EP0927360A1 - Procede servant a obtenir un signal de sortie compense en temperature dans un detecteur optique de mesure de courant - Google Patents

Procede servant a obtenir un signal de sortie compense en temperature dans un detecteur optique de mesure de courant

Info

Publication number
EP0927360A1
EP0927360A1 EP97918907A EP97918907A EP0927360A1 EP 0927360 A1 EP0927360 A1 EP 0927360A1 EP 97918907 A EP97918907 A EP 97918907A EP 97918907 A EP97918907 A EP 97918907A EP 0927360 A1 EP0927360 A1 EP 0927360A1
Authority
EP
European Patent Office
Prior art keywords
quotient
component
derived
periodically fluctuating
field strength
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.)
Ceased
Application number
EP97918907A
Other languages
German (de)
English (en)
Inventor
Peter Menke
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.)
Siemens AG
Original Assignee
Siemens AG
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 Siemens AG filed Critical Siemens AG
Publication of EP0927360A1 publication Critical patent/EP0927360A1/fr
Ceased legal-status Critical Current

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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
    • G01R15/245—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices using magneto-optical modulators, e.g. based on the Faraday or Cotton-Mouton effect
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/032—Measuring direction or magnitude of magnetic fields or magnetic flux using magneto-optic devices, e.g. Faraday or Cotton-Mouton effect
    • G01R33/0322—Measuring direction or magnitude of magnetic fields or magnetic flux using magneto-optic devices, e.g. Faraday or Cotton-Mouton effect using the Faraday or Voigt effect

Definitions

  • the invention relates to a method for obtaining a temperature response-compensated output signal in an optical sensor for measuring a periodically fluctuating electrical and / or magnetic field strength, according to the preamble of patent claim 1.
  • Optical sensors of the type mentioned are known, in particular in the form of current measuring sensors for measuring the current strength of an alternating current carried in a conductor, which generates an electromagnetic field in the immediate vicinity of the conductor of an electrical and magnetic field strength that fluctuates periodically according to the current strength of the alternating current.
  • the sensor uses the Faraday effect to measure the periodically fluctuating magnetic field strength, according to which the current strength can be deduced.
  • Voltage measuring sensors work similarly to measure an AC voltage present on a conductor, which generates an electric field in the immediate vicinity of the conductor of an electrical field strength that fluctuates periodically in accordance with the AC voltage.
  • This sensor measures, for example, the periodically fluctuating electrical field strength according to the Pockels effect, according to which the AC voltage can be deduced.
  • the respective field strength is measured by the fact that light that can be influenced by the field strength is sent through the periodically fluctuating field and by the light that is transmitted and influenced by it, two separate intensities that are periodically fluctuating in phase, depending on the field strength of the periodically fluctuating field. intensity signals containing intensity components are generated.
  • the influencing of the light by the field can be based on various known physical effects, for example the Faraday or Pockels effect mentioned.
  • the Faraday effect which is frequently used in current measurement sensors, is explained as an example, in which linearly polarized light from a polarizer is influenced by the magnetic field strength such that the polarization plane of the polarized light is rotated as a function of the field strength relative to the polarization plane determined by the polarizer, in the case of periodically fluctuating field strength correspondingly fluctuating periodically.
  • the linearly polarized light which is influenced by the field strength, can be fed to an analyzer, which uses this light to form two mutually perpendicularly polarized light components, the intensities of which, relative to one another, depend on the polarization state of the field strength-influenced light relative to the polarization plane determined by the polarizer and become one complete intensity independent of the angular position of the polarization plane of the field strength-influenced light.
  • these light components form the two intensity signals which have the periodically fluctuating containing intensities.
  • Such voltage signals can be obtained with voltage measurement sensors that use, for example, the Pockels effect.
  • Size that corresponds to the quotient of the difference between the intensities of the two intensity signals and the sum of these intensities and that corresponds to the DC component and the periodically fluctuating AC component to which an effective value can be assigned, is the output signal of a measured field strength and thus the current or voltage won such a sensor.
  • This output signal in particular a periodically fluctuating component contained therein, often shows a temperature drift, the cause of which lies in the physical effect on which the measurement is based and / or in disturbances such as mechanical stresses and / or linear birefringence.
  • a temperature change compensation method is proposed in relation to a magneto-optical sensor based on the Faraday effect, in which the two intensity signals in the manner described above with the aid of linearly polarized light from a polarizer, for example a laser di - ode, and an optical analyzer.
  • a polarizer for example a laser di - ode
  • an optical analyzer it is necessary to adjust the polarizer and analyzer very precisely to one another, i.e. so that the polarization plane determined by the polarizer and the polarization plane determined by the analyzer are as precisely as possible at an angle of 45 ° to one another.
  • the invention specified in claim 1 provides a novel method for obtaining a temperature-compensated output signal, with the advantage that in a sensor of the type mentioned, when the two intensity signals are obtained with the aid of a polarizer and analyzer, larger compared to the known temperature compensation method angular misalignments between polarizer and analyzer are permissible.
  • the method according to the preamble of patent claim 1, in which the size is derived from the two intensity signals, which corresponds to a quotient from a difference between the intensities of the two intensity signals and the sum of these intensities, is known as -7+ intensity normalization.
  • the inventive concept on which the method according to the invention is based is not restricted to this intensity standardization, but can also be applied analogously to sensors in which the so-called AC / CD intensity standardization is present, ie in sensors according to the preamble of patent claim 2.
  • the invention specified in claim 2 also provides a novel method for obtaining a temperature-compensated output signal, with the advantage that in a sensor of the type mentioned, if the two intensity signals are obtained with the aid of a polarizer and analyzer, compared to the known one Temperature compensation procedures larger angular misalignments between polarizer and analyzer are permissible.
  • angular misalignments between the polarizer and analyzer of more than 5 ° advantageously impair the function of the method according to the invention only insignificantly.
  • the reduction in sensitivity is small and proportional to the cosine of the error angle between the polarization plane of the polarizer and that of the analyzer. This advantageously simplifies the construction and manufacture of the sensor in which the method according to the invention is used.
  • the method according to the invention is not limited to sensors that work with polarizers and analyzers, both in the embodiment according to claim 1 and in the embodiment according to claim 2, but can generally also be applied to other sensors according to the preamble of claims 1 and / or 2 and enriches the technology in this way.
  • the function to be used in the method according to the invention and determined by the calibration measurement can be approximated by a degree which can be predetermined by a polynomial (claim 2) and / or approximately stored in a lookup table (lookup table).
  • a preferred arrangement for carrying out a method according to claim 1 emerges from claim 4 and a preferred arrangement for carrying out a method according to claim 2 emerges from claim 5.
  • FIG. 1 shows a schematic illustration of an output part of an optical sensor with - / + - intensity normalization, which generates the two intensity signals and the quantity derived therefrom, and an arrangement coupled to this output part for carrying out the method for obtaining a temperature-compensated output signal in this sensor,
  • FIG. 2 shows a schematic representation of an output part of an optical sensor with AC / DC intensity normalization that generates the two intensity signals and the two normalized variables derived therefrom, and an arrangement coupled to this output part for carrying out a method for obtaining a temperature response-compensated output signal in this sensor ,
  • FIG. 3 shows a diagram which shows the percentage deviation of the output temperature which is not compensated for
  • Figure 4 is a diagram showing the percentage deviation of the output signal of the magneto-optical sensor corrected with the inventive method with an angular misalignment of 5 ° between analyzer and polarizer.
  • the optical sensor is a magnetic or electro-optical sensor as described in more detail above, which detects the periodically fluctuating magnetic and / or electrical field strength of a magnetic and / or electric field, for example using the Faraday or Pockels effect.
  • Light L of a certain polarization p generated by a polarizer (not shown) is sent through the periodically fluctuating field, which influences the polarization as a function of the magnetic or electrical field strength, such that the light L has a polarization p 'after passing through the field is changed compared to the specific polarization generated by the polarizer. Since the magnetic or electric field or its field strength fluctuates periodically, the polarization p 'of the polarized light that has passed through this field also fluctuates periodically with respect to the polarization determined by the polarizer.
  • the polarizer (not shown) generates light L of a certain linear polarization p, which is passed through an optical medium with a Verdet constant arranged in the periodically fluctuating magnetic field, for example a glass fiber coil surrounding a current-carrying conductor.
  • the periodically fluctuating magnetic field influences the linearly polarized light L such that, after passing through the field, the linear polarization p 'fluctuates periodically compared to the determined linear polarization.
  • the light L fluctuating polarization p ' is an analyzer 9 with a polar fed risk level, which is set as precisely as possible at an angle of 45 ° to the polarization plane of the specific polarization p of the linearly polarized light L generated by the polarizer, for example a laser diode.
  • the analyzer 9 generates from the light L of the fluctuating linear polarization p '
  • the periodically fluctuating intensity components of the intensities II and 12 of both intensity signals L1 and L2 fluctuate periodically in phase opposition to one another as a function of the periodically fluctuating field strength.
  • An example of such an analyzer 10 is, for example, a Wollaston prism, which is frequently used in such current measurement sensors.
  • the quantity P is derived from the two intensity signals L1 and L2, which gives a quotient from, for example, the difference II-12 of the intensities II and 12 of the two intensity signals L1 and L2 and the sum II + 12 of these two Intensity signals II and 12 corresponds.
  • the device 10 in FIG. 1 which preferably has a digital processor and the supplied contents Sity signals Ll and L2 digitally processed, although analog processing is equally possible.
  • the derived variable P identifies the sensor as the sensor with - / + intensity standardization.
  • the derived variable P contains a constant component P ß C and an alternating component PAO which fluctuates periodically according to the magnetic field strength and to which an effective value PACeff can be assigned.
  • the direct component Ppc is obtained from the derived variable P in the device 11 in FIG. 1, while the alternating component P A c of the derived variable P is obtained in the device 12 and the effective value PACeff of this component P A c is formed.
  • P Q C can be obtained, for example, by low-pass filtering, P A c, for example, by high-pass filtering or by forming P - P ⁇ c.
  • the device 12 can for example be designed so that a device 12 ! is provided, which derives from the derived variable P the alternating component P A c, which is fed to a separate device 122, in which the effective value P AC eff is formed.
  • the temperature signal-compensated output signal S is obtained by forming the quotient
  • the device 13 In order to form the functional value belonging to this sampling point, the device 13 is provided, to which the value of the direct component P ⁇ belonging to this sampling point and the effective value P AC eff belonging to this sampling point are supplied and which provide the value of the direct component Pj ⁇ and this effective value P eff C belonging function value of the predetermined function f (PDC 'p A eff C) al - s the touch point to this waste associated function value of this function at the
  • Device 14 outputs which device 14, on the other hand, is supplied with the value of the alternating component PAC belonging to this sampling point and which forms and outputs the temperature response-compensated output signal S belonging to this sampling point from this function value and this value of the alternating component P C.
  • the device 13 can contain a look-up table in which a function value of the function f is assigned to each pair of values consisting of a value of the direct component P ⁇ J and an effective value P AC eff of the alternating component PAC.
  • the device 13 can also contain a processor which calculates the function values of the function f assigned to the different value pairs from a value of the direct component -QQ and an effective value PACeff, for example approximately with the aid of a polynomial of selectable order.
  • the value of the DC component P- QQ and the RMS value PACeff do not change compared to the value of the AC component PAC over a longer period of time, so that these values can be regarded as constant in this respective period and not as frequently as the value of AC component PAC needed to be determined.
  • a sensor with AC / DC intensity normalization is the basis.
  • a normalized variable S 1 or S 2 is derived from each intensity signal L 1 and L 2 from the analyzer 9.
  • the normalized variable S derived from the intensity signal L1; j _ corresponds to the quotient X c / l ° from the alternating component I c and the equal component J ° c to the intensity II of the intensity signal Ll and the size S2 to the quotient I * c / l c from the alternating component X * c and the equal component X ° c the intensity 12 of the intensity signal L2.
  • the normalized variable S ⁇ is formed in the example according to FIG. 2 by the device 15 ⁇ _, which for example a device 15 ⁇ for obtaining the alternating component I * c , a device 15 ⁇ _2 for obtaining the direct component I ° c of the intensity signal L1 and a device 15 ⁇ _ 3 for forming of the quotient X * c / I ° c .
  • the standardized quantity S 2 is formed by the device 15 2 , which for example has a device 152i for obtaining the alternating component I * c of the intensity signal L2, a device 1522 for obtaining the direct component c of the intensity signal L2 and a device 15 2 3 for forming the quotient ! * 0 / l c .
  • the first quotient P'DC corresponds to the direct component P ⁇ JC of the derived variable P according to FIG. 1 and the periodically fluctuating quotient P'AC corresponds to the alternating component PAC of this derived variable P.
  • the device 17 can consist, for example, of a device 17] _ for forming the second quotient P'AC and a device 172 for forming the effective value P'ACeff of the second quotient P'AC, the second quotient P'AC is supplied to the device 172.
  • the device 18 corresponds to the device 13 in FIG. 1 and the device 19 to the device 14 in FIG. 1.
  • the device 18 is supplied with the value of the first quotient P'DC belonging to a sampling point and the effective value P'ACeff belonging to this sampling point of the second quotient P'AC, and the device with the effective value P associated with this value of the first quotient P'DC Outputs the function value belonging to the predetermined function f (P'DC » p 'ACeff) to the device 19 as the function value of this function belonging to this sampling point, to which the value of the second quotient P'AC belonging to this sampling point is supplied and those from this functional value and this Value of the second quotient P'AC forms and outputs the temperature response-compensated output signal S 'belonging to this sampling point.
  • the device 18 can contain a look-up table in which a function value of the function f is assigned to each pair of values consisting of a value of the first quotient P'DC ⁇ n d and an effective value P ' AC eff of the second quotient P'AC.
  • the device 19 can also contain a processor which calculates the function values of the function f assigned to the different value pairs from a value of the first quotient P'DC and an effective value P'A C eff of the second quotient P'AC, for example approximately Selectable order polynomial.
  • Essential in the inventive method the inclusion is also the effective value of the alternating component PACeff PAC or effective value P 'eff of the second AC quotient P'AC un not only the DC component PDC or first quotient P'DC-
  • PDC is a good measure of the sensor head temperature for optical adjustment and thus for its current current or Tension sensitivity.
  • a misalignment between analyzer and polarizer causes the direct component PDC or first quotient P'DC to depend on the field strength, as a result of which the previous compensation of the temperature response fails.
  • a field strength dependency of the direct component PDC or first quotient P'DC is taken into account and the temperature response compensation works even with poor adjustment between analyzer and polarizer.
  • FIG. 3 shows, for example, the percentage deviation of the derived variable P according to FIG. 1, which is not temperature-compensated, from its ideal value without linear birefringence ⁇ , which likewise influences the light polarization and is caused by mechanical stresses, in particular with Temperature fluctuations.
  • the percentage deviation is plotted against the circular birefringence 2p / °, which is directly proportional to the magnetic field strength, and against the linear birefringence ⁇ / ° whose change with temperature essentially causes the temperature response of the derived variable P.
  • FIG. 4 shows in the same representation as in FIG. 3 the percentage deviation of the signal S or S 'corrected with the method according to the invention from its ideal value without linear birefringence with an angular misalignment of 5 ° between analyzer and polarizer.
  • a third order polynomial was used for the function f to be determined by calibration measurement.
  • the percentage error largely remains below 0.5%.
  • the error that is actually to be expected during a measurement is still much smaller, since it cannot be expected that the linear birefringence ⁇ will change with the temperature over such a large range.
  • Fluctuations in the Verdet constant of the optical medium of the sensor, which is decisive for the Faraday effect, with temperature are also compensated for by determining the adaptation function f by calibration measurement.
  • the accuracy can be further increased by choosing an adaptation function f in the form of an even higher order polynomial.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Measuring Magnetic Variables (AREA)

Abstract

Dans un détecteur magnéto-optique présentant une intensité normalisée -/+, on obtient un signal de sortie (S) compensé en température par formation d'un quotient à partir de la composante alternative (PAC) du signal (P) normalisé en intensité et à partir d'une fonction définie par mesure d'étalonnage (f(PDC, PACeff)) d'une composante continue (PDC) du signal (P) normalisé en intensité et d'une valeur efficace (PACeff) de la composante alternative (PAC). L'invention concerne également un procédé correspondant pour des détecteurs normalisés en intensité de courant alternatif et de courant continu.
EP97918907A 1996-09-20 1997-08-26 Procede servant a obtenir un signal de sortie compense en temperature dans un detecteur optique de mesure de courant Ceased EP0927360A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19638644 1996-09-20
DE19638644 1996-09-20
PCT/DE1997/001854 WO1998012570A1 (fr) 1996-09-20 1997-08-26 Procede servant a obtenir un signal de sortie compense en temperature dans un detecteur optique de mesure de courant

Publications (1)

Publication Number Publication Date
EP0927360A1 true EP0927360A1 (fr) 1999-07-07

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EP97918907A Ceased EP0927360A1 (fr) 1996-09-20 1997-08-26 Procede servant a obtenir un signal de sortie compense en temperature dans un detecteur optique de mesure de courant

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Country Link
US (1) US6417660B2 (fr)
EP (1) EP0927360A1 (fr)
CA (1) CA2266470A1 (fr)
WO (1) WO1998012570A1 (fr)

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Publication number Priority date Publication date Assignee Title
JP3718412B2 (ja) * 2000-06-01 2005-11-24 キャボットスーパーメタル株式会社 ニオブまたはタンタル粉末およびその製造方法
US6946827B2 (en) * 2001-11-13 2005-09-20 Nxtphase T & D Corporation Optical electric field or voltage sensing system
JP4631907B2 (ja) * 2005-03-08 2011-02-16 東京電力株式会社 強度変調型光センサおよび光電流・電圧センサ
WO2006095620A1 (fr) * 2005-03-08 2006-09-14 The Tokyo Electric Power Company, Incorporated Photo-capteur et capteur de tension/photo-courant
RS50440B (sr) * 2007-07-06 2009-12-31 Miodrag HADŽIĆ Merna magnetooptička glava sa podesivim analizatorom za merenje struje na srednjim i visokim naponima
US9465052B2 (en) * 2013-06-10 2016-10-11 General Electric Company Systems and methods for monitoring fiber optic current sensing systems

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US4564754A (en) * 1982-03-08 1986-01-14 Hitachi, Ltd. Method and apparatus for optically measuring a current
US4973899A (en) * 1989-08-24 1990-11-27 Sundstrand Corporation Current sensor and method utilizing multiple layers of thin film magneto-optic material and signal processing to make the output independent of system losses
DE4312183A1 (de) * 1993-04-14 1994-10-20 Siemens Ag Optisches Meßverfahren zum Messen eines elektrischen Wechselstromes mit Temperaturkompensation und Vorrichtung zur Durchführung des Verfahrens
DE4312184A1 (de) * 1993-04-14 1994-10-20 Siemens Ag Optisches Meßverfahren zum Messen eines elektrischen Wechselstromes mit Temperaturkompensation und Vorrichtung zur Durchführung des Verfahrens
CA2173142C (fr) * 1993-10-01 2000-11-14 Thomas Bosselmann Procede et dispositif permettant de mesurer une grandeur electrique alternative avec compensation de temperature
JP2705543B2 (ja) * 1993-11-24 1998-01-28 住友金属鉱山株式会社 磁界強度の測定方法およびこれを用いた光磁界センサ
JP3300184B2 (ja) * 1994-12-27 2002-07-08 ホーヤ株式会社 光ファイバ型計測装置及び計測方法
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Also Published As

Publication number Publication date
US20020000801A1 (en) 2002-01-03
CA2266470A1 (fr) 1998-03-26
US6417660B2 (en) 2002-07-09
WO1998012570A1 (fr) 1998-03-26

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