US6828771B1
Expired / Lapsed
US
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Electrical power measurement
Assignee: Electric Power Research Ltd
•
Filing: 1999-07-08
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Granted: 2004-12-07
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Expires: 2019-07-08
Abstract
Abstract An electric power meter measures the value of an electrical power parameter, e.g., Universal Apparent Power or Universal Power Factor, of an electrical power signal in the time domain by: calculating a first instantaneous power component as the product of an instantaneous voltage signal and an instantaneous current signal of the electrical power signal, carrying out a relative phase shift between the instantaneous voltage signal and the instantaneous current signal; and calculating a second instantaneous power component as the product of the relatively phase-shifted instantaneous voltage and instantaneous current signals. The first and second instantaneous power components are then RMS averaged to determine their respective magnitudes. Both of the calculated magnitudes are then used to determine the value of the electrical power parameter. The method can alternatively be implemented in the frequency domain to produce equivalent measurement values.
Inventors
- 👤 Foroozan Ghassemi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 12:11
CPC Classifications
G; G01; G01R; G01R21/00; G01R21/133; G01R21/1331
Claims Analysis
Total Claims: 55
Claim 1
Independent Claim
121 words
A method of measuring the value of an electrical power parameter of an electrical power signal, the method comprising: calculating a first instantaneous power component as the product of an instantaneous voltage signal of the electrical power signal and an instantaneous current signal of the electrical power signal; carrying out a relative phase shift between the instantaneous voltage signal and the instantaneous current signal; calculating a second instantaneous power component as the product of the relatively phase-shifted instantaneous voltage and instantaneous current signals; RMS averaging each of the first and second power components to determine their respective magnitudes; and using both of the calculated magnitudes, as determined from the RMS averaging step, to determine the value of the electrical power parameter.
Claim 2
Independent Claim
121 words
A method of measuring the value of an electrical power parameter of an electrical power signal, the method comprising: calculating a first instantaneous power component as the product of an instantaneous voltage signal of the electrical power signal and an instantaneous current signal of the electrical power signal; carrying out a relative phase shift between the instantaneous voltage signal and the instantaneous current signal; calculating a second instantaneous power component as the product of the relatively phase-shifted instantaneous voltage and instantaneous current signals; RMS averaging each of the first and second power components to determine their respective magnitudes; and using both of the calculated magnitudes, as determined from the RMS averaging step, to determine the value of the electrical power parameter.
Claim 3
Dependent Claim
36 words
A method according to claim 1 , wherein the step of carrying out a relative phase shift comprises phase shifting the instantaneous voltage of the electrical power signal prior to calculating the second instantaneous power component.
Claim 4
Dependent Claim
27 words
A method according to claim 1 , wherein the step of carrying out a relative phase shift comprises carrying out a relative phase shift of 90 degrees.
Claim 5
Dependent Claim
41 words
A method according to claim 1 , further comprising determining the Apparent Power of the electrical power signal by calculating the square root of the sum of the squares of the RMS values of the first and second instantaneous power components.
Claim 6
Dependent Claim
66 words
A method according to claim 4 , further comprising: measuring the mean value of the first instantaneous power component to determine the Active Power of the electrical power signal; and calculating the ratio of measured Active Power of the electrical power signal to the measured Apparent Power of the electrical power signal, the value of the ratio being the Power Factor of the electrical power signal.
Claim 7
Dependent Claim
29 words
A method according to claim 1 , further comprising measuring the mean value of the first instantaneous power component to determine the Active Power of the electrical power signal.
Claim 8
Dependent Claim
26 words
A method according to claim 6 , further comprising integrating the Active Power value over time to determine the Energy Consumption of the electrical power signal.
Claim 9
Dependent Claim
28 words
A method according to claim 1 , further comprising measuring the mean value of the second instantaneous power component to determine the Reactive Power of the electrical system.
Claim 10
Dependent Claim
34 words
A method according to claim 1 , further comprising filtering at least one of the instantaneous voltage or instantaneous current signals of the electrical power signal, prior to their use in the calculating steps.
Claim 11
Dependent Claim
31 words
A method according to claim 9 , wherein the filtering step results in the fundamental frequency component of at least one of the instantaneous voltage or instantaneous current signals being obtained.
Claim 12
Dependent Claim
35 words
A method according to claim 9 , wherein the filtering step results in at least one of the harmonic frequency components of at least one of the instantaneous voltage or instantaneous current signals being obtained.
Claim 13
Dependent Claim
43 words
A method according to claim 9 , wherein the filtering step comprises: filtering the instantaneous voltage signal to obtain its fundamental frequency components; and using the filtered instantaneous voltage signal and the unfiltered instantaneous current signal to measure a Network Delivered Power Parameter.
Claim 14
Dependent Claim
67 words
A method according to claim 12 , further comprising comparing the Delivered Power Parameter, the Harmonic Apparent Power Parameter, the Voltage Distortion Power Parameter, or the Current Distortion Power Parameter with another power parameter determined by the method to produce a dimensionless figure of merit representative of the waveform distortion produced, in the electrical power signal, by a load to which the electrical power signal is supplied.
Claim 15
Dependent Claim
50 words
A method according to claim 9 , wherein the filtering step comprises: filtering the instantaneous voltage signal to obtain its fundamental frequency components; filtering the instantaneous current signal to obtain at least one of its harmonic frequency components; and using the filtered signals to determine a Current Distortion Power Parameter.
Claim 16
Dependent Claim
50 words
A method according to claim 9 , wherein the filtering step comprises: filtering the instantaneous voltage signal to obtain at least one of its harmonic frequency components; filtering the instantaneous current signal to obtain its fundamental frequency components; and using the filtered signals to determine a Voltage Distortion Power Parameter.
Claim 17
Dependent Claim
54 words
A method according to claim 9 , wherein the filtering step comprises: filtering the instantaneous voltage signal to obtain at least one of its harmonic frequency components; filtering the instantaneous current signal to obtain at least one of its harmonic frequency components; and using the filtered signals to determine a Harmonic Apparent Power Parameter.
Claim 18
Dependent Claim
34 words
A method according to claim 9 , further comprising: providing two or more different types of filtering; and selecting between these different types of filtering to obtain two or more different electrical power parameters.
Claim 19
Dependent Claim
94 words
A method according to claim 1 , wherein: the electrical power signal is a multiple-phase signal; the calculating steps comprise: calculating a single first instantaneous power component for each of the multiple phases; summing the single first instantaneous components together; calculating a single second instantaneous power component for each of the multiple phases; and summing the single second instantaneous components together; and the RMS averaging step comprises: averaging the summed first instantaneous power components and the summed second instantaneous components; and combining them together to provide the first and second averaged instantaneous power components.
Claim 20
Dependent Claim
17 words
A method according to claim 18 , wherein the electrical power signal comprises an unbalanced multiple-phase signal.
Claim 21
Dependent Claim
17 words
A method according to claim 18 , wherein the electrical power signal comprises a balanced multiple-phase signal.
Claim 22
Dependent Claim
31 words
A method according to claim 18 , further comprising resolving the multiple-phase signal into a phase sequence for use in establishing the effect of a load on an electric power network.
Claim 23
Dependent Claim
34 words
A method according to claim 21 , wherein the phase sequence comprises a positive-phase sequence in order to obtain a measure representative of the power generated at a source of the electrical power signal.
Claim 24
Dependent Claim
53 words
A method according to claim 22 , wherein the phase sequence comprises negative and zero-phase sequences in order to obtain a measure representative of the power converted in the load and the positive, the negative and the zero-phase sequences are used to obtain a measure representative of the power used by the load.
Claim 25
Dependent Claim
30 words
A method according to claim 21 , wherein the phase sequence comprises negative and zero-phase sequences in order to obtain a measure representative of the power converted in the load.
Claim 26
Dependent Claim
17 words
A method according to claim 21 , wherein the resolving step is operatively selectable by a user.
Claim 27
Dependent Claim
33 words
A method according to claim 1 , further comprising converting the instantaneous current signal of the electrical power signal into a proportional voltage representation signal for use in the calculating and averaging steps.
Claim 28
Dependent Claim
44 words
A method according to claim 1 , further comprising converting the instantaneous voltage and instantaneous current signals of the electrical power signal into frequency spectra, and wherein the calculating and averaging steps are implemented in the frequency domain with equivalent frequency spectra processing steps.
Claim 29
Dependent Claim
33 words
A method according to claim 1 , further comprising sampling the instantaneous voltage and instantaneous current signals to obtain a digital representation thereof and using the digital representations in the subsequent processing steps.
Claim 30
Dependent Claim
17 words
A method according to claim 1 , wherein the electrical power signal comprises a non-sinusoidal waveform signal.
Claim 31
Dependent Claim
30 words
A power meter for measuring the value of an electrical power parameter of an electrical power signal, the meter being arranged to implement a method according to claim 1 .
Claim 32
Independent Claim
100 words
A method of measuring an electrical power parameter of an electrical power signal, the method comprising: filtering at least one of an instantaneous voltage signal or an instantaneous current signal of the electrical power signal; using the filtered instantaneous voltage or current signal in: calculating first and second instantaneous power components as the respective products of non phase-shifted/phase-shifted, instantaneous voltage and instantaneous current signals; RMS averaging each of the first and second instantaneous power components to determine their respective magnitudes; and using the calculated magnitudes determined from the RMS averaging step, to determine the value of the electrical power parameter.
Claim 33
Independent Claim
100 words
A method of measuring an electrical power parameter of an electrical power signal, the method comprising: filtering at least one of an instantaneous voltage signal or an instantaneous current signal of the electrical power signal; using the filtered instantaneous voltage or current signal in: calculating first and second instantaneous power components as the respective products of non phase-shifted/phase-shifted, instantaneous voltage and instantaneous current signals; RMS averaging each of the first and second instantaneous power components to determine their respective magnitudes; and using the calculated magnitudes determined from the RMS averaging step, to determine the value of the electrical power parameter.
Claim 34
Dependent Claim
31 words
A method according to claim 31 , wherein the filtering step results in the fundamental frequency component of at least one of the instantaneous voltage or instantaneous current signals being obtained.
Claim 35
Dependent Claim
35 words
A method according to claim 31 , wherein the filtering step results in at least one of the harmonic frequency components of at least one of the instantaneous voltage or instantaneous current signals being obtained.
Claim 36
Dependent Claim
44 words
A method according to claim 31 , wherein the filtering step comprises: filtering the instantaneous voltage signal to obtain its fundamental frequency components; and using the filtered instantaneous voltage signal and the unfiltered instantaneous current signal to measure a Delivered Power Parameter frequency spectrum.
Claim 37
Dependent Claim
72 words
A method according to claim 34 , further comprising comparing one of the group comprising: the Delivered Power Parameter, the Harmonic Apparent Power Parameter, the Voltage Distortion Power Parameter, and the Current Distortion Power Parameter, with another power parameter determined by the method to produce a dimensionless figure of merit representative of the waveform distortion produced, in the electrical power signal, by a load to which the electrical power signal is supplied.
Claim 38
Dependent Claim
50 words
A method according to claim 31 , wherein the filtering step comprises: filtering the instantaneous voltage signal to obtain its fundamental frequency components; filtering the instantaneous current signal to obtain at least one of its harmonic frequency components; and using the filtered signals to determine a Current Distortion Power Parameter.
Claim 39
Dependent Claim
50 words
A method according to claim 31 , wherein the filtering step comprises: filtering the instantaneous voltage signal to obtain at least one of its harmonic frequency components; filtering the instantaneous current signal to obtain its fundamental frequency components; and using the filtered signals to determine a Voltage Distortion Power Parameter.
Claim 40
Dependent Claim
54 words
A method according to claim 31 , wherein the filtering step comprises: filtering the instantaneous voltage signal to obtain at least one of its harmonic frequency components; filtering the instantaneous current signal to obtain at least one of its harmonic frequency components; and using the filtered signals to determine a Harmonic Apparent Power Parameter.
Claim 41
Dependent Claim
34 words
A method according to claim 31 , further comprising: providing two or more different types of filtering; and selecting between these different types of filtering to obtain two or more different electrical power parameters.
Claim 42
Independent Claim
107 words
A method of measuring a power quantity of a multiple-phase electrical power signal, the method comprising: resolving the multiple-phase signal into a phase sequence for use in establishing the effect on the electrical power signal of a load to which the electrical power signal is supplied; using the phase sequence in: calculating first and second instantaneous power components as the respective products of non phase-shifted/phase-shifted, instantaneous voltage and instantaneous current signals; and RMS averaging each of the first and second power components to determine their respective magnitudes; and using the calculated magnitudes determined from the RMS averaging step, to determine the value of the electrical power parameter.
Claim 43
Independent Claim
107 words
A method of measuring a power quantity of a multiple-phase electrical power signal, the method comprising: resolving the multiple-phase signal into a phase sequence for use in establishing the effect on the electrical power signal of a load to which the electrical power signal is supplied; using the phase sequence in: calculating first and second instantaneous power components as the respective products of non phase-shifted/phase-shifted, instantaneous voltage and instantaneous current signals; and RMS averaging each of the first and second power components to determine their respective magnitudes; and using the calculated magnitudes determined from the RMS averaging step, to determine the value of the electrical power parameter.
Claim 44
Dependent Claim
35 words
A method according to claim 40 , wherein the phase sequence comprises a positive phase sequence in order to obtain a measure representative of the power generated at a source of the electrical power signal.
Claim 45
Dependent Claim
54 words
A method according to claim 41 , wherein the phase sequence comprises negative and zero phase sequences in order to obtain a measure representative of the power generated in the load and the positive, the negative and the zero-phase sequences are used to obtain a measure representative of the power used by the load.
Claim 46
Dependent Claim
31 words
A method according to claim 40 , wherein the phase sequence comprises negative and zero phase sequences in order to obtain a measure representative of the power generated in the load.
Claim 47
Dependent Claim
17 words
A method according to claim 40 , wherein the resolving step is operatively selectable by a user.
Claim 48
Dependent Claim
18 words
A method according to claim 40 , wherein the electrical power signal comprises an unbalanced multiple-phase power signal.
Claim 49
Dependent Claim
129 words
An electrical power meter for measuring the value of an electrical power parameter of an electrical power signal, the meter comprising: means for calculating a first instantaneous power component as the product of an instantaneous voltage signal of the electrical power signal and an instantaneous current signal of the electrical power signal; means for implementing a relative phase shift between the instantaneous voltage signal and the instantaneous current signal; means for calculating a second instantaneous power component as the product of the relatively phase-shifted instantaneous voltage and instantaneous current signals; means for RMS averaging each of the first and second power components to determine their respective magnitudes; and means for using the calculated magnitudes determined by the RMS averaging means to determine the value of the electrical power parameter.
Claim 50
Dependent Claim
129 words
An electrical power meter for measuring the value of an electrical power parameter of an electrical power signal, the meter comprising: means for calculating a first instantaneous power component as the product of an instantaneous voltage signal of the electrical power signal and an instantaneous current signal of the electrical power signal; means for implementing a relative phase shift between the instantaneous voltage signal and the instantaneous current signal; means for calculating a second instantaneous power component as the product of the relatively phase-shifted instantaneous voltage and instantaneous current signals; means for RMS averaging each of the first and second power components to determine their respective magnitudes; and means for using the calculated magnitudes determined by the RMS averaging means to determine the value of the electrical power parameter.
Claim 51
Dependent Claim
37 words
A power meter according to claim 46 , wherein the phase shifting means shifts the instantaneous voltage signal of the electrical power signal by 90 degrees prior to the calculating means calculating the second instantaneous power component.
Claim 52
Dependent Claim
35 words
A power meter according to claim 46 , further comprising a step-down voltage means for stepping down the instantaneous voltage signal of the electrical power signal to a level suitable for measurement by the meter.
Claim 53
Dependent Claim
28 words
A power meter according to claim 46 , further comprising a conversion means for converting the instantaneous current signal of the electrical power signal to a representative voltage.
Claim 54
Dependent Claim
34 words
A power meter according to claim 46 , the meter being arranged to calculate several different power parameters and further comprising means for selectively displaying information regarding the values of the calculated power parameters.
Claim 55
Dependent Claim
38 words
A power meter according to claim 46 , further comprising means for sampling the instantaneous voltage and instantaneous current signals to obtain a digital representation thereof and means for using the digital representations in the subsequent processing steps.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2007-12-07 | 2008-06-07 | 2008-12-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2011-12-07 | 2012-06-07 | 2012-12-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2015-12-07 | 2016-06-07 | 2016-12-07 | $7700.00 | Window Closed / Lapsed |