WO2024083490A1 - Détermination d'un spectre de fréquence d'un courant électrique - Google Patents

Détermination d'un spectre de fréquence d'un courant électrique Download PDF

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Publication number
WO2024083490A1
WO2024083490A1 PCT/EP2023/077239 EP2023077239W WO2024083490A1 WO 2024083490 A1 WO2024083490 A1 WO 2024083490A1 EP 2023077239 W EP2023077239 W EP 2023077239W WO 2024083490 A1 WO2024083490 A1 WO 2024083490A1
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Prior art keywords
vector
fourier
current
measurement signal
previous
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PCT/EP2023/077239
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German (de)
English (en)
Inventor
Stefan Schuberth
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Siemens Energy Global GmbH & Co. KG
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Application filed by Siemens Energy Global GmbH & Co. KG filed Critical Siemens Energy Global GmbH & Co. KG
Publication of WO2024083490A1 publication Critical patent/WO2024083490A1/fr

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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10—Complex mathematical operations
    • G06F17/14—Fourier, Walsh or analogous domain transformations, e.g. Laplace, Hilbert, Karhunen-Loeve, transforms
    • G06F17/141—Discrete Fourier transforms
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
    • G01R23/16—Spectrum analysis; Fourier analysis
    • 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
    • G01R15/246—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 based on the Faraday, i.e. linear magneto-optic, effect

Definitions

  • the invention relates to a method and a current analysis device for determining a frequency spectrum of an electric current.
  • the frequency distribution in a current measurement signal is usually determined by a so-called fast Fourier transform (FFT for short), which is an efficient calculation of a so-called discrete Fourier transform (DFT for short). Since the complete calculation of a fast Fourier transform is time-consuming, it usually cannot be carried out after every current measurement, although this would be desirable from a signal processing point of view. For this reason, the frequency amplitude, for example, is only calculated for selected frequencies. This may be sufficient for certain analysis purposes, but a back transformation from the frequency domain to the time domain is not possible.
  • FPGA abbreviation for Field Programmable Gate Array
  • the invention is based on the object of specifying an improved method and an improved current analysis device for determining a frequency spectrum of an electric current.
  • the object is achieved according to the invention by a method having the features of claim 1 and a current analysis device having the features of claim 7.
  • a current measurement signal is recorded by means of a current measuring device at equidistantly successive measurement times.
  • a measurement signal vector is formed from the n most recent current measurement signals, where n is a predetermined number of current measurement signals.
  • a Fourier vector is calculated from the measurement signal vector using a Fourier matrix, which is a discrete Fourier transformation of the measurement signal vector.
  • An updated Fourier vector is formed from the previous Fourier vector by adding to the previous Fourier vector the product of the column of the Fourier matrix which corresponds to the oldest current measurement signal contained in the previous measurement signal vector and the difference between the most recent current measurement signal and the oldest current measurement signal contained in the previous measurement signal vector is added.
  • W ( t 2 ) (w 2 , ..., w k , ..., w n ) denote the measurement signal vector which is formed from the n most recent current measurement signals w 2 ,...,w n recorded up to a measurement time ti (including the measurement time ti), where the k-th component w k is the oldest current measurement signal contained in the measurement signal vector W(t 2 ).
  • the Fourier vector X(t 2 ) for the measurement time t 2 is calculated according to the invention from the Fourier vector X(t 2 ) as follows:
  • X(t 2 ) X(t 2 ) + (M lk , ...,M nk ) - (w 0 -w k ) , where (M lk , ...,M nk ) denotes the k-th column of the Fourier matrix, written as a row vector.
  • the method according to the invention therefore provides for calculating the Fourier vector of a discrete Fourier transformation for a measurement time from the previous Fourier vector, i.e. from the Fourier vector for the previous measurement time, according to the rule described above.
  • the arithmetic operations to be carried out for this rule are proportional to the number n of components of the measurement signal vector and thus enable a more effective (faster) calculation of the Fourier vector than a conventional fast Fourier transformation, the number of arithmetic operations of which scales with n-log(n). This is made possible by the fact that the method according to the invention for calculating the Fourier vector for a measurement time no matrix multiplication of the Fourier matrix with the complete current measurement signal vector is provided.
  • the method according to the invention provides an updating of the previous Fourier vector, which only requires a multiplication of a column of the Fourier matrix with the difference between the most recent current measurement signal and the oldest current measurement signal contained in the previous measurement signal vector and the addition of the result of this multiplication to the previous Fourier vector.
  • the current measuring device has at least one optical current transformer.
  • An optical current transformer is understood here to be an optical measuring device for measuring an electric current flowing in a current conductor, which is based on the magneto-optical Faraday effect. This effect is understood to be the rotation of the polarization direction of a linearly polarized electromagnetic wave in a medium by a magnetic field parallel to the direction of propagation of the wave. The rotation of the polarization direction is proportional to the magnetic flux density of the magnetic field.
  • linearly polarized light is sent through an optical fiber arranged near the current conductor, which exhibits the Faraday effect. The magnetic field generated by the current in the current conductor causes a rotation of the polarization direction of the light.
  • the current strength can be measured by detecting the rotation of the polarization direction of the light.
  • the light output from the light guide is passed through a polarizer, for example, and a light intensity of the light transmitted by the polarizer is detected.
  • the Fourier vector is a frequency vector whose Components are amplitudes of the current measurement signal depending on frequencies of the current measurement signal.
  • a temporal change in the Fourier vector is continuously calculated, a stability value is calculated from the temporal change in the Fourier vector and the stability value is used to control a protective device of an electrical switchgear.
  • This embodiment of the method according to the invention takes advantage of the fact that large temporal changes in the Fourier vector can indicate, for example, fault currents or damage to an electrical switchgear.
  • the components of a Fourier vector which fall below a threshold value are set to zero.
  • the threshold value is calculated, for example, as the product of a predetermined factor and an average value of the components of the Fourier vector.
  • n is a predetermined number of current measurement signals
  • an updated Fourier vector from the previous Fourier vector is formed by adding to the previous Fourier vector the product of that column of the Fourier matrix which corresponds to the oldest current measurement signal contained in the previous measurement signal vector and the difference between the most recent current measurement signal and the oldest current measurement signal contained in the previous measurement signal vector.
  • a current analysis device enables the method according to the invention to be carried out.
  • the advantages of such a current analysis device therefore correspond to the above-mentioned advantages of the method according to the invention.
  • the current measuring device has at least one optical current transformer.
  • the Fourier vector formed by the evaluation unit is a frequency vector whose components are amplitudes of the current measurement signal as a function of frequencies of the current measurement signal.
  • the evaluation unit is set up to continuously calculate a temporal change of the Fourier vector, to calculate a stability value from the temporal change of the Fourier vector and to use the stability value to control a protective device of an electrical switchgear.
  • the Current analysis device is the evaluation unit set up, to set the components of each Fourier vector that fall below a threshold value to zero.
  • the evaluation unit is set up to calculate the threshold value as the product of a predetermined factor and an average value of the components of the Fourier vector.
  • FIG 1 is a block diagram of an embodiment of a current analysis device for determining a frequency spectrum of an electrical current
  • FIG 2 is a flow diagram of an embodiment of a method for determining a frequency spectrum of an electric current.
  • FIG. 1 shows a block diagram of an embodiment of a current analysis device 1 for determining a frequency spectrum of an electrical current.
  • the current analysis device 1 comprises a current measuring device 3 and an evaluation unit 5.
  • the current measuring device 3 is designed to record a current measuring signal at equidistant measuring times.
  • the current measuring device 3 has at least one optical current transformer.
  • the evaluation unit 5 is set up to form a measurement signal vector from the n most recent current measurement signals, where n is a predetermined number of current measurement signals. Furthermore, the evaluation unit 5 is set up to form a Fourier vector which is a discrete Fourier transformation of the measurement signal vector. For this purpose, the evaluation unit 5 is set up to form an updated Fourier vector from the previous Fourier vector by adding to the previous Fourier vector the product of that column of the Fourier matrix which corresponds to the oldest current measurement signal contained in the previous measurement signal vector and the difference between the most recent current measurement signal and the oldest current measurement signal contained in the previous measurement signal vector.
  • the evaluation unit 5 can also be configured to set the components of a Fourier vector that fall below a threshold value to zero.
  • the threshold value is calculated by the evaluation unit 5, for example, as the product of a predetermined factor and an average value of the components of the Fourier vector.
  • FIG. 2 shows a flow chart of an embodiment of the method according to the invention for determining a frequency spectrum of an electric current. The method is carried out using a current analysis device 1 described with reference to Figure 1.
  • a current measurement signal is recorded at n consecutive measurement times using the current measuring device 3.
  • a first measurement signal vector is formed from these current measurement signals by the evaluation unit 5.
  • a first Fourier vector is calculated from this measurement signal vector by the evaluation unit 5 by matrix multiplication with a Fourier matrix.
  • a second method step 12 is carried out.
  • the previous Fourier vector is updated.
  • the evaluation unit 5 forms an updated Fourier vector from the previous (previous) Fourier vector by adding to the previous Fourier vector the product of that column of the Fourier matrix which corresponds to the oldest current measurement signal contained in the previous measurement signal vector and the difference between the current measurement signal recorded in the previous method step 12 (and thus most recent) and the oldest current measurement signal contained in the previous measurement signal vector.
  • the second method step 12 is carried out again.
  • the evaluation unit 5 sets the components of the respective Fourier vector to zero which fall below a threshold value.
  • the threshold value is calculated by the evaluation unit 5, for example, as the product of a predetermined factor and an average value of the components of the Fourier vector.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Mathematical Physics (AREA)
  • Engineering & Computer Science (AREA)
  • Computational Mathematics (AREA)
  • Mathematical Analysis (AREA)
  • Mathematical Optimization (AREA)
  • Pure & Applied Mathematics (AREA)
  • Data Mining & Analysis (AREA)
  • Theoretical Computer Science (AREA)
  • Discrete Mathematics (AREA)
  • Algebra (AREA)
  • Databases & Information Systems (AREA)
  • Software Systems (AREA)
  • General Engineering & Computer Science (AREA)
  • Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)

Abstract

L'invention concerne un procédé de détermination d'un spectre de fréquence d'un courant électrique. Dans le procédé, à des temps de mesure se suivant à équidistance dans le temps, des signaux de mesure de courant respectifs sont capturés. Un vecteur de signal de mesure est formé à partir des n derniers signaux de mesure de courant, n étant un nombre spécifié de signaux de mesure de courant. Un vecteur de Fourier est calculé à partir du vecteur de signal de mesure au moyen d'une matrice de Fourier. Ici, un vecteur de Fourier mis à jour est formé à partir du vecteur de Fourier précédent de la manière suivante : le produit de la colonne de la matrice de Fourier qui correspond au tout premier signal de mesure de courant contenu dans le vecteur de signal de mesure précédent et de la différence entre le tout dernier signal de mesure de courant et le tout premier signal de mesure de courant qui est contenu dans le vecteur de signal de mesure précédent est ajouté au vecteur de Fourier précédent.
PCT/EP2023/077239 2022-10-19 2023-10-02 Détermination d'un spectre de fréquence d'un courant électrique WO2024083490A1 (fr)

Applications Claiming Priority (2)

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DE102022211090.0 2022-10-19
DE102022211090.0A DE102022211090A1 (de) 2022-10-19 2022-10-19 Ermitteln eines Frequenzspektrums eines elektrischen Stroms

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Citations (5)

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Publication number Priority date Publication date Assignee Title
JP2000046899A (ja) * 1998-07-31 2000-02-18 Nec Corp 電源電流のスペクトル観測方法及びその観測装置
CN106885941A (zh) * 2017-03-15 2017-06-23 国网福建省电力有限公司 基于频谱极值点的电网基波频率检测方法
CN113267676A (zh) * 2020-02-14 2021-08-17 武汉市聚芯微电子有限责任公司 格策尔算法下的频谱确定方法、系统、设备及存储介质
KR20210122342A (ko) * 2020-03-30 2021-10-12 한국전력공사 주파수 추정 장치 및 방법
CN114720765A (zh) * 2022-03-15 2022-07-08 贵州师范大学 一种基于态势感知的主动配电网的谐波算法及其控制系统

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Publication number Priority date Publication date Assignee Title
US10359473B2 (en) 2012-05-29 2019-07-23 Nutech Ventures Detecting faults in turbine generators
DE102019103270A1 (de) 2019-02-11 2020-08-13 Beckhoff Automation Gmbh Verfahren zur verteilten elektrischen leistungsbestimmung

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Publication number Priority date Publication date Assignee Title
JP2000046899A (ja) * 1998-07-31 2000-02-18 Nec Corp 電源電流のスペクトル観測方法及びその観測装置
CN106885941A (zh) * 2017-03-15 2017-06-23 国网福建省电力有限公司 基于频谱极值点的电网基波频率检测方法
CN113267676A (zh) * 2020-02-14 2021-08-17 武汉市聚芯微电子有限责任公司 格策尔算法下的频谱确定方法、系统、设备及存储介质
KR20210122342A (ko) * 2020-03-30 2021-10-12 한국전력공사 주파수 추정 장치 및 방법
CN114720765A (zh) * 2022-03-15 2022-07-08 贵州师范大学 一种基于态势感知的主动配电网的谐波算法及其控制系统

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Title
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