Hybrid arc quenching system and method of arc quenching

Abstract

This invention discloses a hybrid arc-extinguishing system and its arc-extinguishing method, comprising: a mechanical current-carrying main branch connected in series to the power grid to be protected, wherein the mechanical current-carrying main branch includes a fast mechanical switch and a magnetically coordinated arc-extinguishing chamber coaxially linked with it, used to carry the rated current in steady state and perform physical disconnection when a disconnection command is received; and a solid-state commutation bypass connected in parallel with the mechanical current-carrying main branch, wherein the solid-state commutation bypass includes an anti-parallel power semiconductor device group and a transient voltage suppression buffer circuit coupled to both ends of the devices. This invention does not increase any steady-state losses, but cleverly utilizes the accompanying potential energy of mechanical action, that is, the kinetic energy of the moving contact compressing the gas, and the magnetic field energy generated by the short-circuit current itself, to artificially create an extremely high arc voltage, making forced commutation extremely fast and reliable, fundamentally solving the problem of commutation failure in existing hybrid circuit breakers.

Description

Technical Field

[0001] This invention relates to the field of power electronic equipment and high-voltage switchgear technology, specifically to a hybrid arc extinguishing system and its arc extinguishing method. Background Technology

[0002] With the rapid development of the energy internet and the large-scale integration of renewable energy, DC power grids, with their outstanding advantages such as zero reactive power loss, large transmission capacity, and ease of asynchronous grid connection, have gradually become a core component of modern power systems. However, DC systems have a fatal weakness: DC fault current rises extremely quickly. This is because the line impedance is extremely low, and DC current does not have a natural zero-crossing point, which means that traditional AC circuit breakers cannot be directly applied to fault isolation in DC systems.

[0003] Currently, in the engineering field, three main technical approaches have emerged for interrupting DC short-circuit currents, each with its own advantages and disadvantages, as detailed below: The first type is the purely mechanical DC circuit breaker. These circuit breakers typically employ an LC artificial resonant circuit, injecting a reverse high-frequency oscillating current into the mechanical break to artificially create a current zero-crossing point, thereby extinguishing the arc. However, the LC device in this scheme is very bulky, and the start-up time is long, often requiring tens of milliseconds to complete fault disconnection. For flexible DC systems that require fault isolation within milliseconds, the response speed is far from sufficient, easily leading to insulation breakdown in the converter station, causing serious equipment damage and power grid accidents.

[0004] The second type is the pure solid-state circuit breaker. This type of circuit breaker is entirely composed of fully controlled power semiconductor devices such as IGBTs, IGCTs, or SiC connected in series and parallel. It boasts extremely fast response speeds, reaching microsecond levels, and generates no electric arc during the arc-extinguishing process. However, its fatal flaw is the extremely high conduction loss during steady-state operation. With hundreds or thousands of devices connected in series in the main line, the resulting heat not only requires a massive water-cooling system, increasing equipment costs, but also makes the high operating electricity costs unbearable for power grid companies, hindering its large-scale application.

[0005] The third type is the hybrid DC circuit breaker. This is currently recognized by academia and industry as the optimal solution. It combines the low steady-state loss advantage of mechanical switches with the fast interruption capability of solid-state switches. In steady state, the current flows through the mechanical branch. In case of a fault, the mechanical switch arcs, transferring the current to the solid-state branch, and then the solid-state device completes the shutdown, thus taking into account both the requirements of low loss and fast response.

[0006] However, extensive field operation and in-depth mechanism analysis have revealed a significant physical obstacle in existing hybrid arc-extinguishing systems: the failure of the commutation bottleneck due to competition with dielectric recovery. In existing hybrid circuit breakers, after an arc is generated at the mechanical break, the arc voltage is typically only tens of volts, and even as low as 20 to 30 volts for vacuum arcs. Meanwhile, the parallel solid-state branch contains numerous series-connected semiconductor devices, resulting in a forward voltage drop that can reach hundreds or even thousands of volts. According to Kirchhoff's voltage law, the low arc voltage is insufficient to force the enormous short-circuit current into the high-impedance solid-state branch, easily leading to commutation failure. The mechanical break will then be completely burned out by the continuously burning high-energy arc.

[0007] To address this issue, some existing technologies connect hundreds or even thousands of power electronic diodes in series in the main mechanical branch to artificially increase the steady-state voltage drop and assist in commutation. However, this contradicts the design intent of hybrid circuit breakers to achieve low steady-state losses. Other technologies attempt to utilize the unstable arc region of the vacuum interrupter for high-frequency oscillation commutation, but the randomness of the vacuum arc's movement results in a very low success rate for commutation control, failing to guarantee the reliability of equipment operation. Furthermore, even if the current is managed to be transferred to the solid branch, the opening distance is extremely small due to the limitation of the mechanical moving contact's speed. Once the solid branch is turned off, generating a transient recovery voltage of tens of kilovolts, the mechanical break point, which has just extinguished the arc, is highly susceptible to dielectric breakdown, i.e., reignition, leading to complete failure of current interruption and inability to achieve fault isolation.

[0008] Therefore, how to increase the arc impedance rapidly through physical means in a very short time without increasing steady-state current loss, thereby achieving forced commutation, while simultaneously solving the precise coupling problem between the mechanical break distance stroke and the solid-state turn-off timing, is a fundamental engineering challenge that urgently needs to be overcome in the current field of DC power-off technology.

[0009] Therefore, a hybrid arc extinguishing system and its arc extinguishing method are proposed. Summary of the Invention

[0010] The purpose of this invention is to provide a hybrid arc extinguishing system and arc extinguishing method thereof, aiming to solve one of the problems existing in the prior art.

[0011] Firstly, to solve the aforementioned technical problems, this application adopts a technical solution as follows: a hybrid arc-extinguishing system, comprising: The mechanical current-carrying main branch is connected in series to the power grid to be protected. The mechanical current-carrying main branch includes a fast mechanical switch and a magnetically coordinated arc-extinguishing chamber that is coaxially linked with it. It is used to carry the rated current in steady state and to perform physical disconnection when a disconnection command is received. A solid-state commutator bypass is connected in parallel with the mechanical current-carrying main branch. The solid-state commutator bypass includes an anti-parallel power semiconductor device group and a transient voltage suppression buffer circuit coupled to both ends of the device. The nonlinear energy-dissipating branch, connected in parallel with the solid-state converter bypass, is composed of a multi-pillar stacked metal oxide varistor array, used to absorb inductive energy storage in the system and limit overvoltage. The magnetic-pneumatic co-operated arc-extinguishing chamber is equipped with a self-excited racetrack-shaped arc-extinguishing coil and a Laval micro-nozzle. When the moving contact of the fast mechanical switch separates from the stationary contact and the arc is extinguished, the fault current flows through the self-excited racetrack-shaped arc-extinguishing coil to generate a transverse Ampere force, driving the arc to move at high speed towards the grid area of ​​the arc-extinguishing chamber. At the same time, the contact separation action compresses the gas chamber, forcing the insulating gas to form a supersonic airflow through the Laval micro-nozzle to cut the arc. This causes the arc voltage to surge within 0.5 milliseconds and exceed the turn-on threshold voltage drop of the solid-state converter bypass, forcing the fault current to completely drop from the mechanical current main branch and be switched to the solid-state converter bypass.

[0012] In one possible implementation, the fast mechanical switch is driven by an electromagnetic repulsion mechanism. The moving plate of the electromagnetic repulsion mechanism is made of beryllium bronze alloy with high conductivity, and the stationary plate is embedded with an eddy current repulsion coil. The initial acceleration of the moving contact is greater than 5000g to ensure that the mechanical break has the dielectric insulation strength required to withstand the transient recovery voltage of the system after the current has completed the commutation to the solid-state commutation bypass.

[0013] In one possible implementation, the self-excited racetrack-shaped arc-blowing coil is connected to the circuit only during a specific stroke in the process of opening the rapid mechanical switch. It bypasses the switch through the sliding friction finger behind the stationary contact: when the coil is closed in a steady state, it is short-circuited and does not heat up. When the moving contact reaches 15% of the total stroke, the sliding friction finger disengages, and the arc current is forcibly introduced into the arc-blowing coil.

[0014] In one possible implementation, the anti-parallel power semiconductor device group in the solid-state commutation bypass adopts a cascaded structure of integrated gate commutated thyristors or insulated gate bipolar transistors; each power device unit is connected in parallel with a voltage equalizing capacitor and a voltage equalizing resistor network, and the transient voltage suppression buffer circuit includes a fast recovery diode and a non-inductive absorption capacitor connected in series to suppress the dv / dt peak value at the moment of device turn-off.

[0015] In one possible implementation, the residual voltage of the metal oxide varistor array is set to 1.5 to 1.8 times the rated voltage of the system, and the multi-column varistors are connected in parallel through a cross-braided copper flexible busbar to reduce the uneven distribution of inductance caused by the skin effect due to microsecond-level pulse current impact.

[0016] In one possible implementation, an ultra-high-speed measurement and control unit is also included. The measurement and control unit acquires the di / dt rate of change of the trunk current in real time through the Rogowski coil. When the di / dt value of three consecutive sampling cycles exceeds the preset short-circuit fault threshold, a repulsive trigger pulse is sent to the fast mechanical switch, and a gate turn-on signal is sent to the solid-state commutator bypass at the same time.

[0017] Secondly, to solve the above-mentioned technical problems, another technical solution adopted in this application is: an arc extinguishing method based on the system, comprising the following steps: Step S1: After the measurement and control unit detects the short-circuit fault current, it simultaneously sends an action command to the electromagnetic repulsion mechanism and the solid-state converter bypass. The solid-state converter bypass is in a zero-current pre-conduction state waiting for commutation. Step S2: The electromagnetic repulsion mechanism drives the moving contact to separate, and an arc is drawn out between the breaks. The arc current is displaced with the moving contact and is generated by a self-excited racetrack-shaped arc blowing coil. The Lorentz force generated, combined with the supersonic insulating airflow blown out by the Laval micro-nozzle, strongly elongates, cools and cuts the arc plasma channel. The equivalent arc impedance of the mechanical main branch increases exponentially. When the arc voltage is greater than the sum of the on-state voltage drop of the solid-state converter bypass and the stray inductance voltage drop of the line, the fault current is rapidly transferred to the solid-state converter bypass within 0.5 milliseconds to 1.5 milliseconds. Step S3: After the current is completely switched to the solid-state bypass, the arc at the mechanical break is extinguished. At this time, the electromagnetic repulsion mechanism continues to drive the moving contact to the limit opening distance. The insulating gas quickly fills the free channel, restoring the dielectric insulation strength of the mechanical break to be sufficient to resist the subsequent transient recovery voltage. Step S4: After confirming the safe distance for the insulation restoration of the mechanical break, the measurement and control unit cancels the gate signal of the solid-state commutation bypass, and the power semiconductor device performs a hard shutdown; the branch current drops instantaneously, and the huge inductive magnetic field energy accumulated in the line is converted into overvoltage that breaks down the metal oxide varistor array, and the current is finally commutated to the nonlinear energy-consuming branch. Step S5: The varistor clamps the system overvoltage to a safe level and dissipates the fault magnetic field energy as heat; as the energy is depleted, the fault current is forced to zero, completing a complete current interruption and isolation without arc leakage. In one possible implementation, ...

[0018] In one possible implementation, in step S2, the commutation process is subject to strict constraints by dynamic boundary conditions: the rising slope of the arc voltage must be greater than the conduction time hysteresis of the solid bypass; if the commutation time is detected to exceed 2 milliseconds and there is still residual current in the mechanical branch, the system will trigger the backup gas-generating propellant at the rear end of the Laval nozzle to generate gas explosively and perform secondary forced gas blowing to extinguish the arc.

[0019] In one possible implementation, in step S4, the power semiconductor device turn-off command is not issued synchronously, but rather a microsecond-level staggered turn-off strategy is adopted for the cascaded device group, that is, the device is turned off at each stage every 2-5 microseconds, in order to weaken the common-mode voltage oscillation impact generated by the overall stray inductance.

[0020] In one possible implementation, after the current returns to zero in step S5, the low-speed disconnect switch configured inside the system will perform a physical disconnection action in a passive state, forming a clear safety insulation break point and completely eliminating the leakage current hazard of solid-state devices.

[0021] The present invention has the following beneficial effects: 1. This invention does not increase any steady-state losses. It cleverly utilizes the accompanying potential energy of mechanical action, namely the kinetic energy of the moving contact compressing the gas, and the magnetic field energy generated by the short-circuit current itself, to artificially create an extremely high arc voltage, making forced commutation extremely fast and reliable, and fundamentally solving the problem of commutation failure in existing hybrid circuit breakers.

[0022] 2. The supersonic airflow blown out by the Laval nozzle of this invention is not only used to increase the arc voltage in the initial stage, but also to deeply clean the mechanical break in the zero rest zone after the current is switched into the solid branch, thoroughly removing the remaining metal vapor and free electrons, greatly accelerating the insulation recovery speed, reducing the probability of arc reignition by two orders of magnitude, and improving the reliability of equipment operation.

[0023] 3. The solid-state device of this invention only bears a short-circuit current of a few milliseconds during a fault, eliminating the need for a large heat dissipation system and reducing equipment costs. At the same time, by adopting a microsecond-level staggered turn-off strategy and a non-inductive absorption circuit, the voltage spike at the moment of device turn-off is effectively smoothed out, reducing the loss of solid-state devices, extending the lifespan of extremely expensive power semiconductors, and reducing the operation and maintenance costs of the equipment. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the hybrid arc extinguishing method of the present invention; Figure 2 This is a block diagram of the hybrid arc extinguishing system of the present invention; Figure 3 This is a schematic diagram of the structure of the electronic device of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] refer to, Figure 1 This is a schematic flowchart of the hybrid arc extinguishing method according to an embodiment of the present invention.

[0028] like Figure 2 The diagram shows a block diagram of the hybrid arc-extinguishing system of the present invention. It should be noted that if substantially the same result is achieved, the method of this application is not based on... Figure 1 The sequence of processes shown is limited. Example 1

[0029] The present invention adopts the following technical solution, constructing a hybrid arc extinguishing system comprising three parallel physical channels: a low-resistivity mechanical current-carrying main branch, a solid-state converter bypass, and a nonlinear energy-dissipating branch. Each branch works collaboratively to complete fault arc extinguishing and isolation. The specific structure and working principle are as follows: This system incorporates a self-excited racetrack-shaped arc-blowing coil and a Laval micro pneumatic nozzle around a conventional fast-acting mechanical contact. The two work together to achieve a rapid surge in arc voltage.

[0030] During steady-state operation of the system, the arc-extinguishing coil is physically short-circuited by the sliding contact finger behind the stationary contact and does not participate in current flow. Therefore, the problems of coil heating and increased steady-state losses are completely avoided, ensuring the economic efficiency of the system's steady-state operation. Once a short-circuit fault occurs in the power grid, the ultra-high-speed electromagnetic repulsion mechanism will drive the moving contact to rapidly pull back at an acceleration of several thousand Gs, initiating the fault arc-extinguishing process.

[0031] At the critical point when the moving contact reaches 15% of its total stroke, the sliding contact finger disengages from the main flow tube. At this moment, the thousands or even tens of thousands of amperes of current generated by the short-circuit fault are instantly and forcibly introduced into the racetrack-shaped arc-blowing coil. The arc-blowing coil establishes a high-intensity transverse strong magnetic field in an extremely short time. As a highly conductive fluid, the arc plasma is subjected to a huge Lorentz force in the transverse strong magnetic field and is pushed towards the arc-extinguishing grid area on one side at an extremely high speed, thus stretching the arc.

[0032] Meanwhile, this invention utilizes the high-speed retraction of the moving contact to design an ingenious pneumatic backpressure chamber. The movement of the moving contact acts like a piston, extremely compressing the insulating gas within the chamber, such as SF6 or N2. This high-pressure gas is forced through Laval micro-nozzles arranged around the contact. According to aerodynamic principles, the subsonic gas accelerates to supersonic speeds after passing through the throat of the Laval nozzle. This supersonic, icy airflow, like an invisible blade, vertically cuts the electric arc being stretched by the magnetic field, achieving both cooling and severing of the arc.

[0033] The stretching effect of the strong magnetic field, combined with the cooling and stripping effect of the supersonic airflow, drastically removes the internal energy of the arc plasma channel, causing the cross-sectional area of ​​the arc to shrink dramatically. This dual magnetic-aerodynamic effect leads to a precipitous drop in the conductivity of the arc plasma, and an exponential surge in the equivalent arc resistance. The arc voltage, which was originally only tens of volts, is forcibly increased to two thousand volts or even higher within a mere 0.5 milliseconds, far exceeding the on-state voltage drop of the solid-state converter bypass.

[0034] At this moment, the potential difference of up to two thousand volts will overwhelm the on-state voltage drop of the solid-state converter bypass and the stray inductance impedance of the line. The short-circuit current will drop completely from the mechanical break and flow into the solid-state converter bypass in a very short time, completing the forced commutation and preventing the mechanical break from being burned by the electric arc.

[0035] After successful commutation, the arc-extinguishing method of this invention does not end immediately. Instead, it ensures complete fault isolation through precise timing control. The system's measurement and control unit monitors the commutation process in real time. Once the current transfers to the solid-state branch, it means the arc at the mechanical break has been completely extinguished. However, the solid-state branch cannot be immediately shut off at this point. This is because the mechanical moving contact is still moving backward due to inertia. The current physical gap is too small, and the insulation performance is extremely fragile. If the solid-state branch is shut off at this time, the resulting transient recovery voltage will instantly break down the mechanical break, causing the arc to reignite and resulting in arc-extinguishing failure.

[0036] Therefore, the control unit will command the solid-state commutator bypass to remain on for approximately 1 to 2 milliseconds. This period, known as the zero-rest zone, is the golden time to ensure the insulation recovery of the mechanical break. During this time, the moving contact will continue to move to its maximum opening distance, while the supersonic airflow from the Laval nozzle will completely blow away any remaining metal vapor and free electrons between the breaks, completing the complete reconstruction of the dielectric insulation strength of the mechanical break, making it sufficient to resist subsequent transient recovery voltages.

[0037] Once the insulation of the mechanical break is confirmed to have recovered to a safe level and can withstand transient recovery voltage, the control unit instantly cancels the gate drive signal to the solid-state device, and the semiconductor device is forcibly turned off within microseconds. Due to the inductance of the line, the sudden current change will generate an extremely strong induced high voltage. At this time, the third line of defense in parallel with the system, namely the metal oxide varistor array, will be broken down and turned on by this high voltage. The varistor will clamp the system overvoltage to a safe level, typically 1.5 to 1.8 times the system rated voltage, and convert the huge electromagnetic energy accumulated in the line into heat energy for dissipation. As the energy is gradually depleted, the fault current is completely cut off, and the system completes a complete hybrid deep arc extinguishing, achieving complete fault isolation. Example 2

[0038] The mechanical current-carrying main branch in this embodiment is not just a simple conductive channel, but a sophisticated electromechanical-hydraulic-gas coupling device. Its core components include an electromagnetic repulsion mechanism, a magnetic-gas coordinated arc-extinguishing chamber, moving contacts, stationary contacts, etc. The components work together to achieve rapid arc stretching and voltage surge.

[0039] Its core driving source is a dual-coil, double-sided driven electromagnetic repulsion mechanism, designed to achieve ultra-high-speed movement of the moving contact. Upon receiving a trigger command from the measurement and control unit, the repulsion energy storage capacitor, pre-charged to 800V, discharges instantaneously to the fixed pulse coil through a thyristor. According to Lenz's law, a huge eddy current is induced in the beryllium bronze moving disk above the pulse coil. The magnetic field generated by the pulse coil and the magnetic field generated by the eddy current in the moving disk repel each other, imparting an initial acceleration of up to 6000g to the moving contact rod within 0.2 milliseconds, enabling it to reach a maximum speed of 25 meters per second. This ensures rapid separation of the moving contact, buying time for subsequent arc processing.

[0040] Both the moving and stationary contacts are placed inside a sealed insulating cylinder filled with 0.2 MPa of insulating gas. In this embodiment, an environmentally friendly mixed gas C4F7N / CO2 is used, which not only ensures good insulation performance but also meets environmental protection requirements, replacing the traditional high-pollution insulating gas.

[0041] A set of self-excited racetrack-shaped arc-blowing coils, made of oxygen-free copper, is nested and sintered around the stationary contact. Oxygen-free copper has excellent conductivity, reducing coil resistance losses and ensuring coil stability when carrying large currents. The winding direction of this coil has undergone rigorous calibration and testing to ensure that the direction of the magnetic field lines it generates is perpendicular to the arc column between the contacts. This maximizes the Lorentz force on the arc, achieving efficient arc stretching. At the root of the stationary contact, a ring of beryllium bronze sliding friction-shaped plum blossom contact fingers is provided. In the steady-state closed position, the conductive rod of the moving contact directly contacts these plum blossom contact fingers, and the current flows directly through the conductive rod and plum blossom contact fingers. The arc-blowing coil is completely short-circuited and does not participate in current flow, avoiding steady-state losses caused by coil heating.

[0042] Behind the moving contact, a miniature piston chamber is designed to be linked with the pull rod, and the piston chamber moves synchronously with the moving contact. The gas outlet of the piston chamber is tightly surrounded around the separation and contact surface of the moving and stationary contacts, and the gas outlet is precisely machined into a Laval nozzle shape, that is, a cross-sectional geometry that first contracts and then expands. This shape enables the gas to be ejected at supersonic speed, providing power for the cooling and cutting of the electric arc.

[0043] The dynamic physical process of the main mechanical branch circuit is broken down in detail below, clearly demonstrating its working principle: When a short-circuit fault occurs in the power grid, the monitoring and control unit issues a trigger command, activating the repulsive mechanism and causing the moving contact to move backward at high speed. When the moving contact reaches a stroke of 3 mm (the total stroke is typically 20 mm), taking approximately 0.8 milliseconds, the conductive rod disengages from the sliding swivel contact finger, and a violent, high-temperature electric arc begins to form between the moving and stationary contacts. Due to the short-circuit fault, a fault current of several thousand amperes is instantly forced into the self-excited racetrack-shaped arc-blowing coil surrounding the stationary contact. Under the influence of this high current, the arc-blowing coil is instantly activated, establishing a transverse dipole magnetic field of approximately 1.5 Tesla in the contact gap.

[0044] Arc plasma is a fluid composed of charged particles. Under the cross-action of a strong magnetic field of 1.5 Tesla and a large current of 5kA, it will be subjected to an extremely strong Lorentz thrust, which will force it to bend and elongate, and then collide at high speed with the arc-extinguishing grid plate arranged on one side. The arc-extinguishing grid plate is composed of dozens of copper-plated iron plates, which can further divide the arc and accelerate the extinguishing of the arc.

[0045] Simultaneously, the moving contact is violently pulled back, and the linked piston intensely compresses the gas behind the insulating cylinder. Due to the extremely high speed of the contact movement, the pressure in the gas chamber soars to 1.5 MPa in less than one millisecond. The high-pressure gas cannot remain in the gas chamber and can only be ejected from the Laval nozzle surrounding the arc. After passing the sonic limit at the nozzle throat, the gas rapidly expands and depressurizes in the expansion section, accelerating to supersonic speeds of Mach 1.5. This high-speed, icy insulating gas flow cuts perpendicularly into the arc column being stretched by the magnetic field, intensely cooling and cutting the arc.

[0046] Under the pulling force of the transverse magnetic field and the cutting and cooling effect of the supersonic airflow, the recombination rate of free electrons and positive ions in the high-temperature electric arc increases exponentially, and the conductive cross-section of the arc shrinks sharply. According to the current-voltage characteristics of the arc, the equivalent impedance of the arc increases sharply, and the arc voltage is forcibly raised to over 2500 volts within a very short time of a fraction of a millisecond, providing sufficient voltage driving force for subsequent forced commutation. Example 3

[0047] In this embodiment, the solid-state converter bypass uses a reverse-conducting integrated gate commutating thyristor. Compared with an insulated gate bipolar transistor, the integrated gate commutating thyristor has a stronger short-time surge current carrying capacity and a lower on-state voltage drop, making it more suitable for withstanding the large current impact during short-circuit faults, thereby improving the reliability and service life of the solid-state converter bypass.

[0048] Since this embodiment targets a 10kV system, and considering the rated voltage of the integrated gate commutating thyristors, we connect six integrated gate commutating thyristors with a rated voltage of 4.5kV in forward and reverse directions to form a bidirectional solid-state valve group. This design can meet the voltage level requirements of the 10kV system while ensuring the conduction performance of the solid-state converter bypass. At this time, the total dynamic on-state voltage drop of the entire solid-state bypass and the transient voltage drop caused by stray inductance of the line are approximately 1200 volts.

[0049] As can be seen from Example 1, the arc voltage forcibly activated at the mechanical break reaches as high as 2500 volts, far exceeding the 1200-volt threshold of the solid-state branch. Under this powerful driving voltage difference of 1300 volts, the short-circuit current of up to 5kA has no choice but to surge from the near-collapse mechanical break to the standby solid-state commutator bypass in less than 0.8 milliseconds, completing the forced commutation and ensuring that the mechanical break is not burned by the arc.

[0050] The nonlinear energy dissipation branch is connected in parallel across the integrated gate commutated thyristor valve group. Its core component is a multi-column parallel zinc oxide varistor. The zinc oxide varistor has excellent nonlinear characteristics and can quickly conduct under overvoltage to clamp the voltage at a safe level, while absorbing the inductive energy stored in the system.

[0051] To cope with the enormous destructive energy released by the line inductance when the system cuts off the current, which can be as high as several megajoules, we designed the zinc oxide varistor to avalanche breakdown at 15kV, which is 1.5 times the rated voltage of the system. This design can ensure that the varistor does not conduct during normal system operation, and can also start in time when overvoltage occurs to protect solid-state devices and other equipment.

[0052] Furthermore, in order to address the potential risk of single-column varistors burning out due to current concentration caused by inconsistent distributed inductance under microsecond-level high-frequency pulses, this embodiment creatively employs a three-dimensional cross-braided connection using wide copper strips. This connection method can greatly reduce the high-frequency parasitic inductance of the system, making the current distribution of each column varistor more uniform, and improving the stability and service life of the nonlinear energy-consuming branch. Example 4

[0053] A complete hybrid arc extinguishing system relies on a robust hardware structure as its foundation and a sophisticated control strategy as its core. This invention's ultra-high-speed collaborative arc extinguishing control strategy, based on a DSP+FPGA underlying architecture measurement and control unit, precisely directs the coordinated operation of each branch within milliseconds to complete fault arc extinguishing and isolation. Its core lies in the precise timing control of each stage, preventing problems such as commutation failure and arc reignition.

[0054] The following section breaks down the timing logic of the entire arc extinguishing control process in detail, using specific time points to clearly demonstrate the collaborative working process of each stage: At time T0, the moment the fault occurs, the measurement and control unit reads the current signal transmitted back by the Rogowski coil in the line in real time at an ultra-high sampling rate of 1MHz. The Rogowski coil can accurately detect changes in line current, providing reliable data support for fault diagnosis. When the FPGA calculates the rate of change of current and the absolute amplitude of current using a differential algorithm, and both exceed the preset extreme value warning line, the system determines that a short-circuit fault has occurred in the power grid, immediately issues a trigger command, and initiates the arc extinguishing process.

[0055] At time T1, 0.1 milliseconds after the fault occurs, a parallel triggering operation is executed. Simultaneously, the control unit sends a gate-on pulse signal to the integrated gate-commutating thyristor in the solid-state branch. The integrated gate-commutating thyristor enters the conducting state within a few microseconds, like opening the gate of a backup floodgate, preparing for commutation. However, at this time, the mechanical switch is in the closed state, and its impedance is almost zero. Therefore, current still flows through the mechanical branch, and the solid-state branch does not temporarily bear current. At the same time, the control unit triggers a discharge command to the thyristor of the repulsion mechanism. The electromagnetic repulsion mechanism starts, and the moving contact begins to accelerate, preparing for separation.

[0056] At time T2, 1.0 millisecond after the fault occurred, the pressure generation and current transfer operation was executed. At this time, the moving contact had been pulled apart by a certain distance, the sliding contact finger had separated from the conductive rod, and the self-excited racetrack-type arc-blowing coil officially started working. Subsequently, the magnetic-pneumatic coordinated arc-extinguishing process described in Example 1 occurred, and the arc voltage surged from the initial 30V to 2500V, far exceeding the conduction voltage drop threshold of the solid-state branch. The fault current began to transfer to the integrated gate commutation thyristor branch, which was already in the conducting state.

[0057] At time T3, 1.8 milliseconds after the fault occurred, the system enters the zero-rest zone and dielectric recovery phase. The measurement and control unit, through the current detection module, detects that the current in the mechanical branch has completely returned to zero, indicating successful current commutation and the extinguishing of the arc at the mechanical break. This is the key innovation of the control logic of this invention: never immediately turn off the integrated gate commutating thyristor.

[0058] This is because the moving contact has only retreated less than halfway, about 8 millimeters, at this point. The physical gap between the contacts is extremely small, and metal vapor and free electrons remain between the contacts, making the insulation extremely fragile. If the solid-state branch is switched off at this time, the 15kV overvoltage generated by the zinc oxide varistor will immediately break down this fragile 8-millimeter gap again, causing the arc to reignite, which in turn will burn out the circuit breaker and result in arc extinguishing failure.

[0059] Therefore, the control unit commands the integrated gate commutating thyristor to continue conducting, which is to perform a zero-rest delay operation, with a delay time of 1.5 to 2.0 milliseconds. During this valuable delay time, the supersonic gas flow from the Laval nozzle continues to thoroughly clean the metal vapor and free electrons between the fracture surfaces, while the moving contact, driven by the electromagnetic repulsion mechanism, continues to retract to the full opening limit position of 20 mm. At this point, the clean insulating gas between the fracture surfaces has the dielectric strength to withstand high voltages of over 50 kV, effectively resisting subsequent transient recovery voltages.

[0060] At time T4, 3.5 milliseconds after the fault occurs, a kill shutdown operation is executed. After confirming through the insulation detection module that the insulation performance of the mechanical break has been restored, the measurement and control unit instantly issues a shutdown command to the integrated gate commutation thyristors. To avoid simultaneous shutdown of all six integrated gate commutation thyristors in series, which could cause extreme common-mode oscillation and damage the solid-state devices, the measurement and control system employs a microsecond-level staggered shutdown algorithm. This means that one integrated gate commutation thyristor is shut down every 3 microseconds, gradually cutting off the current in the solid-state branch and effectively smoothing out voltage spikes during the shutdown process.

[0061] Under the action of the turn-off command, the charge carriers inside the integrated gate commutated thyristor are forcibly extracted, and the branch current drops rapidly within tens of microseconds, completing the turn-off of the solid-state branch.

[0062] At time T5, 4.0 milliseconds after the fault occurs, clamping and energy absorption operations are performed. As the current in the solid-state branch rapidly drops, the enormous inductive energy stored in the line generates an extremely high induced electromotive force due to the sudden change in current. This causes the voltage across the line to surge instantaneously to 15kV, reaching the avalanche breakdown threshold of the zinc oxide varistor, triggering its avalanche conduction. At this point, the fault current shifts from the solid-state branch to the energy-absorbing branch of the zinc oxide varistor. The magnetic field energy in the line is absorbed by the zinc oxide varistor and converted into heat, which is dissipated through the zinc oxide lattice. Simultaneously, the voltage is clamped firmly within the 15kV safety line, protecting other equipment in the system from overvoltage damage.

[0063] At time T6, approximately 8.0 milliseconds after the fault occurs, a complete isolation operation is performed. As the zinc oxide varistor continuously dissipates energy, the fault current in the circuit gradually decreases to the leakage current level, typically in the milliampere range. At this point, the fault is essentially under control. The passive slow-speed disconnect switch at the back end of the system will automatically open in a passive state, forming a visible physical break, completely severing the connection between the faulty circuit and the normal circuit, eliminating the leakage current hazard of solid-state devices, ensuring that the fault is completely isolated, and preventing the fault from escalating.

[0064] like Figure 3 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present disclosure. It illustrates a structural schematic diagram suitable for implementing the electronic device in the embodiment of the present disclosure. Figure 3 The electronic device shown is merely an example and should not be construed as limiting the functionality and scope of the embodiments disclosed herein.

[0065] like Figure 3 As shown, the electronic device includes a processor, a memory, and a communication interface. The memory stores a computer program, and when the processor executes the computer program, it implements the hybrid arc extinguishing method of the aforementioned embodiments of this disclosure. The electronic device can exchange data with other devices or systems through the communication interface, enabling real-time updates and sharing of data information.

[0066] The processor in the aforementioned electronic device serves as its core, responsible for executing the computer program stored in the memory to implement various functions of the hybrid arc extinguishing method. The processor can employ a high-performance multi-core CPU or a dedicated chip to meet the demands of complex calculations and real-time processing. The memory stores the operating system, applications, data, and computer programs. In this embodiment, the memory stores the computer program implementing the hybrid arc extinguishing method. The memory can be RAM, ROM, Flash memory, or other types of non-volatile memory. The communication interface connects the electronic device to other devices or networks, enabling data transmission and exchange. In this embodiment, the communication interface supports multiple communication protocols and interface standards, such as Wi-Fi, Bluetooth, USB, and Ethernet, to meet communication needs in different scenarios.

[0067] For a detailed description of this embodiment, please refer to the corresponding descriptions in the foregoing embodiments, which will not be repeated here.

[0068] According to embodiments of the present disclosure, a computer-readable storage medium stores a computer program, which, when executed by a processor, implements the functions of the hybrid arc extinguishing methods described in the foregoing embodiments of the present disclosure.

[0069] The aforementioned computer-readable storage media include, but are not limited to: optical storage media (e.g., CD-ROM and DVD), magneto-optical storage media (e.g., MO), magnetic storage media (e.g., magnetic tape or portable hard drive), media with built-in rewritable non-volatile memory (e.g., memory card), and media with built-in ROM (e.g., ROM cartridge).

[0070] For a detailed description of this embodiment, please refer to the corresponding descriptions in the foregoing embodiments, which will not be repeated here.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A hybrid arc extinguishing system, characterized in that, include: A mechanical current-carrying main branch is connected in series to the power grid to be protected. The mechanical current-carrying main branch includes a fast mechanical switch and a magnetically coordinated arc-extinguishing chamber that is coaxially linked with it. A solid-state commutator bypass is connected in parallel with the mechanical current-carrying main branch. The solid-state commutator bypass includes an anti-parallel power semiconductor device group and a transient voltage suppression buffer circuit coupled to both ends of the device. The nonlinear energy-consuming branch, connected in parallel with the solid-state converter bypass, is composed of a multi-pillar stacked metal oxide varistor array; The magnetic-pneumatic co-operated arc-extinguishing chamber is equipped with a self-excited racetrack-shaped arc-extinguishing coil and a Laval micro-nozzle. When the moving contact of the fast mechanical switch separates from the stationary contact and the arc is extinguished, the fault current flows through the self-excited racetrack-shaped arc-extinguishing coil to generate a transverse Ampere force, driving the arc to move at high speed towards the grid area of ​​the arc-extinguishing chamber. At the same time, the contact separation action compresses the gas chamber, forcing the insulating gas to form an airflow through the Laval micro-nozzle to cut the arc. This causes the arc voltage to surge within 0.5 milliseconds and exceed the turn-on threshold voltage drop of the solid-state converter bypass, forcing the fault current to completely drop from the mechanical current main branch and be switched to the solid-state converter bypass.

2. The hybrid arc-extinguishing system according to claim 1, characterized in that, The rapid mechanical switch is driven by an electromagnetic repulsion mechanism. The moving plate of the electromagnetic repulsion mechanism is made of beryllium bronze alloy with high conductivity, and the stationary plate is embedded with an eddy current repulsion coil. The initial acceleration of the moving contact is greater than 5000g.

3. The hybrid arc-extinguishing system according to claim 1, characterized in that, The self-excited racetrack-shaped arc-blowing coil is connected to the circuit during the stroke of the rapid mechanical switch opening process, and it bypasses the circuit through the sliding friction contact finger behind the stationary contact: when the steady-state is closed, the arc-blowing coil is short-circuited and does not generate heat.

4. The hybrid arc-extinguishing system according to claim 1, characterized in that, The anti-parallel power semiconductor device group in the solid-state converter bypass adopts a cascaded structure of integrated gate commutated thyristors or insulated gate bipolar transistors; each power device unit is connected in parallel with a voltage equalizing capacitor and a voltage equalizing resistor network, and the transient voltage suppression buffer circuit includes a fast recovery diode and a non-inductive absorption capacitor connected in series.

5. A hybrid arc-extinguishing system according to claim 1, characterized in that, The residual voltage of the metal oxide varistor array is set to 1.5 to 1.8 times the rated voltage of the system, and the multi-column varistors are connected in parallel through a cross-braided copper flexible busbar.

6. A hybrid arc-extinguishing system according to claim 1, characterized in that, It also includes an ultra-high-speed measurement and control unit, which acquires the di / dt rate of change of the trunk current in real time through the Rogowski coil. When the di / dt value of three consecutive sampling cycles exceeds the preset short-circuit fault threshold, it sends a repulsive trigger pulse to the fast mechanical switch and simultaneously sends a gate turn-on signal to the solid-state commutator bypass.

7. An arc-extinguishing method based on the system according to any one of claims 1 to 6, characterized in that, Specifically, the following steps are included: Step S1: After the measurement and control unit detects the short-circuit fault current, it simultaneously sends an action command to the electromagnetic repulsion mechanism and the solid-state converter bypass. The solid-state converter bypass is in a zero-current pre-conduction state waiting for commutation. Step S2: The electromagnetic repulsion mechanism drives the moving contact to separate, and an electric arc is drawn out between the breaks. The arc current is displaced by the moving contact and is generated by a self-excited racetrack-shaped arc blowing coil. The Lorentz force generated, combined with the insulating airflow blown out by the Laval micro-nozzle, strongly elongates, cools and cuts the arc plasma channel. When the arc voltage is greater than the sum of the on-state voltage drop of the solid-state converter bypass and the stray inductance voltage drop of the line, the fault current is transferred to the solid-state converter bypass within 0.5 milliseconds to 1.5 milliseconds. Step S3: After the current is completely switched to the solid-state bypass, the arc at the mechanical break is extinguished. At this time, the electromagnetic repulsion mechanism continues to drive the moving contact to the limit opening distance, and the insulating gas fills the free channel, restoring the dielectric insulation strength of the mechanical break. Step S4: After confirming the safe distance for the insulation restoration of the mechanical break, the measurement and control unit cancels the gate signal of the solid-state commutation bypass, and the power semiconductor device performs a hard shutdown. Step S5: The varistor clamps the system overvoltage to a safe level and dissipates the energy of the fault magnetic field as heat. As the energy is depleted, the fault current is forced to zero, completing a complete disconnection and isolation without arc leakage.

8. The arc extinguishing method according to claim 7, characterized in that, In step S2, the commutation process is subject to strict constraints by dynamic boundary conditions: the rising slope of the arc voltage must be greater than the conduction time hysteresis of the solid-state bypass.

9. The arc extinguishing method according to claim 7, characterized in that, In step S4, the power semiconductor device shutdown command is not issued synchronously, but a microsecond-level staggered shutdown strategy is adopted for the cascaded device group, that is, the first-level device is shut down every 2-5 microseconds.

10. The arc extinguishing method according to claim 7, characterized in that, After the current returns to zero in step S5, the low-speed disconnect switch configured inside the system will perform a physical disconnection action in a passive state.

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