WO2001055733A1 - System and method for digitally compensating frequency and temperature induced errors in amplitude and phase shift in current sensing of electronic energy meters - Google Patents

System and method for digitally compensating frequency and temperature induced errors in amplitude and phase shift in current sensing of electronic energy meters Download PDF

Info

Publication number
WO2001055733A1
WO2001055733A1 PCT/US2000/001663 US0001663W WO0155733A1 WO 2001055733 A1 WO2001055733 A1 WO 2001055733A1 US 0001663 W US0001663 W US 0001663W WO 0155733 A1 WO0155733 A1 WO 0155733A1
Authority
WO
WIPO (PCT)
Prior art keywords
phase shift
degrees
value
shift value
processor
Prior art date
Application number
PCT/US2000/001663
Other languages
French (fr)
Inventor
Edward John Beroset
Richard William Blasco
Rodney Hemminger
Peter W. Heuel
Scott Turner Holdsclaw
Konstantin Zh. Lobastov
Stig Leira
Valentin Suta
Original Assignee
Abb Automation Inc.
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 Abb Automation Inc. filed Critical Abb Automation Inc.
Priority to PCT/US2000/001663 priority Critical patent/WO2001055733A1/en
Publication of WO2001055733A1 publication Critical patent/WO2001055733A1/en

Links

Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R22/00Arrangements for measuring time integral of electric power or current, e.g. by electricity meters
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R21/00Arrangements for measuring electric power or power factor
    • G01R21/14Compensating for temperature change
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R21/00Arrangements for measuring electric power or power factor
    • G01R21/133Arrangements for measuring electric power or power factor by using digital technique

Abstract

The phase shift in an electronic energy meter is compensated for by obtaining temperature (100) and frequency (200) readings in the meter and using these readings in a digital signal processor (DSP) (14) residing within the electronic energy meter. The frequency and temperature compensation is performed to each phase calibration and the result is stored in the DSP. To reduce the possible influence of noise in the system, the compensated DSP values are filtered (120) to provide a smoothing of the data.

Description

SYSTEM AND METHOD FOR DIGITALLY COMPENSATING FREQUENCY

AND TEMPERATURE INDUCED ERRORS IN AMPLITUDE AND PHASE

SHIFT IN CURRENT SENSING OF ELECTRONIC ENERGY METERS

FIELD OF THE INVENTION

The present invention relates in general to the field of utility meters. More particularly, the present invention relates to systems and methods for temperature-dependent and frequency-dependent phase shift compensation of low permeability current sensors in electronic energy meters.

BACKGROUND OF THE INVENTION

Programmable electronic energy meters are rapidly replacing electro-mechanical meters due to the enhanced functionality achieved using programmable logic integrated into solid-state electronic meters. Some of these meters can be used to meter various different electrical services without hardware modification. For example, meters having a voltage operating range between about 98 Vims and about 526 Vims are capable of operation with either 120 V or 480 V services. U.S. Patent No. 5,457,621, dated October 10, 1995, entitled SWITCHING POWER SUPPLY HAVING VOLTAGE BLOCKING CLAMP, assigned to ABB Automation Inc. discloses examples of such meters. In addition, some meters are constructed for use with any 3 -wire or any 4- wire service, also disclosed in U.S. Patent No. 5,457,621.

Electronic energy meters are instruments that measure the flow of energy. Electronic energy meters typically do this by sensing the current and voltage. The power is derived from the sensed currents and voltages, and energy is defined as the measurement of power over time.

Voltage and current signals are primarily sinusoidal. Voltage and current sensors are used in a meter to convert the primary signals to a signal that can be processed. One type of current sensor commonly used in electronic meters is a current transformer. In an ideal current transformer the secondary current is equal to the primary current divided by the turns ratio. In practice, current tran formers are non-ideal, having losses in the burden, the copper wire in the windings, and the core itself. These characteristics result in amplitude and phase deviations as compared to an ideal current transformer. The current transformer' s phase shift is predominately determined by the inductance, the winding resistance, and the burden resistance. The current transformer essentially behaves as a high pass filter with the inductance and the sum of the winding and burden resistances setting the break frequency. In order to reduce this phase shift error, electronic energy meters typically use core materials having a very high relative permeability to obtain a high inductance. It is not uncommon for a core's relative permeability to be as high as 100,000 in order to achieve phase shifts of less than 0.1 degrees.

In some markets, it is desired for meters in direct-connected applications to be accurate even in the presence of significant half-wave rectified currents. An example of this can be found in the IEC-1036 requirements. As a half-wave rectified waveform has significant DC content, it is necessary for current sensors in such meters to be sufficiently immune to DC in the primary current. High permeability cores become saturated quickly in the presence of DC current and hence have limited application with this requirement.

For current transformers, immunity from DC current can be improved by increasing core area, by selecting alternative core materials that have a higher saturation level, and by lowering the relative permeability of the core material. In general, increasing the core geometry is limited due to cost and space requirements. Examples of alternative core materials are nanocrystalline and amorphous materials. These materials have recently become economically feasible and reliable. Although such materials improve the DC immunity it is still necessary to lower the overall relative permeability to provide an appropriate solution. This DC immunity comes at a cost, however. As the permeability and inductance of the current sensors are reduced, the phase shift error is greater. With phase shifts greater than about 0.5 degrees, changes in the phase shift with operating conditions can no longer be ignored. The current transformer's inductance is a function of the line frequency and the winding resistance is a function of temperature (as a result of the copper wire). Thus, the phase shift is a function of temperature and frequency, and because the phase shift in low permeability materials is larger, they are more sensitive to temperature and frequency. Thus, a need exists to compensate for the frequency and temperature induced errors in the phase and amplitude output of the current sensors in an electronic energy meter.

SUMMARY OF THE INVENTION

The present invention is directed to a system and method for compensating for temperature-induced and/or line frequency-induced changes in the phase shift of the current sensors in an energy meter. To compensate for temperature-induced phase shift, a temperature reading from a temperature sensor within the energy meter is obtained. The temperature reading is converted to a digital signal. The digital signal is then converted to a degrees of phase shift value. A processor in the meter adjusts its output based on the degrees of phase shift value.

To compensate for line frequency-induced phase shift, a line frequency of the signals is obtained. The line frequency is converted to an engineering units value. The engineering units value is then converted to a degrees of phase shift value. A processor in the meter adjusts its output based on the degrees of phase shift value. To compensate for both temperature-induced phase shift and line frequency-induced phase shift, the respective degrees of phase shift values are combined to obtain a total degrees of phase shift value. The processor then adjusts its output based on the total degrees of phase shift value.

According to aspects of the invention, converting a digital signal or an engineering units value to a degrees of phase shift value comprises solving an associated linear equation for phase shift based on temperature or line frequency. The linear equation is determined by an approximation of the theoretical and experimental data.

According to further aspects of the invention, the output of the processor is delayed by an amount equal to the degrees of phase shift value, or by a time shift determined based on the degrees of phase shift value. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood, and its numerous objects and advantages will become apparent, by reference to the following detailed description of the invention when taken in conjunction with the following drawings, in which: Figure 1 is a block diagram showing the functional components of an exemplary meter and their interfaces in accordance with the present invention;

Figure 2A is a schematic diagram showing an exemplary current sensor circuit in accordance with the present invention;

Figure 2B is a schematic diagram of an equivalent circuit of the current transformer of Figure 2 A;

Figure 3 is a schematic diagram of an exemplary temperature sensor in accordance with the present invention;

Figure 4 is a flow chart of an exemplary temperature compensation method in accordance with the present invention; Figure 5 is a flow chart of an exemplary frequency compensation method in accordance with the present invention; and

Figure 6 is a flow chart of an exemplary method of combining the temperature compensation and the frequency compensation in accordance with the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS AND BEST MODE The present invention dynamically corrects for phase shift in an electronic energy meter by obtaining temperature and frequency readings in the meter and using these readings in a digital signal processor (DSP) residing within the electronic energy meter. The temperature and frequency readings are used to compensate for temperature and frequency-dependent phase shifts. The frequency and temperature compensation adjusts each phase's calibration values and the result is stored in the DSP. To reduce the possible influence of noise in the system, the compensation values are averaged to provide a smoothing of the data. Figure 1 is a block diagram showing the functional components of an exemplary meter and their interfaces in accordance with the present invention. As shown in Figure 1 , a meter for metering three-phase or single phase electrical energy preferably includes a digital LCD type display 30, a meter integrated circuit (IC) 14 which preferably comprises A/D converters and a programmable DSP, and a microcontroller 16. The microcontroller also comprises an A/D converter.

Analog voltage and current signals propagating over power transmission lines between the power generator of the electrical service provider and the users of the electrical energy are sensed by voltage sensors 12A, 12B, 12C and current sensor circuits 18A, 18B, 18C, respectively. The outputs of the voltage sensors 12A-12C and current sensor circuits 18A- 18C, or sensed voltage and current signals, are provided as inputs to meter IC 14. The A/D converters in the meter IC 14 convert the sensed voltage and current signals into digital representations of the analog voltage and current signals. In a preferred embodiment, the A/D conversion is carried out as described in U.S. Patent No. 5,544,089 dated August 6, 1996, and entitled PROGRAMMABLE ELECTRICAL METER USING MULTIPLEXED ANALOG- TO-DIGITAL CONVERTERS, assigned to ABB Automation Inc. The digital voltage and current signals are then input to the programmable DSP in the meter IC 14 for generating pulsed signals representing various power measurements, e.g., Watts, VAs, or VARs. These pulsed signals may be processed by the microcontroller 16 to perform revenue metering functions for billing purposes.

The exemplary microcontroller 16 performs numerous revenue metering functions as well as instrumentation functions. Instrumentation functions, in contrast to revenue functions, are intended to assist a technician in evaluating a service based on near-instantaneous conditions at the meter. Instrumentation measurements may include system parameters such as frequency, Watts, VARs, and VAs, and per phase information such as voltage, current, phase angles, power factor, current to voltage angle, kWatts, kVARs, kVA, and harmonic distortion related parameters.

The microcontroller 16 preferably interfaces with the meter IC 14 and one or more memory devices through an IIC bus 36. An EEPROM 35 is provided to store revenue data as well as programs and program data. Upon a power up (either after an installation or a power failure) or a data altering communication, for example, selected programs and program data stored in the EEPROM 35 may be downloaded to program RAM and data RAM associated with the DSP in the meter IC 14. The DSP under the control of the microcontroller 16 processes the digital voltage and current signals in accordance with the downloaded programs and data stored in the respective program and data RAM. To perform instrumentation functions, the microcontroller 16 may use voltage and current, real and apparent energy with lead/lag indication, frequency, and relative voltage or current phase angle information from the DSP. The meter IC 14 monitors the digital phase voltage signals and phase current signals over two line cycles (at about 50 or 60 Hz, two line cycle measurements are defined herein as RMS measurements even though they are near instantaneous) and then computes the RMS voltage and current values, real and apparent energies with lead/lag indication, average frequency, and relative voltage and current phase angle information. It should be understood that the number of line cycles is preferably programmable and a different number of line cycles, such as four line cycles for example, may be used for designated measurements. The RMS parameters are computed for a single phase at a time and stored in the data RAM in meter IC 14. The microcontroller 16 polls for data in these registers via the IIC bus 36 for requested instrumentation measurements. Because the instrumentation measurements are near-instantaneous, no values are stored other than the ones presently being requested.

The current sensor circuits 18 A, 18B, 18C employ current transformers 40. Figure 2A shows a schematic diagram of an exemplary current sensor circuit, and Figure 2B shows the equivalent circuit of the current transformers as a combination of ideal parts. Each current transformer preferably has a low permeability core (e.g., a permeability less than about 10,000, and preferably between about 1000 and 10,000). These cores may also be constructed with nanocrystalline or amorphous material. A temperature sensor 50 is disposed within the meter, such as on the current sensor, though the temperature sensor could be disposed elsewhere, such as directly on the printed circuit board (PCB). A schematic diagram of an exemplary temperature sensor 50 is shown in Figure 3. The analog output voltage VT from the temperature sensor 50 is electrically connected to the A/D converter of the microcontroller 16 and is sensed in order to determine the temperature of the meter. Exemplary values for the resistors are RS=1000 Ω, each RP=100 kΩ, RST=10 kΩ, and for the thermistor T= 10 kΩ. For the exemplary temperature sensor, the output voltage VT is non-linear. The following linear equations (1), (2), and (3) are good approximations and are used to determine the temperature T (in °C) based on the voltage VT:

VT= -0.048/2 x T + 3.927; for T < -15 °C (1) VT= -0.048 x T + 3.565; for T < -15 °C < 45 °C (2)

VT= -0.048/2 x T + 2.453; for T > 45 °C (3)

These linear equations are preferred as they require less computational overhead. If the temperature sensor is located on the PCB, it is assumed that the PCB temperature reasonably corresponds to the current transformers temperature. It is noted that any conventional temperature sensor can be used in accordance with the present invention and that the temperature in °C can be obtained, if not directly, then from the voltage or another measured value based on the manufacturer's data sheets.

Exemplary equations (4) and (5) describe the relations of amplitude and phase shift to temperature and frequency. Equations (4) and (5) are based on the equivalent ideal circuit as shown in Figure 2B.

FΓΠ = + ' 2 tfL

(4)

Figure imgf000009_0001

where:

F(T) is the error amplitude of the voltage measured at the burden of the current sensor, φ(T) is the phase shift of the secondary burden voltage relative to the primary current,

RB is the burden resistance,

Rw is the resistance of the winding, f is the frequency, and

L is the inductance of the current transformer. Thus, for phase shift compensation, the role of the frequency component can be described, as shown in Equation (5). In the numerator, RB in the exemplary embodiment is approximately 3.3 Ω and is relatively immune to temperature variation. As is well known in the art, the Rw term is a function of the copper winding and varies with temperature. For example, in the exemplary embodiment, Rw is approximately 10 Ω at 25 °C and varies with temperature by about 0.4% per °C, which is temperature coefficient for copper. Ideally, from a new temperature and frequency value one would calculate a new value for Rw and then calculate a new phase shift φ(T) according to Equation (5). In order to simplify the calculations, it is desired to approximate the temperature and frequency components of this calculation separately. In the exemplary embodiment, Equation (5) is represented by piecewise linear approximations for both temperature and frequency compensation.

The temperature sensor 50 can also be used to improve the readability of the LCD display 30. The readability of the LCD display 30 is temperature-dependent. According to one embodiment of the invention, the LCD bias voltages are adapted or adjusted responsive to the temperature, as shown in Figure 3.

Figure 4 is a flow chart of an exemplary method of temperature compensation in accordance with the present invention. At step 100, the present temperature reading is obtained from the temperature sensor. At step 110, the temperature is converted by the A/D converter to obtain a digital signal. If desired, and if additional or continuous temperature readings are being taken, the temperature (represented by a digital signal) can be filtered in order to reduce noise. The optional filtering is shown in step 120. An exemplary filter can be an infinite impulse response filter, for example, and is given by equation (6):

Tavg,n = [( - 1 )/m]Tavg,n_, + ( 1 /m)Tinstantaneous (6) where Tavg n_, is the past filter output and Tavg n is the current filter output, Tjnstantaneous is the presently obtained temperature reading, and m is the filter constant. It is noted that the first temperature reading is not filtered (because there is no average temperature reading yet).

The digital signal is then converted to degrees of phase shift at step 130 by solving a linear equation that has been found to be a close approximation of the temperature effect in Equation (5). For the exemplary embodiment, for example, the following linear Equation (7) is obtained: (T) = Φ0seπsor + φ/τ(T-25°C) (7)

Φosensor *s the phase shift of the specific current sensor being compensated at 25 °C (room temperature). This value is normally calibrated for each current sensor at the point of manufacture. For the exemplary embodiment O0sensor is typically 6.18° and mφ/τ is = 0.012 °/°C.

At step 140, the calculated value Φ(T) is stored in the memory of microcontroller 16 and the value is provided to the DSP in the meter IC 14, for example by the exemplary procedure described with respect to Figure 6. The microcontroller either uses this temperature-based phase shift compensation value alone or in conjunction with the below described frequency-based phase shift compensation value to compensate for the temperature and/or frequency induced phase shift(s) through calibration factors within the DSP.

As described above with respect to Figure 1 , the meter IC 14 monitors the voltage and current signals, and then computes frequency, among other things. Varying frequency induces varying amounts of phase shift error in the low permeability current sensors according to

Equation (5). The present invention compensates for this frequency induced phase shift error.

Figure 5 is a flowchart of an exemplary method of frequency compensation in accordance with the present invention. At step 200, the actual line frequency is measured in DSP units at a predetermined rate, with each value being stored in memory, such as the data

RAM in meter IC 14. At step 210, the line frequency is read from the meter IC by the microcontroller and converted to a value in engineering units.

At step 220, the value in engineering units is smoothed using an IIR filter, for example, similar to the one described above with respect to the temperature compensation. In this case, the filter is given by equation (8):

favg,n = [(m- l)/m]fav&n., + (l/m)fjnstamaneous (8) where favg>π-ι is the past filter output and favg n is the current filter output, finstantaneous is the presently obtained frequency value, and m is the filter constant. It is noted that the first frequency reading is not filtered (because there is no average frequency reading yet). The value in engineering units is then converted to degrees of phase shift at step 230 by solving a linear equation that has been determined from experimental data to be a good approximation for the effect of frequency in Equation (5). This is performed by measuring the phase shift of the current sensor at several different line frequencies to obtain a series of phase shift vs. line frequency curves for a 50 Hz system and/or a 60 Hz system. Using these curves and conventional mathematical techniques, a linear equation representing the phase shift for any line frequency can be determined. For example, the following linear equation (9) is obtained:

Φ( = Φϋsensor + niφ f (^nominal Hz) (9) At 50 Hz, mφ/f = -0.126 °/Hz. For 60 Hz, = -0.088 °/Hz. Here again Φ0sensor represents the actual phase shift of the individual current sensor at the nominal line frequency (and room temperature). At 50 Hz O0sensor is nominally 6.18°, and at 60 Hz Φosensor is nominally 5.15°. Φ0sensor is normally calibrated for each current sensor at the point of manufacture. fnominaι is either 50 Hz or 60 Hz, as appropriate. The resulting value for Φ(f) is saved at step 240 in the memory of the microcontroller, and the value is provided to the DSP in the meter IC 14, for example by the exemplary procedure described with respect to Figure 6. The resulting value of Φ(f) is the phase shift resulting from an off-nominal frequency.

Figure 6 is a flowchart of an exemplary method of compensating for the phase shift errors in accordance with the present invention. The temperature compensation value is obtained (from the exemplary method of Figure 4, for example) at step 300. At step 310, the frequency compensation value is obtained (from the exemplary method of Figure 5, for example). At step 320, the temperature compensation value is combined with the frequency compensation value as shown in Equation (10): Φ(combined) = Φ0sensor + mφ/τ(T-25°C) + mφ/f(f-fnominal Hz) (10)

The result is written back to the DSP in the IC 14 at step 330. In other words, for each current sensor, a phase shift calibration value in the DSP's data memory is changed by the microcontroller to reflect the change in the compensation value. The DSP uses this phase shift calibration value in determining the output signals (including energy, instrumentation and potential indicator outputs) that the DSP provides to the microcontroller 16. Thus, if, for example, the phase shift is determined to be 5.5 degrees, then an offset of 5.5 degrees is provided to the DSP, and the DSP uses this offset (incorporates a 5.5 degree delay or a time shift based on the phase shift) in providing output values to the microcontroller 16. The measured temperature and frequency values are applied for all current sensors.

Because of the unit to unit variations in the initial phase shift Φosensorr each current sensor, there is a unique Φ0sensor and final phase calibration value for each current sensor.

It should be noted that the present invention can be used with any electronic meter and is not limited to the meter described herein. While the invention has been described and illustrated with reference to specific embodiments, those skilled in the art will recognize that modification and variations may be made without departing from the principles of the invention as described hereinabove.

Claims

What is claimed is:
1. A method of compensating for temperature-induced phase shift in an energy meter, comprising: obtaining a temperature reading from a temperature sensor within the energy meter; converting the temperature reading to a digital signal; converting the digital signal to a degrees of phase shift value; providing the degrees of phase shift value to a processor in the energy meter; and adjusting the output of the processor responsive to the degrees of phase shift value.
2. The method according to claim 1 , wherein converting the digital signal to the degrees of phase shift value comprises solving a linear equation for phase shift based on temperature.
3. The method according to claim 2, further comprising previously determining the linear equation from at least one of experimental data and product specifications.
4. The method according to claim 3, wherein the experimental data comprises a series of phase shift vs. temperature curves.
5. The method according to claim 1, wherein adjusting the output of the processor comprises delaying the output of the processor by an amount equal to the degrees of phase shift value.
6. The method according to claim 1, wherein adjusting the output of the processor comprises delaying the output of the processor by a time shift determined based on the degrees of phase shift value.
7. The method according to claim 1, further comprising filtering the digital signal prior to converting the digital signal to the degrees of phase shift value.
8. A method of compensating for frequency-induced phase shift in an energy meter, comprising: obtaining a line frequency reading from the energy meter; converting the line frequency reading to a value in engineering units; converting the value to a degrees of phase shift value; providing the degrees of phase shift value to a processor in the energy meter; and adjusting the output of the processor responsive to the degrees of phase shift value.
9. The method according to claim 8, wherein converting the value to the degrees of phase shift value comprises solving a linear equation for phase shift based on line frequency.
10. The method according to claim 9, further comprising previously determining the linear equation from at least one of experimental data and product specifications.
11. The method according to claim 10, wherein the experimental data comprises a series of phase shift vs. line frequency curves.
12. The method according t_) claim 8, wherein adjusting the output of the processor comprises delaying the o tput of the processor by an amount equal to the degrees of phase shift value.
13. The method according to claim 8, wherein adjusting the output of the processor comprises delaying the output of the processor by a time shift determined based on the degrees of phase shift value.
14. The method according to claim 8, further comprising filtering the value prior to converting the value to the degrees of phase shift value.
15. A method of compensating for temperature-induced phase shift and frequency-induced phase shift in an energy meter, comprising: obtaining a temperature reading from a temperature sensor within the energy meter; converting the temperature reading to a first digital signal; converting the first digital signal to a first degrees of phase shift value; providing the first degrees of phase shift value to a processor in the energy meter; obtaining a line frequency reading from the energy meter; converting the line frequency reading to a value in engineering units; converting the value in engineering units to a second degrees of phase shift value; providing the degrees of phase shift value to the processor in the energy meter; and adjusting the output of the processor responsive to the first degrees of phase shift value and the second degrees of phase shift value.
16. The method according to claim 15, wherein converting the first digital signal to the first degrees of phase shift value comprises solving a first linear equation for phase shift based on temperature, and converting the value in engineering units to the second degrees of phase shift value comprises solving a second linear equation for phase shift based on line frequency.
17. The method according to claim 16, further comprising previously determining the first and second linear equations from at least one of experimental data and product specifications.
18. The method according to claim 17, wherein the experimental data comprises a series of phase shift vs. temperature curves and a series of phase shift vs. line frequency curves.
19. The method according to claim 15, wherein adjusting the output of the processor comprises combining the first degrees of phase shift value and the second degrees of phase shift value to obtain a total degrees of phase shift value, and delaying the output of the processor by an amount equal to the total degrees of phase shift value.
20. The method according to claim 15, wherein adjusting the output of the processor comprises combining the first degrees of phase shift value and the second degrees of phase shift value to obtain a total degrees of phase shift value and delaying the output of the processor by a time shift determined based on the total degrees of phase shift value.
21. The method according to claim 15, further comprising filtering the first digital signal prior to converting the first digital signal to the first degrees of phase shift value, and filtering the value in engineering units prior to converting the value in engineering units to the second degrees of phase shift value.
22. A system for compensating for temperature-induced phase shift in an energy meter, comprising: a temperature sensor for obtaining a temperature reading; an analog to digital converter for receiving the temperature reading from the temperature sensor and converting the temperature reading to a digital signal; and a processor for receiving the digital signal from the converter and converting the digital signal to a degrees of phase shift value, the processor adjusting its output responsive to the degrees of phase shift value.
23. The system according to claim 22, further comprising a current transformer for sensing current provided to the energy meter.
24. The system according to claim 23, wherein the current transformer comprises a core having a permeability below 10,000.
25. The system according to claim 23, wherein the temperature sensor is disposed on the current transformer.
26. The system according to claim 22, further comprising a filter that filters the digital signal prior to the processor receiving the digital signal.
27. A system for compensating for line frequency-induced phase shift in an energy meter, comprising: a processor for obtaining a line frequency reading; and an analog to digital converter for receiving the line frequency reading from the processor and converting the line frequency reading to a value in engineering units, wherein the processor receives the value in engineering units from the converter, converts the value in engineering units to a degrees of phase shift value, and adjusts its output responsive to the degrees of phase shift value.
28. The system according to claim 27, further comprising a filter that filters the value in engineering units prior to the processor receiving the digital signal.
29. A system for compensating for temperature-induced phase shift and frequency-induced phase shift in an energy meter, comprising: a temperature sensor for obtaining a temperature reading; a processor for obtaining a line frequency reading; and an analog to digital converter for receiving the temperature reading from the temperature sensor and converting the temperature reading to a first digital signal, and for receiving the line frequency reading from the processor and converting the line frequency reading to a value in engineering units; wherein the processor receives the first digital signal and the value in engineering units from the converter, converts the first digital signal and the value in engineering units to first and second degrees of phase shift values, and adjusts its output responsive to the first and second degrees of phase shift values.
30. The system according to claim 29, further comprising a current transformer for sensing current provided to the energy meter.
31. The system according to claim 30, wherein the current transformer comprises a core having a permeability below 10.000.
32. The system according to claim 30, wherein the temperature sensor is disposed on the current transformer.
33. The system according to claim 29, further comprising a filter that filters at least one of the first digital signal and the value in engineering units prior to the processor receiving the first digital signal and the value in engineering units.
34. An apparatus comprising a storage device that stores software that compensates for temperature-induced phase shift and frequency-induced phase shift in an energy meter and performs the acts of: obtaining a temperature reading from a temperature sensor within the energy meter; converting the temperature reading to a first digital signal; converting the first digital signal to a first degrees of phase shift value; obtaining a line frequency reading from the energy meter; converting the line frequency reading to a value in engineering units; converting the value in engineering units to a second degrees of phase shift value; and adjusting the output of a processor in the energy meter responsive to the first degrees of phase shift value and the second degrees of phase shift value.
35. The apparatus according to claim 34, wherein the software performs converting the first digital signal to the first degrees of phase shift value by solving a first linear equation for phase shift based on temperature, and converting the value in engineering units to the second degrees of phase shift value by solving a second linear equation for phase shift based on line frequency.
36. The apparatus according to claim 34, wherein the software performs adjusting the output of the processor by combining the first degrees of phase shift value and the second degrees of phase shift value to obtain a total degrees of phase shift value, and delaying the output of the processor by an amount equal to the total degrees of phase shift value.
37. The apparatus according to claim 34, wherein the software performs adjusting the output of the processor by combining the first degrees of phase shift value and the second degrees of phase shift value to obtain a total degrees of phase shift value, and delaying the output of the processor by a time shift determined based on the total degrees of phase shift value.
38. The apparatus according to claim 35, wherein the software further performs filtering the first digital signal prior to converting the first digital signal to the first degrees of phase shift value, and filtering the value in engineering units prior to converting the value in engineering units to the second degrees of phase shift value.
PCT/US2000/001663 2000-01-26 2000-01-26 System and method for digitally compensating frequency and temperature induced errors in amplitude and phase shift in current sensing of electronic energy meters WO2001055733A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/US2000/001663 WO2001055733A1 (en) 2000-01-26 2000-01-26 System and method for digitally compensating frequency and temperature induced errors in amplitude and phase shift in current sensing of electronic energy meters

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
EP00903407A EP1257832A4 (en) 2000-01-26 2000-01-26 System and method for digitally compensating frequency and temperature induced errors in amplitude and phase shift in current sensing of electronic energy meters
PCT/US2000/001663 WO2001055733A1 (en) 2000-01-26 2000-01-26 System and method for digitally compensating frequency and temperature induced errors in amplitude and phase shift in current sensing of electronic energy meters
AU2515500A AU2515500A (en) 2000-01-26 2000-01-26 System and method for digitally compensating frequency and temperature induced errors in amplitude and phase shift in current sensing of electronic energy meters
BRPI0017072A BRPI0017072B8 (en) 2000-01-26 2000-01-26 system and method for digitally compensating for frequency and temperature induced errors in a phase shift in the current detection of electronic energy meters

Publications (1)

Publication Number Publication Date
WO2001055733A1 true WO2001055733A1 (en) 2001-08-02

Family

ID=21740991

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2000/001663 WO2001055733A1 (en) 2000-01-26 2000-01-26 System and method for digitally compensating frequency and temperature induced errors in amplitude and phase shift in current sensing of electronic energy meters

Country Status (4)

Country Link
EP (1) EP1257832A4 (en)
AU (1) AU2515500A (en)
BR (1) BRPI0017072B8 (en)
WO (1) WO2001055733A1 (en)

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6563697B1 (en) 2001-02-23 2003-05-13 Power Measurement, Ltd. Apparatus for mounting a device on a mounting surface
US6745138B2 (en) 2001-02-23 2004-06-01 Power Measurement, Ltd. Intelligent electronic device with assured data storage on powerdown
US6798190B2 (en) 2001-02-23 2004-09-28 Power Measurement Ltd. Compact intelligent electronic device incorporating transformers
US6813571B2 (en) 2001-02-23 2004-11-02 Power Measurement, Ltd. Apparatus and method for seamlessly upgrading the firmware of an intelligent electronic device
US6871150B2 (en) 2001-02-23 2005-03-22 Power Measurement Ltd. Expandable intelligent electronic device
EP1639376A2 (en) * 2003-07-01 2006-03-29 Itron Electricity Metering, Inc. System and method for acquiring voltages and measuring voltage into an electrical service using a non-active current transformer
US7305310B2 (en) 2004-10-18 2007-12-04 Electro Industries/Gauge Tech. System and method for compensating for potential and current transformers in energy meters
US7917314B2 (en) 2001-02-23 2011-03-29 Power Measurement Ltd. Intelligent electronic device having network access
CN103454490A (en) * 2012-05-28 2013-12-18 湖南省电力公司科学研究院 Intelligent metering system and intelligent metering method on basis of Blackman-harris window spectrum correction
US8878517B2 (en) 2005-01-27 2014-11-04 Electro Industries/Gauge Tech Intelligent electronic device with broad-range high accuracy
CN104849523A (en) * 2015-05-15 2015-08-19 威胜集团有限公司 Single-phase watt-hour meter temperature compensation method
US9194898B2 (en) 2005-01-27 2015-11-24 Electro Industries/Gauge Tech Intelligent electronic device and method thereof
US9989618B2 (en) 2007-04-03 2018-06-05 Electro Industries/Gaugetech Intelligent electronic device with constant calibration capabilities for high accuracy measurements
US10345416B2 (en) 2007-03-27 2019-07-09 Electro Industries/Gauge Tech Intelligent electronic device with broad-range high accuracy
WO2019202075A1 (en) * 2018-04-20 2019-10-24 Sagemcom Energy & Telecom Sas Electrical energy meter comprising a current-measuring circuit and a voltage-measuring circuit
US10628053B2 (en) 2004-10-20 2020-04-21 Electro Industries/Gauge Tech Intelligent electronic device for receiving and sending data at high speeds over a network
US10641618B2 (en) 2004-10-20 2020-05-05 Electro Industries/Gauge Tech On-line web accessed energy meter

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5017860A (en) * 1988-12-02 1991-05-21 General Electric Company Electronic meter digital phase compensation
US5467012A (en) * 1994-05-10 1995-11-14 Load Controls Incorporated Power monitoring
US5485393A (en) * 1990-08-30 1996-01-16 Metricom, Inc. Method and apparatus for measuring electrical parameters using a differentiating current sensor and a digital integrator
US5903145A (en) * 1992-02-21 1999-05-11 Abb Power T & D Company Inc. Universal electronic energy meter for use with 4-wire standard services

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0727669B1 (en) * 1995-02-17 2002-03-20 Siemens Metering AG Temperature compensation means
US5673196A (en) * 1995-11-30 1997-09-30 General Electric Company Vector electricity meters and associated vector electricity metering methods

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5017860A (en) * 1988-12-02 1991-05-21 General Electric Company Electronic meter digital phase compensation
US5485393A (en) * 1990-08-30 1996-01-16 Metricom, Inc. Method and apparatus for measuring electrical parameters using a differentiating current sensor and a digital integrator
US5903145A (en) * 1992-02-21 1999-05-11 Abb Power T & D Company Inc. Universal electronic energy meter for use with 4-wire standard services
US5467012A (en) * 1994-05-10 1995-11-14 Load Controls Incorporated Power monitoring

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP1257832A4 *

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7249265B2 (en) 2001-02-23 2007-07-24 Power Measurement, Ltd. Multi-featured power meter with feature key
US6745138B2 (en) 2001-02-23 2004-06-01 Power Measurement, Ltd. Intelligent electronic device with assured data storage on powerdown
US6798190B2 (en) 2001-02-23 2004-09-28 Power Measurement Ltd. Compact intelligent electronic device incorporating transformers
US6813571B2 (en) 2001-02-23 2004-11-02 Power Measurement, Ltd. Apparatus and method for seamlessly upgrading the firmware of an intelligent electronic device
US6871150B2 (en) 2001-02-23 2005-03-22 Power Measurement Ltd. Expandable intelligent electronic device
US7979221B2 (en) 2001-02-23 2011-07-12 Power Measurement Ltd. Intelligent electronic device having network access
US7191076B2 (en) 2001-02-23 2007-03-13 Power Measurement Ltd. Expandable intelligent electronic device
US7917314B2 (en) 2001-02-23 2011-03-29 Power Measurement Ltd. Intelligent electronic device having network access
US6563697B1 (en) 2001-02-23 2003-05-13 Power Measurement, Ltd. Apparatus for mounting a device on a mounting surface
EP1639376A4 (en) * 2003-07-01 2007-04-25 Itron Electricity Metering Inc System and method for acquiring voltages and measuring voltage into an electrical service using a non-active current transformer
EP1639376A2 (en) * 2003-07-01 2006-03-29 Itron Electricity Metering, Inc. System and method for acquiring voltages and measuring voltage into an electrical service using a non-active current transformer
US7305310B2 (en) 2004-10-18 2007-12-04 Electro Industries/Gauge Tech. System and method for compensating for potential and current transformers in energy meters
US7660682B2 (en) 2004-10-18 2010-02-09 Electro Industries/Gauge Tech System and method for compensating for potential and current transformers in energy meters
US8073642B2 (en) 2004-10-18 2011-12-06 Electro Industries/Gauge Tech System and method for compensating for potential and current transformers in energy meters
US10628053B2 (en) 2004-10-20 2020-04-21 Electro Industries/Gauge Tech Intelligent electronic device for receiving and sending data at high speeds over a network
US10641618B2 (en) 2004-10-20 2020-05-05 Electro Industries/Gauge Tech On-line web accessed energy meter
US8878517B2 (en) 2005-01-27 2014-11-04 Electro Industries/Gauge Tech Intelligent electronic device with broad-range high accuracy
US9903895B2 (en) 2005-01-27 2018-02-27 Electro Industries/Gauge Tech Intelligent electronic device and method thereof
US9194898B2 (en) 2005-01-27 2015-11-24 Electro Industries/Gauge Tech Intelligent electronic device and method thereof
US10345416B2 (en) 2007-03-27 2019-07-09 Electro Industries/Gauge Tech Intelligent electronic device with broad-range high accuracy
US9989618B2 (en) 2007-04-03 2018-06-05 Electro Industries/Gaugetech Intelligent electronic device with constant calibration capabilities for high accuracy measurements
CN103454490A (en) * 2012-05-28 2013-12-18 湖南省电力公司科学研究院 Intelligent metering system and intelligent metering method on basis of Blackman-harris window spectrum correction
CN104849523A (en) * 2015-05-15 2015-08-19 威胜集团有限公司 Single-phase watt-hour meter temperature compensation method
WO2019202075A1 (en) * 2018-04-20 2019-10-24 Sagemcom Energy & Telecom Sas Electrical energy meter comprising a current-measuring circuit and a voltage-measuring circuit
FR3080457A1 (en) * 2018-04-20 2019-10-25 Sagemcom Energy & Telecom Sas Electric energy meter comprising a current measurement circuit and a voltage measurement circuit

Also Published As

Publication number Publication date
BR0017072B1 (en) 2013-08-27
BR0017072A (en) 2005-02-09
EP1257832A4 (en) 2006-01-11
BRPI0017072B8 (en) 2015-12-22
EP1257832A1 (en) 2002-11-20
AU2515500A (en) 2001-08-07

Similar Documents

Publication Publication Date Title
US10527651B2 (en) Current measurement
US9151818B2 (en) Voltage measurement
CA2148961C (en) Linear alternating current interface for electronic meters
US5151866A (en) High speed power analyzer
KR100213838B1 (en) Method for determining electrical energy consumption
AU676998B2 (en) Solid state electric power usage meter and method for determining power usage
US6984979B1 (en) Measurement and control of magnetomotive force in current transformers and other magnetic bodies
US7511468B2 (en) Harmonics measurement instrument with in-situ calibration
US5302890A (en) Harmonic-adjusted power factor meter
JP5938104B2 (en) System and method for calculating power using a non-contact voltage waveform sensor
US7447603B2 (en) Power meter
US6791315B2 (en) Current detector and current measuring apparatus including such detector with temperature compensation
US6414475B1 (en) Current sensor
CA2106290C (en) Method and apparatus providing half-cycle digitization of ac signals by an analog-to-digital converter
US7359809B2 (en) Electricity metering with a current transformer
US20130076343A1 (en) Non-contact current and voltage sensing clamp
US7305310B2 (en) System and method for compensating for potential and current transformers in energy meters
US7173429B2 (en) Activity-based battery monitor with a universal current measuring apparatus
US6023160A (en) Electrical metering system having an electrical meter and an external current sensor
DE102004010707B4 (en) Energy meter arrangement and method for calibration
US5180978A (en) Proximity sensor with reduced temperature sensitivity using A.C. and D.C. energy
US7212930B2 (en) Method and apparatus for phase determination
US6911813B2 (en) Methods and apparatus for phase compensation in electronic energy meters
US4535287A (en) Electronic watt/watthour meter with automatic error correction and high frequency digital output
US7075288B2 (en) System and method for acquiring voltages and measuring voltage into and electrical service using a non-active current transformer

Legal Events

Date Code Title Description
AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG

AK Designated states

Kind code of ref document: A1

Designated state(s): AE AL AM AT AU AZ BA BB BG BR BY CA CH CN CR CU CZ DE DK DM EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MD MG MK MN MW MX NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG UZ VN YU ZA ZW

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
WWE Wipo information: entry into national phase

Ref document number: 2000903407

Country of ref document: EP

WWP Wipo information: published in national office

Ref document number: 2000903407

Country of ref document: EP

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642