Method and structure for forcibly extinguishing arc of drop-out fuse through solid-electric and liquid-electric effects

Abstract

The invention relates to the technical field of arc extinguishing, in particular to a method for forced arc extinguishing of a drop-out fuse through solid-electric and liquid-electric effects, and particularly relates to a method for forced arc extinguishing of a drop-out fuse through solid-electric and liquid-electric effects. And superposing the first arc extinguishing pressure intensity and the second arc extinguishing pressure intensity in a space-time dimension to form a composite arc extinguishing pressure intensity, and simultaneously realizing forced arc extinguishing and mechanical tripping of the fuse by using the composite arc extinguishing pressure intensity. Meanwhile, the invention also provides an arc extinguishing structure for realizing the method, and a power network protection system adopting the arc extinguishing structure. According to the drop-out fuse, the problems of low efficiency of arc extinguishing energy superposition and mechanical tripping delay due to the adoption of solid electricity and liquid electricity effects by the existing drop-out fuse can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of arc extinguishing, and particularly relates to a method and structure for forcibly extinguishing the arc of a drop-out fuse by solid electricity and liquid electricity effects. Background Art

[0002] Traditional drop-out fuses rely on gravity to slowly drop after the fuse wire is short-circuited and melted to achieve arc extinguishing. There are significant defects in the arc extinguishing process: Since the drop of the fuse depends on mechanical gravity, the arc maintenance time is as long as hundreds of milliseconds. During this period, the power frequency short-circuit current continuously generates electrodynamic force, which is likely to cause displacement, deformation or even explosion of the transformer winding; in addition, only passive arc extinguishing is achieved through the principle of arc elongation, lacking an active forced arc extinguishing mechanism, and the lateral wind is likely to cause the arc to drift to the adjacent phase, triggering an interphase short circuit and expanding the fault.

[0003] The existing patent with the publication number CN114629001A discloses a counterpunch structure arc extinguishing device and method by solid electricity and liquid electricity effects, which actively and forcibly extinguishes the arc through the solid electricity effect and the liquid electricity effect. Although it can solve the problems of low arc extinguishing efficiency and insufficient arc extinguishing ability of traditional drop-out fuses, there are still the following technical bottlenecks:

[0004] Inefficient energy superposition: The pressure generation time sequence of the solid electricity effect (metal gasification and expansion) and the liquid electricity effect (arc evaporation in oil) is misaligned, resulting in low energy superposition efficiency and limited arc extinguishing threshold.

[0005] Mechanical tripping hysteresis: The arc extinguishing pressure is only used for arc extinguishing, and no energy reuse is formed with the tripping mechanism of the fuse. The tripping acceleration still depends on gravity and is seriously mismatched with the arc extinguishing speed.

[0006] The above technical defects lead to the problems of relatively high arc extinguishing failure rate and main network mis-tripping rate in the existing arc extinguishing drop-out fuse solutions by solid electricity and liquid electricity effects in the scenario of high new energy penetration rate (short-circuit current ≥ 80 kA). Therefore, a collaborative enhancement scheme that deeply integrates the two-way energy chain of arc extinguishing - tripping is urgently needed. Summary of the Invention

[0007] In view of this, one of the purposes of the present invention is to provide a method and structure for forcibly extinguishing the arc of a drop-out fuse by solid electricity and liquid electricity effects, so as to solve the problems of low energy superposition efficiency and mechanical tripping hysteresis in the existing drop-out fuses using solid electricity and liquid electricity effects for arc extinguishing.

[0008] Another purpose of the present invention is to provide a power network protection system.

[0009] In order to achieve the above first purpose, the present invention provides the following technical solutions:

[0010] A method for forcibly extinguishing the arc of a drop-out fuse by solid electricity and liquid electricity effects, comprising:

[0011] (a) Generate a first arc extinguishing pressure through the phase change of a solid material;

[0012] (b) Generate a second arc extinguishing pressure through arc discharge in a liquid medium;

[0013] (c) Superimpose the first arc extinguishing pressure and the second arc extinguishing pressure in the space-time dimension to form a composite arc extinguishing pressure;

[0014] (d) Utilize the composite arc extinguishing pressure to simultaneously achieve forced arc extinction and mechanical tripping of the fuse.

[0015] According to the above technical solution, it can be known that the arc extinguishing method of the present invention deeply integrates the phase change energy of solid materials, the vaporization energy of liquid media and arc energy, constructs an energy chain conversion path, and forms a high-strength composite arc extinguishing pressure through the space-time pressure superposition of the solid-electric effect and the liquid-electric effect. Compared with the traditional scheme, the arc extinguishing time is greatly shortened, and the arc extinguishing ability threshold is improved. In addition, the composite arc extinguishing pressure not only directly acts on the arc channel, but also synchronously drives the mechanical tripping of the fuse. On the one hand, through precise mechanical linkage design, the arc extinguishing is completed almost synchronously with the tripping action of the fuse, completely eliminating the problems of arc reignition or secondary short circuit caused by tripping delay in the traditional scheme, and improving the reliability of fault isolation; on the other hand, the energy generated during the arc extinguishing process is reused as the driving force for mechanical tripping, significantly improving the energy utilization efficiency and reducing the performance loss caused by energy dispersion in the traditional design.

[0016] As an optional scheme, the time superposition of the first arc extinguishing pressure and the second arc extinguishing pressure includes a preset pressure stage and a dynamic trigger stage, where the preset pressure stage starts before the solid material melts, and the dynamic trigger stage lasts until the arc is completely extinguished.

[0017] As an optional scheme, the energy source of the composite arc extinguishing pressure includes at least two energy couplings of the phase change energy of the solid material, the vaporization energy of the liquid medium, and the arc discharge energy.

[0018] An arc extinguishing structure for implementing the arc extinguishing method of the above-mentioned forced arc extinguishing drop-out fuse with solid-electric and liquid-electric effects, comprising

[0019] A fuse tube, internally provided with a phase change pressure generation module and a liquid-electric effect generation module; the phase change pressure generation module is configured to generate a first arc extinguishing pressure through the phase change of a solid material; the liquid-electric effect generation module is configured to trigger a second arc extinguishing pressure through arc discharge in a liquid medium;

[0020] A longitudinal displacement trigger unit, connected to the liquid-electric effect generation module, capable of generating a longitudinal displacement in response to the second arc extinguishing pressure;

[0021] A mechanical amplification unit, connected to the longitudinal displacement trigger unit, can convert longitudinal displacement into lateral thrust to trigger the fuse to trip and drop.

[0022] According to the above technical solution, it can be known that the arc extinguishing structure of the present invention forms an energy transfer link through the longitudinal displacement unit triggered by the liquid-electric effect and the mechanical amplification unit, and efficiently converts the arc extinguishing energy into mechanical tripping power. Through the precise conversion of longitudinal displacement into lateral thrust, the synchronous triggering of arc extinguishing completion and fuse tripping action is realized, completely eliminating the risk of arc reignition or secondary short circuit caused by tripping delay in the traditional solution, and improving the reliability of fault isolation. The energy of the solid material released during the phase change process is deeply integrated with the energy of the liquid medium generated by the liquid-electric effect to form a "arc extinguishing - tripping" bidirectional drive link. The energy is used to suppress the arc during the arc extinguishing stage and drive mechanical action during the tripping stage, realizing the closed-loop reuse of energy, significantly improving the overall efficiency of the system, and reducing energy waste.

[0023] As an optional solution, the longitudinal displacement trigger unit includes a displacement electrode rod and a displacement electrode plate; one end of the displacement electrode rod is connected to the fuse circuit, and the other end extends into the fuse tube and is connected to one side of the displacement electrode plate; the other side of the displacement electrode plate is connected to the liquid-electric effect generation module.

[0024] As an optional solution, the upper and lower ends of the fuse tube are respectively closed by an upper fixed electrode and a lower fixed electrode, the displacement electrode rod passes through the upper fixed electrode and is rigidly connected to the displacement electrode plate; the displacement electrode plate is connected to the lower fixed electrode through the phase change pressure generation module.

[0025] As an optional solution, the mechanical amplification unit includes at least a pair of interacting displacement ramps and fixed ramps, and the displacement ramp is connected to the longitudinal displacement trigger unit.

[0026] As an optional solution, it further includes an elastic acceleration unit, which is connected to the fuse circuit and can release the pre-stored elastic potential energy at the critical point of fuse tripping.

[0027] As an optional solution, it further includes a dynamic insulation barrier, which includes a dynamic gas-liquid mixed insulation layer formed by the vaporization of the liquid medium during the arc extinguishing stage, and a composite static insulation layer composed of the residual liquid medium film and the external air gap after the tripping stage.

[0028] To achieve the above second objective, the present invention also provides a power network protection system, including a main network overcurrent protection device and at least one of the above arc extinguishing structures, and the arc extinguishing structure is deployed at the connection node between the main network and the microgrid. Description of the Drawings

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0030] Figure 1 It is a three-dimensional view of the arc extinguishing structure described in the embodiment of the present invention when it is installed on the fuse and works normally;

[0031] Figure 2 For Figure 1 It is a plan view of the internal structure of the arc extinguishing structure described in the embodiment;

[0032] Figure 3 For Figure 1 It is a three-dimensional view of the internal structure of the arc extinguishing structure described in the embodiment;

[0033] Figure 4 For Figure 3 It is a schematic diagram when the fuse trips;

[0034] Figure 5 For Figure 3 It is a schematic diagram when the fuse trips successfully.

[0035] The corresponding relationship between the labels of each component in the figure and the component names is as follows:

[0036] 1. Fuse tube; 11. Tube body; 12. Phase change pressure generation module; 13. Liquid-electric effect generation module; 14. Upper fixed electrode; 15. Lower fixed electrode; 16. Fixed electrode rod; 17. Support crossbar; 2. Displacement electrode rod; 21. Displacement electrode piece; 22. End; 23. Pull ring; 31. Spring; 32. Pressure plate; 33. Pressure electrode; 41. Fixed slope; 42. Displacement slope; 51. Fixed buckle; 52. Upper power line fixed end; 53. Lower power line fixed end; 54. Lower bracket; 6. Insulator; 61. Mounting bracket. Detailed implementation manners

[0037] In the following, only some exemplary embodiments are briefly described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present invention. Therefore, the following description is considered to be exemplary in nature and not restrictive.

[0038] In an embodiment of the method for a solid-electric and liquid-electric effect forced arc extinguishing drop-type fuse provided by the invention, the method for the arc extinguishing drop-type fuse includes:

[0039] (a) Generating the first arc extinguishing pressure through the phase change of solid materials: Among them, the solid material can adopt a metal fuse, which undergoes a solid → gas phase change under the action of a short-circuit current (≥10 kA), generates metal vapor with a volume expansion rate ≥100:1, and forms an instantaneous high pressure (the pressure of the solid-electric effect P1 = 15 - 25 MPa).

[0040] (b) Generating the second arc extinguishing pressure through arc discharge in a liquid medium: Among them, the liquid medium can adopt insulating oil. After the fuse melts, the power-frequency arc discharges in the insulating oil. The oil absorbs the arc energy (about 10^6 J / m3) and then vaporizes and expands, generating the pressure of the liquid-electric effect (P2 = 20 - 30 MPa).

[0041] (c) Superposing the first arc extinguishing pressure and the second arc extinguishing pressure in the time-space dimension to form a composite arc extinguishing pressure: In terms of time, the solid-electric effect (P1) dominates in the initial stage of fuse melting (t = 0 - 2 ms), and the liquid-electric effect (P2) enhances during the arc establishment period (t = 2 - 10 ms), and the pressure curves of the two form continuous coverage. In terms of space, a coaxial injection channel is set in the arc extinguishing chamber, so that the pressure wave fronts of P1 and P2 are superposed at the arc root (the area with the highest field strength), generating a composite pressure.

[0042] (d) Using the composite arc extinguishing pressure to simultaneously achieve forced arc extinction and mechanical tripping of the fuse: The arc extinguishing mechanism is that the composite pressure directly impacts the arc plasma, forcibly diffuses charged particles through the pressure gradient, so that the resistivity of the arc channel suddenly increases (≥10^4 Ω·m), and forced arc extinction is achieved within 10 ms. The tripping mechanism is that the pressure of the liquid-electric effect (P2) drives the longitudinal movement of the displacement electrode, and converts the longitudinal displacement into a lateral thrust through the inclined plane impact structure, so that the tripping acceleration of the fuse reaches 3 - 5 g (only 0.5 g in the traditional scheme).

[0043] Preferably as an embodiment, the time superposition of the first arc extinguishing pressure and the second arc extinguishing pressure includes a preset pressure stage and a dynamic trigger stage, where the preset pressure stage starts before the solid material melts, and the dynamic trigger stage lasts until the arc is completely extinguished. Specifically, the above-mentioned preset pressure stage is that when the short-circuit current passes through the metal fuse, the surface first vaporizes to generate an initial pressure, and this pressure is enclosed in the arc extinguishing chamber to form a preloaded high-pressure environment. The preset pressure enables the subsequent arc to be established in a high-pressure environment, improving the triggering sensitivity of the liquid-electric effect; the dynamic trigger stage is the time period when the insulating oil violently vaporizes after the fuse completely melts. By adjusting the fuse alloy composition (such as adding low-boiling-point bismuth elements), the decay time constant of the solid-electric effect and the rise time constant of the liquid-electric effect partially overlap, realizing seamless connection of the pressure.

[0044] As an alternative, the energy sources for the composite arc extinguishing pressure include at least two types of energy coupling among the phase change energy of solid materials, the vaporization energy of liquid media, and the arc discharge energy. In this embodiment, three types of energy coupling (phase change + vaporization + arc) are adopted. The preset pressure is triggered by the phase change energy of the metal fuse, the arc energy excites the vaporization of the oil, and the vaporization energy and the residual phase change energy jointly drive the fuse to trip. Of course, the coupling of phase change energy and vaporization energy can also be adopted: the phase change energy released by the vaporization of the metal fuse heats the insulating oil in the arc extinguishing chamber. The coupling of vaporization energy and arc energy can also be adopted: the gas-liquid mixed medium formed by the vaporization of the insulating oil interacts with the arc plasma, and the arc extinguishing is enhanced through mechanisms such as enhanced turbulence and enhanced heat conduction.

[0045] Please refer to Figures 1-5 , in one embodiment, the arc extinguishing structure for implementing the method of the forced arc extinguishing drop-out fuse with the above-mentioned solid electricity and liquid electricity effects provided by the present invention is installed on the fuse. The fuse includes a fixing buckle 51, an upper power line fixing end 52, a lower power line fixing end 53, and a lower bracket 54; the fixing buckle 51 and the lower bracket 54 are respectively arranged at the top and bottom of one side of the insulator 6, and an installation bracket 61 is arranged in the middle of the other side of the insulator 6; the upper power line fixing end 52 is installed on the fixing buckle 51, and the lower power line fixing end 53 is installed on the lower bracket 54; the upper power line fixing end 52 and the lower power line fixing end 53 are respectively connected to the power lines, and a normal and reliable electrical working circuit is formed in series through the arc extinguishing structure.

[0046] Importantly, the arc extinguishing structure includes a fuse tube 1, a longitudinal displacement trigger unit, and a mechanical amplification unit:

[0047] Among them, the fuse tube 1 includes a tube body 11 with closed ends at both ends. The interior of the tube body 11 is an arc extinguishing chamber with a stepped shape that is larger at the upper end and smaller at the lower end; a phase change pressure generation module 12 and a liquid electricity effect generation module 13 are arranged in the arc extinguishing chamber. The phase change pressure generation module 12 is configured to generate a solid electricity effect pressure through the phase change of solid materials. The phase change pressure generation module 12 is encapsulated in the tube body 11 in a fuse-like structure. The solid material of the phase change pressure generation module 12 includes metals, metal alloys, or conductive composite materials, and its volume expansion ratio from solid state to gaseous state is ≥100:1; the liquid electricity effect generation module 13 is configured to trigger a liquid electricity effect pressure through the arc discharge of a liquid medium. The liquid electricity effect generation module 13 is filled in the tube body 11. The liquid medium of the liquid electricity effect generation module 13 includes modified insulating oil, fluorinated liquid, or nanofluid, its dielectric strength is in the order of 10^6 V / m, and its latent heat of vaporization ≤500 kJ / kg.

[0048] Among them, the longitudinal displacement trigger unit is connected to the liquid-electric effect generation module 13 and can generate a longitudinal displacement in response to the liquid-electric effect pressure. Specifically, the longitudinal displacement trigger unit includes a displacement electrode rod 2 and a displacement electrode plate 21; the upper end of the displacement electrode rod 2 has an end 22 and a pull ring 23 connected to the end 22, which is convenient for manually operating the trip fuse; the upper end of the displacement electrode rod 2 is largely wrapped by the metal sheets on both sides of the fixing buckle 51, and the displacement electrode rod 2 is connected to the upper power supply line fixed end 52 through the fixing buckle 51; the upper and lower ends of the fuse tube 1 are respectively closed by an upper fixed electrode 14 and a lower fixed electrode 15, the displacement electrode rod 2 passes through the upper fixed electrode 14 and is rigidly connected to the middle part of one side of the displacement electrode plate 21; the outer periphery of the other side of the displacement electrode plate 21 is connected to the liquid-electric effect generation module 13, and the center is connected to the lower fixed electrode 15 through the phase change pressure generation module 12, and a fixed electrode rod 16 is connected to the lower fixed electrode 15, the lower end of the fixed electrode rod 16 extends out of the fuse tube 1 and is connected to the lower power supply line fixed end 53, thereby connecting the fuse circuit; a support cross bar 17 is connected to the lower end of the fixed electrode rod 16, and the support cross bar 17 horizontally penetrates and is rotatably connected to the lower bracket 54, so that the fuse tube 1 can rotate around the lower bracket 54.

[0049] Among them, the mechanical amplification unit is connected to the longitudinal displacement trigger unit and can convert the longitudinal displacement of the longitudinal displacement trigger unit into a lateral thrust on the longitudinal displacement trigger unit, so that the displacement electrode rod 2 drives the fuse tube 1 to rotate and break away from the fixing buckle 51, thereby triggering the fuse to trip and fall. Specifically, the mechanical amplification unit includes a pair of interacting displacement ramps 42 and fixed ramps 41. The inclined surface of the displacement ramp 42 faces upward and is integrally formed and connected to the displacement electrode rod 2; the inclined surface of the fixed ramp 41 faces downward and is integrally formed and connected to the fixing buckle 51; the inclination angle θ of the inclined surfaces of the displacement ramp 42 and the fixed ramp 41 satisfies: tanθ > μ (μ is the sliding friction coefficient of the displacement ramp 42 and the fixed ramp 41), and the inclination angle θ is usually set to 30 - 60° to achieve stepless acceleration after self-locking release.

[0050] As a preference of the embodiment, the arc extinguishing structure further includes an elastic acceleration unit. The elastic acceleration unit is connected to the fuse circuit and can release the pre-stored elastic potential energy at the fuse tripping critical point, so that the elastic acceleration unit maintains a low contact resistance during normal operation and releases the elastic potential energy to accelerate the falling off during tripping, so that different functions are played in different working stages.

[0051] Specifically, the elastic acceleration unit includes a spring 31, a pressing plate 32 and a pressure electrode 33; the spring 31 is vertically connected to the lower bracket 54, the pressure electrode 33 is vertically connected to the fixed electrode rod 16, one end of the spring 31 far from the lower bracket 54 is connected to the pressing plate 32, and the pressing plate 32 can abut against the pressure electrode 33 under the elastic force of the spring 31; the fixed electrode rod 16 is connected to the lower power supply line fixed end 53 through the pressure electrode 33, the pressing plate 32 and the spring 31 in sequence.

[0052] When the fuse is operating normally, the spring 31 is compressed by the pressure electrode 33 to generate a pre-tightening force, which pushes the pressure plate 32 to keep in close contact with the pressure electrode 33, reducing the contact resistance, decreasing the Joule heat loss during normal operation, avoiding local temperature rise caused by poor contact, and prolonging the service life of the fuse. When the fuse trips, the elastic potential energy of the spring 31 is instantaneously released, providing an additional acceleration to drive the fuse tube 1 body to break away, increasing the tripping speed by more than 50%, shortening the duration of the external arc, and preventing phase-to-phase short circuit caused by arc drift.

[0053] As a preference of the embodiment, the arc extinguishing structure further includes a dynamic insulation barrier. The dynamic insulation barrier includes a dynamic gas-liquid mixed insulation layer formed by the vaporization of the liquid medium during the arc extinguishing stage, and a composite static insulation layer formed by the residual liquid medium film and the external air gap after the tripping stage. The breakdown field strength of the dynamic gas-liquid mixed insulation layer reaches 50 - 80 kV / cm, which is 2 - 3 times that of the pure liquid medium, and the vaporization gas flow velocity is 200 - 300 m / s, which can cause strong turbulence, increasing the resistivity of the arc channel from 10^-3 Ω·m to 10^2 Ω·m within 1 ms and enhancing the arc extinguishing effect. The residual liquid medium film of the composite static insulation layer adheres to the inner wall of the arc extinguishing chamber, cooperating with the external air gap to form a series insulation structure, which can persistently block the current.

[0054] During the arc extinguishing stage, the liquid medium of the liquid-electric effect generation module 13 absorbs the arc energy and evaporates to generate a high pressure. After the fuse drops off, the residual liquid medium film and the external air gap cooperate to block the arc re-ignition path. It can be seen that the liquid-electric effect generation module 13 plays different roles during the arc extinguishing stage (dynamic) and after dropping off (static), forming a dynamic-static cooperative insulation barrier to solve the deficiency of traditional fuses relying only on the air gap.

[0055] The working principle of the arc extinguishing structure of this embodiment is as follows:

[0056] 1. Normal state

[0057] The phase change pressure generation module 12 fixes the displacement electrode piece 21, the liquid-electric effect generation module 13 fills the arc extinguishing chamber inside the fuse tube 1, and the fuse is connected to the power line through the upper power line fixed end 52 and the lower power line fixed end 53 at its upper and lower ends respectively to form a closed loop.

[0058] 2. Short circuit trigger

[0059] The short-circuit current passes through the phase change pressure generation module 12, causing it to quickly vaporize and fuse, forming an initial discharge break.

[0060] 3. The superposition of the solid-electric effect and the liquid-electric effect for arc extinguishing

[0061] When the phase change pressure generation module 12 vaporizes, the solid material rapidly expands to generate high-pressure gas (the pressure of the solid-electric effect). After the phase change pressure generation module 12 fuses, the power frequency arc discharges in the liquid-electric effect generation module 13. The liquid-electric effect generation module 13 is heated and evaporated and expands violently to form the pressure of the liquid-electric effect. The pressures generated by the two effects are superimposed in terms of time and intensity to form a high-intensity shock wave, which directly acts on the arc channel to forcibly extinguish the arc.

[0062] It should be noted that the interior of the arc extinguishing chamber is a coaxial injection channel, and the inner diameter of this channel matches the outer diameter of the displacement electrode rod 2 to ensure that the gas pressure (P1) generated by the solid-electric effect is axially concentrated and injected to the root area of the arc (the area of the displacement electrode piece 21). In this way, the pressure (P2) generated by the liquid-electric effect is coaxially superimposed with the solid-electric effect pressure (P1) through the annular gap of the arc extinguishing chamber at the root of the arc to form a composite arc extinguishing pressure gradient.

[0063] 4. Driving and tripping

[0064] The pressure of the liquid-electric effect pushes the displacement electrode piece 21 to move towards the top of the arc extinguishing chamber, thereby driving the longitudinal displacement of the displacement electrode rod 2, causing its end 22 to disengage from the fixed buckle 51. At this time, the displacement ramp 42 impacts the fixed ramp 41 to generate a lateral thrust, forcing the fuse tube 1 to rotate rapidly and disengage from the mounting bracket 61.

[0065] 5. Rapid drop and external gap arc extinguishing

[0066] The spring 31 releases elastic potential energy, pushes one end of the pressure electrode 33 through the pressure plate 32, thereby driving the fuse tube 1 to rotate at an accelerated speed, providing an additional acceleration for the disengagement of the fuse tube 1, and quickly forming an external air gap. The external air gap and the residual pressure in the arc extinguishing chamber act together to completely eliminate the arc and avoid secondary short circuits caused by arc drift.

[0067] In addition, the present invention also provides a power network protection system, including a main network overcurrent protection device and at least one of the above arc extinguishing structures. The arc extinguishing structure is deployed at the connection node between the main network and the microgrid, communicates and synchronizes with the main network protection device, obtains its actual response time, and dynamically adjusts the T threshold, so that the forced arc extinguishing time threshold T of the arc extinguishing structure satisfies: T < 0.7 × the response delay time of the main network overcurrent protection device, preventing the main network protection device from tripping the main network circuit breaker and expanding the power outage range due to acting prior to the arc extinguishing device. Through the time threshold coupling design, the performance of the arc extinguishing structure is deeply embedded in the power grid protection system, realizing the local arc extinguishing solution for microgrid short-circuit faults and avoiding affecting the main network; the misoperation rate of the main network protection device is reduced from 30% to less than 5%; the power outage compensation and equipment maintenance costs caused by main network tripping are reduced (the expected annual cost savings is at least in the tens of millions of yuan level).

[0068] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes should be covered within the protection scope of the present invention.

Claims

1. A method for forcibly extinguishing the arc of a drop-out fuse with solid and liquid electric effects, characterized in that, Comprising: (a) generating a first arc extinguishing pressure through the phase change of a solid material; (b) generating a second arc extinguishing pressure through arc discharge in a liquid medium; (c) superimposing the first arc extinguishing pressure and the second arc extinguishing pressure in the space-time dimension to form a composite arc extinguishing pressure; (d) using the composite arc extinguishing pressure to simultaneously achieve forced arc extinction and mechanical tripping of the fuse.

2. The method of the solid-state and liquid-state electric effect forced arc extinguishing drop-out fuse according to claim 1, characterized in that: The time superposition of the first arc extinguishing pressure and the second arc extinguishing pressure includes a preset pressure stage and a dynamic trigger stage, wherein the preset pressure stage starts before the solid material melts, and the dynamic trigger stage lasts until the arc is completely extinguished.

3. The method of a fixed - electricity and liquid - electricity effect forced arc - extinguishing drop - out fuse according to claim 2, characterized in that: The energy source of the composite arc extinguishing pressure includes at least two energy couplings among the phase change energy of the solid material, the vaporization energy of the liquid medium, and the arc discharge energy.

4. An arc extinguishing structure for implementing the method of the solid-state and liquid-state electric effect forced arc extinguishing drop-out fuse described in any one of claims 1-3, characterized in that, Comprising: A fuse tube (1) internally provided with a phase change pressure generation module (12) and a liquid-electric effect generation module (13); the phase change pressure generation module (12) is configured to generate a first arc extinguishing pressure through the phase change of a solid material; the liquid-electric effect generation module (13) is configured to trigger a second arc extinguishing pressure through arc discharge in a liquid medium; A longitudinal displacement trigger unit connected to the liquid-electric effect generation module (13), which can generate a longitudinal displacement in response to the second arc extinguishing pressure; A mechanical amplification unit connected to the longitudinal displacement trigger unit, which can convert the longitudinal displacement into a lateral thrust to trigger the fuse to trip and fall.

5. The arc extinguishing structure according to claim 4, wherein: The longitudinal displacement trigger unit includes a displacement electrode rod (2) and a displacement electrode plate (21); one end of the displacement electrode rod (2) is connected to the fuse circuit, and the other end extends into the fuse tube (1) and is connected to one side of the displacement electrode plate (21); the other side of the displacement electrode plate (21) is connected to the liquid-electric effect generation module (13).

6. The arc extinguishing structure according to claim 5, wherein: The upper and lower ends of the fuse tube (1) are respectively closed by an upper fixed electrode (14) and a lower fixed electrode (15), the displacement electrode rod (2) passes through the upper fixed electrode (14) and is rigidly connected to the displacement electrode plate (21); the displacement electrode plate (21) is connected to the lower fixed electrode (15) through the phase change pressure generation module (12).

7. The arc extinguishing structure according to claim 4, characterized in that: The mechanical amplification unit includes at least a pair of interacting displacement ramps (42) and fixed ramps (41), and the displacement ramps (42) are connected to the longitudinal displacement trigger unit.

8. The arc extinguishing structure according to claim 4, characterized in that, Further comprising: An elastic acceleration unit, the elastic acceleration unit is connected to the fuse circuit and can release the pre-stored elastic potential energy at the fuse tripping critical point.

9. The arc extinguishing structure according to claim 4, wherein, Further comprising: A dynamic insulation barrier, the dynamic insulation barrier includes a dynamic gas-liquid mixed insulation layer formed by the vaporization of a liquid medium during the arc extinguishing stage, and a composite static insulation layer formed by the residual liquid medium film and the external air gap after the tripping stage.

10. A power network protection system, including an overcurrent protection device for the main network, characterized in that, Further comprising: At least one arc extinguishing structure according to any one of claims 4-9, the arc extinguishing structure is deployed at the connection node between the main grid and the microgrid.

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