CN201075681Y - 3-3.5kV neutral point non-effective grounding system for fast extinguishing arc and extinguishing humorous and over-voltage protection device - Google Patents

Abstract

The utility model discloses a rapid arc extinction and harmonic elimination and overvoltage protective device for a 3-35KV neutral point non-effective grounding system, which includes a combined type overvoltage protection device, an arc extinction subassembly, a singlechip controller, a PT voltage transformer and a nonlinear resistor harmonic eliminator; the overvoltage protection device is a four-star combined type overvoltage protector, and the arc extinction subassembly is composed of three high-speed vacuum switches that are connected in parallel; one end of the PT voltage transformer is connected with the three phases A, B and C of a system bus bar by a limiting fuse, another end of the higher voltage side of the voltage transformer is grounded by the nonlinear resistor harmonic eliminator after being connected, and a secondary voltage output end of the PT voltage transformer is connected with a signal collection interface of the singlechip controller. The protection scope of the utility model is a power distribution system under the bus bar of the system; the function is not influenced by the system scale and the operation mode so long as the selection is reasonable; the utility model creates conditions for the capacity expansion of the system and has wide applicability.

Description

3-35kV system with non effectively earth ed neutral rapid arc extinction harmonic elimination and overvoltage protection

Technical field

The utility model relates to a kind of extinguishing arc harmonic elimination apparatus that uses in the electric power system, says so more specifically to be used for 3～35kV system with non effectively earth ed neutral rapid arc extinction harmonic elimination and overvoltage protection.

Technical background

Along with the continuous development of national economy and improving constantly of living standards of the people, urban and rural power grids constantly enlarge, and cable line constantly increases, especially urban distribution network and industrial and mining enterprises, there is cable line to replace the trend of overhead transmission line greatly, thereby solves the air corridor deficiency, reach the purpose of beautifying the environment.Cable line is to adopt solid insulation, in case puncture, insulation is a nonvolatil destruction and can not recovering.The cable line direct-to-ground capacitance is very big, and single-phase earth fault current is very big, wherein high-frequency current bigger and the decay very slow, because of the insulation destruction make the electric current of keeping arc grounding very little, the residual flow behind the arc suppression coil compensation is enough to burning away of pilot arc.Therefore arc suppression coil is not have extinguishing arc and suppress the overvoltage effect in cable line, and more and more higher with the requirement of reliable power supply to the safe operation of electrical network, harm and spread area that each insulation fault causes certainly will increase.

China 3-35KV power distribution network great majority adopt the not directly grounded operational mode of neutral point.When the metallic earthing fault took place, the fault phase voltage was zero, and non-fault phase voltage improves 3 times of √, can not damage the insulation of normal electric equipment, and therefore, the permission system operated with failure two hours.Win the time for fixing a breakdown, improved the reliability of electric power system greatly, significantly reduced improper frequency of power cut.So such electrical network is widely adopted in China and world many countries.When intermittent arc light single-phase earthing took place, the arcing → blow-out → arc of restriking alternately took place, and produces serious power frequency and high frequency overvoltage.It involves whole electrical network, and the duration is quite long, and the intermittent arcing ground of as easy as rolling off a log formation → stable arcing ground → insulation burns out, lead scorification, phase fault or permanent earth.In the industrial frequency superimposed high frequency overvoltage that fault takes place and evolution produces, the lower electric equipment of insulation level is constituted threat greatly, even cause that insulation breakdown, equipment burn out, phase fault.Cause simultaneously accidents such as voltage transformer blast or Explosion of on Arrester easily.

Solve the problem that this type of power distribution network exists at present, great majority adopt the operational mode of grounding through arc traditionally.Arc suppression coil can reduce single-phase-to-ground current, impels the electric arc self-gravitation, plays and shortens the arcing time, reduces the number of times of restriking, and has reduced the superpotential probability of occurrence of high amplitude, is conspicuous to the effect of Single Phase Metal earth fault.No matter be from motion tracking or arc-suppression coil with automatic tuning, 50HZ power frequency capacitance current designs during all for the compensation single-phase fault.During intermittent arc grounding, what flow through the fault point not only has a power frequency capacitance current, also has the very high high-frequency current of amplitude that produces in current in resistance property and the single phase intermittent electric arc transitional processes, it is on arc suppression coil and electrical network electric capacity (equivalent lumped capacitance distributes), and the frequency characteristic that is showed is diverse.When the electric network capacitance and current component reaches hundreds of peace maximum, the inductive current component of arc suppression coil does not also get up, after treating that electric network capacitance and current decays to stable state, arc suppression coil just produces the saturability inductive current of hundreds of peace, has improved the overvoltage amplitude so in some cases on the contrary and the possibility that punctures when the high-frequency current zero crossing increases greatly.Therefore, the power frequency capacitance current when arc suppression coil can only compensate for failed does not have compensating action to the high frequency capacitance electric current.That is to say that arc suppression coil is that can not to eliminate intermittent arc grounding superpotential, and the arc suppression coil complex structure, operational reliability is poor, and investment cost is big.

Present domestic minority area takes neutral point to move through the mode of low resistance grounding to this type of power distribution network, because arc suppression coil not only can not be avoided cable fault, when normal operation, also there are above-mentioned problems, fundamentally solved the normal problem of bringing in service of arc suppression coil, overvoltage when having alleviated arc grounding, but the fault current when having enlarged single-phase earthing has aggravated the burn of fault point, has sacrificed the reliability to user's power supply.For electricity consumption enterprise, be forced to have a power failure and cause enormous economic loss.

At present domestic existing several utility model patents, abandoned the theory of traditional arc suppression coil, one quantum leap in the extinguishing arc of saying so in a sense field, started the new way in extinguishing arc field: as take the intermittence arc grounding is converted into the fault bus direct metal ground connection (patent No. 99229228, X) the fault phase voltage reduces to zero, electric arc disappears, reach the purpose of extinguishing arc, but in this patent working process, not only busbar grounding with disconnect moment and cause impact system, the single-phase intermittence arc grounding that causes may take place once more, particularly after earth fault is eliminated, the transient overvoltage that open failure phase vacuum contactor moment produces makes the single-phase earthing that descends and cause by insulation, the accident that develops into alternate and three-phase shortcircuit still exists, and after ground connection disconnects, direct current electric charge unnecessary on the sound electric capacity relatively will cause the moment magnetic saturation by the winding discharge of instrument transformer, still can excite iron porcelain resonance.Employing is converted into the controlled high-power nonlinear resistance ground connection (patent No. ZL02287644,8) of multistage in this patent practice process with the intermittence arc grounding, because of adopting single nonlinear resistance voltage limiter, the action set point is single, when the recovery voltage in scratch start road of often breaking down is lower than nonlinear resistance voltage limiter set point, so-called high energy voltage limiter is inoperative in fact, electric arc finally causes the extinguishing arc failure still in the fault point burning.Can be for what satisfy electric power rules regulations with two hours regulation of earth fault continuous service, and can go the free time fully in order to guarantee the fault point, high energy voltage limiter as energy absorbing device is long because of operate time, need the big energy capacity of energy, in practice process because the restriction of high-power zinc oxide production technology, monolithic energy capacity is difficult to produce the product greater than 30KJ, in order to satisfy the requirement of energy capacity, must adopt a large amount of nonlinear resistance connection in series-parallel costs high, for guaranteeing the through-flow time, the operation curve that must guarantee each crosstalk resistance valve block is consistent, if inconsistent, will cause the current unevenness that each crossfire is crossed in the extinguishing arc implementation process, directly cause the overcurrent of weak link to be damaged, to cause the blast of whole high energy voltage limiter when serious, and bury hidden danger for the safe operation of electrical network.

Summary of the invention

The weak point that the utility model exists for fear of above-mentioned extinguishing arc protected mode; a kind of 3～35kV neutral point system with non effectively earth ed neutral rapid arc extinction harmonic elimination and overvoltage protection are provided; this device all can effectively limit single-phase arc grounding overvoltage under various operational modes; resonance overvoltage and switching overvoltage; the mechanism of its extinguishing arc and system capacitance current size over the ground is irrelevant; thereby be not subjected to the change of power system operating mode and expand the influence of netting; big minor scale power net all can use, and is suitable equally to the system that arc suppression coil is housed in the original system.

The technical solution of the utility model is as follows:

3～35kV system with non effectively earth ed neutral rapid arc extinction harmonic elimination and overvoltage protection is characterized in that comprising combination overvoltage protector, extinguishing arc assembly, singlechip controller and PT voltage transformer and nonlinear resistance resonance eliminator:

Described overvoltage protection device is the box-like overvoltage protection device of four stars structural group: after being three groups of FR1～FR3 ZnO resistors parallel connection, the one end is connected with system busbar A, B, C three, ground connection after the other end is connected with one group of FR4 ZnO resistors;

Described extinguishing arc assembly is: three high-speed vacuum switch in parallel, one end cause system busbar A, B, C three-phase, ground connection after the other end parallel connection by current limiting fuse respectively; The three-phase main contact two ends of each high-speed vacuum switch are connected to RC capacitance-resistance absorption plant, and this capacitance-resistance absorption plant is absorbing electric capacity two ends and joint defence resonant resistance formation again by absorption resistance and absorption capacitances in series;

Described PT voltage transformer one end is connected with system busbar A, B, C three respectively by current limiting fuse, the on high-tension side other end of PT voltage transformer links together after harmonic elimination nonlinear resistor ground connection, and the secondary voltage output of PT voltage transformer links to each other with the signals collecting interface of singlechip controller.

The high speed limited pressure vacuum switch that described high-speed vacuum switch is a permanent magnet mechanism.

Described singlechip controller is a core processor with the PIC single-chip microcomputer of high anti-jamming capacity, troubleshooting speed is exceedingly fast, signals collecting, measurement, demonstration, computing, communication and implementation center as whole device, the voltage signal acquisition interface of singlechip controller is connected with PT voltage transformer secondary output, and control high-speed vacuum switch.

Architectural feature of the present utility model is: described extinguishing arc assembly adopts high-performance, the high-speed vacuum switch of low energy consumption permanent-magnet operating mechanism, as execution unit of the present utility model, high-speed vacuum switch three-phase main contact ZKa, ZKb, the mutual locking of ZKc, promptly wherein one closed mutually, back two-phase is all by locking.During normal operation, contact is in off-state, and as to the sucking coil energising, iron core will produce magnetic field, make the high-speed vacuum switch contact from the off-position to the attracted position fast moving, the while has also stored energy for the release of moving contact.In a single day produce electric arc between the contact, the electromagnetism gap smaller, at this moment permanent magnetism power will increase severely, sucting speed is accelerated (pickup time is less than 20ms), thereby the ablation when having significantly reduced the contact adhesive, permanent magnetism power keep contact pressure moment constant after making the contact adhesive, are not subjected to the influence of net voltage fluctuation, even if to depress the adhesive contact also be one-time action facing dielectric, contact is chatter not.After the contacts of vacuum switch adhesive, current control module is the current cut-off of sucking coil, this moment coil do not work, not power consumption, the electric current of coil is zero, no energy consumption, and coil surely not generates heat, more can not burn, rely on permanent magnetism power that contact is remained on attracting state this moment fully.High-speed vacuum switch three-phase main contact two ends also connect special RC capacitance-resistance absorption plant, form the controlled limited pressure vacuum switch in three-phase Unit four, described special RC capacitance-resistance absorption plant absorption resistance R1 connects with the absorption capacitor C, absorbing the capacitor C two ends and taking over control resonant resistance R2, constitute special capacitance-resistance absorption plant.Unsettled single-phase arc grounding overvoltage to system's appearance, singlechip controller sends signal immediately by analysis and judgement makes the mutually controlled limited pressure high-speed vacuum of fault switch close a floodgate fast, unsettled arc grounding is converted into stable metallic earthing apace, the electric arc of fault point extinguishes immediately, eliminate in fault, during the action involution, the recovery voltage amplitude and the rate of climb of special RC capacitance-resistance absorption plant fault restriction phase, make the fault point can not cause that overvoltage restrikes, thereby improve the success rate of eliminating single-phase arc grounding greatly because of operating controlled limited pressure high-speed vacuum switch.When power frequency or high-frequency resonant appear in system, WKQ singlechip controller analysis and judgement, moment changes Zero sequence parameter at the PT voltage transformer secondary side open delta power resistor that has high input, and destroys condition of resonance.

Compared with the prior art, the utility model beneficial effect is embodied in:

1, when distribution system generation Single Phase Metal ground connection or arc grounding fault, no matter the fault point wherein, the utility model can both must be transferred to the fault point in the device rapidly under the diagnosis of singlechip controller, realizes that fault shifts.Reduce the step voltage of fault point, prevent the accident development, ensure the safety of the person and equipment.

2, adopt high-performance, the high-speed vacuum switch of low energy consumption permanent-magnet operating mechanism, its service behaviour is compared more reliable and more stable with the A.C. contactor of routine, sucting speed is accelerated (pickup time is less than 20ms), thereby the ablation when having significantly reduced the contact adhesive, permanent magnetism power keep contact pressure moment constant after making the contact adhesive, are not subjected to the influence of net voltage fluctuation, even if to depress the adhesive contact also be one-time action facing dielectric, contact is chatter not.

3, eliminate the intermittent arc grounding fault fast and effectively, suppress overvoltage, prevent the accident extension, improve the fail safe and the reliability of electric power system, remedied the deficiency of arc suppression coil.

4, adopting low residual voltage combination overvoltage protector, can effectively must suppress atmospheric over-voltage, switching overvoltage, resonance overvoltage and intermittent arc grounding overvoltage, is the replacement new product of lightning arrester, and it is more perfect to play protective value.

5, the electric arc of fault point extinguishes immediately, fault is eliminated, during high-speed vacuum switch motion involution, the recovery voltage amplitude and the rate of climb of RC capacitance-resistance absorption plant fault restriction phase, make the fault point can not cause that overvoltage restrikes, thereby improve the success rate of eliminating single-phase arc grounding greatly because of operating controlled limited pressure high-speed vacuum switch.

7, described special RC capacitance-resistance absorption plant, it is characterized in that absorption resistance R1 connects with the absorption capacitor C, absorb the capacitor C two ends and taking over control resonant resistance R2, constitute special capacitance-resistance absorption plant, the inductance that anti-resonant resistance R2 prevents to absorb in capacitor C and the circuit produces resonance, for electric capacity provides discharge loop, also play the effect that suppresses resonance simultaneously.

8, be connected in series the non-linear harmonic-eliminating resistor of XXQ between PT voltage transformer primary side neutral point and the ground, under low pressure resonance eliminator is high resistance (can reach hundreds of kilo-ohm) and makes resonance be difficult for development at initial period, during single-phase earthing, over thousands of volt voltage appears on the XXQ resonance eliminator, its nonlinear resistance value descends, make and press the saturated superpotential most of voltage drop of change to drop on the resistance XXQ, thereby avoided core sataration, limited to press and become saturated superpotential generation, avoid the generation of ferro resonance, had the function that suppresses low-frequency oscillation simultaneously.

9, substitute conventional voltage transformer cabinet, measure and demonstration three-phase voltage value, realize system voltage digitlization metering by singlechip controller.

10, the utility model protection range is the following distribution system of device bus, as long as select rationally, its function is not subjected to the influence of system size and operational mode, has created condition for the development of System Expansion, and applicability is extensive.

11, the utility model can be pieced together cabinet with the switch cubicle of various models, and is simple in structure, easy to install.Be send out, for, optimal selection with electric unit during newly-built or modernization system.

11, the utility model singlechip controller is provided with the microcomputer communication interface, for transfer of data has been created condition.

Description of drawings

Fig. 1 is the utility model electrical schematic diagram

Embodiment

Below in conjunction with accompanying drawing, the utility model is further described by embodiment.

The utility model comprises composite type GBQ overvoltage protection device, ZNKG extinguishing arc assembly, WKQ singlechip controller, PT voltage transformer and the non-linear harmonic-eliminating resistor of XXQ.

Described GBQ overvoltage protection device is the box-like overvoltage protection device of four stars structural group, be three groups of FR1～FR3 ZnO resistors parallel connection after, the one end is connected with system busbar A, B, C three, the other end connect with one group of FR4 ZnO resistors the back ground connection.In order to protection thunder and lightning and high-amplitude Value Operations overvoltage; its protection value is lower; the higher ability of bearing temporary overvoltage is arranged; can be before follow-up protective device action; the initial temporary overvoltage of high amplitude arc grounding that system is occurred effectively limits; be all kinds of superpotential first devices of restriction in this device, be mainly used to limit atmosphere voltage and switching overvoltage.

Described ZNKG extinguishing arc assembly is by high-performance; the high-speed vacuum switch of low energy consumption permanent-magnet operating mechanism; the one end causes A, B, the C three-phase of protected circuit respectively through FU2; ground connection after the other end parallel connection; it is characterized in that the capacitance-resistance absorption plant and meet three-phase main contact ZKa with the high-speed vacuum switch of permanent magnet mechanism, ZKb, ZKc two ends; form three-phase Unit four controlled limited pressure high-speed vacuum switch, described RC capacitance-resistance absorption plant is the connection in series-parallel of resistance and electric capacity.When system normally moved, three-phase Unit four controlled limited pressure high-speed vacuum switch main contact all was in off-state, and the operation of system is not had any influence.If the fault that takes place is intermittent arcing ground, the WKQ singlechip controller is after judging ground connection separate, make the controlled limited pressure high-speed vacuum switch closure of fault phase, make system be quickly converted to the direct ground connection of stable metallicity by instable arc grounding, the fault phase voltage reduces to zero, and electric arc disappears.After several seconds, make the controlled limited pressure high-speed vacuum switch of ground connection disconnect again, at this moment RC capacitance-resistance absorption plant work in parallel, the resume speed of fault restriction phase voltage and amplitude, avoid earth point to restrike because of overvoltage, if fault disappears, illustrate that this arcing ground fault is to impact the instantaneity earth fault that causes because of overvoltage, system restoration normally moves.After if controlled limited pressure high-speed vacuum switch closes and disconnects, system stable arc ground connection occurs mutually in former fault once more, arc-extinction device assert that this fault is nonvolatil earth fault, so the controlled limited pressure high-speed vacuum switch of closed once more fault phase is treated operator on duty or microcomputer route selection processing.Because the effect of the non-linear harmonic elimination resistance of XXQ that is connected in series between PT voltage transformer primary side and the ground has effectively prevented the generation of ferro resonance or low-frequency oscillation.When phylogenetic WKQ singlechip controller analysis and judgement when being power frequency or Subharmonic Resonance, moment changes Zero sequence parameter at the PT voltage transformer secondary side open delta power resistor that has high input, and destroys condition of resonance.

Claims (2)

1.3～35kV system with non effectively earth ed neutral rapid arc extinction harmonic elimination and overvoltage protection is characterized in that comprising combination overvoltage protector, extinguishing arc assembly, singlechip controller and PT voltage transformer and nonlinear resistance resonance eliminator:

Described overvoltage protection device is the box-like overvoltage protection device of four stars structural group: after being three groups of FR1～FR3 ZnO resistors parallel connection, the one end is connected with system busbar A, B, C three, ground connection after the other end is connected with one group of FR4 ZnO resistors;

Described extinguishing arc assembly is: three high-speed vacuum switch in parallel, one end cause system busbar A, B, C three-phase, ground connection after the other end parallel connection by current limiting fuse respectively; The three-phase main contact two ends of each high-speed vacuum switch are connected to RC capacitance-resistance absorption plant, and this capacitance-resistance absorption plant is absorbing electric capacity two ends and joint defence resonant resistance formation again by absorption resistance and absorption capacitances in series;

Described PT voltage transformer one end is connected with system busbar A, B, C three respectively by current limiting fuse, the on high-tension side other end of PT voltage transformer links together after harmonic elimination nonlinear resistor ground connection, and the secondary voltage output of PT voltage transformer links to each other with the signals collecting interface of singlechip controller.

2. 3～35kV system with non effectively earth ed neutral rapid arc extinction harmonic elimination according to claim 1 and overvoltage protection is characterized in that the high speed limited pressure vacuum switch that described high-speed vacuum switch is a permanent magnet mechanism.