WO2015070345A1 - Technique de mesure simultanée pour courant de phase, courant induit géomagnétiquement (gic) et courants transitoires dans des réseaux électriques - Google Patents

Technique de mesure simultanée pour courant de phase, courant induit géomagnétiquement (gic) et courants transitoires dans des réseaux électriques Download PDF

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Publication number
WO2015070345A1
WO2015070345A1 PCT/CA2014/051082 CA2014051082W WO2015070345A1 WO 2015070345 A1 WO2015070345 A1 WO 2015070345A1 CA 2014051082 W CA2014051082 W CA 2014051082W WO 2015070345 A1 WO2015070345 A1 WO 2015070345A1
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WO
WIPO (PCT)
Prior art keywords
current
core
voltage
secondary winding
induced
Prior art date
Application number
PCT/CA2014/051082
Other languages
English (en)
Inventor
Udaya ANNAKKAGE
Chithra Kirthi Gamini PIYADASA
Aniruddha GOLE
Shaahin FILIZADEH
Athula RAJAPAKSE
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The University Of Manitoba
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 The University Of Manitoba filed Critical The University Of Manitoba
Publication of WO2015070345A1 publication Critical patent/WO2015070345A1/fr

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Classifications

    • 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
    • G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
    • G01R19/2513—Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging
    • 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
    • G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
    • G01R15/183—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using transformers with a magnetic core
    • 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
    • G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
    • G01R15/183—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using transformers with a magnetic core
    • G01R15/185—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using transformers with a magnetic core with compensation or feedback windings or interacting coils, e.g. 0-flux sensors

Definitions

  • the present invention relates to a method of measuring alternating line current, geomagnetically induced currents, or transient pulses in a power line of a power system.
  • CT Current transformers
  • ac alternative current
  • GIC Geomagnetically induced currents
  • the newly invented system can measure line currents, fault currents, and
  • the newly proposed system can measure both current and voltage transients up to several MHz. This will lead to fast identification of fault location and in turn reducing the risk of damage to the power system enabling better protection systems to be employed.
  • the proposed system can be incorporated into the proposed line current and GIC measurements in power systems.
  • a novel aspect of the present invention is the ac current to be measured is not converted into another ac current, but instead the rate of change of flux is measured when the flux wave is crossing the zero (or reversal of flux direction inside the magnetic core). This happens twice in each cycle when the core has come out of saturation. So, even if the core is saturated, it comes out of saturation and crosses zero twice in each cycle. Voltage pulses are produced at these instances as a result of time derivative of magnetic flux inside the core and we measure the strength of these voltage pulses to determine the primary current.
  • the peak amplitude of differential waveform (when the magnetic flux in the core reverses its direction) is used to measure the amplitude of the alternative current (AC).
  • DC is injected into another winding around the magnetic core to eliminate the time difference between measured peaks.
  • the GIC is then determined from the injected current.
  • the magnetic core used to measure AC and/or DC can be in any current carrying section (live or neutral) of the electric circuit.
  • the induced transient of the secondary of the said magnetic core is used, independent of the saturation of the magnetic core, to measure the transient occurring in the power lines.
  • the said magnetic core is thus used to simultaneously measure, line current, geomagnetically induced current, and transients occurring in any electrical system from its induced voltage in secondary coil wound with any number of turns in the said magnetic core.
  • the line current is measured using a conventional CT.
  • GIC induced DC currents
  • GIC direct measuring system
  • This proposed system provides simultaneous measurements of both AC and DC under normal and fault conditions at very high resolutions.
  • the materials are readily available inexpensive ferrite materials. The size and weight is also greatly reduced compared to the present CTs.
  • Measurement of any type of current waveforms is very useful for monitoring power systems. This will help to identify type fault conditions, interferences for protection of power systems.
  • the measurements using the time tag at zero crossing when magnetic flux reversal in the magnetic core as in this invention with high magnetic permeability and low saturation shows promising results for possibility of measuring any kind of wave shape with integrated noise.
  • a method of measuring characteristics of an alternating line current of a power line in an electrical power system comprising:
  • a current sensor having a core comprising an annular body receiving the power line therethrough and a secondary winding extending about a portion of the annular body in which the core has a high magnetic permeability and a low saturation level relative to the line current, and in which the secondary winding is either open or connected to a high impedance;
  • the method further comprises: providing an auxiliary winding extending about a portion of the annular body of the core of the current sensor;
  • the method of the preferred embodiment further comprises: removing the repeating peak magnitudes from the monitored induced voltage;
  • a line current having a dc component superimposed on an alternating current in a power line in an electrical power system comprising:
  • a current sensor having a core comprising an annular body receiving the power line therethrough, a secondary winding extending about a portion of the annular body, and an auxiliary winding extending about a portion of the annular body in which the core has high magnetic permeability and a low saturation level relative to the line current, and in which the secondary winding is either open or connected to a high impedance;
  • monitoring a voltage induced in the secondary winding by an alternating current in the power line by identifying a first duration between a first initial peak magnitude of the induced voltage and a second initial peak magnitude of the induced voltage which is consecutive and opposing in relation to the first initial peak magnitude;
  • a method of measuring characteristics of a direct current of a power line in an electrical power system comprising:
  • a current sensor having a core comprising an annular body receiving the power line therethrough, a secondary winding extending about a portion of the annular body, and an auxiliary winding extending about a portion of the annular body in which the core has a high magnetic permeability and a low saturation level relative to the line current, and in which the secondary winding is either open or connected to a high impedance;
  • a method of measuring transient pulses in a line current of a power line in an electrical power system comprising:
  • a current sensor having a core comprising an annular body receiving the power line therethrough and a secondary winding extending about a portion of the annular body in which the core has a high magnetic permeability and a low saturation level relative to the line current, and in which the secondary winding is either open or connected to a high impedance;
  • the method may further include providing a current sensor in which the core is arranged to be in a region of magnetic saturation relative to the line current. More preferably, the current sensor may have a core which comprises ferrite.
  • the method in each instance further includes monitoring a voltage induced in the secondary winding by taking measurements as a time signature when magnetic flux reverses direction, or as a time derivative of a reversal of magnetic flux in the core.
  • Figure 1 is a schematic representation of a first embodiment of the current sensor shown with single ferrite core and an electromotive force sensing winding around the core.
  • Figure 2 is a graphical representation of the relationship between the magnetic fiux B and the magnetizing field H.
  • Figure 3 is a graphical representation of the variation of current / ' or magnetizing force H over time in curve 1 and the resultant magnetic flux in the core over time in curve 2.
  • Figure 4a is a graphical representation of the waveform of the input sinusoidal current and the voltage induced on the sensing coil.
  • Figure 4b is an enlarged view of the highlighted portion of one of the curves shown in Figure 4a.
  • Figure 5 is a graphical representation of the relationship between the peak of the sensing winding voltage and the primary current.
  • Figure 6a shows the sensing coil voltage, which is proportional to the time derivative of flux density B, for AC current without any super imposed DC component.
  • Figure 6b shows the same when there is a DC current superimposed on the AC current.
  • Figure 7 is a schematic representation of a second embodiment of the current sensor for geomagnetically induced current measurements.
  • Figure 8 is a schematic representation of a third embodiment of the current sensor for transient measurements.
  • Figure 9 shows a 60 Hz current waveform with two transients superimposed on it.
  • Figures 10a through 10c show the waveforms of four measurements for three different voltage/current pulse widths (1 s, 10 s, 100 ⁇ ). More particularly, in each waveform, CH4 (green curve) is the exciting pulse, CH. 1 (yellow curve) is the voltage at the load, CH. 3 (purple curve) is the output obtained from a Rogowski coil that is conventionally used for the transient measurement, and CH.2 (blue curve) is the voltage induced on the sensing coil of the proposed sensor.
  • Figure 11 is a schematic representation of the circuit used for the measurements represented in Figure 10.
  • Figure 12 is a schematic representation of an embodiment of the present invention comprising an integrated sensor capable of measuring AC, DC, and transients.
  • the current sensor consists of a single ferrite core and an electromotive force (EMF) sensing winding around the core as shown in Fig. 1 .
  • Ferrite is used because of its high magnetic permeability and low saturation level.
  • the EMF v is induced [ref 1] in terminals of the sensing winding when the current flows in the primary circuit passing through the ferrite core.
  • CT is designed to operate in the magnetically non-saturated region.
  • CTs are usually made of high permeability iron alloy and the size and the weight depend on the current capacity of the power system.
  • ferrtte is used as a medium which is comparatively light in weight to the iron and the operational region of the ferrite is by design kept in the region of the magnetic saturation [ref 2,3]. Therefore, the physical size and the weight of the core are greatly reduced compared to the conventionally used ion core CTs.
  • ⁇ is the permeability of the ferrite material
  • n 1 in the number of turns and / is the mean length of the core.
  • the sensing winding induces an emf at its output terminals and connected to high impedance input terminals of a data acquisition system (DAQ).
  • DAQ data acquisition system
  • Induced voltage v in sensor winding is proportional to the rate of change of magnetic flux linkage, ( ⁇ ) (Faraday's second law) [ref 1 ].
  • n ⁇ is the number of turns of the sensor winding and A is the cross section area of the magnetic core. If the primary current is sinusoidal, the maximum change of the flux density B in cores occur when the flux curve cross the zero flux axis (Eq. 2 and Fig. 5).
  • the variation of the flux density B is no longer sinusoidal, and has the shape illustrated in Fig. 3.
  • the core operates in the regions close to a or d in Fig.2, thus the variation of the flux density B is small.
  • the induced voltage v which is proportional to dB/dt, remains small.
  • the core operates around the regions b and e in Fig. 2.
  • the magnetic flux density B in the core changes polarity within a short period of time.
  • the magnitude of the voltage induced on the sensing coil v is high.
  • the value of the induced voltage v is proportional to i max and can be used as a measurement of the magnitude of current /.
  • Fig. 4a The waveforms of the input sinusoidal current and the voltage induced on the sensing coil are shown in Fig. 4a.
  • An enlarged view of the peak of the induced voltage is shown in Fig. 4b.
  • the sensing coil voltage v is measured using a real time data acquisition system, it is possible to relate the peak values of the measured voltages with the corresponding primary current in the conductor passing through the core, with the assistance of a calibration curve.
  • the peak of the measured voltage v, and thereby the sensitivity of measurement can be easily controlled by the number of turns of the sensor winding. The number of turns can be increased to increase the sensitivity with negligible effect on the primary system because the current in the sensing winding is nearly zero.
  • the relationship between the peak of sensing winding voltage and the primary current (rms) is shown in Fig. 5 for a particular ferrite core. The range of primary currents is from 100 A to 2000A.
  • GIC Geomaqneticallv induced current
  • the current waveform sifts upwards (assuming positive DC current in this case) and the zero crossing points of the AC current is shifted to the negative half cycle, causing the time difference between the adjacent positive and negative peaks in the induced voltage to become asymmetrical as in Fig. 6b. If ti is the time difference between negative and positive peaks (in that order) when there is no DC component, addition of a positive DC component into the current alters the time between the same peaks to fc.
  • Fig. 6a shows practical values of 40AAC through the ferrite core and 6b show DC 20A superposition on the AC.
  • ti is a constant frequency sinusoidal current
  • Addition of DC current, laic to the AC current changes the time difference ti according to the polarity of the DC component.
  • This change of ti can be recognized using a suitable software through the DAQ (Fig. 7) and devise a feedback controller to inject an appropriate reverse current iac/rev via a digitally programmable current source to neutralize the magnetic field caused by the ieic.
  • the magnitude of the neutralizing current, ieic/rev is then proportional to the DC component in the primary current, hie. 3) Transient measurements
  • the bandwidth of conventional current and voltage transformers used in high voltage power systems is limited and therefore, they are not suitable for transient measurements required for applications such as travelling wave based transmission line protection and fault location. Such applications require detection of high frequency (>100 kHz) transient signals superimposed on power frequency currents and voltages.
  • the new transient sensor uses the same arrangement as described in the previous sections and shown in Fig. 8. The core is designed to saturate under the normal AC current. The sensor uses the open circuit voltage induced in the sensing winding as the transient detection signal.
  • Fig. 9 shows a 60 Hz current waveform (yellow curve) with two transients super imposed on it.
  • the sudden change of current / due to transient change the magnetic field H in the ferrite core.
  • a small change in the magnetic flux density B occurs, as the B-H characteristics never become flat.
  • the rate of change of B is high as the change is occurring in a short time. Therefore, a voltage pulse with a significant magnitude is induced on the sensing coil and that can be used to detect the occurrence of the transient. This induced voltage is shown by the light blue curve in Fig. 9. Note that the pulse due to transient is much sharper and larger than those occurring at the zero crossing of the 60 Hz current waveform.
  • Fig. 11 The circuit used for measurements is shown in Fig. 11. in Fig, 10, CH4 (green curve) is the exciting pulse, CH. 1 (yellow curve) is the voltage at the load, CH. 3 (purple curve) is the output obtained from a Rogowski coil that is conventionally use for the transient measurement, and CH.2 (blue curve) is the voltage induced on the sensing coil of the proposed sensor.
  • Fig. 10.1-3 shows the waveforms of above four measurements for three different voltage/current pulse widths (1 ps, 10 ps, 100 ps). The measurement bandwidth of the sensor will be limited by the self-inductance of the sensing coil that depend on the core material and the number of turns of the sensing coils.
  • the advantages in transient detection using a ferrite core are its wider frequency response compared to conventional iron cores and the higher output signal amplitudes compared to air core CTs such as Rogowski coils.
  • CTs with ferrite cores are used as internal CTs in instrumentation, they are expected to operate in unsaturated region.
  • the new sensor is expected to operate independent of magnetic saturation by design.
  • the proposed sensor can be used to detect the transients in current signals.
  • the high frequency transients in a power network are generated by events such as faults, switching actions, or lighting, and in most occasions, the current transient is associated with a corresponding voltage transient. Therefore, measurement of current transients indirectly allows detection of voltage transients as well.
  • Fig. 12 The final arrangement of an integrated sensor capable of measuring AC, DC, and transients is shown in Fig. 12.
  • the detection voltage v is processed to remove repetitive voltage peaks at the zero crossings of the 60 Hz signal.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)

Abstract

Selon la présente invention, des caractéristiques d'un courant de phase d'une ligne électrique dans un réseau électrique sont mesurées à l'aide d'un capteur de courant ayant un noyau comprenant un corps annulaire recevant la ligne électrique à travers ce dernier et un enroulement secondaire s'étendant autour d'une partie du corps annulaire dans lequel le noyau présente une perméabilité magnétique élevée et un niveau de saturation faible par rapport au courant de phase. Tout en surveillant une tension induite dans l'enroulement secondaire, une amplitude de pic de répétition de la tension induite, résultant d'une inversion de flux magnétique dans le noyau, est identifiée et associée à un courant alternatif primaire dans la ligne électrique. Ainsi, le courant CA à mesurer n'est pas converti en un autre courant CA, mais plutôt le taux de changement de flux est mesuré lorsque l'onde de flux passe par le point zéro.
PCT/CA2014/051082 2013-11-12 2014-11-10 Technique de mesure simultanée pour courant de phase, courant induit géomagnétiquement (gic) et courants transitoires dans des réseaux électriques WO2015070345A1 (fr)

Applications Claiming Priority (2)

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US201361902905P 2013-11-12 2013-11-12
US61/902,905 2013-11-12

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WO2015070345A1 true WO2015070345A1 (fr) 2015-05-21

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109212300A (zh) * 2017-06-30 2019-01-15 日置电机株式会社 电流检测装置及测定装置
US11404861B2 (en) 2020-08-28 2022-08-02 The Mitre Corporation System and methods for mitigating ground induced currents on commercial power infrastructure

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5811965A (en) * 1994-12-28 1998-09-22 Philips Electronics North America Corporation DC and AC current sensor having a minor-loop operated current transformer
US6078172A (en) * 1996-05-06 2000-06-20 Vacuumschmelze Gmbh Current-compensated current sensor for hysteresis-independent and temperature-independent current measurement
US6927563B2 (en) * 2001-10-02 2005-08-09 Abb Patent Gmbh Method and device for current value determination using a current transformer which operates in the core saturation region
US7071678B2 (en) * 2003-07-03 2006-07-04 Danaher Motion Stockholm Ab Low power consuming current measurements for high currents
US7432699B2 (en) * 2003-06-27 2008-10-07 Forskarpatent I Syd Ab Transformer with protection against direct current magnetization caused by zero sequence current
US8217642B2 (en) * 2008-06-20 2012-07-10 Vacuumschmelze Gmbh & Co. Kg Current sensor arrangement for measurement of currents in a primary conductor
CN102944853A (zh) * 2012-10-18 2013-02-27 华中科技大学 一种利用噪声驱动的磁通门传感器精密测量磁场的方法

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5811965A (en) * 1994-12-28 1998-09-22 Philips Electronics North America Corporation DC and AC current sensor having a minor-loop operated current transformer
US6078172A (en) * 1996-05-06 2000-06-20 Vacuumschmelze Gmbh Current-compensated current sensor for hysteresis-independent and temperature-independent current measurement
US6927563B2 (en) * 2001-10-02 2005-08-09 Abb Patent Gmbh Method and device for current value determination using a current transformer which operates in the core saturation region
US7432699B2 (en) * 2003-06-27 2008-10-07 Forskarpatent I Syd Ab Transformer with protection against direct current magnetization caused by zero sequence current
US7071678B2 (en) * 2003-07-03 2006-07-04 Danaher Motion Stockholm Ab Low power consuming current measurements for high currents
US8217642B2 (en) * 2008-06-20 2012-07-10 Vacuumschmelze Gmbh & Co. Kg Current sensor arrangement for measurement of currents in a primary conductor
CN102944853A (zh) * 2012-10-18 2013-02-27 华中科技大学 一种利用噪声驱动的磁通门传感器精密测量磁场的方法

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109212300A (zh) * 2017-06-30 2019-01-15 日置电机株式会社 电流检测装置及测定装置
CN109212300B (zh) * 2017-06-30 2021-10-08 日置电机株式会社 电流检测装置及测定装置
US11404861B2 (en) 2020-08-28 2022-08-02 The Mitre Corporation System and methods for mitigating ground induced currents on commercial power infrastructure

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