built-in self-test module, which is used to detect the working conditions of the electronic controller, the dedicated current transformer and the explosion bridge cabinet in real time. The line end tube (4) is made of epoxy resin insulating sleeve material, and a sealing ring is provided at the penetration point between it and the explosion bridge cabinet (5) to achieve insulation isolation and dustproof sealing between the main circuit components and the external cabinet (1).

Images