CN102323527B - Power transformer partial discharge detection system and method based on fiber bragg grating - Google Patents

Power transformer partial discharge detection system and method based on fiber bragg grating Download PDF

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Publication number
CN102323527B
CN102323527B CN 201110266331 CN201110266331A CN102323527B CN 102323527 B CN102323527 B CN 102323527B CN 201110266331 CN201110266331 CN 201110266331 CN 201110266331 A CN201110266331 A CN 201110266331A CN 102323527 B CN102323527 B CN 102323527B
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fiber
bragg grating
fiber coupler
fiber bragg
mouth
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CN 201110266331
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Chinese (zh)
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CN102323527A (en
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魏鹏
刘奇
孙志平
李成贵
屈玉福
涂万里
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北京航空航天大学
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Abstract

The invention discloses a power transformer partial discharge detection system based on a fiber bragg grating, which comprises an LD (Lead Detector) pumping source, a wavelength multiplexer, an erbium doped fiber, an isolator, a first fiber coupler, a second fiber coupler, a first fiber bragg grating, a second fiber bragg grating, a photoelectric detector, an acoustic emission collection card and a computer, wherein two input ends of the LD pumping source, the wavelength multiplexer, the erbium doped fiber and the first fiber coupler are in the same loop to form an annular cavity erbium doped fiber laser; one output end of the first fiber coupler is connected with the first fiber bragg grating, the other output end of the first fiber bragg grating is connected with one input end of the second fiber coupler; one output end of the second fiber coupler is connected with the second fiber bragg grating, the other input end of the second fiber coupler is connected with the photoelectric detector; and the photoelectric detector is connected with the computer through the acoustic emission collection card. The power transformer partial discharge detection system is used for carrying out in service real time and continuous monitoring on a transformer, and has the advantages of strong anti-electromagnetic interference capacity, small temperature influence, high detection precision and good flexibility.

Description

Partial Discharge in Power Transformer detection system and detection method based on Fiber Bragg Grating FBG
Technical field
The present invention relates to a kind of Partial Discharge in Power Transformer detection system and detection method based on Fiber Bragg Grating FBG, belong to the acoustic emission technical field of nondestructive testing.
Background technology
Large-scale power transformer is one of visual plant of electric system, is the nucleus equipment of transformer station, and its operation conditions direct relation the safety and economic operation of electric system.Along with the development of electric system and the raising of electric pressure, shelf depreciation (Partial Discharge, be called for short PD) become electric power transformer insulated deteriorated one of the main reasons, thereby the detection of shelf depreciation also just becomes the important means of transformer insulated condition detection with evaluation.During the inner generation of operating power transformer shelf depreciation, the size of its partial discharge quantity has reflected the situation of insulation defect to a certain extent, the power of discharge power has reflected the power of insulation ag(e)ing Process Energy conversion, and speed and the degree of insulation ag(e)ing reflected at discharge time and discharge interval.When the part discharge developed into the serious stage, solid insulating material and oil decomposed rapidly, cause whole insulation breakdown, therefore detected the degree of shelf depreciation and can know insulation status.
Transformer in the shelf depreciation process, the phenomenons such as the pulse current that invariably accompanies, electromagnetic radiation and sound, light, heat.The method of utilizing in recent years the acoustic emission signal that produces in the shelf depreciation process that it is judged and locating more and more causes people's attention.This is because when in medium, shelf depreciation occuring, because the fierceness of molecule is clashed into, and the formation and development of bubble, the small cracking of the mobile and solid material of liquid can produce certain acoustic emission signal.Find by research, these acoustical signals that shelf depreciation produces and degree and the type of shelf depreciation have certain corresponding relation, so can monitor shelf depreciation with the acoustic emission detection means, thereby obtain the health status of power transformer.
The problems such as existing Chinese patent 200510000496.3 " method for measurement of partial discharge and device thereof " is directly measured the electric impulse signal of shelf depreciation, and the quantity of information that have poor anti jamming capability, survey frequency is low, frequency band is narrow, comprises is few; Chinese patent CN201010023128.1 " Partial Discharge in Power Transformer detects and positioning system online ", 200920102761.2 " a kind of be applicable to the ultrasonic planar array sensor that partial discharge of transformer detects " use be all ultrasonic Detection Method, the sensitivity of ultrasonic sensor is relatively poor, and the scene detects signal effectively again; Chinese patent 200820152381.5 " local discharge of gas-insulator switchgear detection system " has integrated ultrahigh frequency and has detected and acoustic emission testing technology, detection efficiency is high, but calibrate AE sensor used is traditional piezoelectric transducer, and volume is large, is subject to the impact of electromagnetic interference (EMI).
Summary of the invention
The object of the invention is to, overcome existing technology limitation, a kind of Partial Discharge in Power Transformer detection system and detection method based on Fiber Bragg Grating FBG is provided, can carry out in-service real-time and continuous monitoring to transformer, anti-electromagnetic interference capability is strong, temperature influence is little, and accuracy of detection is high, and dirigibility is good.
Technical scheme of the present invention: the Partial Discharge in Power Transformer detection system based on Fiber Bragg Grating FBG comprises: LD pumping source, wavelength division multiplexer, erbium-doped fiber, isolator, the first fiber coupler, the second fiber coupler, the first Fiber Bragg Grating FBG, the second Fiber Bragg Grating FBG, photodetector, acoustic emission capture card and computing machine; Two input end A mouths of LD pumping source, wavelength division multiplexer, erbium-doped fiber, isolator, the first fiber coupler and B mouth form Erbium-doped-fiber Ring Laser in the same circuit; An output terminal C mouth of the first fiber coupler connects the first Fiber Bragg Grating FBG, and another output terminal D mouth of the first fiber coupler connects an input end E mouth of the second fiber coupler; An output terminal G mouth of the second fiber coupler connects the second Fiber Bragg Grating FBG, and another input end F mouth of the second fiber coupler connects photodetector; Photodetector is connected with computing machine by the acoustic emission capture card.
The light that the LD pumping source sends will be introduced erbium-doped fiber through wavelength division multiplexer; After bait Ions Absorption energy in erbium-doped fiber, population inversion occurs, and then produce amplified spont-aneous emission, light signal is exaggerated; Be transferred on the first fiber coupler by isolator again; Most light is through the output of another output terminal D of the first fiber coupler mouth, and the light of fraction is after an output terminal C mouth of the first fiber coupler is reflected by the first Fiber Bragg Grating FBG, in the feedback light return loop; The laser of narrowband of another output terminal D mouth output of the first fiber coupler, enter input end E mouth of the second fiber coupler as input, an output terminal G mouth from the second fiber coupler arrives the second Fiber Bragg Grating FBG again, the light that meets centre wavelength is got back to another input end F mouth outgoing of the second fiber coupler, enters photodetector; After photodetector was converted into electric signal with light signal, input acoustic emission capture card carried out analysis-by-synthesis and the processing of signal in the acoustic emission capture card, shown in computing machine at last.
The centre wavelength of described LD pumping source is 980nm, output power 〉=180mW, and the Output optical power long-term stability is ± 0.01dB.
The operation wavelength of described wavelength division multiplexer is 980nm or 1550nm, and isolation characteristic is 29.6dB.
The splitting ratio of described the first fiber coupler is 90: 10, and the splitting ratio of the second fiber coupler is 50: 50.
Described the first Fiber Bragg Grating FBG is as the wave filter of annular erbium-doped fiber laser instrument, and the second Fiber Bragg Grating FBG is as the sensor of acoustic emission detection system; The parameters such as the reflectivity of the first and second Fiber Bragg Grating FBGs, side mode suppression ratio, three dB bandwidth, temperature control coefficient are basically identical, and centre wavelength differs 0.1nm; During Site Detection, the first and second Fiber Bragg Grating FBGs should be positioned in the same temperature environment.
The centre wavelength 1550nm of described the second Fiber Bragg Grating FBG, reflectivity>90%, three dB bandwidth<0.20nm.
The present invention's advantage compared with prior art is: existing Partial Discharge in Power Transformer ultrasonic sensor sensibility is poor, be subject to again the impact of electromagnetic interference (EMI) based on the piezoceramic transducer of acoustic emission principle, and the present invention introduces Fiber Bragg Grating FBG voice sending sensor technology the detection of the local voltage of power transformer, highly sensitive, anti-electronic interferences ability is strong, volume is little, and dirigibility is good; The present invention adopts the double grating method, filtering FBG and sensing FBG are placed in the same temperature environment, and their centre wavelength variation with temperature is with the skew of rhythm, and this just greatly reduces power transformer variation of ambient temperature on every side to the impact of acoustic emission detection, precision is high, and signal to noise ratio (S/N ratio) is high.
Description of drawings
Fig. 1 is structured flowchart of the present invention.
In figure: 1, LD pumping source, 2, wavelength division multiplexer (WDM), 3, erbium-doped fiber (EDF), 4, isolator (ISO), the 5, first fiber coupler, 6, the first Fiber Bragg Grating FBG (FBG), 7, the second Fiber Bragg Grating FBG (FBG), the 8, second fiber coupler, 9, photodetector, 10, acoustic emission capture card, 11, computing machine.
Embodiment
As shown in Figure 1, Partial Discharge in Power Transformer detection system based on Fiber Bragg Grating FBG of the present invention comprises: LD pumping source 1, wavelength division multiplexer (WDM) 2, erbium-doped fiber (EDF) 3, isolator (ISO) 4, first, second fiber coupler 5,8, first, second Fiber Bragg Grating FBG (FBG) 6,7, photodetector 9, acoustic emission capture card 10, computing machine 11; Wherein, LD pumping source 1, WDM 2, EDF 3, ISO 4, the first fiber coupler 5 form Erbium-doped-fiber Ring Laser in the same circuit; The A mouth of the first fiber coupler 5 and B mouth are in above-mentioned loop; The C mouth of the first coupling mechanism 5 connects the D mouth of FBG 6, the first fiber couplers 5, connects the E mouth of the second fiber coupler 8; The G mouth of the second fiber coupler 8 connects the F mouth of the 2nd FBG 7, the second fiber couplers 8, connects photodetector 9; Photodetector 9 is connected with computing machine 11 with acoustic emission capture card 10 more successively.
The light that LD pumping source 1 sends will be introduced EDF 3 through WDM 2, after bait Ions Absorption energy in optical fiber, population inversion occurs, and then generation amplified spont-aneous emission, light signal is exaggerated, be transferred on the first fiber coupler 5 by isolator 4 again, 90% light is through the output of D mouth, and 10% light is after the C mouth is by FBG 6 reflections, in the feedback light return loop.Transmit in the chamber clockwise on the feedback light edge, then be coupled into EDF3 through WDM 2, completes once circulation.In cyclic process, the energy of light wave all is amplified each time, when gaining greater than the loss in the loop, produces vibration, thereby forms annular erbium-doped fiber laser instrument.
The laser of narrowband of the D mouth output of the first fiber coupler 5 enters the E mouth of the second fiber coupler 8, then arrives the 2nd FBG 7 from the G mouth as input, the light that meets centre wavelength is got back to the second fiber coupler 8 afterwards from the outgoing of F mouth, enters photodetector 9.After photodetector 9 was converted into electric signal with light signal, input acoustic emission capture card 10 carried out analysis-by-synthesis and the processing of signal in acoustic emission capture card 11, shown in computing machine 11 at last.
Pump light source can provide energy for the bait ion in erbium-doped fiber, and population inversion occurs.The selection of pumping source is very crucial, and it directly affects the output performance of fiber laser, requires pumping source that stable energy and long service life can be provided.The 980nm laser diode has the advantages such as noise is low, pumping efficiency is high, drive current is little, flat gain is good, therefore selected by the present embodiment.Its output power 〉=180mW, the Output optical power long-term stability is ± 0.01dB.
Fiber coupler is a kind of optical passive component, is to connect two or multifiber, the light signal that transmits in optical fiber is coupled in special coupled zone, and carries out the components and parts of power or Wavelength Assignment.Mainly contain at present fused biconical taper legal system single-mode optical-fibre coupler, it is that the optical fiber that two (or more than two) remove coat is drawn close with certain method, melting under high-temperature heating simultaneously to two side stretchings, finally forms the special Wave guide structure of bicone form in the heating zone.The splitting ratio of described the first fiber coupler is 90: 10, and the splitting ratio of the second fiber coupler is 50: 50.
Optoisolator can make flashlight can only transmit along positive dirction in optical fiber circuit, can prevent effectively that like this retroreflection and scattering process from affecting the output stability of laser instrument.Its selection index is that insertion loss is low, isolation is better than 40dB.
Wavelength division multiplexer is to improve transport information capacity, the device that the pump light of the flashlight of input and pump light source output is mixed.In this fact Example, the operation wavelength of wavelength division multiplexer used is 980nm or 1550nm, and isolation characteristic is 29.6dB.
A described FBG is as the wave filter of annular erbium-doped fiber laser instrument, and the 2nd FBG is as the sensor of acoustic emission detection system; On device was selected, it is basically identical that the one the second FBG will choose the parameters such as reflectivity, side mode suppression ratio, three dB bandwidth, temperature control coefficient, and centre wavelength differs the Fiber Bragg Grating FBG of 0.1nm left and right; When detecting at the scene, the one the second FBG are positioned in the same temperature environment, their centre wavelength are equivalently changed in the same way along with the drift of scene temperature, thereby eliminate temperature factor to the impact of system's detection accuracy.

Claims (4)

1. the Partial Discharge in Power Transformer detection system based on Fiber Bragg Grating FBG, is characterized in that comprising: LD pumping source (1), wavelength division multiplexer (2), erbium-doped fiber (3), isolator (4), the first fiber coupler (5), the second fiber coupler (8), the first Fiber Bragg Grating FBG (6), the second Fiber Bragg Grating FBG (7), photodetector (9), acoustic emission capture card (10) and computing machine (11); Two input end A mouths of LD pumping source (1), wavelength division multiplexer (2), erbium-doped fiber (3), isolator (4), the first fiber coupler (5) and B mouth form Erbium-doped-fiber Ring Laser in the same circuit; An output terminal C mouth of the first fiber coupler (5) connects the first Fiber Bragg Grating FBG (6), and another output terminal D mouth of the first fiber coupler (5) connects an input end E mouth of the second fiber coupler (8); An output terminal G mouth of the second fiber coupler (8) connects the second Fiber Bragg Grating FBG (7), and another input end F mouth of the second fiber coupler (8) connects photodetector (9); Photodetector (9) is connected 11 by acoustic emission capture card (10) mutually with computing machine) connect;
The reflectivity of described the first Fiber Bragg Grating FBG (6), the second Fiber Bragg Grating FBG (7), side mode suppression ratio, three dB bandwidth and temperature control coefficient are substantially consistent, but centre wavelength differs 0.1nm;
Described the first Fiber Bragg Grating FBG (6), the second Fiber Bragg Grating FBG (7) should be positioned in the same temperature environment when detecting at the scene;
The centre wavelength 1550nm of described the second Fiber Bragg Grating FBG (7), reflectivity〉90%, three dB bandwidth<0.20nm;
The light that LD pumping source (1) sends will be introduced erbium-doped fiber (3) through wavelength division multiplexer (2); After bait Ions Absorption energy in erbium-doped fiber (3), population inversion occurs, and then produce amplified spont-aneous emission, light signal is exaggerated; Be transferred on the first fiber coupler (5) by isolator (4) again; Most light is through the output of another output terminal D of the first fiber coupler (5) mouth, and the light of fraction is after an output terminal C mouth of the first fiber coupler (5) is reflected by the first Fiber Bragg Grating FBG (6), in the feedback light return loop; The laser of narrowband of another output terminal D mouth output of the first fiber coupler (5), enter (8) input end E mouths of the second fiber coupler as input, an output terminal G mouth from the second fiber coupler (8) arrives the second Fiber Bragg Grating FBG (7) again, the light that meets centre wavelength is got back to another input end F mouth outgoing of the second fiber coupler (8), enters photodetector (9); After photodetector (9) was converted into electric signal with light signal, input acoustic emission capture card (11) was carried out analysis-by-synthesis and the processing of signal by acoustic emission capture card (11), shown in computing machine (11) at last.
2. the Partial Discharge in Power Transformer detection system based on Fiber Bragg Grating FBG according to claim 1, it is characterized in that: the centre wavelength of described LD pumping source (1) is 980nm, output power 〉=180mW, the Output optical power long-term stability is ± 0.01dB.
3. the Partial Discharge in Power Transformer detection system based on Fiber Bragg Grating FBG according to claim 1, it is characterized in that: the operation wavelength of described wavelength division multiplexer (2) is 980nm or 1550nm, isolation characteristic is 29.6dB.
4. the Partial Discharge in Power Transformer detection system based on Fiber Bragg Grating FBG according to claim 1, it is characterized in that: the splitting ratio of described the first fiber coupler (5) is 90:10, the splitting ratio of the second fiber coupler is 50:50.
CN 201110266331 2011-09-09 2011-09-09 Power transformer partial discharge detection system and method based on fiber bragg grating CN102323527B (en)

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