CN102288866B - Method and equipment for detecting single-phase earth fault of transmission and distribution line - Google Patents
Method and equipment for detecting single-phase earth fault of transmission and distribution line Download PDFInfo
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- CN102288866B CN102288866B CN201110209114.3A CN201110209114A CN102288866B CN 102288866 B CN102288866 B CN 102288866B CN 201110209114 A CN201110209114 A CN 201110209114A CN 102288866 B CN102288866 B CN 102288866B
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- transient current
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Abstract
The invention provides a method and equipment for detecting a single-phase earth fault of a transmission and distribution line. The method comprises the following steps of: 1, detecting the mutation rate of transient current of the line, wherein the mutation rate Delta Ip/Delta t of the transient current is greater than Rh when the transient current positively jumps; and 2, determining a short-circuit earth fault when detecting that line voltage drops and V is smaller than Vh, wherein the sequence of the step 1 and the step 2 can be changed. According to the fault detection equipment, false alarm or alarm omission can be prevented, demands of different users can be met, and the equipment is applicable for mass production.
Description
Technical field
The present invention relates to power equipment, relate in particular to the detection of electric line singlephase earth fault.
Background technology
Electric line branch is many, and circuit is long, and load is complicated.But, when there is earth fault, must get rid of as early as possible these faults, otherwise phase voltage raises, can grievous injury power-supply unit and the insulating property of circuit, and and then cause phase fault, thereby reduced power supply quality and efficiency.And the position that will fix a breakdown and first must find fault to occur.
For neutral point indirect earthing electrical power trans mission/distribution system, during due to generation singlephase earth fault, line voltage is constant, and line load electric current is constant, and characteristic quantity is not clearly, so the fault detect of single-phase earthing is a global problem.With regard to the detection of earth fault, the method that current checkout equipment mainly adopts has three classes:
Half-wave method headed by the first kind, is judged to be earth fault and occurs while utilizing the capacitance voltage of ground connection instant earthing phase to be greater than preset value with this phase phase voltage homophase and capacitance current.This method can play a role.But maximum problem is this method to be based upon singlephase earth fault and to occur in phase voltage peak value constantly, at this moment can compare phase place.Yet most singlephase earth faults occur in the position of non-crest or even waveform pass zero point, now just cannot detect and judge earth fault, referring to Fig. 1.
Equations of The Second Kind method is quintuple harmonics method.These class methods there will be quintuple harmonics utilization when quintuple harmonics is greater than preset value, to be judged to be earth fault generation while utilizing circuit generation singlephase earth fault.This method is unreliable, because line load is various, under normal circumstances, just exists a large amount of harmonic components to comprise the situation of quintuple harmonics.If the fluctuation of electrical network causes 5 subharmonic to surpass preset value, just there will be the situation of wrong report; Or line construction is simple, quintuple harmonics during ground connection is very little, now just cannot detect quintuple harmonics.
The 3rd class methods detect transient current exactly.Although transient current is obvious, but because the duration of transient is very short, and be a quick attenuation process, less than 1/4th of power frequency cycle, checkout equipment obviously cannot accurately detect the instant value of transient, therefore also just cannot accurately detect transient size, line load is ever-changing still more, the unexpected fluctuation of load, variation all likely cause circuit frequency of occurrences scope and the overlapping signal of transient current frequency range, at this moment just there will be erroneous judgement, referring to Fig. 2.
Therefore, above three class earth-fault detecting methods all cannot reliable detection singlephase earth fault.
Summary of the invention
The object of this invention is to provide and be a kind ofly subject to electric line operational management, geographical environment, load fluctuation, climate change etc. to affect earth-fault detecting method smaller, reliable operation.
The present invention provides a kind of detection method of electric line singlephase earth fault in first aspect.The method comprises:
(1) detection line transient current mutation rate, there is positive transition in transient current, transient current mutation rate Δ I
p/ Δ t > R
h;
(2) detection line lower voltage, V < V
h;
When two conditions all meet, judge earth fault; The order of step (1) and (2) can change.
The present invention provides a kind of checkout equipment of electric line fault in second aspect.This equipment comprises: circuit transient current mutation rate testing circuit, line current is carried out to bandpass filtering, and obtain the mutation rate information of circuit transient current outlet line transient current; Line voltage distribution field coupled circuit, detects electric line voltage; Microcontroller circuit, is configured for: the mutation rate of judgement circuit transient current, Δ I
p/ Δ t > R
h; Judgement line voltage distribution reduces, V < V
h; When two conditions all meet, judge short circuit grounding fault.
Wherein, Δ I
pbe the positive transition value of transient current, Δ t is the time of transient sudden change, R
hthe effective threshold values of judgement transient current mutation rate of presetting, V
hit is the threshold values of the judgement voltage drop preset.
Optionally, with transient circuit Sudden Changing Rate Δ I
p> I
hreplace Δ I
p/ Δ t > R
has the detection of singlephase earth fault according to one of, I wherein
hit is default transient sudden change threshold values.
Fault test set according to the present invention there will not be mistake alarm or leaks alarm phenomenon, can meet the demand of different user, is suitable for large-scale production.
Accompanying drawing explanation
Below with reference to accompanying drawings specific embodiment of the invention scheme is described in detail, wherein:
Fig. 1 is for adopting first half-wave method to detect the schematic diagram of singlephase earth fault;
Fig. 2 is for adopting transient current value detection method to detect the schematic diagram of singlephase earth fault;
Fig. 3 is for adopting the schematic diagram of the method detection of ground faults of transient current root-mean-square value of the present invention positive transition;
Fig. 4 is the principle schematic of line voltage distribution V field coupled circuit of the present invention;
Fig. 5 is the schematic block circuit diagram that detects the checkout equipment of singlephase earth fault;
Fig. 6 is the schematic diagram of line current tracking and conversion circuit and circuit transient current mutation rate testing circuit;
Fig. 7 is the schematic diagram of line voltage distribution V field coupled circuit;
Fig. 8 is the schematic diagram of microcontroller circuit;
Fig. 9 is the schematic diagram of warning circuit.
Embodiment
During neutral point isolated neutral system generation singlephase earth fault, an essential characteristic of circuit is exactly to occur transient current positive transition moment, and Earth Phase voltage drop.Because the Characteristics of Mutation of transient current is obvious, the present invention utilizes the generation of this feature reliable detection singlephase earth fault.
The detection method that the invention provides a kind of singlephase earth fault is:
(1) mutation rate of detection line transient current, Δ I
p/ Δ t > R
h;
(2) detection line lower voltage, V < V
h.
Wherein, Δ I
pbe the sudden change value of transient current, Δ t is transient bound-time constant, R
hthe effective threshold values of judgement transient current mutation rate of presetting, V
hit is the threshold values of the judgement voltage drop preset.
Wherein, also available transient circuit Sudden Changing Rate Δ I
p> I
hreplace Δ I
p/ Δ t > R
has the detection of singlephase earth fault according to one of, I wherein
hit is default transient sudden change threshold values.
Single-phase earth fault detecting method of the present invention can overcome the defect of first half-wave method, quintuple harmonics method, transient method.First half-wave method cannot be differentiated the initial time of earth fault but artificially suppose that earth fault occurs in line voltage distribution peak value constantly, and this is a wrong differentiation, does not meet the essential characteristic of singlephase earth fault; Quintuple harmonics method cannot accurately detect because of the existence of line-hit signal; Because the circuit transient duration is very short and decay is very fast, cannot effectively detect; And first half-wave method, quintuple harmonics method, these three class methods of transient method all when realizing circuit generation singlephase earth fault line voltage distribution this key character that declines detect, this is another major defect of these methods.And detection method of the present invention is the mutation rate Δ I of the transient current amount of for example 300Hz to 4000Hz by the mutation rate testing circuit identification circuit electric current medium frequency component of circuit transient current
p/ Δ t > R
h, and simultaneously by line voltage distribution V field coupled circuit (104) detection line voltage.If the mutation rate Δ I of transient current
p/ Δ t > R
hand line voltage distribution decline V < V
hthese two conditions meet simultaneously, just can reliably, accurately judge line single phase grounding failure.
Therefore, fault test set according to the present invention there will not be mistake alarm or leaks alarm phenomenon, can meet the demand of different user, is suitable for large-scale production.
Fig. 4 is the principle schematic that detects electric line primary side voltage.In figure, C
rcoupling capacitance for formation between (surface conduction layer) 42 places, position of checkout equipment shell and circuit 46 contacts and checkout equipment circuit board common port 44.C
pfor the distributed capacitance between checkout equipment common port 44 and the earth 48.The position that checkout equipment shell contacts with electric line scribbles conductive layer or is equipped with conductive component as conductive rubber etc.C
routput coupled voltages V, electric line primary voltage equals (1+C
r/ C
p) * V, as long as therefore detect V, just can be through calculating the primary voltage of electric line.
Fig. 5 is the schematic block circuit diagram of checkout equipment of the detection singlephase earth fault of the embodiment of the present invention.In figure, checkout equipment comprises line current tracking and conversion circuit 101, circuit transient current mutation rate testing circuit 103, line voltage distribution field coupled circuit 104, microcontroller circuit 105 and warning circuit 106.
Line current is followed the tracks of and conversion circuit 101 completes induction and the conversion to electric line primary side actual current.
Circuit transient current mutation rate testing circuit 103 is realized the real-time follow-up to line current transient, and exports the mutation rate information of transient.Specifically, line current is carried out to bandpass filtering, obtain the mutation rate information of circuit transient current outlet line transient current.
The detection that line voltage distribution V field coupled circuit 104 completes electric line primary side voltage, and the voltage signal after output coupling.
The judgement that microcontroller circuit 105 is realized each signal, and outputting alarm enabling signal.Specifically, the positive transition rate of judgement circuit transient current and judgement line voltage distribution reduce; When two conditions all meet, judge earth fault.
Warning circuit 106 receives after the alarm enabling signal of MCU microprocessor output, according to present condition, drives alarm device to realize mechanical board turning alarm or luminous alarm.
Fig. 6 is the schematic diagram of line current tracking and conversion circuit and circuit transient current mutation rate testing circuit.
In line current tracking and conversion circuit 101, L1 is current signal induction pick-up, and induced signal forms all-wave signal by 1 output by diode D1, D2, and this signal exports circuit transient current mutation rate testing circuit 103 to.
Certainly, L1 also can not need to carry out rectification through diode, but directly exports original AC signal to circuit transient current mutation rate testing circuit 103.
Circuit transient current mutation rate testing circuit 103 is comprised of resistance R 11, R12, R13, R14, R15, R23, R24, capacitor C 4, C5, C6, C10, C11, diode D5, D11, comparison amplifier U2, wherein R24 is much larger than R23, C11 is differential capacitance, C11 and R23 form differentiating circuit, the detection of realization to mutation rate Δ Ip/ Δ t, time constant Δ t=R23*C11.R11, R12, C4, C5 form two-stage high-pass wave filter, and filtering is the low frequency signal below 300Hz for example from the half-wave AC signal medium frequency of L1, and R13, C6 form low-pass filtering, and filtering is high-frequency signal more than 4000Hz for example.The rectifying and wave-filtering of signal process D11, the C10 exporting after the band-pass filter forming through R11, R12, R13, C4, C5, C6 is the formal output with signal HXH by comparison amplifier U2.In fact, because C10 is that for example each component of current signal of 300Hz to 4000Hz carries out smothing filtering to all frequency ranges, therefore, in fact the signal at C10 two ends is exactly root-mean-square value or the effective value of each frequency component of transient current signal.R14, the corresponding preset value R forming of R15 dividing potential drop
hsignal is to comparer negative pole.Under normal circumstances, due to the existence of differential capacitance C11, R23 two ends no signal.When positive transition Δ I appears in circuit transient current
ptime, due to the differential action of C11, R23, Δ I
p/ Δ t signal appears at R23 two ends.If this positive transition Δ I
p/ Δ t signal is greater than the preset value R consisting of R14, R15 dividing potential drop correspondence
h, comparer U2 exports high level pulse.
Although what the embodiment here realized is a kind of detection method to transient current mutation rate, the i.e. detection to transient current root-mean-square value or effective value mutation rate, thus also can utilize other method for example the Sudden Changing Rate of the component signal of certain frequency in transient current or certain band frequency scope or mutation rate to be detected the differentiation of the earth fault that achieves a butt joint.For example, obtain Δ I
p/ Δ t, due to Δ t=R23*C11, therefore calculates Δ I by MCU
p/ Δ t* (R23*C11) can obtain Δ I
psudden Changing Rate.
When adopting transient current Sudden Changing Rate, Sudden Changing Rate Δ I
p> I
hcan replace Δ I
p/ Δ t > R
has the detection of singlephase earth fault according to one of, I wherein
hit is default transient sudden change threshold values.
Although Fig. 6 combined circuit current tracking and conversion circuit and circuit transient current mutation rate testing circuit are described in the lump, this is the object for clear explanation, and does not mean that two concrete implementing circuits in Fig. 6 must combine.Such as, the circuit transient current mutation rate in Fig. 6 or transient detection circuit 103 can follow the tracks of with the line current of other type and conversion circuit 101 together with work.
Fig. 7 is the schematic diagram of line voltage distribution V field coupled circuit.Line voltage distribution V field coupled circuit 104 is comprised of diode D7, D8, D9, resistance R 18, capacitor C 9.The position contacting with electric line on the main body cover surface of checkout equipment is coated conductive material and is formed conductive layer, or assemble a conductive devices and be connected to the anodal tie point with D8 negative pole of D7 as conductive rubber and by lead-in wire, thereby make to form a coupling capacitance C between electric line and the public terminal GND of checkout equipment circuit board
r, between circuit board public terminal GND and the earth, form a distributed capacitance C
p, coupling capacitance and distributed capacitance form bleeder circuit (referring to Fig. 4), and the tie point that the dividing potential drop V of coupling capacitor is inputed to D7 positive pole and D8 negative pole, through the amplitude limit of D7, the filtering of R18, C9, exports with signal VXH.
Fig. 8 is the schematic diagram of microcontroller circuit.Microcontroller circuit 105 comprises capacitor C 7, C8, resistance R 16, R17, transistor Q2 and microprocessor U3.Microcontroller circuit can be by realizations such as microprocessor, single-chip microcomputers.
When circuit generation singlephase earth fault, moment the frequency of occurrences be for example 300H
zto 4000H
zbetween the positive transition of transient current signal, if Δ I
p/ Δ t > R
h, circuit transient current mutation rate testing circuit 103 is exported transient current jump signal HXH, and this signal inputs to the pin one 3 of U3, causes that U3 enters ground fault interruption handling procedure.Then, U3 detects the line voltage signal V that C9 two ends input to pin 8 (VXH), through (1+C
r/ C
p) the formula Conversion Calculation of * V goes out electric line primary voltage, if V < is V
h, be judged to be singlephase earth fault and occur.Preset value V
hby U3, according to actual requirement, set.
When checkout equipment judges that singlephase earth fault occurs, in one embodiment, U3 pin one 2 output high level.If daytime, the conducting of Q2 two ends forms low-resistance, and at this moment the pin 5 (DAY) of U3 detects low level signal; If evening, Q2 cut-off is high-impedance state, and now U3 pin 5 detects high level signal, colour of sky state when U3 judges that according to this mode line fault occurs.If carry out mechanical board turning alarm mode daytime; If carry out luminous or sounding alarm mode evening.
Fig. 9 is the schematic diagram of warning circuit.Warning circuit 106 comprises luminous or phonation circuit 1061 and board turning driving circuit 1062.These 2 circuit can be by the above battery of 3V (can be comprised of or a plurality of battery is in series single battery) power supply, and also can through overcommutation, filtering, form working power by L1 induced signal is that warning circuit is powered.
Luminous or phonation circuit 1061 comprises resistance R 19, R20, diode D10, D11 and transistor Q3, and D11 is luminescent device or microphone device.
Board turning driving circuit 1062 comprises resistance R 21, R22, triode Q4, Q5, Q6, Q7, drive coil L2.Wherein, Q4, Q5, Q6, Q7 can be also the devices such as relay, field effect transistor, controllable silicon; L2 can and have mercy on and join end to end by bifilar enameled wire and form, the built-in permanent magnetic material of coil, so L2 is when the drive current, can realize positive and negative rotation magnetic field, wherein L2, Q4, Q5 provide forward field drives current path, and L2, Q6, Q7 provide reversed magnetic field drive current path.When U3 judges circuit generation earth fault, if daytime, U3 is by pin 6 output driving pulses, through R21, Q4, Q5, L2, form forward field drives electric current, if now mechanical board is the magnetic permanent magnetic material of diametrical magnetization, mechanical board is just rotated in the forward to send fault warning information; When U3 is when default reset time, counting finished, a driving pulse of pin 7 outputs of U3, forms reversed magnetic field drive current through R22, Q6, Q7, L2, now mechanical board reverse rotation and involution, and this fault warning finishes.
If evening, U3 pin one 2 output pulse strings drive Q3 to enter the lasting recurrent state of conducting, cut-off through R19, D10, and the current impulse that D11 is limited by R20 drives luminous or sounding.Luminous or tune can be a kind of in uninterrupted luminous or two kinds of patterns of light period flicker, until U3 just stops luminous or sounding default reset time when counting finishes.
Checkout equipment of the present invention can be battery-powered, and logical circuit can be battery-powered, and also can through overcommutation, filtering, form working power by L1 induced signal is that warning circuit is powered.
Obviously, the present invention described here can have many variations, and this variation can not be thought and departs from the spirit and scope of the present invention.Therefore, all changes that it will be apparent to those skilled in the art, within being all included in the covering scope of these claims.
Claims (6)
1. a detection method for electric line singlephase earth fault, is characterized in that, comprising:
(1) detection line transient current mutation rate, there is positive transition in transient current, transient current mutation rate △ I
p/ △ t > R
h, wherein, △ I
pbe the sudden change value of transient current, △ t is the mutation time of transient current, R
hit is the effective threshold values of judgement transient current mutation rate of presetting;
(2) detection line lower voltage, V < V
h, wherein, V is line voltage distribution, V
hit is the threshold values of the judgement voltage drop preset;
When two conditions all meet, judge singlephase earth fault; The order of step (1) and (2) can change;
Wherein transient current mutation rate is transient current root-mean-square value mutation rate, or the mutation rate of transient current effective value, or the mutation rate of the transient current signal of certain frequency or certain band frequency scope in transient current.
2. detection method as claimed in claim 1, wherein uses transient current Sudden Changing Rate △ I
p> I
hreplace △ I
p/ △ t > R
has the detection of singlephase earth fault according to one of, I wherein
hit is default transient current sudden change threshold values.
3. a checkout equipment for transmission and distribution line singlephase earth fault, comprising:
Circuit transient current mutation rate testing circuit (103), carries out bandpass filtering to line current, obtains the mutation rate information of circuit transient current outlet line transient current; Wherein transient current mutation rate is transient current root-mean-square value mutation rate, or the mutation rate of transient current effective value, or the mutation rate of the transient current signal of certain frequency or certain band frequency scope in transient current;
Line voltage distribution field coupled circuit (104), detects electric line voltage;
Microcontroller circuit (105), is configured for: judgement circuit transient current mutation rate signal, △ I
p/ △ t > R
h; Judgement line voltage distribution reduces, V < V
h; When two conditions all meet, judge short circuit grounding fault; Wherein, △ I
pbe the sudden change value of transient current, △ t is the mutation time of transient current, R
hbe the effective threshold values of judgement transient current mutation rate of presetting, V is line voltage distribution, V
hit is the threshold values of the judgement voltage drop preset.
4. checkout equipment as claimed in claim 3, follows the tracks of and conversion circuit (101) comprising line current, the AC signal providing based on line current, and circuit transient current mutation rate testing circuit (103) obtains circuit transient current according to AC signal.
5. checkout equipment as claimed in claim 3, wherein line voltage distribution field coupled circuit (104) comprises coupling capacitance and is formed on a distributed capacitance between circuit board public terminal GND and the earth, the position that wherein coupling capacitance contacts with electric line by the main body cover surface at checkout equipment is coated conductive material and is formed conductive layer, or assemble a conductive devices, thereby make to form between electric line and the common port of checkout equipment circuit board, and the partial pressure value based on coupling capacitance is calculated electric line voltage.
6. checkout equipment as claimed in claim 3, wherein microcontroller circuit (105) comprises microprocessor or single-chip microcomputer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110209114.3A CN102288866B (en) | 2011-07-25 | 2011-07-25 | Method and equipment for detecting single-phase earth fault of transmission and distribution line |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110209114.3A CN102288866B (en) | 2011-07-25 | 2011-07-25 | Method and equipment for detecting single-phase earth fault of transmission and distribution line |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN102288866A CN102288866A (en) | 2011-12-21 |
| CN102288866B true CN102288866B (en) | 2014-07-30 |
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ID=45335444
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201110209114.3A Expired - Fee Related CN102288866B (en) | 2011-07-25 | 2011-07-25 | Method and equipment for detecting single-phase earth fault of transmission and distribution line |
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| CN (1) | CN102288866B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102944804B (en) * | 2012-11-13 | 2015-03-11 | 航天科工深圳（集团）有限公司 | Overhead line fault detection system |
| CN104101812B (en) * | 2013-04-09 | 2017-02-22 | 北京映翰通网络技术股份有限公司 | Single-phase grounding fault detection and positioning method and system for low-current grounding power distribution network |
| CN105676059B (en) * | 2014-11-18 | 2019-01-29 | 德信东源电力技术服务（北京）有限公司 | Earth-fault detecting method and device |
| DE102016208960B3 (en) | 2016-05-24 | 2017-11-09 | Continental Automotive Gmbh | Monitoring device and method for monitoring a relative to a reference potential galvanically decoupled AC voltage source |
| CN106526280A (en) * | 2016-08-25 | 2017-03-22 | 北京电力经济技术研究院 | Testing method and separating method for railway power load impact transient process |
| CN109256762B (en) * | 2017-07-13 | 2021-10-22 | 许继集团有限公司 | Power distribution network single-phase fault current compensation control method, device and system |
| CN110350483B (en) | 2018-04-04 | 2022-03-08 | 台达电子工业股份有限公司 | Power converter device with ground fault detection function and fault detection method |
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| CN1144338A (en) * | 1995-08-28 | 1997-03-05 | 北京科锐创新电力技术有限公司 | Method for detecting short-circuit fault current path and indicator |
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|---|---|
| CN102288866A (en) | 2011-12-21 |
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Effective date of registration: 20140911 Address after: 100088, room 12, block B, 8, Xinjie street, No. 310, Xinjie, Beijing, Xicheng District Patentee after: De Xin Dongyuan County power technology service (Beijing) Co., Ltd Address before: 100088, Beijing, Xicheng District, 8 Xinjie street, Jin Feng, and business court, block B, room 316, room 3 Patentee before: He Jinzhang |
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| C56 | Change in the name or address of the patentee | ||
| CP01 | Change in the name or title of a patent holder |
Address after: 100088, room 12, block B, 8, Xinjie street, No. 310, Xinjie, Beijing, Xicheng District Patentee after: DEXINDONGYUAN INTELLIGENT TECHNOLOGY (BEIJING) CO., LTD. Address before: 100088, room 12, block B, 8, Xinjie street, No. 310, Xinjie, Beijing, Xicheng District Patentee before: De Xin Dongyuan County power technology service (Beijing) Co., Ltd |
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| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20140730 Termination date: 20170725 |