CN201038753Y - Stable state zero-sequence current boosting device - Google Patents
Stable state zero-sequence current boosting device Download PDFInfo
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- CN201038753Y CN201038753Y CNU2007200213658U CN200720021365U CN201038753Y CN 201038753 Y CN201038753 Y CN 201038753Y CN U2007200213658 U CNU2007200213658 U CN U2007200213658U CN 200720021365 U CN200720021365 U CN 200720021365U CN 201038753 Y CN201038753 Y CN 201038753Y
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Abstract
The utility model discloses a steady state zero sequence current feeding device, which has solved the defects that the amplitude of the electrical quantity is quite small and is not easily detected by using the steady state quantity earthing selection and positioning measure for the fault signals when the system is broken down. After the electricity grid happens to the grounding fault in single phase, instantaneously enlarge the steady state quantity of the fault signals so as to ensure the earthing selection and positioning device that is based on the steady state quantity of the single phase grounding fault can be accurate to act, thereby achieving the targets of positioning and earthing selection. The structure of the utility model is shown as follows: the utility model comprise a busbar that protects the power distribution system, while a steady state zero sequence current feeding device is arranged on the busbar. The device is also connected with a pressure transformer that is connected with the busbar. The current feeding device consists of a power capacitor unit, a switching switch and a control device. The control device monitors whether the power distribution system occurs to the single phase grounding fault. The power capacitor unit feeds in the grounding current and the control device controls the switching of the power capacitor unit through the switching switch.
Description
Technical field
The utility model relates to Earth Fault Detection technology in a kind of electric power system, relates in particular to a kind of isolated neutral or help through the stable status zero-sequence current that arc suppression coil earthing system is used to increase device.
Background technology
At present, for the distribution system of operation, because system neutral is earth-free or through grounding through arc, do not form short-circuit loop, the very little zero-sequence current that has only system's distributed capacitance to cause behind the generation single phase ground fault.Both at home and abroad the various devices of searching single phase ground fault be exactly according to these smaller amounts as basis for estimation, False Rate is bigger.To this, still not having accurately and reliably at present, the microcomputer line selection apparatus can move in tripping operation.
Colleges and universities and producer release three types earthing wire-selecting positioner both at home and abroad, are respectively: the route selection positioner of reaction single phase ground fault transient state amount, the route selection positioner of reaction single phase ground fault steady-state quantity, the route selection positioner that utilization " injection method " principle constitutes.The defective of preceding two kinds of prior aries is: for the route selection localization method of reflection fault transient amount, the short defective that is difficult for gathering fault data of fault electric parameters life period is arranged; There is electric parameters amplitude defective less than normal in route selection localization method for reflection fault steady-state quantity, because the fault component amplitude is too little, causes criterion malfunctioning, has reduced the reliability of device.
Summary of the invention
The purpose of this utility model is exactly the defective that has the difficult detection less than normal of system's faults itself electric parameters amplitude at present for the method for utilizing route selection of fault-signal steady-state component and location in order to solve, providing a kind of has behind electrical network generation single phase ground fault, moment is amplified the fault-signal steady-state component, make the route selection positioner precision maneuver based on the single phase ground fault steady-state quantity, the stable status zero-sequence current that reaches advantages such as location and route selection purpose helps and increases device.
For achieving the above object, the utility model adopts following technical scheme:
A kind of stable status zero-sequence current helps and increases device, and it comprises the bus of protected distribution system, and the installation stable status zero-sequence current helps and increases device on the described bus, and this device also is connected with voltage transformer, and voltage transformer then is connected with bus; Help and increase device and form by power capacitor group, fling-cut switch and control device, whether control device monitoring distribution system single phase ground fault takes place, the power capacitor group then helps earth current and increases, and by the switching of control device by fling-cut switch control power capacitor group.
Described power capacitor group is included in each at least one capacitor that upward is provided with mutually of bus, and their constitute capacitor group, and an end of each capacitor is connected with fling-cut switch separately respectively, other end ground connection.
Described control device is made up of three-phase voltage, residual voltage harvester, single phase ground fault judgment means and switch on-off drive unit, monitoring distribution system three-phase voltage and residual voltage also judges whether system single phase ground fault takes place, thus the switching of control power capacitor; Wherein, three-phase voltage, residual voltage harvester are made of voltage transmitter, RC low-pass filtering, the pre-process circuit and the A/D change-over circuit that are made of operational amplifier; The single phase ground fault judgment means is made of the AT89C52 single-chip microcomputer; The switch on-off drive unit is made of relay drive circuit and control relay.
Described each fling-cut switch is formed one group of control switch, and they are connected between bus and the corresponding separately capacitor, according to the order switching power capacitor group of control device.
The course of work of the present utility model is: for the distribution system of operation, monitor the three-phase voltage and the system zero sequence voltage of bus in real time by the control section of this device, and whether the real-time judge distribution system single phase ground fault takes place.When distribution system was normally moved, fling-cut switch K disconnected, and this device does not drop into.When single phase ground fault takes place when, by control section with fling-cut switch K closure, stable status zero-sequence current helps and increases device and put in the failure system rapidly, make fault zero-sequence current moment obtain amplifying, the found back of fault is disconnected fling-cut switch K immediately by control section, this device withdraws from from system, can not cause adverse effect to the operation of distribution system.
The beneficial effects of the utility model are: (1) can protect coupling with single-phase earth fault line selection and location based on stable state fault amount; when small current neutral grounding system generation single phase ground fault; help by stable status zero-sequence current and to increase device and increase the fault stable status zero-sequence current artificially; the zero-sequence fault difference between current that the fault zero-sequence current of moment amplification makes faulty line and non-fault line is improved thereby make based on the single-phase earth fault line selection of fault steady-state quantity and the action accuracy rate of location protection apart from increase.(2) improved based on the single-phase earth fault line selection of stable state fault amount and the anti-transition resistance ability of location protection,, strengthened the fault degree of fault point, improved the ability of anti-transition resistance accordingly owing to artificially increased the fault zero-sequence current.(3) to the outlet of high-tension fuse is housed, the fault zero-sequence current that has increased makes the high-tension fuse quick-break, earth fault can be isolated rapidly.
This device can improve effectively based on the single-phase earth fault line selection of stable state fault amount and the action accuracy rate of location protection in a word; To the circuit of high-tension fuse is housed, fault can be isolated rapidly, shorten fault handling time.
Description of drawings
Fig. 1 is a structural representation of the present utility model;
Fig. 2 is the control device structural representation;
Fig. 3 increases method flow diagram for helping.
Wherein, 1, bus, 2, capacitor, 3, control device, 4, fling-cut switch, 5, three-phase voltage, residual voltage harvester, 6, the single phase ground fault judgment means, 7, the switch on-off drive unit, 8, voltage transformer.
Specific embodiment
Embodiment 1:
Among Fig. 1, connect capacitor 2 on mutually in each of the isolated neutral system bus 1 of shielded distribution system, each capacitor 2 its corresponding fling-cut switches 4 series connection, the other end ground connection of capacitor 2, whole capacitors 2 are formed the power capacitor groups.Control device 3 is used to monitor distribution system whether single phase ground fault takes place, and the switching of control fling-cut switch 4, as shown in Figure 2.Control device 4 comprises three-phase voltage, residual voltage harvester 5, single phase ground fault judgment means 6 and switch on-off drive unit 7 compositions, in order to monitoring distribution system three-phase voltage and residual voltage and judge whether system single phase ground fault takes place, thus the switching of control power capacitor group; Wherein, three-phase voltage, residual voltage harvester 5 are made of voltage transmitter, RC low-pass filtering, the pre-process circuit and the A/D change-over circuit that are made of operational amplifier; Single phase ground fault judgment means 6 is made of the AT89C52 single-chip microcomputer; Switch on-off drive unit 7 is made of relay drive circuit and control relay.Control device 3 also is connected with voltage transformer 8, and an end of voltage transformer 8 is connected with bus 1.
Of the present utility model helping increases method as shown in Figure 3:
When (1) distribution system was moved, fling-cut switch disconnected, and the power capacitor group does not drop into, and control device is monitored busbar voltage and system zero sequence voltage in real time, and judges whether system single phase ground fault takes place;
(2) if there is not single phase ground fault that repeating step (1) takes place; If have, immediately with the fling-cut switch closure, the power capacitor group is dropped into failure system, to increase the fault zero-sequence current;
(3) continue monitoring busbar voltage and system zero sequence voltage, and judge whether single phase ground fault exists;
(4) if fault still exists, proceed the operation of step (3);
(5) if fault is removed, fling-cut switch is disconnected, the power capacitor group is excised from system;
(6) turn back to step (1) then and carry out aforesaid operations again.
Among Fig. 1, single phase ground fault takes place in C mutually that suppose circuit II, the faulty line zero-sequence current equals the zero-sequence current of non-fault line I and helps to increase the zero-sequence current sum that device produces, help the zero-sequence current that increases the device generation to be the zero-sequence current of artificial increase, the zero-sequence current of this current ratio system itself is much bigger, can calculate according to actual needs add the size of electric current.As seen; the artificial fault zero-sequence current that increases increases the fault current that flows through in the faulty line greatly; and remain the fault zero-sequence current that distributed capacitance causes in the non-fault line; thereby widened the gap between faulty line and the non-fault line, can improve the judging nicety rate that utilizes route selection of fault-signal steady-state component and location protection.
With certain oil recovery factory's 35kV/6kV power transformation example of doing, it has 2 6300kVA main transformers, Y Δ-11 wiring, and Uk%=7.5%, 6kV bus have 8 outlets, outlet parameter and load condition such as following table 1:
Table 1
| The outlet sequence number | Line length (km) | Burden with power (MW) | Load or burden without work (MVar) |
| 1 | 15 | 0.46 | 0.25 |
| 2 | 10 | 0.56 | 0.35 |
| 3 | 20 | 0.36 | 0 |
| 4 | 12 | 0.33 | 0.03 |
| 5 | 17 | 0.42 | 0.18 |
| 6 | 2 | 0.91 | 0.41 |
| 7 | 19 | 0.49 | 0.12 |
| 8 | 3 | 0.90 | 0.43 |
Wherein, wire type is LGJ-70, horizontally, and spacing 0.45m.Help and increase every phase power capacitor capacity 80kVar in the device, transition resistance 0～3k Ω.
Comparing result
No. 1 single phase ground fault data such as table 2 take place in outlet 3km place:
The single phase ground fault emulated data takes place in table 21# outlet 3km place
| Transition resistance (ohm) | 0 | 10 | 50 | 100 | 500 | 1000 | 1500 | 2000 | 2500 | 3000 |
| Helpless faulty line zero-sequence current 3I when increasing electric current 0(A) | 1.2 | 1.2 | 1.2 | 1.2 | 1.1 | 0.9368 | 0.7622 | 0.6280 | 0.5283 | 0.4535 |
| Faulty line zero-sequence current 3I when adding 0.24MVar electric capacity 0（A) | 38 | 36.9 | 25.1 | 15.5 | 3.4 | 1.7 | 1.1 | 0.8613 | 0.6892 | 0.5744 |
From test data as can be seen, the zero-sequence current of faulty line increases the back transition resistance and hour obviously increases helping, and transition resistance also has increase when big, but the increase amplitude is less.
Because stable status zero-sequence current helps and increases device when the system failure, artificial increase the fault zero-sequence current, enough big earth current promptly is provided, the high-tension fuse fuse of oil well transformer is generally at 3A-5A at present, so during metallic earthing, because zero-sequence current helps and increases device moment and increased the fault zero-sequence current, the high-tension fuse fuse can quick-break, and earth fault is isolated.This has become the peculiar methods of facing the grounding fault of coiling oilfield electric net.
Claims (4)
1. a stable status zero-sequence current helps and increases device, and it comprises the bus of protected distribution system, it is characterized in that: the installation stable status zero-sequence current helps and increases device on the described bus, and this device also is connected with voltage transformer, and voltage transformer then is connected with bus; Help and increase device and form by power capacitor group, fling-cut switch and control device, whether control device monitoring distribution system single phase ground fault takes place, the power capacitor group then helps earth current and increases, and by the switching of control device by fling-cut switch control power capacitor group.
2. stable status zero-sequence current according to claim 1 helps and increases device, it is characterized in that: described power capacitor group is included in each at least one capacitor that upward is provided with mutually of bus, they constitute the capacitor group, and an end of each capacitor is connected with fling-cut switch separately respectively, other end ground connection.
3. stable status zero-sequence current according to claim 1 helps and increases device, it is characterized in that: described control device is made up of three-phase voltage, residual voltage harvester, single phase ground fault judgment means and switch on-off drive unit; Wherein, three-phase voltage, residual voltage harvester are made of voltage transmitter, RC low-pass filtering, the pre-process circuit and the A/D change-over circuit that are made of operational amplifier; The single phase ground fault judgment means is made of the AT89C52 single-chip microcomputer; The switch on-off drive unit is made of relay drive circuit and control relay.
4. stable status zero-sequence current according to claim 1 helps and increases device, it is characterized in that: described each fling-cut switch is formed one group of control switch, and they are connected between bus and the corresponding separately capacitor, according to the order switching power capacitor group of control device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2007200213658U CN201038753Y (en) | 2007-05-10 | 2007-05-10 | Stable state zero-sequence current boosting device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2007200213658U CN201038753Y (en) | 2007-05-10 | 2007-05-10 | Stable state zero-sequence current boosting device |
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| CN201038753Y true CN201038753Y (en) | 2008-03-19 |
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| CNU2007200213658U Expired - Fee Related CN201038753Y (en) | 2007-05-10 | 2007-05-10 | Stable state zero-sequence current boosting device |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100511908C (en) * | 2007-05-10 | 2009-07-08 | 济南大学 | Stable status zero-sequence current increase and assistance device and method |
| CN104638635A (en) * | 2013-11-08 | 2015-05-20 | 中国石油化工股份有限公司 | Power grid neutral point active resistor grounding method |
| EP2985613A4 (en) * | 2013-03-29 | 2017-05-17 | Beijing Inhand Networks Technology Co., Ltd. | Method and system for detecting and locating single-phase ground fault on low current grounded power-distribution network |
-
2007
- 2007-05-10 CN CNU2007200213658U patent/CN201038753Y/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100511908C (en) * | 2007-05-10 | 2009-07-08 | 济南大学 | Stable status zero-sequence current increase and assistance device and method |
| EP2985613A4 (en) * | 2013-03-29 | 2017-05-17 | Beijing Inhand Networks Technology Co., Ltd. | Method and system for detecting and locating single-phase ground fault on low current grounded power-distribution network |
| CN104638635A (en) * | 2013-11-08 | 2015-05-20 | 中国石油化工股份有限公司 | Power grid neutral point active resistor grounding method |
| CN104638635B (en) * | 2013-11-08 | 2018-04-10 | 中国石油化工股份有限公司 | Power network neutral point active pull-up earthing method |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20080319 Termination date: 20100510 |