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
  • G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
  • G01R15/181—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using coils without a magnetic core, e.g. Rogowski coils
• • 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
  • G01R19/2506—Arrangements for conditioning or analysing measured signals, e.g. for indicating peak values ; Details concerning sampling, digitizing or waveform capturing

Definitions

• a Rogowski coil sensor 12 is shown in FIG. L
• the flexi e coil IZ n be clamped around a current carr ing conductor 10 without interrupting the conductor circuii, Is- linear over all practical current ranges, and forms therefore an attractive -.current sensor solution in the AC power dusfry; With the AO line ; centered In the coil 12, the produce voltage fe ' is: ⁇ ⁇ « A dl
• FIG. ⁇ shows an example of am integrator 1 coupled to coil 12 at terminal 16 with basic harmonic transfer function:
• Integrator 1 widi the shown coniponenr values is an inadequate solution when accurate phase information is required-
• the ⁇ 3 ⁇ 4i3 ⁇ 4 ' -' product at 60 Hz is only about L2 resulting in Infeg aior 14 haying a substantial Undesirable phase : shift at the- line frequency.
• the desired phase shift of 90 degrees is obtained with. removing R i so that the transfer function btains the pure integrator form;
• An integrator circuit for a eorrent sensor includes an integrator having an input for receiving a signal from a current sensor and havrag i output providing voltage signal,
• a high-pass fi lter has an input coupled to the output of the integrator and has an output, and the high-pass filter, substantiatly removes a DC content from the voltage ssg l,
• a feedback loop has ah input coupled to the output of the integrator and to the ontpot of the high-pass,fi
• FIG. 1 is a diagram of a prior art integrating preamplifier for a ogowski coil sensor
• FIG, 2 is a diagram of an in tegrator circuit for a Rogo wski coil sensor
• FIG.. 3 is a . raph ⁇ ⁇ . ⁇ 3 ⁇ 4ttfl fin ⁇ ⁇ 3 ⁇ 4 ⁇ - e ⁇ 3 ⁇ 4 ⁇ 3 ⁇ 4d by a:3 ⁇ 4tir. «M:-ti3 ⁇ 4nsi[3 ⁇ 4riner and-lhe- integrator circuit of FIG. 2;
• FIG. A. i is a graph of tire: amplitude response: of the integrator circuit of FIG, 2;
• FIG. 5 is a graph of the phase response of the integrato circuit of FIG, 3 ⁇ 4 and
• FIG 6 is . graph of the tine ste current and impulse response .of the integrator circuit of FIG. 2.
• Rogo.wski coil sensors are routinely used to monitor or measure 6d Hz line: currents in the AC: power grid. Developments in fee smart grid inft trneture will require vast deployment of these sensors.
• Roge wsk sensors are coraroereialiy available i»d require a preamplifier to bring the coil amplitude to an acceptabl level Generally-, a Rogo ski coil roduces roughly 25 ⁇ per ampere of line current, too weak to he directly nsefaif r processing electronics that prefer an amplilkation of about TmV/ ' A,
• FIG, 2 is a diagram of an integrator circuit 20 solution containing three QPAMPs (operational
• OPAMF 21 is followed by a passive first Order high-pass filter, forme by capacitor Ci and resistor Rz, having an input receiving the signal s and : hav1 ⁇ 2g an output delivering, a DC free version: of t 3 ⁇ 4 integrated signal to the r Iri iit of the second 0P AMP 22 serving as a voltage follower and - having an output (26;) providing the signal 3 ⁇ 4.
• the high-pass filter can.
• Integrator eirctut 20 receives a signal from a R gowslq coil sensor, or other e rien sensor, a terminal 16 and presides an output signal » «t at ' terminal.24.
• Circuit 2 ⁇ ⁇ outputs a signal at terminal 24 related to the signal from the current sensor, for example a . .decaying ringing signal in response to a large eurrest:ste in ' :tfce : ltifl& ' -c3 ⁇ 4ii4w ⁇ tor momtofeitf bf : th& current sensor.
• Circuit 20 at output terminal 24 can foe coupled to an analog-to-digita! converter in order to,prO ⁇ signal to a necessor 13 ⁇ 4f use in smart grid infrastructure monitoring such as line fault analysis, for example, Circuit 20 can also be used to monitor and detec tine faults in three-phase cables.
• circuit 20 The performance of circuit 20 is show in El@, comparing..a -line current Kj as!ure y- t-curresn ⁇ ansfQrmer (H mnniiqyjd CT5 : 0QA) and by integrato circuit 20 in ! C i. 2.
• the potentiometer Rt variable resisior in eireuit 29 adjusted to a 1 3 ⁇ 43 ⁇ 43 ⁇ 4 amplification, the traces in FIG, 3 show almost perfect correspondence with a minute and generally acceptable phase difference,.
• the foll win provides: harmonic anal sis of the operation of circuit 20. If the non-inverting input voltage V+
• Equation (l ) is that of ah ideal integrato 1 with a pole at DC or ote realistically at a very low frequency with extremely high amplification, i the primary application forms an integrator for a 60 Hz signal, as in this exemplary case , then: the integration of low frequenc noise . results in a slowly varying drift: with, large amplitude that becomes a nuisance. Thisinuisance can he avoided by occasionally resetting the integrato ' DC state or by limiting the amplification at. low f equencies that are not of interest.
• one remedy involves occasionall discharging the capacitor C i b shorting it through a OSFET, effective but not the most elegant solution.
• Another ⁇ comm n . emedy t limit the amplification at low frequencies is to place a large feedback
• Equatin voltage to voltage through direct feedback as shown in circuit 20, and combinin eq tions ) ⁇ (33, . and (6):
• equation ⁇ 7 ⁇ approaches an id ⁇ 3 ⁇ 4a! integrator if ⁇ % » ti said a result reveals seif lf the total integrator transfer function is derived:
• Circuit 20 requires a low noise environment, especially near 1 ⁇ 2, hich fo a monochromatic ⁇ O Ife line signal can be comfortabl assumed.
• circuit 20 can be corhpared against a first order fitter eircoit formed by placing- resistor Rt across capacitor Ci, Syeh comparison will demonstrate the benefits of circuit 20 with an extremely sharp transition from differentiation t integration extending over only a few hertz bandwidth.
• the frec eneies an and ⁇ 3 ⁇ 43 ⁇ 4 are evaluated as complex ic nfa aiesi
• Eqriation (.1.7) is a very good approximation when
• I®:. 6 is a g Sph. of die line current step, response of circuit 20, sliowihg an actual Mne current step of 2S0 A and the resulting, integrator circuit 20 ringing .res onse,
• Qmer component values can be used dependin upon, for example, a ⁇ ' particular' ap licati n of circuit 2( ) ,
• the components- can e directi coupled or coupled through other components ..for electrical, eonimunicati on among thern.
• the terru input to componen can Include single input. r multiple inputs.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Measurement Of Current Or Voltage (AREA)
• Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
• Measurement Of Resistance Or Impedance (AREA)

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• 2015
  • 2015-02-04 US US14/613,589 patent/US9588147B2/en active Active
• 2016
  • 2016-01-18 CA CA2975688A patent/CA2975688A1/en not_active Abandoned
  • 2016-01-18 EP EP16746949.3A patent/EP3254123A4/en not_active Withdrawn
  • 2016-01-18 JP JP2017541065A patent/JP2018504605A/ja not_active Ceased
  • 2016-01-18 CN CN201680008654.6A patent/CN107209211B/zh not_active Expired - Fee Related
  • 2016-01-18 WO PCT/US2016/013783 patent/WO2016126406A1/en not_active Ceased
  • 2016-01-18 KR KR1020177023853A patent/KR20170110103A/ko not_active Withdrawn

Patent Citations (5)

Non-Patent Citations (1)

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