CN102788934B - Search method and the device of line-to-ground fault point - Google Patents
Search method and the device of line-to-ground fault point Download PDFInfo
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- CN102788934B CN102788934B CN201210258767.5A CN201210258767A CN102788934B CN 102788934 B CN102788934 B CN 102788934B CN 201210258767 A CN201210258767 A CN 201210258767A CN 102788934 B CN102788934 B CN 102788934B
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Abstract
The invention provides a kind of method of searching line-to-ground fault point, be grounded trouble spot search by sender unit and signal receiver, wherein said sender unit is used for that circuit to be measured is produced and sends current signal; Comprise the following steps: (a) described signal receiver produce one with the reference voltage signal of described transmission voltage signal same frequency; B () described signal receiver carries out reference point setting; C () described signal receiver calculates the correction phase am ' of transmission current signal relative to the reference point arranged of this Ka Cedianchu, and according to described correction phase am ', indicate this Ka Cedianchu to send the direction of current signal.The present invention also provides a kind of device of correspondence.The present invention by signal receiver produce one with the reference voltage signal sending voltage signal same frequency, to obtain the direction of the transmission current signal in circuit to be measured, the earth fault on circuit to be measured can be located accurately and rapidly.
Description
Technical field
The present invention relates to wireline inspection field, more particularly, relate to a kind of method and the device of searching line-to-ground fault point.
Background technology
When there is earth fault in circuit, needs are searched, fault point.Usual employing following methods is searched, fault point: exchanged or the voltage signal of direct current with sending between ground to circuit to be measured by a sender unit, due to the existence of line-to-ground resistance and distributed capacitance over the ground, circuit to be measured can produce and search current signal accordingly, use a signal receiver to search current signal along wireline inspection to be measured simultaneously, occur that the place of cataclysm is earth fault in the intensity or phase place of searching current signal.
Due to search current signal be from sender unit output terminal flow out, flow through circuit to be measured, finally flow out from earth fault, sender unit is flowed back to by ground, if therefore signal receiver can indicate and search sense of current, then along searching sense of current, earth fault can be found fast.By which, when searching the earth fault of complicated circuit network, work efficiency can significantly improve.
At present, when searching line-to-ground fault point, the method in the detection of leaks current signal direction usually adopted has following several:
(1) AC signal method: by sender unit to the voltage signal (reference signal) of alternation sending lower frequency between circuit to be measured and ground, namely produce in circuit to be measured and search current signal accordingly, this frequency of searching current signal is identical with voltage signal (reference signal), but phase place difference to some extent.Sender unit is simultaneously also by wired, wireless or sent the modulated signal of upper frequency after being modulated by reference signal and high-frequency signal by circuit to be measured self to signal receiver.Signal receiver detects along line trace to be checked and searches current signal, with receiving by wired, wireless or by circuit to be measured self, receive the modulated signal sent by sender unit, after reference signal is restored to its demodulation, compare with the phase place of the Leakage Current signal detected.If phase differential is close to 0 °, then signal receiver indicated direction is identical with searching current signal direction; If phase differential is close to 180 °, then signal receiver indicated direction is contrary with searching current signal direction.
The shortcoming of the method is, needs sender unit to be intercomed mutually by wired or wireless mode with signal receiver.When adopting wired mode to communicate, need special telecommunication cable to come connection signal transmitter and signal receiver, and search in earth fault point process, need telecommunication cable in tow to move around, extremely inconvenient; When adopting communication, sender unit and signal receiver may be positioned at different location, centre has the barriers such as wall and intercepts mutually, radio communication is often interrupted, and due to signal receiver be portable set, generally adopt powered battery, radio communication can cause power consumption significantly to increase, after battery is full of electricity, in use procedure, the electricity of battery storage exhausts very soon, and the working time of equipment is very limited.If utilize and looked into survey line road itself to transmit carrier signal, when there is larger undesired signal when Leakage Current is faint, on circuit, the carrier signal decay of upper frequency is very large, causes phase measurement error larger, be difficult to correctly indicate Leakage Current direction, cannot practical application be dropped into.
(2) direct current signaling: send d. c. voltage signal by sender unit to circuit to be measured and make circuit to be measured generation search current signal accordingly, then follow the tracks of reception along circuit to be measured by signal receiver and search current signal.Direct current signal itself is directive, and signal receiver utilizes the directivity of direct current signal, thus the direction of instruction Leakage Current.
The shortcoming of the method is: first, due to the zero point drift of acceptor circuit, be difficult to faint Leakage Current signal be detected, therefore when Leakage Current is faint, when there is larger undesired signal in circuit, metrical error is comparatively large, correctly cannot indicate the direction of Leakage Current.The second, the method is only suitable for the troubleshooting at not live line work circuit, when circuit live line work, because on circuit, itself has working current, cannot carry out troubleshooting.
(3) direct current signaling of zero compensation is with: the similar direct current signaling of the method, but sender unit produces low-frequency square-wave signal (searching signal), sender unit, signal receiver are by wired, wireless or communicated by circuit own pattern to be measured, when square-wave signal low level (namely no signal exports), manually or automatically by signal receiver zero setting, when square-wave signal high level, carry out the detection of searching signal.
Although the method can avoid the zero point drift of signal receiver circuit, but when circuit existing the undesired signal of complicated alternating current-direct current, the impact of undesired signal cannot be eliminated, thus when the undesired signal larger when Leakage Current is faint, on circuit, the method error is comparatively large, cannot correctly indicate the direction of searching current signal.In addition, the method also needs sender unit to be intercomed mutually by wired or wireless mode with signal receiver.When adopting wired mode to communicate, need special telecommunication cable to come connection signal transmitter and signal receiver, and search in earth fault point process, need telecommunication cable in tow to move around, extremely inconvenient; When adopting wireless communication mode mode, sender unit and signal receiver may be positioned at different location, centre has the barriers such as wall and intercepts mutually, radio communication can often be interrupted, and due to signal receiver be portable set, generally adopt powered battery, radio communication can cause power consumption significantly to increase, after battery is full of electricity, in use procedure, the electricity of battery storage can exhaust very soon, and the working time of equipment is very limited.Looked into survey line road itself to transmit carrier signal if utilize, when there is larger undesired signal when Leakage Current is faint, on circuit, the carrier signal decay of upper frequency is very large, cannot drop into practical application.
In sum, the method of searching earth fault and device of searching direction of current can be detected at present, use extremely inconvenient, be not easy to indicate the direction of searching current signal exactly, especially for searching searching of the very faint high resistance earthing fault point of electric current, and there is searching of the earth fault of stronger interference in scene.
Summary of the invention
The technical problem to be solved in the present invention is, cannot accurately indicate the problem of searching current signal direction in searching for above-mentioned earth fault, provides a kind of method and the device of searching line-to-ground fault point.
The technical scheme that the present invention solves the problems of the technologies described above is, a kind of method of searching line-to-ground fault point is provided, be grounded trouble spot by sender unit and signal receiver to search, it is that the transmission voltage signal of f0 is to make circuit to be measured generation transmission current signal that wherein said sender unit is used for applying frequency to circuit to be measured; Comprise the following steps:
(a) described signal receiver produce one with the reference voltage signal of described transmission voltage signal same frequency;
B () described signal receiver, according to the transmission current signal in described circuit to be measured and described reference voltage signal, carries out reference point setting;
C () described signal receiver carries out synchronized sampling to the transmission current signal of Ka Cedianchu, reference voltage signal, calculate the correction phase am ' of transmission current signal relative to the reference point arranged of this Ka Cedianchu, and according to described correction phase am ', indicate this Ka Cedianchu to send the direction of current signal.
Search in the method for line-to-ground fault point of the present invention, described signal receiver sends current signal direction by the direction signs be arranged on signal receiver and the direction signs shown on a display screen instruction, and described step (b) comprising:
(b1) described signal receiver synchronized sampling detects transmission current signal and the reference voltage signal of datum on circuit to be measured, described reference point for send in circuit to be measured current signal direction known a bit and the direction signs arranged on signal receiver described in this datum are identical with the direction sending current signal in described circuit to be measured;
(b2) described signal receiver calculates when receiving reference point setting instruction and stores the phase differential of described transmission current signal and reference voltage signal: Δ φ b=φ a0-φ b0, the wherein phase place of φ a0 to be the frequency that datum signal receiver receives the transmission current signal calculated when reference point arranges instruction the be signal content of f0, the phase place of φ b0 to be the frequency of corresponding reference voltage signal the be signal content of f0.
Search in the method for line-to-ground fault point of the present invention, also comprise in described step (b2): calculate when receiving reference point setting instruction the amplitude I0 that the frequency sending current signal is the signal content of f0, and store the reference value I b:Ib=I0 that this amplitude I0 is transmission current signal size.
Search in the method for line-to-ground fault point of the present invention, described step (c) comprises; The frequency calculating described Ka Cedianchu transmission current signal is the amplitude Im of the signal content of f0, and calculates the relative magnitude that this place sends current signal: Im '=Im/Ib × 100%.
Search in the method for line-to-ground fault point of the present invention, in described step (c), the correction phase am '=φ am-φ bm-Δ φ b at the transmission current signal relative datum point place of described Ka Cedianchu, wherein φ am is the phase place that Ka Cedianchu sends that the frequency of current signal is the signal content of f0, the phase place of φ bm to be the frequency of corresponding reference voltage signal the be signal content of f0.
Search in the method for line-to-ground fault point of the present invention, in described step (c): as-90 ° of < φ am ' < 90 °, it is " forward " that the display screen display of described signal receiver sends direction of current; When 90 °≤φ am '≤180 ° or-180 °≤φ am '≤-90 °, it is " oppositely " that the display screen display of described signal receiver sends direction of current.
Present invention also offers a kind of device searching line-to-ground fault point, comprise sender unit and signal receiver, it is that the transmission voltage signal of f0 is to make circuit to be measured generation transmission current signal that wherein said sender unit is used for applying frequency to circuit to be measured; Described signal receiver comprises signal generating unit, current detecting unit, analysis and processing unit, direction unit and reference point setting unit, wherein: described signal generating unit, for generation of a reference voltage signal with described transmission voltage signal same frequency; Described current detecting unit, for detecting the transmission current signal in circuit to be measured; Described analysis and processing unit, for carrying out synchronized sampling to described transmission current signal and reference voltage signal, and calculates the correction phase am ' sending current signal relative datum point place; Described direction unit, for indicating according to described correction phase am ' direction sending current signal in circuit to be measured; Described reference point setting unit, for carrying out reference point setting according to the transmission current signal in described circuit to be measured and described reference voltage signal.
Search in the device of line-to-ground fault point of the present invention, described direction unit comprises the direction signs be arranged on signal receiver and the direction signs shown on a display screen, described analysis and processing unit is also for the phase difference φ b=φ a0-φ b0 of the transmission current signal and reference voltage signal that calculate datum on circuit to be measured, the wherein phase place of φ a0 to be the frequency that datum signal receiver receives the transmission current signal calculated when reference point arranges instruction the be signal content of f0, the phase place of φ b0 to be the frequency of corresponding reference voltage signal the be signal content of f0, described reference point setting unit stores the phase difference φ b that described analysis and processing unit calculates transmission current signal and the reference voltage signal obtained when receiving and arranging instruction.
Search in the device of line-to-ground fault point of the present invention, it is the amplitude Im of the signal content of f0 and the relative magnitude Im ' relative to reference point that described analysis and processing unit also sends the frequency of current signal for computer card measuring point place, described reference point setting unit also for be stored in receive instruction is set time analysis and processing unit to calculate the amplitude I0 obtained be the reference value I b:Ib=I0 sending current signal size.
Search in the device of line-to-ground fault point of the present invention, the correction phase am '=φ am-φ bm-Δ φ b at described transmission current signal relative datum point place, wherein φ am is the phase place that Ka Cedianchu sends that the frequency of current signal is the signal content of f0, the phase place of φ bm to be the frequency of corresponding reference voltage signal the be signal content of f0; As-90 ° of < φ am ' < 90 °, it is " forward " that the display screen display of described signal receiver sends direction of current; When 90 °≤φ am '≤180 ° or-180 °≤φ am '≤-90 °, it is " oppositely " that the display screen display of described signal receiver sends direction of current.
The method and apparatus searching line-to-ground fault point of the present invention, by signal receiver inside generation one and the reference voltage signal sending voltage signal same frequency, and synchronized sampling, analysis are carried out to transmission current signal, reference voltage signal, determine the correction phase place relative to reference point of diverse location transmission current signal on circuit, direction and relative magnitude, thus determine the direction of the transmission current signal in circuit, to locate the earth fault on circuit to be measured accurately and rapidly.Especially, in the present invention, signal receiver only utilizes the phase relation of reference voltage signal circuit to be measured sending current signal and self produce, differentiate that on circuit to be measured, each position sends sense of current, thus quick position earth fault, and without the need to adopting any wired or wireless communication method to communicate with sender unit.
Accompanying drawing explanation
Fig. 1 is the schematic diagram that the present invention searches the application scenarios of line-to-ground fault point apparatus.
Fig. 2 is the schematic diagram of signal receiver embodiment in Fig. 1.
Fig. 3 is the schematic diagram of the transmission current signal at A, B, D 3 place in Fig. 1.
Fig. 4 is the schematic diagram of the phase place of the transmission current signal at A, B, C, D each point place in Fig. 1.
Fig. 5 is the schematic flow sheet that the present invention searches the embodiment of the method for line-to-ground fault point.
Embodiment
In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.
As shown in Figure 1, 2, the device searching line-to-ground fault point of the present invention comprises sender unit 1 and signal receiver 2, wherein sender unit 1 is by connecting line 3 to applying the transmission voltage signal (such as sine wave, square wave, triangular wave) that frequency is f0 between circuit to be measured and ground, produces send current signal (existence due to stake resistance and distributed capacitance) to make circuit to be measured.Particularly, the positive output end of above-mentioned sender unit 1 is connected to circuit to be measured, negative output terminal ground connection.Signal receiver 2 detects the transmission current signal on above-mentioned circuit to be measured, its inner generation one and the reference voltage signal sending voltage signal same frequency simultaneously, this signal receiver 2 is by carrying out synchronized sampling, analysis to transmission current signal, reference voltage signal, determine the phase place of diverse location transmission current signal on circuit to be measured, direction and amplitude, thus locate the earth fault on circuit to be measured accurately and rapidly.
Signal receiver 2 comprises signal generating unit 21, current detecting unit 22, analysis and processing unit 23, direction unit 25 and reference point setting unit 24.Above-mentioned signal generating unit 21, current detecting unit 22, analysis and processing unit 23, direction unit 25 and reference point setting unit 24 can be realized by hardware, software or its combination.
Signal generating unit 21 is for generation of a reference voltage signal with the transmission voltage signal same frequency of sender unit 1.
Current detecting unit 22 is for the transmission current signal in the circuit to be measured at test card measuring point place.Particularly, this current detecting unit 22 comprises the current sensor that has pincerlike opening, to may be stuck on circuit to be measured and to obtain the current signal in circuit to be measured by way of electromagnetic induction.When specific implementation, namely the above-mentioned current sensor with pincerlike opening can be connected with other parts of signal receiver 2 by connecting line, also can be fixed on signal receiver 2.
Analysis and processing unit 23 carries out synchronized sampling for the transmission current signal that obtains current detecting unit 22 and reference voltage signal, and the correction phase am ' at the transmission current signal relative datum point place at computer card measuring point place and relative magnitude Im '.Particularly, the transmission current signal of this analysis and processing unit 23 pairs of synchronized samplings and reference voltage signal, adopt respectively and pay sharp leaf algorithm, calculate the phase am that the frequency sending current signal is the signal content of f0, the frequency calculating reference voltage signal is the phase bm of the signal content of f0, and the datum of storage sends the phase difference φ b of current signal and reference voltage signal, and calculate the correction phase place of transmission current signal now accordingly: φ am '=φ am-φ bm-Δ φ b.
Reference point setting unit 24 is for carrying out reference point setting according to the transmission current signal in circuit to be measured and described reference voltage signal.Particularly, the parameter that this reference point setting unit 24 is receiving analysis and processing unit 23 calculating acquisition when reference point arranges instruction (such as specific button is pressed) stores, above-mentioned parameter comprises the phase difference φ b that datum sends current signal and reference voltage signal, and datum sends the reference value I b of current signal size, and in this, as reference point parameter.
Direction unit 25 indicates this Ka Cedianchu to send the direction of current signal for calculating the correction phase am ' obtained according to analysis and processing unit 23.Particularly, above-mentioned direction unit 25 comprises the direction signs (such as direction arrow etc.) being arranged on (such as side) on the current sensor with pincerlike opening of signal receiver 2 and the direction signs shown on a display screen (such as " forward ", " oppositely ", direction arrow etc.), wherein, the method of the direction signs display of display screen display is: as-90 ° of < φ am ' < 90 °, be shown as " forward ", represent that the direction of the transmission current signal of Ka Cedianchu is identical with the direction signs that signal receiver is arranged, when 90 °≤φ am '≤180 ° or-180 °≤φ am '≤-90 °, be shown as " oppositely ", represent that the transmission current signal of Ka Cedianchu is contrary with the direction signs that signal receiver is arranged.
When the current sensor with pincerlike opening is fixed on signal receiver 2, above-mentioned direction unit 25 can only export with transmission current signal actual flow to consistent direction signs to display screen, and identifies without the need to the shell setting direction at signal receiver.
Use signal receiver 2 carry out reference point arrange time, can select to send in circuit to be measured that direction of current determines a bit as reference point, such as, E point in Fig. 1 is (near the junction of sender unit 1 with circuit to be measured, other parts by E point sensing circuit to be measured of transmission direction of current herein can be determined), or the positive output line of sender unit (can determine that transmission direction of current is herein point to circuit to be measured by sender unit 1).After selected reference point, make the direction signs of the direction unit 25 of signal receiver 2 identical with transmission current signal direction, now analysis and processing unit 23 calculates the phase differential of transmission current signal now and reference voltage signal, when receiving reference point and arranging instruction (such as specific button is pressed), reference point setting unit 24 inventory analysis processing unit 23 calculates the phase differential of transmission current signal and the reference voltage signal obtained: Δ φ b=φ a0-φ b0, the wherein phase place of φ a0 to be the frequency of the transmission current signal of datum the be signal content of f0, the phase place of φ b0 to be the frequency of corresponding reference voltage signal the be signal content of f0.
Above-mentioned analysis and processing unit 23 also can calculate the amplitude Im that the frequency sending current signal is the signal content of f0, and calculates the relative magnitude that this place sends current signal: Im '=Im/Ib × 100%.And reference point setting unit 24 is also stored in the reference value I b:Ib=I0 that the amplitude I0 receiving analysis and processing unit 23 calculating acquisition when arranging instruction is transmission current signal size.
As shown in Figure 1, with earth fault C in circuit to be measured, trouble spot stake resistance is R, and the distributed capacitance over the ground of both sides, trouble spot circuit is equivalent to C respectively
1, C
2.First by sender unit 1 to applying sinusoidal wave voltage signal between circuit to be measured and ground: u
0(t)=U
0* sin (2 π f
0t), due to the existence of line-to-ground resistance and distributed capacitance, produce and sinusoidal wavely send current signal: i
am(t)=Iamsin (2 π f
0t+ φ am).
At circuit each point place to be measured, the amplitude Iam sending current signal is different with phase am, as shown in Figure 3: at the A point of circuit to be measured, sends current signal I
a=I
c1+ I
c2+ I
r, phase place sends voltage signal φ in advance
aangle.At the B point of circuit to be measured, send current signal I
b=I
c2+ I
r, phase place sends voltage signal φ in advance
bangle.At the D point of circuit to be measured, send current signal I
c=I
c2, phase place sends voltage signal φ in advance
dangle.
In fact, the distributed capacitance over the ground of circuit is all exist in whole circuit, the change of current signal phase place is sent as shown in Figure 4 in actual track, Fig. 4 (b) sends current signal amplitude situation of change along circuit to be measured, Fig. 4 (c) sends current signal phase place situation of change along circuit to be measured, in Fig. 4 (c), the phase place sending current signal is all send current signal for benchmark with reference point E place, numerical value is for just to represent advanced, and numerical value is that negative indication is delayed.
Signal receiver 2 is not owing to communicating with sender unit 1, and therefore signal receiver 2 cannot know the phase place sending voltage signal.Invention introduces the concept of " the correction phase place " of " reference point " and transmission current signal, the correction phase place of the transmission current signal of " reference point " is 0 °, and on circuit to be measured, the correction phase place of the transmission current signal of other each point is all the relative phase of the transmission current signal relative to " reference point ".
Signal receiver 2 presses signal by the inner electric reference with sending voltage signal same frequency that is that generate: u
b(t)=U
b* sin (2 π f
0t+ φ b), as reference point and the foundation revising phase calculation.
Using method of searching the device of line-to-ground fault point of the present invention is below described.
First the positive output end of sender unit 1 is connected to circuit to be measured, negative output terminal ground connection, to applying the transmission voltage signal that frequency is f0 between circuit to be measured and ground.
Signal receiver produce one with the reference voltage signal sending voltage signal same frequency.
Signal receiver 2 is stuck on signal positive output line, using this card measuring point as " reference point ", makes the direction signs on signal receiver 2 side identical with the direction that transmission current signal flows out on signal positive output line; Signal receiver 2 carries out synchronized sampling to transmission current signal, reference voltage signal, adopt and pay sharp leaf algorithm, calculate amplitude I0, phase a0 that the frequency sending current signal is the signal content of f0 respectively, the frequency calculating reference voltage signal is the phase b0 of the signal content of f0.
Press " reference settings " button on signal receiver 2, using the card measuring point of now signal receiver as the reference point sending current signal, calculate and store the transmission current signal of datum and the phase differential of reference voltage signal: Δ φ b=φ a0-φ b0; Calculate the amplitude I0 that the frequency sending current signal is the signal content of f0, and store the reference value I b:Ib=I0 that this amplitude I0 is transmission current signal size.
Complete after reference point arranges, can block survey any point on circuit to be measured transmission current signal relative to the correction phase am ' of reference point, with according to described correction phase am ', indicate this Ka Cedianchu to send the direction of current signal; The frequency calculating this Ka Cedianchu transmission current signal is the relative magnitude of the signal content of f0: Im '=Im/Ib × 100%.
Complete after reference point arranges, survey if carry out card at reference point, then can obtain following result: send current signal correction phase am '=0, it be " forward " that display screen display sends direction of current, relative magnitude Im '=100% of transmission current signal.
Again signal receiver 2 is stuck in any point on circuit to be measured, signal receiver 2 carries out synchronized sampling to the transmission current signal at this place, reference voltage signal, adopt and pay sharp leaf algorithm, calculate amplitude Im, phase am that the frequency sending current signal is the signal content of f0 respectively, the frequency of reference voltage signal is f
0the phase bm of signal content, and calculate the correction phase place that this Ka Cedianchu sends current signal: φ am '=φ am-φ bm-Δ φ b.Synchronous signal receiver 2 also can calculate the relative magnitude that this Ka Cedianchu sends current signal: Im '=Im/Ib × 100%.
This Ka Cedianchu of further judgement sends the direction of current signal: when-90 °≤φ am '≤90 °, and the direction that display sends current signal is " forward ", represents that the direction sending current signal is identical with the direction signs that signal receiver 2 is arranged; When 90 °≤φ am '≤180 ° or-180 °≤φ am '≤-90 °, the direction that display sends current signal be " oppositely ", and the direction of expression transmission current signal is contrary with the direction signs that signal receiver 2 is arranged.
Because transmission current signal flows out from the positive output end of sender unit 1, flow through circuit to be measured, finally flow out from the earth fault of circuit to be measured, sender unit 1 is flowed back to again by ground, if therefore signal receiver 2 can indicate the direction sending current signal, then along the direction sending current signal, pointwise card volume, can find earth fault fast.
After circuit to be measured detects the correction phase am ' of transmission current signal signal, direction and relative magnitude Im ', according to circuit and knowledge, earth fault can be determined easily:
Single-wire line: as shown in Figure 1, Figure 3, along the direction sending current signal, at front and back (B, D 2 point on circuit to be measured in as Fig. 1, Fig. 3 of the earth fault C of circuit to be measured, the relative magnitude (i.e. Im ') sending current signal can diminish suddenly, the correction phase place simultaneously sending current signal is at earth fault the most negative (in as Fig. 3 on circuit to be measured C point), after earth fault (as D point on circuit to be measured in Fig. 3), the correction phase place sending current signal can rise suddenly, according to this feature, can accurate positioning both ground trouble spot.
Complicated circuit network: judge according to following features: sending current signal must be flow out from sender unit 1 output terminal, flow through circuit to be measured, finally flow out from earth fault, sender unit 1 is flowed back to again by ground, further, the correction phase place sending current signal is the most negative in earth fault.Therefore, when running into branched line, should continue to look into and surveying the branch road that the relative magnitude sending current signal correction phase place that is maximum, that send current signal is the most negative, send current signal outflow, after branch road is determined, look into survey method again according to single-wire line, finally determine earth fault.
As shown in Figure 5, the present invention also provides a kind of method of searching line-to-ground fault point, it is grounded trouble spot by sender unit and signal receiver and searches, and wherein sender unit is used for applying frequency to circuit to be measured is that the transmission voltage signal of f0 is to make circuit to be measured generation transmission current signal.The method comprises the following steps:
Step S51: signal receiver produce one with the reference voltage signal sending voltage signal same frequency.
Step S52: carry out reference point setting at the transmission current signal of datum and reference voltage signal according in circuit to be measured.
Step S53: signal receiver treats the transmission current signal of each Ka Cedianchu on survey line road, reference voltage signal carries out synchronized sampling, the correction phase am ' at the transmission current signal relative datum point place at computer card measuring point place and relative magnitude Im ', and indicate this Ka Cedianchu to send the direction of current signal according to revising phase am '.
In the above-mentioned methods, signal receiver is provided with direction signs, show direction signs on a display screen, and step S52 can specifically comprise: when signal receiver receives reference point setting instruction synchronized sampling detect datum on circuit to be measured transmission current signal and reference voltage signal after, calculate and store the phase differential sending current signal and reference voltage signal: Δ φ b=φ a0-φ b0, wherein φ a0 sends the phase place that the frequency of current signal is the signal content of f0, the phase place of φ b0 to be the frequency of reference voltage signal the be signal content of f0.
Especially, when reference point is arranged, signal receiver also can calculate the amplitude I0 that the frequency sending current signal is the signal content of f0, and stores the reference value I b:Ib=I0 that this amplitude I0 is transmission current signal size.Correspondingly, at Ka Cedianchu, signal receiver also calculates this Ka Cedianchu and sends the amplitude Im that the frequency of current signal is the signal content of f0, and calculates this place and send the relative magnitude of current signal relative to datum: Im '=Im/Ib × 100%.
Search in the method for line-to-ground fault point above-mentioned, the correction phase am '=φ am-φ bm-Δ φ b at the transmission current signal relative datum point place of Ka Cedianchu on circuit to be measured in step S53, wherein φ am sends the phase place that the frequency of current signal is the signal content of f0, the phase place of φ bm to be the frequency of reference voltage signal the be signal content of f0.Especially, as-90 ° of < φ am ' < 90 °, it is " forward " that the display screen display of described signal receiver sends direction of current, represents that the direction of the transmission current signal of this Ka Cedianchu is identical with the direction signs that signal receiver is arranged; When 90 °≤φ am '≤180 ° or-180 °≤φ am '≤-90 °, it is " oppositely " that the display screen display of described signal receiver sends direction of current, represents that the direction of the transmission current signal of this Ka Cedianchu is contrary with the direction signs that signal receiver is arranged.
The above; be only the present invention's preferably embodiment, but protection scope of the present invention is not limited thereto, is anyly familiar with those skilled in the art in the technical scope that the present invention discloses; the change that can expect easily or replacement, all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain of claim.
Claims (10)
1. search the method for line-to-ground fault point for one kind, be grounded trouble spot by sender unit and signal receiver to search, it is that the transmission voltage signal of f0 is to make circuit to be measured generation transmission current signal that wherein said sender unit is used for applying frequency to circuit to be measured; It is characterized in that: comprise the following steps:
(a) described signal receiver produce one with the reference voltage signal of described transmission voltage signal same frequency;
B () described signal receiver, according to the transmission current signal in described circuit to be measured and described reference voltage signal, carries out reference point setting;
C () described signal receiver carries out synchronized sampling to the transmission current signal of Ka Cedianchu, reference voltage signal, calculate the correction phase am ' of transmission current signal relative to the reference point arranged of this Ka Cedianchu, and according to described correction phase am ', indicate this Ka Cedianchu to send the direction of current signal.
2. method of searching line-to-ground fault point according to claim 1, it is characterized in that: described signal receiver sends current signal direction by the direction signs be arranged on signal receiver and the direction signs shown on a display screen instruction, and described step (b) comprising:
(b1) described signal receiver synchronized sampling detects transmission current signal and the reference voltage signal of datum on circuit to be measured, described reference point for send in circuit to be measured current signal direction known a bit and the direction signs arranged on signal receiver described in this datum are identical with the direction sending current signal in described circuit to be measured;
(b2) described signal receiver calculates when receiving reference point setting instruction and stores the phase differential of described transmission current signal and reference voltage signal: Δ φ b=φ a0-φ b0, the wherein phase place of φ a0 to be the frequency that datum signal receiver receives the transmission current signal calculated when reference point arranges instruction the be signal content of f0, the phase place of φ b0 to be the frequency of corresponding reference voltage signal the be signal content of f0.
3. method of searching line-to-ground fault point according to claim 2, it is characterized in that: also comprise in described step (b2): calculate when receiving reference point setting instruction the amplitude I0 that the frequency sending current signal is the signal content of f0, and store the reference value I b:Ib=I0 that this amplitude I0 is transmission current signal size.
4. method of searching line-to-ground fault point according to claim 3, is characterized in that: described step (c) comprises; The frequency calculating described Ka Cedianchu transmission current signal is the amplitude Im of the signal content of f0, and calculates the relative magnitude that this place sends current signal: Im '=Im/Ib × 100%.
5. method of searching line-to-ground fault point according to claim 2, it is characterized in that: in described step (c), the correction phase am '=φ am-φ bm-Δ φ b at the transmission current signal relative datum point place of described Ka Cedianchu, wherein φ am is the phase place that Ka Cedianchu sends that the frequency of current signal is the signal content of f0, the phase place of φ bm to be the frequency of corresponding reference voltage signal the be signal content of f0.
6. method of searching line-to-ground fault point according to claim 5, it is characterized in that: in described step (c): as-90 ° of < φ am ' < 90 °, it is " forward " that the display screen display of described signal receiver sends direction of current; When 90 °≤φ am '≤180 ° or-180 °≤φ am '≤-90 °, it is " oppositely " that the display screen display of described signal receiver sends direction of current.
7. search a device for line-to-ground fault point, comprise sender unit and signal receiver, it is that the transmission voltage signal of f0 is to make circuit to be measured generation transmission current signal that wherein said sender unit is used for applying frequency to circuit to be measured; It is characterized in that: described signal receiver comprises signal generating unit, current detecting unit, analysis and processing unit, direction unit and reference point setting unit, wherein: described signal generating unit, for generation of a reference voltage signal with described transmission voltage signal same frequency; Described current detecting unit, for detecting the transmission current signal in circuit to be measured; Described analysis and processing unit, for carrying out synchronized sampling to described transmission current signal and reference voltage signal, and calculates the correction phase am ' sending current signal relative datum point place; Described direction unit, for indicating according to described correction phase am ' direction sending current signal in circuit to be measured; Described reference point setting unit, for carrying out reference point setting according to the transmission current signal in described circuit to be measured and described reference voltage signal.
8. the device searching line-to-ground fault point according to claim 7, it is characterized in that: described direction unit comprises the direction signs be arranged on signal receiver and the direction signs shown on a display screen, described analysis and processing unit is also for the phase difference φ b=φ a0-φ b0 of the transmission current signal and reference voltage signal that calculate datum on circuit to be measured, the wherein phase place of φ a0 to be the frequency that datum signal receiver receives the transmission current signal calculated when reference point arranges instruction the be signal content of f0, the phase place of φ b0 to be the frequency of corresponding reference voltage signal the be signal content of f0, described reference point setting unit stores the phase difference φ b that described analysis and processing unit calculates transmission current signal and the reference voltage signal obtained when receiving and arranging instruction.
9. the device searching line-to-ground fault point according to claim 8, it is characterized in that: it is the amplitude Im of the signal content of f0 and the relative magnitude Im ' relative to reference point that described analysis and processing unit also sends the frequency of current signal for computer card measuring point place, described reference point setting unit also for be stored in receive instruction is set time analysis and processing unit to calculate the amplitude I0 obtained be the reference value I b:Ib=I0 sending current signal size.
10. the device searching line-to-ground fault point according to claim 8, it is characterized in that: the correction phase am '=φ am-φ bm-Δ φ b at described transmission current signal relative datum point place, wherein φ am Ka Cedianchu sends the phase place that the frequency of current signal is the signal content of f0, the phase place of φ bm to be the frequency of corresponding reference voltage signal the be signal content of f0; As-90 ° of < φ am ' < 90 °, it is " forward " that the display screen display of described signal receiver sends direction of current; When 90 °≤φ am '≤180 ° or-180 °≤φ am '≤-90 °, it is " oppositely " that the display screen display of described signal receiver sends direction of current.
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| CN201210258767.5A CN102788934B (en) | 2012-07-25 | 2012-07-25 | Search method and the device of line-to-ground fault point |
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| CN201210258767.5A CN102788934B (en) | 2012-07-25 | 2012-07-25 | Search method and the device of line-to-ground fault point |
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| CN104076249A (en) * | 2014-07-15 | 2014-10-01 | 国家电网公司 | Three-phase three-winding transformer one-phase ground fault coverage diagnostic method |
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