EP1299736A1 - Capteur de courant a fibre optique - Google Patents

Capteur de courant a fibre optique

Info

Publication number
EP1299736A1
EP1299736A1 EP01942947A EP01942947A EP1299736A1 EP 1299736 A1 EP1299736 A1 EP 1299736A1 EP 01942947 A EP01942947 A EP 01942947A EP 01942947 A EP01942947 A EP 01942947A EP 1299736 A1 EP1299736 A1 EP 1299736A1
Authority
EP
European Patent Office
Prior art keywords
fiber
current sensor
waves
phase
branch
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP01942947A
Other languages
German (de)
English (en)
Inventor
Klaus Bohnert
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ABB Research Ltd Switzerland
ABB Research Ltd Sweden
Original Assignee
ABB Research Ltd Switzerland
ABB Research Ltd Sweden
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ABB Research Ltd Switzerland, ABB Research Ltd Sweden filed Critical ABB Research Ltd Switzerland
Priority to EP01942947A priority Critical patent/EP1299736A1/fr
Publication of EP1299736A1 publication Critical patent/EP1299736A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/24—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices
    • G01R15/247—Details of the circuitry or construction of devices covered by G01R15/241 - G01R15/246

Definitions

  • the invention relates to a fiber optic current sensor with a reflection interferometer according to the preamble of patent claim 1, a method for setting an operating point in such a current sensor according to the preamble of patent claim 9 and a method for current measurement by means of such a current sensor according to the preamble of patent claim 13.
  • a generic fiber optic current sensor is described in DE-A-4,224,190 and G. Frosio et al., "Reciprocal reflection interferometer for a fiber-optic Faraday current sensor", Applied Optics, Vol. 33, No. 25, page 6111 -6122 (1994), which has a coil-shaped, magneto-optically active sensor fiber which surrounds a current conductor, is mirrored at one end, and at the other end it is connected via a phase delay element to a polarization-maintaining optical feed fiber, via which yourself Lets light into or out of the sensor fiber.
  • the feed fiber propagates optical waves that are orthogonally linearly polarized to one another.
  • these are converted into two circularly polarized waves before entering the sensor coil, the two circularly polarized waves having an opposite direction of rotation. After passing through the sensor coil, the two circular waves are reflected at the end of the coil, whereby they run back through the coil with the polarity sense reversed.
  • the circular waves are converted back into orthogonal linearly polarized waves when they exit the coil in the phase retarder and are guided to a detection system via the feed fiber.
  • the directions of polarization of the returning orthogonal waves are reversed compared to the forward-running waves.
  • the phase shift caused by the current can be detected by causing the two reflected linearly polarized waves to interfere in a polarizer connected to the feed fiber.
  • Interference function This is done by means of a modulation unit with a phase modulator, which birefringence in the supply tion fiber and thus a differential phase of the two waves changed. Since both forward and reverse waves pass through the same phase modulator, it must oscillate at a frequency adapted to the round trip time of the waves in order to non-reciprocally modulate the differential phase of the two interfering waves. Without the modulation unit, the phase difference between the two interfering waves would be zero.
  • the modulation frequency ideally corresponds to the inverse value of twice the circulation time of the light in the interferometer.
  • the frequency of the modulation is typically in the range between 100 kHz and a few MHz and is determined, among other things, by the length of the fiber connection to the sensor fiber, that is to say the feed fiber.
  • the current-induced phase shift can be determined by suitable demodulation.
  • the demodulation techniques are the same which are used for fiber-optic gyroscopes and which are described, for example, in RA Bergh et al, "An Overview of fiber-optic gyroscopes", J. Lightwave Technol. 2, 91'107 (1984) essentially between open-loop and closed-loop configurations.
  • forward and backward waves propagate on part of their route in two separate fiber segments, with at least one of these fiber segments being operatively connected to a means for phase shifting.
  • the known phase modulators are suitable as such means. Thanks to the two segments, a back and forth wave was only influenced once by the same modulator. It is thus possible to use a quasi-static modulator to set the operating point in the
  • Another advantage of the current sensor according to the invention is that the length of the polarization-maintaining fiber no longer has to be adapted to the modulation frequency, but can be selected arbitrarily. There is practically no lower limit for the length of the feed fiber, which in turn can save costs.
  • FIG. 1 shows a fiber optic current sensor according to the invention
  • FIG. 2 shows a graphic representation of an operating point setting in a quasi-static phase control
  • FIG. 3 shows a detector and a modulation unit of the current sensor according to the invention in accordance with a first embodiment of the invention
  • Figure 4 shows a detector of the current sensor according to the invention according to a second embodiment of the invention.
  • FIG. 1 shows a fiber optic current sensor according to the invention with a reflection interferometer.
  • a sensor fiber 1 is wound in a coil shape around a current conductor L. It preferably has a round core cross section and is preferably made of quartz glass.
  • a first end of the sensor fiber 1 is connected to a fiber optic feed line 2.
  • a second end is provided with a reflector 10.
  • the reflector 10 is formed by mirroring the second fiber end.
  • the feed line 2 is at least partially birefringent and thus polarization-maintaining. It preferably has an elliptical core cross section to produce the birefringence. However, the use of a stress-induced birefringent fiber is possible.
  • the connection of the feed line 2 to the sensor fiber 1 takes place via a phase delay element 3, a ⁇ / 4 phase delay fiber segment preferably being used for this.
  • a light source 4 the light of which is transmitted through the fibers.
  • Particularly suitable as the light source are those with a small coherence length, in particular a superluminescent diode, a laser diode operated below the laser threshold, an LED or a broadband fiber light source.
  • the sensor has a detector 5, which detects light propagated by the sensor fiber and brought to interference. This detector 5 is connected via detector signal lines 50 to a signal processor 6 which transmits the sensor signal via a sensor signal line 60 to evaluation electronics (not shown).
  • the feed line 2 has two polarization-maintaining fiber branches 20, 20 '.
  • Fiber segments with an elliptical core are particularly suitable as fiber branches 20, 20 '.
  • the fiber branches 20, 20 ' have at least approximately the same optical length, that is to say they are the same within the coherence length of the light source 4.
  • the optical path differences, which accumulate two modes or waves propagating in different fiber branches, are thus identical.
  • the two fiber branches are connected in parallel and connected to one another in the region of their sensor-side ends via a polarization-maintaining coupler 8.
  • the coupler 8 is a fiber coupler with an elliptical core, its axes being arranged such that they lie parallel to the axes of the fiber branches 20, 20 '.
  • the two fiber branches 20, 20 ' are preferably connected to the coupler in such a way that the directions of the linear polarizations of the forward (branch 20) and the returning (branch 20') waves are mutually interchanged with respect to the fiber axes.
  • An optical wave which oscillates in the first branch 20 parallel to the long core axis, oscillates in the second branch 20 'parallel to the short axis and vice versa.
  • the first fiber branch, the feed branch 20, is operatively connected to the light source 4 at its other end.
  • the second fiber branch, the detection branch 20 ', is operatively connected to the detector 5.
  • the feed branch 20 is connected to a polarizer 21 in the transition to the light source 4.
  • the polarizer 21 is preferably directed such that its polarization directions lie at 45 ° to the main axes of the fiber branch 20.
  • a fiber polarizer 21 is used, which over a 45 ° - Splice 21 'is connected to the feed branch 20, but the use of other polarizers is possible.
  • the fiber branches 20 also preferably have a decoherence element 22 of length 1.
  • This decoherence element 22 generates a differential optical path difference in the forward-traveling waves propagating in the feed branch 20, which is longer than the coherence length of the light source 4. This prevents disruptive effects due to mode coupling in the means for phase shift 7,7 'described below.
  • a modulator is located in the branch 20 ', it is preferably arranged at least a distance of length 1 in front of the fiber end or the detector 5.
  • At least one of the two fiber branches 20, 20 ' is operatively connected to a phase shift unit.
  • the phase shift unit actually corresponds to the known phase modulation unit and essentially consists of the signal processor 6 described above and at least one phase modulator 7, 7 'connected to it via a modulation signal line 61.
  • the at least one phase modulator 7, 7 ' is not used in the known manner for modulating the phase difference, but rather serves as a means for the quasi-stationary phase shift.
  • a piezo-electric modulator is preferably used as the phase modulator 7, part of the respective fiber branch 20, 20 'being wound around a piezo-electric body of the modulator 7.
  • only one of the two fiber branches is
  • Fiber branch is arbitrary. In the exemplary embodiment shown here, however, each fiber branch 20, 20 'is operatively connected to a phase modulator 7, 7'.
  • a forward-running optical wave which is emitted by the light source 4, is linearly polarized in the polarizer 21 and is coupled via the 45 ° splice as two mutually orthogonal polarizations into the polarization-maintaining feed fiber 2, here in the feed branch 20.
  • the two polarizations are also referred to below as two orthogonal linearly polarized waves.
  • the decoherence element 22 of the feed fiber 2 has a coherence-damaging effect on the wave and generates in the two propagating orthogonal polarizations a differential optical path difference which is significantly longer than the coherence length of the light source 4.
  • the orthogonal polarizations of the forward-running wave pass through the area of influence of the first modulator 7 and pass through the coupler 8 and via a further polarization-maintaining fiber segment 23 of the feed line 2 to the phase delay element 3.
  • the orthogonally polarized waves are converted into two left and right circularly polarized waves, as shown in Figure 1.
  • the circular waves pass through the sensor fiber 1, are reflected at the end of the coil 10, swap their polarization states, run back through the coil and are converted back into orthogonally linearly polarized waves in the ⁇ / 4 retarder, the polarization of which is now perpendicular to the polarization of the corresponding waves Forward direction stands.
  • the total differential phase difference of the leading and returning waves, in the event that the branches 20, 20 'have at least approximately the same optical length, is therefore zero at the fiber end on the detector side in the event that no current flows through the current conductor S and is not equal to zero, when a current flows.
  • the returning waves are passed through the coupler 8 and the detector branch 20 ', brought to interference in the detector 5, and interference signals arising thereby are detected.
  • the differential phase of the orthogonal polarizations is checked by means of a quasi-stationary phase control and thus a suitable operating point is set.
  • a quasi-stationary phase control is known from DA Jackson et al, "Elimination of drift in a single-mode optical fiber interferometer using a piezoelectrically stretched coiled fiber", Applied Optics, vol. 19, No. 17, 1980, where they is used in a fiber optic Mach-Zehnder interferometer
  • ⁇ is the combined phase difference that the waves propagated by the current sensor have accumulated in the two separate fiber branches.
  • ⁇ , and ⁇ 2 are the
  • Phase differences in the two branches In the event that the two fiber branches have the same optical length, in the de-energized state and owing to the reverse polarization, ⁇ is equal to - ⁇ 2 .
  • either phases of the orthogonal polarizations of the forward and / or the backward waves can be checked.
  • the setting of the operating point, the control of the phase difference and the signal detection are carried out by dividing the forward and backward waves onto the two separate fiber branches 20, 20 '.
  • the detector 5 used for this and the modulation unit are described in more detail below with reference to FIG. 3.
  • the returning orthogonal, linearly polarized waves pass through the detection branch 20 'into the detector 5.
  • This has a preferably polarization-insensitive beam splitter 51, which splits the light preferably in a ratio of 1: 1.
  • Each of the two resulting pairs of orthogonal waves is brought to interference in a polarizer 52, which acts as an analyzer, and the resulting light I + and I are each detected in a photodiode 53.
  • the analyzers 52 are oriented at an angle of + 45 ° with respect to the fiber axes of the detection branch 20 ', specifically in such a way that their own transmission directions are perpendicular to one another.
  • I ⁇ I 0 (l ⁇ Kcos ( ⁇ + ⁇ ))
  • I 0 is the light intensity in the quadrature point and K is the visibility of the interference fringes.
  • the difference between these two photodiode signals is formed in a subtraction element 62 of the signal processor 6 and fed to a quadrature control 64.
  • This quadrature control 64 regulates the phase modulator (s) in such a way that the difference in the currentless state and without external influences is zero. In this case the quadrature point Q is reached.
  • This regulation is carried out quasi-statically, that is, it is always regulated to the quadrature point, the voltage value in the event of any drift of the operating point or in the case of slow phase changes induced by external influences. shifts is adjusted.
  • a quadrature control 64 with a small frequency bandwidth, for example of 5 Hz, is sufficient for this.
  • the alternating phase modulation which is caused by an alternating current to be measured in the current conductor S, is also additionally compensated.
  • This compensation is a dynamic, closed-loop control.
  • the voltage generated by the " quadrature control and applied to the modulators 7, 7 'simultaneously serves as the output signal of the sensor.
  • the signal processor also has an addition element 63 and a division element 65 for measuring the current flowing through the current conductor L.
  • the difference between the signals I + I obtained at constant light intensity is proportional to the current.
  • the sum of the two signals is proportional to the light intensity.
  • FIG. 4 shows a further embodiment of the current sensor according to the invention, or its modulation unit.
  • the current sensor or its modulation unit.
  • Each of the two reverse waves has thus experienced a reflection and a transmission in the beam splitters.
  • This arrangement has the advantage that both waves have the same variations in the properties of the beam splitters experience which are caused by aging processes, temperature fluctuations and other external influences.
  • a detection signal can be obtained which is independent of the stability of the modulator and its modulation unit.
  • an integrated optical element can also be used as a coil-shaped optical sensor.
  • the coil can consist of a single turn in the fiber optic as well as in the integrated optical design.
  • a polarizing beam splitter can also be used instead of a polarization-insensitive beam splitter and the two analyzers.

Abstract

L'invention concerne un capteur de courant à fibre optique qui comprend un interféromètre à réflexion (1, 10) et dont la ligne à fibre optique (2) comporte une première branche de fibre optique (20) pour le transport de deux ondes polarisées orthogonalement, se déplaçant vers l'avant, et une seconde branche de fibre optique (20') soumise à la polarisation, pour deux ondes polarisées orthogonalement, se déplaçant vers l'arrière. Ces deux branches de fibres optiques (20, 20') sont reliées l'une à l'autre par un coupleur (8) situé côté capteur. La première branche de fibre optique (20) est reliée à une source de lumière (4), et la seconde branche de fibre optique (20') est reliée au détecteur (5). Un moyen servant au décalage de phase (7) est en liaison active avec au moins une des branches de fibre (20, 20'). Ainsi, on peut obtenir une maîtrise quasi-statique de la différence de phase des ondes, de telle sorte que les exigences concernant le moyen servant au décalage de phase peuvent être moins élevées que celles concernant les modulateurs de phase et les processeurs de signal utilisés habituellement dans de tels capteurs de courant.
EP01942947A 2000-07-10 2001-07-04 Capteur de courant a fibre optique Withdrawn EP1299736A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP01942947A EP1299736A1 (fr) 2000-07-10 2001-07-04 Capteur de courant a fibre optique

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
EP00810605A EP1174719A1 (fr) 2000-07-10 2000-07-10 Capteur de courant à fibre optique
EP00810605 2000-07-10
PCT/CH2001/000415 WO2002004963A1 (fr) 2000-07-10 2001-07-04 Capteur de courant a fibre optique
EP01942947A EP1299736A1 (fr) 2000-07-10 2001-07-04 Capteur de courant a fibre optique

Publications (1)

Publication Number Publication Date
EP1299736A1 true EP1299736A1 (fr) 2003-04-09

Family

ID=8174798

Family Applications (2)

Application Number Title Priority Date Filing Date
EP00810605A Withdrawn EP1174719A1 (fr) 2000-07-10 2000-07-10 Capteur de courant à fibre optique
EP01942947A Withdrawn EP1299736A1 (fr) 2000-07-10 2001-07-04 Capteur de courant a fibre optique

Family Applications Before (1)

Application Number Title Priority Date Filing Date
EP00810605A Withdrawn EP1174719A1 (fr) 2000-07-10 2000-07-10 Capteur de courant à fibre optique

Country Status (6)

Country Link
US (1) US7075286B2 (fr)
EP (2) EP1174719A1 (fr)
JP (1) JP2004503751A (fr)
CN (1) CN1213305C (fr)
AU (1) AU2001265738A1 (fr)
WO (1) WO2002004963A1 (fr)

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EP1710589A1 (fr) * 2005-03-30 2006-10-11 VA TECH Transmission & Distribution SA Agencement de capteur optique pour une installation de commutation électrique
CN1963539B (zh) * 2005-11-09 2011-03-09 李岩松 光学电流互感器及其测定电流的方法
CA2531177A1 (fr) * 2005-12-30 2007-06-30 Jesse Zheng Gyroscope de sagnac differentiel a onde entretenue modulee en frequence a fibre birefringente
EP2002267A1 (fr) 2006-04-04 2008-12-17 Abb Research Ltd. Capteur de courant de fibre optique avec detection de somme
WO2007121592A1 (fr) * 2006-04-25 2007-11-01 Abb Research Ltd Capteur de courant a fibre optique avec schéma de détection polarimétrique
CA2672128A1 (fr) * 2006-12-12 2008-06-19 Abb Technology Ag Detecteur multiplexe par repartition dans le temps pour un transducteur de courant magneto-optique
US7492977B2 (en) * 2007-06-14 2009-02-17 Yong Huang All-fiber current sensor
WO2010137752A1 (fr) 2009-05-25 2010-12-02 부산대학교 산학협력단 Capteur de courant à guide d'onde optique polymère
EP2306212B1 (fr) * 2009-09-30 2011-11-02 ABB Research Ltd. Capteur de champ magnétique ou de courant à fibre optique à température compensée doté d'une insensibilité aux variations des paramètres du capteur
ATE554400T1 (de) * 2009-09-30 2012-05-15 Abb Research Ltd Verfahren zur herstellung eines glasfaserstromsensors mit inhärentem temperaturausgleich des faraday-effekts
WO2011069558A1 (fr) * 2009-12-11 2011-06-16 Abb Research Ltd Détection de courant à fibre optique à l'aide d'un capteur doté de sous-modules pouvant être échangés
CN101957399B (zh) * 2010-09-21 2014-04-30 中国电力科学研究院 一种数字闭环型光纤电流传感器
DE102012002984A1 (de) * 2012-02-15 2013-08-22 Northrop Grumman Litef Gmbh Integrierter optischer Schaltkreis und Verfahren zur Strommessung sowie Sensormodul und Messeinrichtung
CN103837716A (zh) * 2012-08-29 2014-06-04 北京恒信创光电技术有限公司 光学电流互感器的固定装置
CN103852613B (zh) * 2012-11-29 2016-08-10 沈阳工业大学 一种辐射电流传感方法及专用传感器
JP6309200B2 (ja) * 2013-03-26 2018-04-11 三菱重工業株式会社 雷電流計測装置及び雷電流計測方法
KR102098626B1 (ko) * 2013-10-16 2020-04-08 한국전자통신연구원 광섬유 전류 센서
KR102159420B1 (ko) * 2013-12-20 2020-09-24 에이비비 슈바이쯔 아게 광 센서
EP3156808A1 (fr) * 2015-10-14 2017-04-19 ABB Technology AG Capteur de courant à fibre optique avec tolérance au désalignement de connecteur
CN106324323B (zh) * 2016-08-30 2019-09-06 中国西电电气股份有限公司 一种全光纤电流互感器及其电流测量方法
WO2019120588A1 (fr) * 2017-12-22 2019-06-27 Abb Schweiz Ag Détection optique de polarisation à précision améliorée dans le régime de signal élevé
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Also Published As

Publication number Publication date
US20040101228A1 (en) 2004-05-27
WO2002004963A1 (fr) 2002-01-17
CN1441907A (zh) 2003-09-10
CN1213305C (zh) 2005-08-03
US7075286B2 (en) 2006-07-11
JP2004503751A (ja) 2004-02-05
AU2001265738A1 (en) 2002-01-21
EP1174719A1 (fr) 2002-01-23

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