WO2002014881A1 - Method and equipment for power measurement in an alternating-current system - Google Patents
Method and equipment for power measurement in an alternating-current system Download PDFInfo
- Publication number
- WO2002014881A1 WO2002014881A1 PCT/FI2001/000722 FI0100722W WO0214881A1 WO 2002014881 A1 WO2002014881 A1 WO 2002014881A1 FI 0100722 W FI0100722 W FI 0100722W WO 0214881 A1 WO0214881 A1 WO 0214881A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- current
- measurement signal
- voltage
- consumption object
- circuit
- Prior art date
Links
- 238000005259 measurement Methods 0.000 title claims abstract description 41
- 238000000034 method Methods 0.000 title claims description 19
- 230000010354 integration Effects 0.000 claims abstract description 16
- 230000006698 induction Effects 0.000 claims abstract description 7
- 230000001052 transient effect Effects 0.000 claims abstract description 4
- 238000004364 calculation method Methods 0.000 claims abstract 3
- 238000012546 transfer Methods 0.000 description 6
- 239000004020 conductor Substances 0.000 description 5
- 230000003321 amplification Effects 0.000 description 4
- 238000003199 nucleic acid amplification method Methods 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- 230000004907 flux Effects 0.000 description 2
- 230000001939 inductive effect Effects 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000018199 S phase Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 229910000859 α-Fe Chemical group 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R21/00—Arrangements for measuring electric power or power factor
- G01R21/06—Arrangements for measuring electric power or power factor by measuring current and voltage
Definitions
- the method concerns a method according to the introductory part of claim 1 for power measurement in an alternating-current system.
- the invention also concerns an equipment according to the introductory part of claim 5.
- consumption object means equipment connected to an electric mains, by which equipment electric power is either taken out from the mains or electric power is supplied to the mains.
- power is normally measured in such a way that a signal proportional to the current of the consumption object and a signal proportional to the voltage of the consumption object are first formed. Then the transient active power is calculated by multiplying by each other at a certain moment the value of the signal proportional to the said current and the value of the signal proportional to the said voltage. The energy consumed in the consumption object is calculated by integrating the power over the desired time interval.
- Measurement of the current in a consumption object is generally based on a resistance, which turns the current into voltage, on an iron or ferrite core current transformer, on the induction phenomenon, where the primary current induces the voltage of the secondary coil, on magnetic sensors, e.g. a Hall sensor or a magneto-resistive sensor) or in certain cases on an optical fibre sensing the magnetic field, hi all others, except the transformer based on resistance, the measurement is based in one way or another on utilisation of the magnetic field caused by the primary current.
- the induction phenomenon alternating current travelling in the primary circuit of the current transformer brings about in the current transformer a magnetic flux changing in relation to time. The said magnetic flux for its part induces a voltage in the secondary circuit of the current transformer.
- This voltage in the current transformer's secondary circuit is proportional to the time derivative of the alternating current in the current transformer's primary circuit, hi order to find out the value of the alternating current travelling in the current transformer's primary circuit, the voltage in the current transformer's secondary circuit must be integrated in relation to time.
- a current measurement signal obtained from the current transformer's secondary circuit is integrated, whereupon the said integrated current measurement signal is multiplied by the voltage measurement signal in order to find out the power.
- Such solutions have usually used active integrators, that is, such which are equipped with an amplifier. This is so because the output signal of an inductive current transformer is usually of a low level.
- the applicant's FI Patent 98865 presents a method based on the induction phenomenon for measuring alternating current, a measuring sensor intended to measure alternating current and its use in a kWh meter.
- a gradi- ometer of at least the first order is fitted inside the electric conductor system or in its immediate neighbourhood, whereby the current travelling in the current system will induce a voltage in the gradiometer.
- the form of the current conductor system and the form of the gradiometer' s coil structure are adapted in such a way to each other that the output signal is essentially independent of any minor changes occurring in the relative position of the current conductor system and the gradiometer.
- the applicant's FI Patent Application 20001048 presents a current transformer based on the induction phenomenon for measuring alternating current.
- the current transformer includes a primary current conductor, wherein there are two current loops of essentially circular shape connected in parallel.
- the current loops are located concentrically in parallel planes located on top of each other and at a distance from each other. Between the current loops there is at least one gradiometer in a plane or planes parallel with the current loop planes.
- the primary current travelling in the current loops of the primary current conductor is connected by way of a magnetic field to the said at least one gradiometer and therein it brings about a voltage proportional to the primary current.
- the solution according to the invention is based on the realization that when one wishes to measure the electric power of a consumption object, information about the real value of the consumption object's current is not necessarily needed. If the current transformer gives such a current measurement signal from its secondary- circuit, which is proportional to the time derivative of the consumption object's current, integration may be applied to the voltage measurement signal of the voltage transformer and not to the current measurement signal of the current transformer's secondary circuit. The electric power is found out by multiplying the current measurement signal proportional to the current's time derivative by the integrated voltage measurement signal.
- a signal can be integrated in relation to time in many different ways.
- the methods may be analogue either based only on passive RC or LR circuits or based on active circuits, that is, those equipped with an amplifier.
- integration may be carried out by numeric methods by various algorithms of the time or frequency level. The integration works in a satisfactory manner when it approximates the transfer function Hi(j ⁇ ) - (jco) " of the ideal integrator well enough within the frequency range concerned in each case. For example, in kWh measurement, the important frequency range is usually about 10 Hz - 1 kHz. Nor must integration produce any interfering signals in the other frequency ranges. Integration is an operation, which enhances low-frequency signals, and with direct current the amplification is even infinite.
- the integrating signal is of a suitable magnitude or it can easily be made so, it contains no direct current components and it is a narrow-band signal. It is in fact more advantageous to apply integration to the voltage signal of the consumption object and not to the current derivative of the consumption object because:
- the voltage signal of the consumption object usually contains no harmful DC component, or if it does, it is very small
- the voltage signal of the consumption object is of a considerably narrower band than the current signal of the consumption object, whereby the integration task is simplified.
- the real current of the consump- tion object is not found out, but it is still possible to calculate the electric power and energy consumed by the consumption object.
- Figure 1 is a schematic view of the measuring circuit of a single-phase kWh meter known as such.
- Figure 2 shows an active integrator known as such, that is, one equipped with an amplifier, which may be used to implement the invention.
- Figure 3 shows a passive integrator known as such, which may be used to implement the invention.
- FIG 1 is a schematic view of the measuring circuit of a single-phase kWh meter, which is known as such.
- the measuring circuit of the voltage arm includes a protection circuit 11, the purpose of which is to protect the kWh meter against over-voltage peaks arriving from the electric mains.
- the protection circuit is followed by a voltage circuit 12, which is connected to the voltage of the consumption object to be measured in between a phase wire and a neutral wire, hi the voltage circuit such a signal level is formed of the mains voltage, which is suitable for a multiplier 15.
- the measuring circuit of the current arm includes a current transformer 13, which is followed by a pre-amplifier 14, by which the voltage signal obtained from the secondary circuit of current transformer 13 is amplified to a level suitable for multiplier 15.
- multiplier 15 signals propor- tional to the voltage of the consumption object to be measured and proportional to the current are multiplied by each other, whereby the electric energy consumed by the consumption object is obtained.
- a mechanical drum counter or a digital LCD display may be used as the counter 16 in the measuring circuit, hi addition, the measuring circuit includes pulse outputs 17 according to the standard, whose pulse number is proportional to the consumption of electric energy, pulses/kWh.
- the signal to be supplied to the multiplier 15 of the current arm is integrated before the value of the current measurement signal is multiplied by the value of the voltage measurement signal to find out the power.
- the signal to be supplied to the multiplier of the voltage arm is integrated before the value of the voltage measurement signal is multiplied by the value of the current measurement signal to find out the power.
- the signal to be supplied to the multiplier 15 of the current arm is not integrated.
- the integrator is located in connection with the input gate of the multiplier 15 in the voltage arm.
- Figure 2 shows an active integrator 20, that is, one equipped with an amplifier.
- the circuit includes an operation amplifier 21, a first resistance Ri connected to the input gate of operation amplifier 21, and a second resistance R 2 connected in parallel in between the input gate and the output gate of operation amplifier 21, and a capacitor C.
- the transfer function of such a circuit is:
- the circuit must be dimensioned so that term ⁇ m in "C-R 2 is of a sufficient magnitude, preferably > 100. At high frequencies ( ⁇ > ⁇ m i n ) the transfer function
- the integrator's phase error at a frequency of 50 Hz is already reasonably small, the signal is of a suitable magnitude in the output of the integrator for further processing, and the DC amplification is about 1.
- the ratio R 2 /R ⁇ must be high, preferably > 100.
- the DC amplification increases at least to a value of 100, which maybe harmful.
- the active integrator shown in Figure 2 is better suitable for integration of a high signal, e.g. 230 N phase ⁇ voltage, than for integration of a low signal proportional to the current derivative.
- Figure 3 shows a simple passive RC integrator 30.
- the transfer function of the circuit is:
- the circuit must be dimensioned so that the term ⁇ min -R-C is sufficiently high, preferably > 100. This circuit functions in the same way as the circuit shown in
- the circuit dampens the phase voltage of the consumption object to a voltage level of 230 N, which is a suitable value for further processing of the signal.
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Current Or Voltage (AREA)
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2001282197A AU2001282197A1 (en) | 2000-08-18 | 2001-08-15 | Method and equipment for power measurement in an alternating-current system |
DE10196481T DE10196481B4 (en) | 2000-08-18 | 2001-08-15 | Method for measuring power in an AC system |
SE0300391A SE521894C2 (en) | 2000-08-18 | 2003-02-14 | Method and equipment for measuring power in an AC system |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FI20001831 | 2000-08-18 | ||
FI20001831A FI110964B (en) | 2000-08-18 | 2000-08-18 | Method and apparatus for measuring power in an AC system |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2002014881A1 true WO2002014881A1 (en) | 2002-02-21 |
WO2002014881A9 WO2002014881A9 (en) | 2002-12-12 |
Family
ID=8558918
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/FI2001/000722 WO2002014881A1 (en) | 2000-08-18 | 2001-08-15 | Method and equipment for power measurement in an alternating-current system |
Country Status (5)
Country | Link |
---|---|
AU (1) | AU2001282197A1 (en) |
DE (1) | DE10196481B4 (en) |
FI (1) | FI110964B (en) |
SE (1) | SE521894C2 (en) |
WO (1) | WO2002014881A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103323712A (en) * | 2013-06-09 | 2013-09-25 | 福州瑞芯微电子有限公司 | Testing method of power consumption of electric device |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4282576A (en) * | 1979-05-22 | 1981-08-04 | Westinghouse Electric Corp. | Indicator diagram based AC electric energy meter |
US4459546A (en) * | 1980-11-03 | 1984-07-10 | Rockwell International Corporation | Electronic kilowatthour meter |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4250552A (en) * | 1979-09-10 | 1981-02-10 | Westinghouse Electric Corp. | AC Electric energy meter utilizing a counter as an integrator |
DE4400418A1 (en) * | 1993-01-14 | 1994-08-04 | Schlumberger Ind Inc | Air coupled current transformer |
ATE204396T1 (en) * | 1993-01-20 | 2001-09-15 | Schlumberger Ind Sa | MULTI-STAGE FREQUENCY MODULATED CIRCUIT |
FI98865C (en) * | 1994-11-07 | 1997-08-25 | Enermet Oy | Method for measuring alternating current, measuring sensor for measuring alternating current and its use in a kWh meter |
FI108165B (en) * | 2000-05-05 | 2001-11-30 | Enermet Oy | Current converter for measuring AC current |
-
2000
- 2000-08-18 FI FI20001831A patent/FI110964B/en not_active IP Right Cessation
-
2001
- 2001-08-15 AU AU2001282197A patent/AU2001282197A1/en not_active Abandoned
- 2001-08-15 WO PCT/FI2001/000722 patent/WO2002014881A1/en active Application Filing
- 2001-08-15 DE DE10196481T patent/DE10196481B4/en not_active Expired - Fee Related
-
2003
- 2003-02-14 SE SE0300391A patent/SE521894C2/en not_active IP Right Cessation
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4282576A (en) * | 1979-05-22 | 1981-08-04 | Westinghouse Electric Corp. | Indicator diagram based AC electric energy meter |
US4459546A (en) * | 1980-11-03 | 1984-07-10 | Rockwell International Corporation | Electronic kilowatthour meter |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103323712A (en) * | 2013-06-09 | 2013-09-25 | 福州瑞芯微电子有限公司 | Testing method of power consumption of electric device |
Also Published As
Publication number | Publication date |
---|---|
AU2001282197A1 (en) | 2002-02-25 |
SE521894C2 (en) | 2003-12-16 |
SE0300391L (en) | 2003-02-14 |
DE10196481B4 (en) | 2006-01-05 |
SE0300391D0 (en) | 2003-02-14 |
FI110964B (en) | 2003-04-30 |
WO2002014881A9 (en) | 2002-12-12 |
FI20001831A (en) | 2002-02-19 |
FI20001831A0 (en) | 2000-08-18 |
DE10196481T1 (en) | 2003-07-03 |
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