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WO1990012325A1 - Circuit d'echantillonnage - Google Patents

Circuit d'echantillonnage Download PDF

Info

Publication number
WO1990012325A1
WO1990012325A1 PCT/AU1990/000067 AU9000067W WO9012325A1 WO 1990012325 A1 WO1990012325 A1 WO 1990012325A1 AU 9000067 W AU9000067 W AU 9000067W WO 9012325 A1 WO9012325 A1 WO 9012325A1
Authority
WO
WIPO (PCT)
Prior art keywords
sampling
signals
sampling circuit
converter
sequence
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
PCT/AU1990/000067
Other languages
English (en)
Inventor
Evan John Stanbury
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.)
Nokia Services Ltd
STC PLC
Alcatel Lucent NV
Original Assignee
Standard Telephone and Cables Pty Ltd
Alcatel Australia Ltd
Standard Telephone and Cables PLC
Alcatel NV
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 Standard Telephone and Cables Pty Ltd, Alcatel Australia Ltd, Standard Telephone and Cables PLC, Alcatel NV filed Critical Standard Telephone and Cables Pty Ltd
Publication of WO1990012325A1 publication Critical patent/WO1990012325A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R21/00—Arrangements for measuring electric power or power factor
    • G01R21/133—Arrangements for measuring electric power or power factor by using digital technique

Definitions

  • This Invention relates to techniques and equipment for sampling two or more signals and will be described in the context of sampling voltage and current amplitudes in an AC kWh meter.
  • the S/H amplifiers or track/hold circuits thus ensure a fairly constant input to the A/D converter while the conversion takes place, otherwise a random phase error is Introduced in the measurement due to the measurement being taken at an indeterminate time in the measurement period.
  • This specification discloses a technique for sampling two or more signals without the use of a S/H amplifier by measuring the signals sequentially.
  • the random phase error introduced by this procedure is cancelled when averaged over a large number of samples by reversing the order of successive samples.
  • the technique produces a residual amplitude error related to the sine of the phase angle between the samples.
  • This residual error can be eliminated by the standard calibration procedure used to eliminate gain errors due to component variation.
  • Fig. 1 shows a block diagram of a single-phase Ac kWh meter embodying the invention
  • Fig. 2 shows a polyphase embodiment
  • transducers 1 and 2 respectively. These signals may be selected by analog multiplexer 3 under control of processing means 5 (which may in turn be controlled by software). The signal selected by 3 is converted to digital format by A/D converter 4, which is started by processing means 5 at intervals dictated by timing means 7.
  • the processing means 5 first selects the desired analog input and then starts A/D converter 4. On completion of the conversion, the value measured by 4 is read by processing means 5 which may then initiate further conversions by controlling multiplexer 3 and A/D converter 4. Processor 5 performs calculations on the values measured by 4 to derive useful quantities (such as kWh, etc.) from the measured quantities by known means.
  • processing means 5 Since the meter does not contain Sample/Hold amplifiers (S/H) to measure the transducer outputs as a simultaneous pair, the processing means 5 must sequentially read the input signals, introducing a phase error into the measurements. However, processing means 5 may cancel this phase error by taking half of the samples with the voltage followed by the current, and the other half by sampling first the current, then the voltage. In a preferred embodiment, the order is reversed on successive samples.
  • S/H Sample/Hold amplifiers
  • the calculations performed by processing means 5 typically include a factory-settable calibration constant to account for component variations. This invention utilises the same calibration means to correct for the ratio error introduced by non-simultaneous sampling of current and voltage.
  • the calibration constant may be entered via a serial calibration port 8.
  • a successive-approximation A/D converter measuring lowfrequency (50 or 60Hz) signals takes 150us to measure a voltage transducer, with a further 50us delay before starting measurement of the current transducer. This results in a phase error of 3.6° at 50Hz, which would produce a power measurement error of 11 per cent at a phase angle of 60° (and greater errors at larger phase angles or higher frequencies).
  • phase errors in the transducers may be corrected by altering the proportion of samples taken in each order from an exact 50%. In a further embodiment, this proportion may change based on the current being measured, to correct phase errors which are worse at low current, for example.
  • Fig. 2 shows a polyphase application of the invention.
  • a multiplicity of current and voltage transducers labc and 2abc are sequentially sa ⁇ pled using miltiplexer 3.
  • the order of sampling current and voltage in each phase may be alternated to correct for phase errors in sampling.
  • Such an embodiment may be used for a polyphase industrial meter capable of calculating further parameters such as V, I, VAR, VA, harmonic power and phase angle. Sets of measurements may be taken over several cycles with alternating order on successive sets and the necessary calculations are performed on the averaged readings.
  • the invention has been described in relation to AC power measurements, it can also be used in other embodiments such as DC power measurements and AC phase meters.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Current Or Voltage (AREA)
  • Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
  • Analogue/Digital Conversion (AREA)

Abstract

Dans le circuit d'échantillonnage décrit, qui sert notamment à l'échantillonnage d'amplitudes de tension et de courant dans un kilowattheuremètre pour courant alternatif, les signaux provenant de transducteurs (1 et 2) et représentant les amplitudes de tension et de courant respectivement sont appliqués sélectivement à un convertisseur analogique/numérique (4) au moyen d'un multiplexeur analogique (3) sous la commande d'un processeur (5), lequel fait varier la séquence dans laquelle les signaux sont appliqués au convertisseur. Le processeur effectue des calculs sur les valeurs mesurées par le convertisseur afin de déduire le nombre de kWh.
PCT/AU1990/000067 1989-04-04 1990-02-22 Circuit d'echantillonnage Ceased WO1990012325A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
AUPJ347189 1989-04-04
AUPJ3471 1989-04-04
AU51574/90A AU5157490A (en) 1989-04-04 1990-02-22 A sampling circuit

Publications (1)

Publication Number Publication Date
WO1990012325A1 true WO1990012325A1 (fr) 1990-10-18

Family

ID=25629293

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU1990/000067 Ceased WO1990012325A1 (fr) 1989-04-04 1990-02-22 Circuit d'echantillonnage

Country Status (3)

Country Link
EP (1) EP0465476A4 (fr)
AU (1) AU5157490A (fr)
WO (1) WO1990012325A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0607257A4 (fr) * 1991-10-08 1994-10-12 K C Corp Compteur de consommation en puissance electrique a semi-conducteur et procede de determination de la consommation en puissance.
EP0564095B1 (fr) * 1992-04-03 1997-09-10 Sanyo Electric Co., Ltd. Détecteur du courant de charge
WO1997039363A1 (fr) * 1996-04-16 1997-10-23 Teijo Miettinen Appareil de mesure de la consommation electrique

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1551076A (en) * 1975-08-21 1979-08-22 Heliowatt Werke Electrical polyphase power meter
GB1575148A (en) * 1976-07-07 1980-09-17 Heliowatt Werke Electrical energy meters
GB1575289A (en) * 1977-05-09 1980-09-17 Heliowatt Werke Compensating for time errors in measuring devices employing analog-stochastic converters
GB2157448A (en) * 1984-04-10 1985-10-23 Yu Chen Watt-hour meter
WO1986003301A1 (fr) * 1984-11-20 1986-06-05 Tee A/S Total Electronic Enterprise Appareil electrique statique de mesure de la comsommation de la puissance et de l'energie fournies par un reseau d'alimentation
DE3620484A1 (de) * 1985-06-19 1987-01-02 Mitsubishi Electric Corp Verfahren zum messen der einer last gelieferten elektrischen energie
EP0267693A1 (fr) * 1986-10-17 1988-05-18 THE GENERAL ELECTRIC COMPANY, p.l.c. Appareil de mesure pour puissance électrique

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2550282C2 (de) * 1975-11-08 1983-09-01 Brown, Boveri & Cie Ag, 6800 Mannheim Leistungs- und Arbeitsmeßverfahren
FR2468129A1 (fr) * 1979-10-24 1981-04-30 Enertec Procede et dispositif de mesure de puissance electrique

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1551076A (en) * 1975-08-21 1979-08-22 Heliowatt Werke Electrical polyphase power meter
GB1575148A (en) * 1976-07-07 1980-09-17 Heliowatt Werke Electrical energy meters
GB1575289A (en) * 1977-05-09 1980-09-17 Heliowatt Werke Compensating for time errors in measuring devices employing analog-stochastic converters
GB2157448A (en) * 1984-04-10 1985-10-23 Yu Chen Watt-hour meter
WO1986003301A1 (fr) * 1984-11-20 1986-06-05 Tee A/S Total Electronic Enterprise Appareil electrique statique de mesure de la comsommation de la puissance et de l'energie fournies par un reseau d'alimentation
DE3620484A1 (de) * 1985-06-19 1987-01-02 Mitsubishi Electric Corp Verfahren zum messen der einer last gelieferten elektrischen energie
EP0267693A1 (fr) * 1986-10-17 1988-05-18 THE GENERAL ELECTRIC COMPANY, p.l.c. Appareil de mesure pour puissance électrique

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP0465476A4 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0607257A4 (fr) * 1991-10-08 1994-10-12 K C Corp Compteur de consommation en puissance electrique a semi-conducteur et procede de determination de la consommation en puissance.
US5391983A (en) * 1991-10-08 1995-02-21 K C Corp. Solid state electric power usage meter and method for determining power usage
US5548209A (en) * 1991-10-08 1996-08-20 Kc Corporation Solid state electric power usage meter and method for determining power usage
EP0564095B1 (fr) * 1992-04-03 1997-09-10 Sanyo Electric Co., Ltd. Détecteur du courant de charge
WO1997039363A1 (fr) * 1996-04-16 1997-10-23 Teijo Miettinen Appareil de mesure de la consommation electrique

Also Published As

Publication number Publication date
AU5157490A (en) 1990-11-05
EP0465476A4 (en) 1992-07-08
EP0465476A1 (fr) 1992-01-15

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