CN2884641Y

CN2884641Y - Overvoltage limit and small current earthing selective integrator of power transfer and distribution system

Info

Publication number: CN2884641Y
Application number: CN 200620024059
Authority: CN
Inventors: 张树仁
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-04-08
Filing date: 2006-04-08
Publication date: 2007-03-28
Anticipated expiration: 2016-04-08

Abstract

The utility model is an integrated device for over-voltage restriction of electric power transmission and distribution system and for selection of low current ground wire and relates to a supporting device of electric power transmission and distribution system. The device comprises a controller WZK that controls four single-phase high voltage vacuum switches under powered on and off state, and the normally opening contacts of the four single-phase high voltage vacuum switches are connected in star shape, wherein three contacts are separately connected with three-phase busbars of the system and the other contact is grounded; and both ends of the normally opening contacts of the four single-phase high voltage vacuum switches are connected with high-energy nonlinear resistors respectively in parallel. The integrated device of said utility model can effectively inhibit over-voltage caused by single-phase intermittent arc grounding and resonance of 3 to 35 kv neutral point non-direct grounding grids, ensuring that the selection of wire is accurate when the branch wire is single-phase grounded, and it can widely be used in 3 to 35 kv substations and high voltage plant systems of power plants, and in the original systems with arc extinction coils likewise.

Description

Power transmission and distribution system overvoltage Limiting and small current earthing wire-selecting integration unit

Technical field

The utility model relates to the power transmission and distribution system matching device, and particularly the device of power transmission and distribution system overvoltage Limiting and earthing wire-selecting is specially power transmission and distribution system overvoltage Limiting and small current earthing wire-selecting integration unit.

Background technology

The power transmission and distribution system, especially high-tension electricity electrical power trans mission/distribution system (3-35KV) mostly adopts system with non effectively earth ed neutral.In the system with non effectively earth ed neutral, except that lightning overvoltage, the most frequent by the overvoltage that single-phase arcing ground and system resonance cause, and this class overvoltage has higher amplitude and long duration, if such overvoltage can not effectively limit, will produce the damage of accumulation property to the electricity supply and use equipment of such electrical network, and may cause generation puncture or alternate flashover over the ground, thereby cause short circuit accident etc. in the external insulation weak spot.

At present, the major measure of restriction arc light grounding surge is still the neutral by arc extinction coil grounding with electrical network.But arc suppression coil can not be eliminated intermittent arcing ground over-voltage, amplitude that can not over-voltage, even in some cases, because of the existence of arc suppression coil, arc reignition may just take place constantly at maximum this least favorable of recovery voltage, and the arc grounding overvoltage is raise.High fdrequency component and the real component of arc suppression coil in can not the compensation of ground electric current, the indirect arc ground connection of high frequency still exists; During greater than certain value, the fault point ground arc can not put out equally certainly in real component.Arc suppression coil cuts little ice to the overvoltage that causes of restriction resonance, and very likely causes ferro resonance when residual voltage and zero-sequence current appear in broken string or high-pressure side.Practical operating experiences proves that also in 3～35kv of neutral by arc extinction coil grounding power distribution network, the accident that is caused by electric arc and resonance still happens occasionally.

The patent No. is that the Chinese patent of 99229228.x discloses a kind of " Triphase Power Networks And Indirect Earthing System Overvoltage Debooster ".It has taked to change intermittent arcing ground the directly grounded extinguishing arc measure of into bus metallicity, but this overvoltage limiter causes impact to system in the moment of busbar grounding and disconnection, particularly disconnect the transient overvoltage of earth bus moment generation, make in insulation level decline and still may take place once more by the single-phase indirect arc ground connection that the overvoltage impact causes, and after ground connection disconnects, stored charge unnecessary on the sound electric capacity relatively will be by the winding discharge of instrument transformer, cause the moment magnetic saturation of winding, still can excite ferro resonance.

Electric equipment always has inductance or electric capacity attribute.When system operates or break down; these inductance, capacity cell form oscillation circuit; produce resonance; cause system serious resonance overvoltage to occur; jeopardize insulation of electrical installation; the overcurrent that resonance continues even burn low capacity inductance element equipment, its lasting characteristic causes selects overvoltage protection measure difficulty.

At present external (domestic also have the minority area to begin to adopt) takes neutral point to suppress this two kinds of overvoltage through low resistance grounding to this type of electrical network, but single-phase earthing when taking place in this system, no matter single phase ground fault is moment, or nonvolatil, all directly the fault earthing circuit is excised, and the operating experience of electric power system shows, the single phase ground fault overwhelming majority is moment, the electrical network that constitutes of overhead transmission line particularly, must cause sharply increasing of power outage like this, obviously reduce power supply reliability.

Another problem that neutral point non-direct grounding system exists is the ground protection poor selectivity; existing little electric current line selection apparatus generally is that the amplitude of zero-sequence current is compared in employing and the method for phase place is carried out route selection; hour accuracy is not high at zero-sequence current; particularly through the system of grounding through arc; under the situation that feeder line length differs greatly, its False Rate is higher.

Summary of the invention

The utility model provides a kind of power transmission and distribution system's overvoltage Limiting and small current earthing wire-selecting integration unit, and is purpose with the hardware configuration that this device is provided only at defective and problem that prior art exists.This device makes neutral nondirect earthing network, under various operational modes, all can effectively limit the overvoltage that single phase intermittent arcing ground and resonance cause, to nonvolatil Single Phase Metal ground connection, the size of system capacitive current no matter all can accurately route selection.

The utility model is to adopt following technical scheme to realize: power transmission and distribution system overvoltage Limiting and small current earthing wire-selecting integration unit, comprise and control by controller WZK that it is charged, the single-phase high voltage vacuum switch of power failure state, the single-phase high voltage vacuum switch is four, the normally opened contact of four single-phase high voltage vacuum switches is star-like connection, wherein three terminations are connected to respectively on system's three-phase bus, and other one terminates at the earth; The normally opened contact two ends of four single-phase high voltage vacuum switches are parallel with high-energy non-linear resistance respectively.The protection operating value of high-energy non-linear resistance that is connected on three normally opened contact parallel connections on the system busbar is identical, and the high-energy non-linear resistance protection operating value in parallel with the normally opened contact of an end ground connection is lower.The high-power resistance that described high-energy non-linear resistance is formed for the high energy ZnO material.When the switching overvoltage that causes owing to the vacuum circuit-breaker operation takes place in the system when, the normally opened contact of four high-pressure vacuum switchs is failure to actuate, four high-energy non-linear resistance are formed the high-octane overvoltage protection device of a star-like connection, will the overvoltage that cause owing to the vacuum switch operation be limited; When the indirect arc grounding surge takes place, the normally opened contact of the high-pressure vacuum switch by closed fault phase, make fault directly insert the high-energy non-linear resistance of ground connection phase mutually, by the high-energy non-linear resistance of ground connection phase the release electromagnetic energy that ground connection causes, the recovery voltage of restriction ground connection phase, the fault point because of recovery voltage be limited the low electric arc extinguishing arc of can not restriking; When stable arcing ground over-voltage takes place, reach the normally opened contact of the high-pressure vacuum switch of ground connection phase mutually by closed fault, make fault be transformed into metallic earthing mutually, thereby the recovery voltage of restriction ground connection phase is eliminated the arc grounding fault.When system's generation Single Phase Metal earth fault, by the arbitrary high-pressure vacuum switch that perfects phase of closure, artificially increase the fault current of system, the fault current of earth point is increased greatly, thereby make microcomputerized controller can select faulty line exactly.

As existing overvoltage limiter, integration unit described in the utility model also comprises the voltage transformer that is connected between three-phase bus and the controller input, be used for the input signal of the voltage signal of acquisition system, and realize real-time monitoring system as controller.The secondary sideband of voltage transformer has auxiliary winding, and will assist winding to connect into the open delta winding, and the open delta winding is connected to the signal input part of controller, is mainly used to finish the monitoring to system voltage; When system's generation resonance fault, by the controller output node, moment the short circuit voltage transformer the open delta winding, destroy the resonant parameter of system, eliminate resonance.

The effect of described controller WZK, be the system voltage gathered with voltage transformer as input signal, correspondingly control each high-pressure vacuum switch action, reach the purpose of overvoltage Limiting and earthing wire-selecting.The structure that realizes the controller of this function is as well known to those skilled in the art and easy realization.As adopting various logic circuitry to constitute, also can realize by single-chip microcomputer.

Integration unit described in the utility model can effectively suppress the overvoltage that the single-phase indirect arc ground connection of 3～35kv neutral nondirect earthing network and resonance cause, accurate route selection in the time of can guaranteeing the branched line single-phase earthing, the mechanism of its extinguishing arc and route selection and the size of electric network capacitance and current are irrelevant, thereby the influence that not enlarged by the change of power system operating mode and electrical network, big and small networks all can use, whole device can be formed a high-voltage board, simple in structure, volume is little, install, debugging is convenient, and is cheap, safe in utilization, can be widely used in the high pressure station-service system in 3～35kv transformer station and power plant, the former system that arc suppression coil is housed is available equally.

Description of drawings

Fig. 1 is the circuit theory diagrams of integration unit described in the utility model;

Fig. 2 is the concrete wiring circuit theory diagrams of voltage transformer;

Embodiment

Power transmission and distribution system overvoltage Limiting and small current earthing wire-selecting integration unit, comprise and control by controller WZK that it is charged, the single-phase high voltage vacuum switch of power failure state, the single-phase high voltage vacuum switch is four, normally opened contact KA, the KB of four single-phase high voltage vacuum switches, KC, KD are star-like connection, wherein three terminations are connected to respectively on system's three-phase bus, and other one terminates at the earth; Normally opened contact KA, the KB of four single-phase high voltage vacuum switches, KC, KD two ends are parallel with high-energy non-linear resistance R A, RB, RC, RD respectively.Also comprise the voltage transformer TV that is connected between three-phase bus and the controller WZK input, the secondary sideband of voltage transformer has auxiliary winding, and will assist winding to connect into the open delta winding, and the open delta winding is connected to the signal input part of controller WZK.Described voltage transformer TV is made of three single-phase potential transformers, three single-phase potential transformers once all adopt star-like the connection with the secondary limit, the auxiliary winding triangle of the three-phase on secondary limit is not connected but closed and form the open delta winding; The characteristics of this voltage transformer are that the range of linearity is wide, phase shift is little, even when in system the most serious arc grounding overvoltage taking place, also can guarantee the amplitude of its output signal and the accuracy of phase place.It is the hardware configuration (being aided with well-designed software) of core that controller WZK adopts with the single-chip microcomputer; Device also comprises high voltage isolator QS1, as the critical piece that this device is connected with electric power system, can realize the break-make of this device and system by this element; Also comprise high-tension fuse 2,, be mainly used to protect the safe operation of voltage transformer as the backup protection unit of this device; Also comprise fast acting fuse 5, as the main backup protection unit of this device, characteristics be switch off time short (＜2ms), cut-off capacity big (＞63KA), be mainly used to the internal short circuit fault of anti-locking apparatus.

During work, provide actuating signal, finish real-time monitoring system by voltage transformer.Singlechip controller under corresponding software is supported, three-phase voltage U a, the Ub, Uc and the residual voltage U that provide according to voltage transformer _z(U is judged in the variation of instantaneous value _nFor being total to the public access line end), and, send corresponding instruction according to the result who judges, make four high-pressure vacuum switchs actions.If because the switching overvoltage that the vacuum switch operation causes, singlechip controller can not send any instruction; When the indirect arc grounding surge takes place, normally opened contact KA or the KB or the KC of the high-pressure vacuum switch by closed fault phase, make fault insert the lower high-energy non-linear resistance R D of operating value mutually, the electromagnetic energy that the ground connection of releasing causes, the recovery voltage of restriction ground connection phase, the fault point is limited lowlyer because of recovery voltage, and electric arc can not be restriked and extinguishing arc.When stable arcing ground over-voltage takes place, the normally opened contact KD of the normally opened contact KA of the high-pressure vacuum switch by closed fault phase or the high-pressure vacuum switch of KB or KC and ground connection phase, make fault be transformed into metallic earthing mutually, thereby the recovery voltage of restriction ground connection phase is eliminated the arc grounding fault; When system's generation resonance fault, by the singlechip controller output node KG of device, the open delta winding (accompanying drawing 2) of the voltage transformer in the moment short-circuit device destroys the resonant parameter of system, eliminates resonance; When system's generation Single Phase Metal earth fault, by the arbitrary high-pressure vacuum switch of phase that perfects of closure (if be that A takes place by ground connection mutually, the vacuum switch of closed B phase or C phase), at this moment system has become two-phase short-circuit fault, and the fault current of system will increase greatly, artificially increases the fault current of system, the fault current of earth point is increased greatly, in the middle of whole system, have only the electric current maximum of faulty line, thereby make microcomputerized controller can select faulty line exactly.Because the two-phase circuit is by nonlinear resistance RD short circuit, because nonlinear resistance RD has current limiting characteristic, so do not need the safe operation problem of taking into account system.

Claims

1, a kind of power transmission and distribution system's overvoltage Limiting and small current earthing wire-selecting integration unit, comprise and control by controller (WZK) that it is charged, the single-phase high voltage vacuum switch of power failure state, it is characterized by: the single-phase high voltage vacuum switch is four, the normally opened contact of four single-phase high voltage vacuum switches (KA, KB, KC, KD) is star-like connection, wherein three terminations are connected to respectively on system's three-phase bus, and other one terminates at the earth; The normally opened contact of four single-phase high voltage vacuum switches (KA, KB, KC, KD) two ends are parallel with high-energy non-linear resistance (RA, RB, RC, RD) respectively.

2, power transmission and distribution system's overvoltage Limiting as claimed in claim 1 and small current earthing wire-selecting integration unit, it is characterized by: also comprise the voltage transformer (TV) that is connected between three-phase bus and controller (WZK) input, the secondary sideband of voltage transformer has auxiliary winding, and will assist winding to connect into the open delta winding, the open delta winding is connected to the signal input part of controller (WZK).

3, power transmission and distribution system's overvoltage Limiting as claimed in claim 2 and small current earthing wire-selecting integration unit, it is characterized by: voltage transformer (TV) is made of three single-phase potential transformers, three single-phase potential transformers once all adopt star-like the connection with the secondary limit, the auxiliary winding triangle of the three-phase on secondary limit is not connected but closed and form the open delta winding.

4, as claim 1 or 2 or 3 described power transmission and distribution system's overvoltage Limiting and small current earthing wire-selecting integration units, it is characterized by: it is the hardware configuration of core that controller (WZK) adopts with the single-chip microcomputer.