CN1564007A - Single phase earthing wire selection method for small earthing current system - Google Patents
Single phase earthing wire selection method for small earthing current system Download PDFInfo
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- CN1564007A CN1564007A CN 200410024015 CN200410024015A CN1564007A CN 1564007 A CN1564007 A CN 1564007A CN 200410024015 CN200410024015 CN 200410024015 CN 200410024015 A CN200410024015 A CN 200410024015A CN 1564007 A CN1564007 A CN 1564007A
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Abstract
The method includes signal generator and signal detector. When relay protection detects short circuit of grounding in single phase occurs, signal generator through TV secondary side sends impulse signal to fault phase. Pulse width of impulse signal is less than 5 ms and impulse cycle is larger than 20 ms. width of impulse and impulse cycle are adjustable through hand regulation or self-regulation. With certain time period, signal generator sends out N kinds of impulse signals I different cycle, where N is greater than or equal to 2.
Description
(1) technical field
The present invention relates to field of relay protection in power, particularly a kind of fault-line selecting method that is used for the small grounding current system single phase ground fault.
(2) background technology
The not directly grounded electric system of power transformer neutral point is called small grounding current system.When this system single phase ground fault, there is not fault loop, can not produce short-circuit current, relay protection of power system can not trip, and electric system allows to continue operation a period of time.Because there is distributed capacitance in power circuit, though distributed capacitance is not too big, produce capacity current at single-phase earthing point, electric system also is harmful to.Therefore, during this system single phase ground fault, relay protection must be sent alerting signal, and the operator on duty makes respective handling by operation, at last faulty line is carried out interruption maintenance.For faulty line is carried out interruption maintenance, relay protection should be sent alerting signal and be pointed out faulty line.Relay protection judges whether single phase ground fault is easy to realize.But the capacity current during owing to the small grounding current system single phase ground fault is less, and it is just very difficult to judge which bar line failure.So far also there is not highly effective way to solve both at home and abroad.
Traditional way is when utilizing electric system generation singlephase earth fault, and the fault component that self produces detects.In the technical scheme that adopts, group's amplitude ratio that each bar circuit zero sequence current amplitude size of comparison is arranged is than principle; Each other faciation comparison principle of bar circuit zero sequence current and phase difference of comparison is arranged; Group's width of cloth faciation comparison principle that both combinations are also arranged.Because the fault capacity current during the small grounding current system single phase ground fault changes with the variation of the system architecture and the method for operation, sometimes very big, sometimes very little, add the influence of factors such as current transformer TA error, under a lot of situations, be difficult to judge faulty line.
For overcoming the above problems, Chinese patent application number has proposed a kind of method of AC signal that adds for the patent of invention of CN-93111309.1.Promptly; The secondary side of voltage transformer (VT) TV adds the sinusoidal ac signal between two harmonic waves from the electrical system bus.Because the neutral ground of TV, like this, the sinusoidal ac signal that adds forms current return between the earth point of TV and single-phase short circuit earth point, detect the flow direction of this sinusoidal ac signal then with a detection instrument, thereby detect faulty line.Because the rated capacity of voltage transformer (VT) is limited, secondary side feeds the electric current that adds sinusoidal ac signal can not be very big, and this will influence the raising of measuring accuracy.In addition, in order to hide the interference of electric system power frequency component and various harmonic signals, select frequency between two harmonic waves as adding the frequency of operation of sinusoidal signal.Because frequency of operation and harmonic frequency are very approaching, detection instrument is wanted the filtering harmonic signal, extracts the working signal that adds, and is just very difficult.These all have influence on the Effect on Detecting of this device.
(3) summary of the invention
The fault-line selecting method that the purpose of this invention is to provide a kind of highly sensitive small grounding current system single phase ground fault.
Fault-line selecting method of the present invention is made up of signal generator and acquisition of signal instrument two parts.
When relay protection detected single phase ground fault, signal generator through TV secondary side sent a kind of pulse signal mutually to fault.The pulse width of pulse signal is less than 5 milliseconds; Recurrence interval is greater than 20 milliseconds; But pulse width and recurrence interval manual adjustments and adjusting automatically.Signal generator sends the pulse signal of N kind different cycles, wherein N 〉=2 by certain time interval.
The acquisition of signal instrument is measured the size of each bar circuit pulse signal amplitude, and pulse signal amplitude the maximum is a faulty line.The pulse signal in corresponding N kind cycle is selected N kind result respectively, and when M kind result was the same line road, wherein M 〉=(2N/3), it was faulty line that the acquisition of signal instrument is specified this circuit.
(4) description of drawings
Fig. 1: 1---represents signal generator; 2---represents the acquisition of signal instrument; 3---represents the electric system transformer.
Three output terminals that Fig. 1 illustrates signal generator respectively with bus on voltage transformer (VT) TV secondary side a, b, c connected mode mutually.Signal generator through TV secondary side sends a kind of applying pulse signal mutually to fault, and the flow direction of pulse signal as shown in phantom in FIG..Fig. 1 also represents a kind of mode of acquisition of signal instrument from the zero sequence TA received pulse signal of transmission line of electricity.
Fig. 2 represents that signal generator sends the waveform of pulse signal.T wherein
1The indicating impulse width; t
2The indicating impulse cycle.
Fig. 3 represents that signal generator sends the waveform of N kind different cycles pulse signal.
Fig. 4 is the structural representation of acquisition of signal instrument.SX wherein
nThe expression input; A1 represents filtering and pulse signal extraction unit; A2 represents amplifying unit; A3 represents amplitude comparison and judging unit; A4 represents to export display unit.
(5) embodiment
Three output terminals that Fig. 1 illustrates signal generator respectively with bus on voltage transformer (VT) TV secondary side a, b, c connected mode mutually.The size of relay protection measurement TV secondary side a, b, c three-phase voltage when a certain phase voltage descends, when two phase voltages raise in addition, differentiate the electric system single phase ground fault, and the separate of voltage decline is that fault is separate.When relay protection detected single phase ground fault, signal generator through TV secondary side sent a kind of pulse signal shown in Figure 2 mutually to fault
If what signal generator sent is sinusoidal ac signal, then sinusoidal ac signal power is bigger, and the current amplitude of signal is just bigger; The current amplitude of signal is bigger, more helps the detection of acquisition of signal instrument; The sensitivity of failure line selection and reliability are just higher.Because the rated power of voltage transformer (VT) TV is limited, signal generator is given the sinusoidal ac signal power of TV can not be very big, and the amplitude of electric current also can not be very big.Yet, if signal generator sends is not sinusoidal ac signal, but pulse signal, and the width t of pulse signal
1Narrower, then under equal power condition, the amplitude of signal just can strengthen greatly.What the acquisition of signal instrument detected is the current amplitude of external signal, and the pulse signal width that adds is less but amplitude is very big, can improve the sensitivity of fault line selection device greatly.
The neutral ground of TV, the pulse signal that adds forms current return between the earth point of TV and single-phase short circuit earth point, the flow direction of pulse signal as shown in phantom in Figure 1, the pulse current of faulty line is bigger.Non-fault line has the pulse leakage electric current, and current ratio is less.The pulse current size of all circuits relatively, pulse current the maximum is a faulty line.
Fig. 1 represents a kind of mode of acquisition of signal instrument from the zero sequence TA received pulse signal of transmission line of electricity.The output of zero sequence current mutual inductor TA is connected to the input end SX of acquisition of signal instrument
n(n=1,2 ... N).The acquisition of signal instrument may be implemented in a variety of ways.Fig. 3 illustrates a kind of structure of acquisition of signal instrument.Zero sequence current mutual inductor is responded to pulse signal and other ac current signals in the transmission line of electricity, and delivers to the input end SX of acquisition of signal instrument
n(n=1,2 ... N).A1 filtering power frequency component, each harmonic component and the various undesired signal of acquisition of signal instrument are extracted the pulse signal that signal generator sends.The pulse signal of work amplifies through the A2 amplifying circuit, delivers to the A3 comparator circuit.Comparator circuit is selected pulse signal the maximum, the faulty line of selecting for this periodic pulse signal, and deliver to storage element.The pulse signal in corresponding N kind cycle is selected N kind result respectively, and when M kind result was the same line road, wherein M 〉=(2N/3), it was faulty line that the acquisition of signal instrument is specified this circuit.A4 shows faulty line.
Undesired signal in the electric system mainly is various higher hamonic waves, and is very approaching a kind of and harmonic frequency, and to come out be very difficult to the sinusoidal alternating current input that has a same characteristic features with harmonic wave again.To distinguish harmonic sine AC signal and pulse signal just easier.Adopt pulse signal as adding working signal, can improve the detection sensitivity of acquisition of signal instrument.
Exist the pulse interference signal in certain cycle in the electric system, the cycle of this undesired signal may to send cycle of pulse signal identical with signal generator, if the acquisition of signal instrument is only selected faulty line with a kind of periodic pulse signal, its result must be wrong.Adopt signal generator to send the pulse signal of multiple different cycles, the acquisition of signal instrument is determined the method for faulty line according to statistics, can improve the correctness of fault line selection device.
Because the progress of disease of voltage transformer (VT) TV pulse signals is a transient state process of having utilized inductance, different pulse width t
1The progress of disease effect of pulse signal in different electric system be different.At different electric system, adjust the pulse width t of pulse signal
1, can make the progress of disease effect of pulse signal and the overall sensitivity of fault line selection device reach best.
Claims (2)
1. fault-line selecting method that is used for the small grounding current system single phase ground fault, fault-line selecting method is made up of signal generator and acquisition of signal instrument two parts, it is characterized in that signal generator through TV secondary side sends a kind of pulse signal mutually to fault, the pulse width of pulse signal is less than 5 milliseconds; Recurrence interval is greater than 20 milliseconds; But pulse width and recurrence interval manual adjustments and adjusting automatically.
2. signal generator according to claim 1 is characterized in that signal generator sends the pulse signal of N kind different cycles, wherein N 〉=2 by certain time interval.
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| Application Number | Priority Date | Filing Date | Title |
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| CNB2004100240158A CN100401079C (en) | 2004-04-14 | 2004-04-14 | Single phase earthing wire selection method for small earthing current system |
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| Application Number | Priority Date | Filing Date | Title |
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| CNB2004100240158A CN100401079C (en) | 2004-04-14 | 2004-04-14 | Single phase earthing wire selection method for small earthing current system |
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| CN1564007A true CN1564007A (en) | 2005-01-12 |
| CN100401079C CN100401079C (en) | 2008-07-09 |
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| CNB2004100240158A Expired - Fee Related CN100401079C (en) | 2004-04-14 | 2004-04-14 | Single phase earthing wire selection method for small earthing current system |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100501429C (en) * | 2005-12-13 | 2009-06-17 | 北京潞电电气设备厂 | Wiring identifying device and method |
| CN102707186A (en) * | 2012-06-08 | 2012-10-03 | 北京泽源惠通科技发展有限公司 | Method for detecting single phase-to-earth faults |
| CN107132444A (en) * | 2017-03-13 | 2017-09-05 | 国网山东省电力公司淄博供电公司 | A kind of small current grounding failure wire selection system |
| CN110161358A (en) * | 2019-04-30 | 2019-08-23 | 云南电网有限责任公司电力科学研究院 | A kind of Earth design method and device |
| CN113725811A (en) * | 2020-12-12 | 2021-11-30 | 保定钰鑫电气科技有限公司 | Method for processing single-phase grounding of non-effective grounding system |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4837519A (en) * | 1985-09-06 | 1989-06-06 | Southern California Edison Company | Fault detection |
| DE59309599D1 (en) * | 1992-03-31 | 1999-07-01 | Siemens Ag | Method and arrangement for the detection of short circuits in line branches of electrical networks |
| CN1039665C (en) * | 1993-06-22 | 1998-09-02 | 山东工业大学 | Universal small current grounding system single-phase grounding selecting and locating apparatus |
| DE4339946A1 (en) * | 1993-11-24 | 1995-06-01 | Walther Bender Gmbh & Co Kg Di | Method and device for monitoring the insulation of unearthed direct and alternating current networks |
| CN2257023Y (en) * | 1995-12-20 | 1997-06-25 | 吴国良 | DC system grounding monitor and seeking apparatus |
-
2004
- 2004-04-14 CN CNB2004100240158A patent/CN100401079C/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100501429C (en) * | 2005-12-13 | 2009-06-17 | 北京潞电电气设备厂 | Wiring identifying device and method |
| CN102707186A (en) * | 2012-06-08 | 2012-10-03 | 北京泽源惠通科技发展有限公司 | Method for detecting single phase-to-earth faults |
| CN107132444A (en) * | 2017-03-13 | 2017-09-05 | 国网山东省电力公司淄博供电公司 | A kind of small current grounding failure wire selection system |
| CN110161358A (en) * | 2019-04-30 | 2019-08-23 | 云南电网有限责任公司电力科学研究院 | A kind of Earth design method and device |
| CN113725811A (en) * | 2020-12-12 | 2021-11-30 | 保定钰鑫电气科技有限公司 | Method for processing single-phase grounding of non-effective grounding system |
| CN113725811B (en) * | 2020-12-12 | 2023-12-05 | 保定钰鑫电气科技有限公司 | Single-phase grounding processing method of non-effective grounding system |
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| CN100401079C (en) | 2008-07-09 |
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Assignee: Shandong Electric Power Engineering Consulting Institute Co., Ltd. Assignor: Shandong University Contract fulfillment period: 2008.8.20 to 2013.8.19 contract change Contract record no.: 2009370000131 Denomination of invention: Single phase earthing wire selection method for small earthing current system Granted publication date: 20080709 License type: Exclusive license Record date: 2009.6.29 |
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Free format text: EXCLUSIVE LICENSE; TIME LIMIT OF IMPLEMENTING CONTACT: 2008.8.20 TO 2013.8.19; CHANGE OF CONTRACT Name of requester: SHANDONG ELECTRIC POWER ENGINEERING CONSULTING INS Effective date: 20090629 |
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