WO2003081264A1 - Watt-heuremetre electronique et circuit de calcul d'une quantite de courant - Google Patents

Watt-heuremetre electronique et circuit de calcul d'une quantite de courant Download PDF

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Publication number
WO2003081264A1
WO2003081264A1 PCT/JP2002/002850 JP0202850W WO03081264A1 WO 2003081264 A1 WO2003081264 A1 WO 2003081264A1 JP 0202850 W JP0202850 W JP 0202850W WO 03081264 A1 WO03081264 A1 WO 03081264A1
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Prior art keywords
power
voltage
sampling frequency
frequency
power supply
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PCT/JP2002/002850
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English (en)
Japanese (ja)
Inventor
Atsufumi Kuroda
Takashi Shindoi
Keishu Kondo
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Mitsubishi Denki Kabushiki Kaisha
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Priority to PCT/JP2002/002850 priority Critical patent/WO2003081264A1/fr
Priority to CN02805485.7A priority patent/CN1292259C/zh
Priority to AU2002239060A priority patent/AU2002239060B1/en
Priority to JP2003578946A priority patent/JP4127676B2/ja
Publication of WO2003081264A1 publication Critical patent/WO2003081264A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R22/00—Arrangements for measuring time integral of electric power or current, e.g. electricity meters

Definitions

  • the present invention relates to an electronic watt-hour meter for measuring electric energy and an electric power-related operation circuit, and in particular, active power, active power, reactive power, reactive power, apparent power, strain power, and effective current.
  • the present invention relates to an electronic dynamometer and a power-related amount calculation circuit capable of calculating a power-related amount such as a voltage effective value, a phase difference between a current and a voltage, and values at harmonics of these orders.
  • Conventional electronic watt-hour meters use analog sensors of voltage and current measured by a voltage sensor (PT) and a current sensor (CT), for example, as described in Japanese Patent No. 3,080,207.
  • the first and second successive approximation type AD converters are provided as means for converting the digital output into a digital value.
  • the digital output (voltage and current) is calculated by a multiplier to obtain power W. I have.
  • the first and second successive approximation type AD converters have a low level since the output of the analog input signal is reduced to a digital value that discretely increases with an equal resolution.
  • a high-resolution successive approximation AD converter is required to obtain absolute digital conversion accuracy for input signals.
  • a method of increasing the sampling frequency of the first and second successive approximation type AD converters (so-called over-one sampling) is known. For example, if the sampling frequency is increased to 128 times the sampling frequency determined by Nyquist's theorem, quantization noise will be distributed over a wide band, and the level of each frequency component spectrum will decrease, and the signal The noise level of the frequency component is improved. This is because the first and second successive approximation AD This is equivalent to increasing the resolution of the converter by several bits.
  • Japanese Patent No. 380,207 discloses that current and voltage are each integrated by an integrator, and a digit value is output through a comparator. Also disclosed is a method of delaying the digital output and feeding back the DZA-converted value to the input side of the integrator 3 described above.
  • the first and second delta-sigma AD modulators for quantizing the current and the voltage by the oversampling frequency, respectively, and the moving average of the quantized current and the voltage by the digital filter.
  • first and second moving average processing means There are provided first and second moving average processing means, multiplying means for multiplying the current and voltage subjected to the moving average processing to obtain a power value, and integrating means for multiplying the power value obtained by the multiplication.
  • the effective output bits of the AD converter have substantially increased compared to the case of the sequential AD converter, so that a highly accurate electronic watt-hour meter can be obtained with a simple circuit configuration. In particular, when a monolithic IC is used, the circuit can be simplified.
  • the conventional electronic watt-hour meter is required to measure (or display) the electric energy in real time, and therefore, at each sampling timing (the sampling frequency of the AD converter). Is fixed) is directly multiplied by the current and voltage to calculate the electric energy.
  • the power amount is calculated by acquiring input signals (current and voltage) of high-frequency components equal to or higher than the Nyquist frequency through a single-pass filter.
  • the electric energy thus calculated is a combination of the fundamental wave and the harmonic, and it is not possible to measure only the fundamental wave or only the harmonic. Nor can it measure reactive power or reactive power of harmonics.
  • many power devices use a thyristor or an invar, and the current often contains harmonics.Therefore, various measurements of power-related quantities including harmonics are required. .
  • the sampling frequency of the AD converter is fixed, so it is necessary to correct the harmonics using the power supply frequency.
  • an electronic watt-hour meter that requires real-time performance requires an expensive processor (CPU).
  • the CPU must control the sampling frequency. For example, for a sampling frequency of several KHz, the resolution of the CPU output clock of several MHz is required.However, when the order of the harmonic to be measured increases, the sampling frequency can be accurately determined from the CPU. There is no control.
  • the oversampling frequency is several hundred kHz. Since the output clock of the CPU has a resolution of several MHz to several tens of MHz, whereas the frequency is up to several MHz (>> several KHz), the CPU cannot control the sampling frequency with high accuracy.
  • the conventional electronic watt-hour meter and the power-related amount calculation circuit are configured as described above.
  • the first and the second Since a successive approximation type AD converter and a multi-bit input multiplier are required, the circuit configuration becomes complicated and the cost rises.
  • the conventional electronic watt-hour meter calculates the electric energy by directly multiplying the current and the voltage at each sampling timing and calculates the electric energy obtained by combining the fundamental wave and the harmonic.
  • the sampling frequency of the AD converter is not a natural number multiple of the power supply frequency, and the Fourier transform value is included in the adjacent order. Therefore, it is necessary to perform a calculation for correcting harmonics using a power supply frequency, so that an expensive processor is required, and there has been a problem that it cannot be used for a general-purpose electronic watt-hour meter.
  • the oversampling frequency is very high (several hundred kHz to several MHz), so The sampling frequency cannot be controlled with high precision at the resolution of the CPU output clock (several MHz to several tens of MHz), and no correction operation is required by making the sampling frequency of the AD converter follow a natural number multiple of the power supply frequency. There was a problem that it could not be done.
  • the current is rotated by the Hilbert transform, and the active power of the fundamental wave and
  • the frequency at which the same Hilbert converter can rotate 90 degrees is narrow, so there is a problem that the reactive power other than the fundamental wave cannot be obtained by one Hilbert converter. .
  • An electronic watt-hour meter and a power-related amount calculation device capable of improving the control accuracy of a sampling frequency and obtaining a power amount with high accuracy. It is intended to provide a circuit.
  • Another object of the present invention is to provide an electronic watt-hour meter and a power-related amount calculation circuit which can measure not only the power amount of a fundamental wave but also the power amount of a harmonic with a simple configuration.
  • the present invention measures the reactive power required to check the power supply efficiency with high accuracy, including harmonics, and obtains the power factor as an index for effective power utilization with high accuracy It is an object of the present invention to provide an electronic watt-hour meter and a power-related amount calculation circuit capable of performing the following. Disclosure of the invention
  • An electronic watt-hour meter converts a measurement signal indicating a current and a voltage of an electric circuit (power supply line) into a digit value by an AD converter and takes in the signal.
  • an electronic watt-hour meter comprising a microprocessor (CPU) for calculating the amount of electric power
  • a power supply frequency detecting means for detecting a power supply frequency of a power supply line and a clock circuit of a microprocessor are provided separately. Since sampling frequency control means for controlling the sampling frequency of the AD converter based on the frequency is provided, it is possible to improve the control accuracy of the sampling frequency and obtain the electric energy with high accuracy.
  • the sampling frequency control means is configured to control the sampling frequency to be a natural multiple of the power supply frequency
  • the power amount calculation means has a harmonic calculation unit for calculating the harmonic power amount.
  • the sampling frequency control means determines that the sampling frequency is equal to the power supply frequency.
  • N is a natural number
  • the power amount calculation means is a fast Fourier transform (FFT) which calculates a harmonic power amount by a fast Fourier transform.
  • FFT fast Fourier transform
  • the AD converter is of the Delaware sigma type requiring over sampling, it is suitable for high precision and monolithic IC.
  • the sampling frequency control means includes means for detecting a rising crossing point of the power supply frequency or a zero crossing point of the power supply frequency and a time point when one cycle has elapsed from the zero crossing point of the last rising or falling power supply frequency. Since it has means for detecting the delay or advance of the power supply frequency as the power supply phase difference from the AD conversion value of the power supply frequency at step (a), and means for controlling the sampling frequency of the AD converter based on the power supply phase difference, the CPU The load on the device is small and the configuration can be simplified.
  • the sampling frequency control means detects the absolute phase of the voltage of the power supply line, and detects the delay or advance of the absolute phase one cycle after the previous absolute phase as a voltage phase difference. And means for controlling the sampling frequency of the AD converter based on the voltage phase difference, so that the effect of white noise can be suppressed.
  • the voltage phase difference detecting means is configured to be based on an absolute phase of 0 degree, 90 degrees, 180 degrees, or 270 degrees, so that the range of adjustment can be widened.
  • the sampling frequency correction means includes sampling frequency correction means for correcting the sampling frequency of the AD converter.
  • the sampling frequency correction means includes a control amount calculation means for obtaining a control amount of the sampling frequency, and a control amount for the sampling frequency.
  • DZA conversion means for performing A / A conversion and output, and offset means for offsetting an output voltage of the D / A conversion means, wherein the offset means offsets the power supply line by a predetermined voltage to a specified frequency side.
  • the offset voltage adjusting means for externally adjusting the predetermined voltage (offset voltage) is provided, it can be applied to various electric circuits, and can use a simple D / A converting means having a small number of bits.
  • the electric energy calculation means includes an AD conversion data packing means for packing the voltage and current measurement signals for one cycle of the power supply frequency, and a first data obtained by performing a Fourier transform on the data packed by the AD conversion data knocking means.
  • a power calculating unit for calculating the power value of the first cycle, a packing time detecting means for detecting a packing time required for knocking a voltage or a current for one cycle, and a first power value for each packing time.
  • Power output means for outputting the first power value as the second power value each time a sampling command of a predetermined operation cycle is generated, and integrating the second power value to obtain a second power value. Since it includes an electric energy pulse output means for outputting an electric energy pulse every time the integrated value reaches a predetermined value, real time characteristics can be satisfied.
  • the electric energy calculation means includes AD conversion data packing means for packing the voltage and current measurement signals for one cycle of the power supply frequency, and Fourier conversion of the data packed by the AD conversion data packing means.
  • the power calculator calculates the power-related values (current, voltage, active power, and reactive power) and the phase difference between the power-related values for each order of the harmonics. By performing a rotation operation so as to obtain a phase difference between the true power-related values and a phase correction means for correcting one cycle of current or voltage, measurement accuracy can be improved.
  • the power-related amount calculation circuit includes an AD converter for converting a measurement signal indicating a current and a voltage of a power supply line into a digit value and capturing the digitized value, and knocking the digit value for one cycle.
  • AD conversion data packing means Fourier transform means for Fourier transforming data packed by AD conversion data packing means, and power-related quantity calculation for calculating a power-related quantity based on the result of conversion by the Fourier transform means.
  • a sampling frequency correction means for calculating the amount of correction of the sampling frequency of the AD converter based on the frequency of the current or the voltage, and a voltage controlled oscillator for outputting a sampling frequency that varies according to the correction amount to the AD converter Therefore, the control accuracy of the sampling frequency can be improved, and the electric energy can be obtained with high accuracy.
  • a sampling frequency correction unit and a voltage control oscillator for following a sampling frequency of AD conversion to L times (L is a natural number) of a power supply frequency are provided.
  • V Voltage Controlled Oscillator or
  • the sampling frequency of the AD converter can be controlled with high accuracy, and as a result, the power-related amount can be obtained with high accuracy.
  • the reactive power required to grasp the power supply efficiency can be measured with high accuracy, including harmonics, so that the power factor, which is an index for effective use of power, can be obtained with high accuracy.
  • FIG. 1 is an explanatory diagram showing a calculation theory of a power-related amount according to Embodiment 1 of the present invention, and shows a voltage and current vector diagram as an example.
  • FIG. 2 is a block diagram showing a main circuit configuration of the electronic watt-hour meter according to Embodiment 1 of the present invention.
  • FIG. 3 is an explanatory diagram showing the behavior of the voltage of the fundamental wave when the power supply frequency changes in the electronic watt-hour meter according to Embodiment 1 of the present invention.
  • FIG. 4 is an explanatory diagram showing a zero crossing point of a power supply voltage and a starting point of sampling in the electronic watt-hour meter according to Embodiment 1 of the present invention.
  • FIG. 5 is a block diagram showing a main circuit configuration of an electronic watt-hour meter according to Embodiment 2 of the present invention.
  • FIG. 6 is an explanatory diagram showing a correction process for causing the sampling frequency of the AD converter according to the second embodiment of the present invention to follow a natural number multiple of the power supply frequency.
  • FIG. 7 is an explanatory diagram showing a starting point of sampling of the electronic watt-hour meter according to Embodiment 3 of the present invention.
  • FIG. 8 is a block diagram showing a main circuit configuration of an electronic watt-hour meter according to Embodiment 4 of the present invention.
  • FIG. 9 is an explanatory diagram showing an operation example of offsetting the V C0 control voltage by the electronic watt-hour meter according to Embodiment 4 of the present invention.
  • FIG. 10 is a block diagram showing a voltage addition circuit capable of further adjusting the V C0 control voltage by the electronic watt-hour meter according to Embodiment 4 of the present invention.
  • FIG. 11 is a block diagram showing a main circuit configuration of an electronic watt-hour meter according to Embodiment 5 of the present invention.
  • FIG. 12 is an electric energy pulse in the electronic watt-hour meter according to Embodiment 5 of the present invention. This is a timing chart showing an output.
  • FIG. 13 is a block diagram showing a main circuit configuration of an electronic watt-hour meter according to Embodiment 6 of the present invention.
  • the power amount and the like are calculated by Fourier transform (preferably, FFT) for one cycle of the data.
  • FFT Fourier transform
  • the sampling frequency of the AD converter is a natural number multiple of the power supply frequency
  • the following power-related quantities can be measured by Fourier transform.
  • the sampling frequency of the AD converter is L times the power supply frequency (L is a natural number), and the harmonic order is nth order.
  • the maximum harmonic order H that can be obtained by the Fourier transform is expressed by the following equation (1).
  • floor () is a function that rounds down the decimal point, and therefore H is a natural number.
  • Equations (2) and (3) j is an imaginary unit, and “is a multiplication symbol.
  • Vn—re, Vn—im, In—re and In—im are real numbers, and the values after Fourier transform are assumed to be normalized by the effective values.
  • the active power Wn of the nth harmonic is obtained by the following equation (4).
  • the reactive power varn of the nth harmonic is obtained by the following equation (6).
  • Varn Vn ⁇ ⁇ ⁇ re-Vn re -In im (6)
  • Vrmsn jVri re-Vn re + Vn im-Vn im (8)
  • the effective voltage value Vrms including all harmonics is obtained by the following equation (9).
  • Irmsn jln — re'In re + In im-In im (10)
  • the current effective value I rms including all harmonics is obtained by the following equation (11).
  • VAH Vrmsn. Irmsn (12) Also, the apparent power VA including all harmonics can be obtained by the following equation (13).
  • the distortion power D is a positive real number, not a negative value.
  • the complex values Vn-cmp and In_cmp of the voltage and current of the n-th harmonic obtained by the Fourier transform are represented as vector diagrams as shown in FIG. However, in Fig. 1, the horizontal axis is the real axis, and the vertical axis is the imaginary axis.
  • 6> is the absolute phase of the complex value Vn-cmp
  • ⁇ is the absolute phase of the complex value In-cmp
  • the reference of the absolute phase is the positive direction of the horizontal axis, where the counterclockwise direction indicates advance (positive) and the clockwise direction indicates delay (negative).
  • phase difference P hase-Vn In is calculated by the following equation (16).
  • Vnln -arccos (Wn / VAn)
  • Phase Vnln arccos (Wn / VAn)
  • Phase difference Phase_Vn In is “positive” when the current is ahead of the voltage, and “negative” when the current is behind the voltage. Also, the range of the phase difference Phase-Vnln is ⁇ 180 degrees.
  • the active power, reactive power, and apparent power are obtained from the sum of the values obtained for each phase, and the distortion power is obtained from the added power using Eq. (16).
  • a phase between the voltages of the respective phases can be newly obtained. That is, first, the A-phase nth-order harmonic voltage Van-cmp is expressed by the following equation (17).
  • Van cmp Van re + j-Van im (17)
  • the B-phase nth harmonic voltage Vbn-cmp is represented by the following equation (18).
  • Vabn Van reVbn re + Van im- Vbn im
  • Vabn 1 Van im-Vbn re-Van re- Vbn im
  • Varmsn JVan reVan re + Van imVan im
  • Vabn represents pseudo active power between a and b phases
  • Va b represents pseudo reactive power between a and b phases.
  • the phase difference can be calculated for voltages and currents having different phases by the same method.
  • the sampling frequency of the AD converter is a natural number multiple of the power supply frequency
  • the result of the Fourier transform is used for each harmonic, all power-related quantities including harmonics, or required harmonics. Can be obtained.
  • the sampling frequency of the AD converter is 2 times the power supply frequency and N times (N is a natural number)
  • FFT can be used for the Fourier transform. Therefore, it is usually preferable that the sampling frequency of the AD conversion be a natural number multiple of the power supply frequency and 2 N times.
  • FIG. 2 is a block diagram showing a specific circuit configuration of the electronic watt-hour meter according to Embodiment 1 of the present invention.
  • an AD converter 1 converts a voltage V and a current I detected by a sensor (not shown) into digital values.
  • the output terminal of the A / D converter 1 is connected to the A / D conversion data packing means 2, the Fourier transform means 3, and the power-related amount calculating means 4 in this order.
  • the AD conversion data knocking means 2 packs the voltage and current measurement signals for one cycle of the power supply frequency.
  • the AD conversion overnight packing means 2 has a function of detecting a power supply frequency on a power supply line and a means of detecting a rising or falling cross point of the power supply frequency.
  • the Fourier transform means 3 performs a Fourier transform
  • the power-related amount calculating means 4 also functions as a harmonic calculating unit for calculating a power-related amount including harmonics.
  • the data packed by the AD conversion data packing means 2 is supplied to a voltage controlled oscillator for controlling the AD converter 1 via the sampling frequency correction means 5. (Hereinafter referred to as “VCO”) Entered in 6.
  • VCO voltage controlled oscillator
  • the voltage V and the current I input to the AD converter 1 are sensor outputs, and are not the physical voltages and currents on the power supply, but are values adjusted to the input of the AD converter 1. Also, an anti-aliasing filter or an operational amplifier for amplification (not shown) may be provided on the input side of the AD converter 1 in some cases.
  • the A / D conversion data packing means 2 collects the A / D conversion data for one cycle of the power supply for each L point.
  • the Fourier transform means 3 performs a Fourier transform for each L point (one cycle) with respect to the AD conversion data (one point L) for one cycle of the power supply input from the A / D conversion data talking means 2.
  • the power-related amount calculating means 4 calculates the power-related amount from the complex values of the voltage and the current after the Fou and Je transform operation processing.
  • the sampling frequency correction means 5 controls the voltage output to the VCO 6 based on the data input from the AD conversion data packing means 2 so that the AD conversion sampling frequency is locked to a natural number L times the power supply frequency. I do.
  • V C06 converts the voltage output from the sampling frequency correction means 5 into a clock output.
  • the clock output from V C 06 to AD converter 1 is the sampling frequency when AD converter 1 is a sequential AD converter, and is the oversampling frequency when AD converter 1 is a Dell Sigma AD converter.
  • V CC6 supplies the clock output before the division.
  • FIG. 3 like FIG. 1, shows a vector space composed of a real axis (horizontal axis) and an imaginary axis (vertical axis).
  • the phase of the fundamental wave is delayed when the power supply frequency is slow, and is advanced when it is fast.
  • the AD conversion sampling frequency from the VCO 6 is faster when the phase of the fundamental wave advances, and slower when the phase of the fundamental wave delays. Is controlled.
  • the simplest way to perform such control is feedback control.
  • the VCO control voltage applied at the m-th time is Vent rl—m
  • the phase difference between the m-th voltage fundamental wave and the m + 1-th voltage fundamental wave is ⁇ (lead is positive).
  • M + 1 The VCO control voltage Vent r 1—m + 1 performed for the first time is expressed by the following equation (20).
  • Vcntrl one m + 1 Vcntrl _ ⁇ + ⁇ - ⁇ (20)
  • the feedback coefficient ⁇ s (e> 0) is determined from the VCO 6 that uses an appropriate value for control, the following speed, and the like.
  • the phase difference is used as it is as the error amount for performing the feedback of the above equation (20)
  • the calculation of the trigonometric function for calculating the phase becomes necessary, and the calculation amount increases.
  • One that corresponds and has a monotonically increasing or decreasing relationship is used as the error amount.
  • Err0r the above equation (20) is represented by the following equation (21).
  • Vcntrl +1 Vcntrl - ⁇ -Error (21)
  • the error amount Error becomes a positive value when the power supply frequency is slow (phase is delayed), and becomes a negative value when the power supply frequency is fast (phase is advanced). Therefore, with respect to the phase difference, the sign is inverted when monotonically increasing, and the value as it is can be used as the error Error when monotonically decreasing.
  • the following processing related to frequency tracking is executed in order to reduce the amount of calculation by replacing the error amount Error with an amount other than the phase.
  • the VCO control voltage Vent r 1 (voltage output of the sampling frequency correction means 5) is usually generated by a D / A converter.
  • Fig. 4 is an explanatory diagram showing the power supply frequency.
  • the horizontal axis shows time, and the vertical axis shows power supply amplitude.
  • the AD conversion value of the voltage will be “0” every time. However, the AD conversion value becomes positive when the power supply frequency increases, and negative when the power supply frequency decreases (see Fig. 4).
  • the error amount Error has a one-to-one correspondence with the phase difference in a range of ⁇ 90 degrees and shows a monotonic increase, so that a value obtained by inverting the AD conversion value of the sampling point selected each time can be obtained.
  • VCO control voltage Vent r 1 is limited to a value that is 1/2 to 2 times the sampling frequency in order to lock at a frequency that is a natural number multiple of the sampling frequency or a frequency that is a fraction of the natural number. Need to be done.
  • the sampling frequency is set to a natural number multiple of the power supply frequency and 2 to the Nth power, locking is performed even at half the sampling frequency. Also, it is necessary to limit the feedback amount “ ⁇ ⁇ Error” in the above equation (21).
  • the sampling frequency is locked to the rising edge of the cross-point of the power supply voltage, but it may be locked to the falling edge.
  • the AD conversion value itself is used as the error amount Error. Become.
  • the sampling frequency of the AD converter 1 to follow a natural number multiple of the power supply frequency
  • the result of the Fourier transform by the Fourier transform means 3 is directly obtained. Since the harmonic component can be obtained, it is possible to measure not only the power of the fundamental wave but also the power of the harmonic with a simple configuration.
  • a sampling frequency of several kHz and a CPU clock of several MHz can be configured by combining the VCO 6 with the VCO 6. This does not necessarily require a particularly high-precision AD converter 1. However, when a monolithic IC is used, the chip area is not increased, which is preferable.
  • the control accuracy can be higher than when the sampling frequency of the AD converter 1 is directly controlled using the CPU clock. Can be measured.
  • the over-sampling frequency can be finely adjusted by VC06, so that the measurement accuracy of power-related quantities including power is improved. It is suitable for monolithic IC.
  • the sampling frequency of the AD converter 1 is set to a natural number multiple of the power supply frequency and 2 to the Nth power, and the Fourier transform means 3 uses an FFT from the viewpoint of computation speed. preferable.
  • active power, active power, reactive power, reactive power, apparent power, distortion power, current rms, voltage rms, phase difference between current and voltage, or harmonics of each of these orders It is possible to measure and calculate power-related quantities, such as values in waves, that cannot be measured and calculated by the conventional configuration.
  • the reactive power required to calculate power supply efficiency can be measured with high accuracy, including harmonics, and the power factor, which is an index for effective use of power, can be obtained with high accuracy.
  • sampling frequency correction means 5 can be realized by the calculation function of the CPU, and the above configuration can be realized only by combining the sampling frequency correction means 5 with the VCO 6, so that the configuration can be simplified.
  • the sampling frequency correction means 5 locks on the basis of the zero crossing point (rising or falling) based on the output data of the AD data packing means 2, so that complicated calculations occur in the CPU. None is done, and a simple configuration can be achieved.
  • the error amount E rror in the above equation (21) is tracked by feedback control, the tracking performance is good and the real-time property is excellent.
  • the absolute phase of the fundamental wave of FFT may be brought into the same position.
  • FIG. 5 is a block diagram showing a main circuit configuration according to Embodiment 2 of the present invention, and shows a case where the absolute phase of the fundamental wave of FFT is locked at the same position as a VC0 control method.
  • the same components as those described above are denoted by the same reference numerals with "A" appended thereto, and detailed description thereof is omitted.
  • the Fourier transform means 3 A constitutes a sampling frequency control means in connection with the sampling frequency correction means 5 A and VC 06 A, and means for detecting the absolute phase of the power supply voltage, and a delay of the absolute phase. Or means for detecting the advance as a voltage phase difference.
  • sampling frequency correction means 5A outputs a VCO control voltage for VCO 6A based on the data from the Fourier transform means 3A.
  • FIG. 6 is an explanatory diagram illustrating a correction process for causing the sampling frequency of the AD converter 1A according to the second embodiment of the present invention to follow a natural number L times the power supply frequency, and is similar to FIGS. 1 and 3 described above. Similarly, it shows a vector space consisting of a real axis (horizontal axis) and an imaginary axis (vertical axis).
  • the absolute phase of the fundamental wave of voltage becomes the same value every time if the sampling frequency of the AD converter 1A is locked to a natural number L times the power supply frequency, but when the power supply frequency becomes slower
  • the motor rotates in the lagging direction, and rotates faster in the leading direction.
  • VI cmp pre Vl pre re + j -Vl pre im
  • the range of the phase difference Phas e—V 1—Error is ⁇ 90 degrees. Also, if the amplitude of the voltage is almost constant each time, the denominator in Equation (23) is regarded as a constant. The numerator in equation (23) has a one-to-one correspondence with the phase difference, and decreases monotonically. Therefore, if the error amount Error is a numerator of the equation (23), the error amount Error can be expressed by the following equation (24).
  • VCO control voltage Vcntr1 must be limited to a value that is 1 to 2 to 2 times the sampling frequency. It is also necessary to limit the amount of feedback (£ ⁇ Error).
  • the second embodiment of the present invention has the following effects in addition to the effects of the first embodiment (locking at rising or falling of the zero point).
  • the phase of the voltage (or current) subjected to the Fourier transform (preferably, FFT) by the Fourier transform means 3A is locked, it is compared with that locked at the zero cross point of the voltage waveform as in the first embodiment. Excellent in high accuracy when white noise and harmonics are superimposed.
  • Embodiment 3 In the second embodiment, the reference of the absolute phase is not specifically mentioned. However, the absolute phase of the fundamental wave of the FFT may be locked at 0, 90, 180, or 270 degrees. .
  • the position at which the coordinates of the voltage fundamental wave are fixed (the absolute phase of the FFT fundamental wave) is selected to be 0, 90, 180, or 270 degrees.
  • FIG. 7 is an explanatory diagram showing a VCQ control operation according to the third embodiment, and shows a vector space composed of a real axis (horizontal axis) and an imaginary axis (vertical axis), as in FIGS. 1, 3, and 6. ing.
  • the real value VI—im has a one-to-one correspondence with the phase difference within a range of ⁇ 90 degrees, and has a monotonically increasing relationship. Therefore, the error amount Error can be expressed by the following equation (25).
  • the amount of calculation of the error amount Error can be made smaller than in the case of the second embodiment, and it is not necessary to store the immediately preceding (previous) coordinates.
  • the error amount Error When the phase difference exceeds 90 °, the error E rror does not change monotonically, but the sign does not change. Therefore, if the error amount Error is set as in the following equation (26), the error amount Error can be monotonically reduced with respect to the phase difference within a range of ⁇ 180 degrees. ifVl_re ⁇ 0
  • the effective value Vrms 1 of the voltage fundamental wave hardly changes, so it can be treated as a constant. In this way, the feedback range of ⁇ 90 degrees can be 180 degrees.
  • the error amount can be similarly defined.
  • the feedback range of ⁇ 90 degrees is obtained in addition to the effect of the second embodiment. Can be expanded to ⁇ 180 degrees, and the adjustment range can be widened.
  • the sampling frequency correcting means is used. Did not mention the number of bits in the D / A converter,
  • An / A converter may be used.
  • FIG. 8 is a block diagram showing a circuit configuration of a main part according to Embodiment 4 of the present invention. Components similar to those described above (FIGS. 2 and 5) are denoted by the same reference numerals with "B" appended thereto. Is omitted.
  • the sampling frequency correction means 5B has a D / A converter with a small number of bits.
  • Adder 52 sets the VCO control voltage offset relative to the small bit number D / A converter.
  • the adder 52 outputs a VCO control voltage obtained by adding the offset voltage VOFF to the VCO 6B so that the VCO control voltage becomes a specified frequency of the power supply (for example, 60 Hz). As a result, the frequency that can be controlled per bit of the D / A converter can be reduced.
  • adder 52 adds offset voltage VOFF such that the clock frequency of VCO 6 B becomes the specified frequency of the power supply.
  • FIG. 9 is an explanatory diagram showing a control operation according to the fourth embodiment of the present invention.
  • FIG. 10 is a block diagram specifically showing the attenuator 51 and the adder 52 in FIG. 8, and shows a case where the adder 52 is configured to adjust the offset voltage V OFF.
  • the attenuator 51 includes a resistor R1 and a variable resistor R2 that divide the output voltage of the D / A converter, and adjusts the divided voltage to control the control range of the VCO control voltage. It is configured to be adjustable.
  • the adder 52 includes a resistor R3 and a variable resistor R4 for dividing the offset voltage VOFF, a divided voltage of the D / A output voltage (output voltage of the attenuator 51), and an offset voltage VOFF. And a voltage addition circuit 52B for adding the divided voltage and outputting the VC0 control voltage.
  • variable adjusters of the variable resistors R2 and R4 are provided outside the electronic wattmeter so that they can be arbitrarily adjusted from the outside.
  • the VC control voltage range corresponds to the arrow length of the VC control voltage in FIG. 9 and means the voltage range when, for example, 45 Hz to 66 Hz is allocated to an 8-bit D / A converter. .
  • the offset voltage VOFF corresponds to the amount of deviation from 0 V in FIG. 9 (see the arrow), and in this case, it can be adjusted arbitrarily.
  • variable resistor R2 in the attenuator 51 when the variable resistor R2 in the attenuator 51 is adjusted, the range of the VCO control voltage changes, and when the variable resistor R4 in the adder 52 is adjusted, it is actually input to the voltage adding circuit 52B.
  • the offset voltage changes.
  • control range of the DZA converter (or the offset amount of the offset voltage) is made variable, so that the power-related amount can be measured with high accuracy according to the electric circuit to be applied. Even in the case of change, it can be handled by an inexpensive and small DZA converter.
  • An electric energy pulse output means 7 for outputting an electric energy pulse may be provided at a stage subsequent to the electric power related amount calculating means 4C.
  • FIG. 11 is a block diagram showing a main part circuit configuration according to a fifth embodiment of the present invention.
  • the electric energy pulse output means 7 performs pulse processing by sampling the electric power calculated by the fixed clock.
  • watt-hour meters are required to output a pulse of electric energy at intervals shorter than one cycle of the power supply.
  • the power-related-amount calculating means 4C is called every time the FFT calculation processing ends, and calculates necessary power such as active power, reactive power, and apparent power.
  • the power amount pulse output means 7 can output only the power amount pulse for each cycle of the power supply.
  • FIG. 12 is a timing chart showing the power calculation and power pulse output operation of the CPU according to the fifth embodiment of the present invention.
  • t, t + l,... Correspond to the data contents at each execution timing of each processing operation.
  • the AD conversion overnight packing means 2C has a function of detecting the packing time required for L-point packing, and the power-related amount calculating means 4C It has the function of outputting the power calculated for each ring command.
  • the CPU Fourier-transforms the packing data by the Fourier transforming means 3C, and calculates the power (first power value) by the power-related amount calculating means 4C (the second power value in FIG. 12). Column).
  • the content of each data at the power calculation timing is delayed by one cycle from the content at the data packing processing timing (see the top row) (t-1, 1, t, ')
  • the time required for the L-point packing (recorded time: see the top row) and the power calculated from the above-mentioned packing data (the power calculated after the Fourier transform: see the second row) are expressed by the power It is passed from the related amount calculation means 4 C to the electric energy pulse output means 7 (see the third row in FIG. 12).
  • the time (cell width of the third stage) passed to the electric energy pulse output means 7 changes in length according to the recorded time.
  • the data content at this power output timing is two cycles later than the data packing at the time of de-evening (see t-2, t-1, 1, ).
  • the CPU samples the electric power passed to the electric energy pulse output means 7 at a constant period (fixed clock) shorter than one period of the power supply frequency, and outputs the electric power for each sampling (the value of the third stage, the second Power) as the amount of power (see the fourth row in Fig. 12)
  • the value of the third stage, the second Power the value of the third stage, the second Power
  • the same data packing is performed. The same amount of power is added for each sampling of the power output corresponding to.
  • the power amount pulse output means 7 outputs a power amount pulse each time the added value of the power amount reaches a desired power amount (see the fifth stage in FIG. 12).
  • phase difference between the voltage and the current for each harmonic may be corrected.
  • FIG. 13 is a block diagram showing a main circuit configuration according to the sixth embodiment of the present invention configured to be able to correct the phase difference between the voltage and the current for each harmonic, and is similar to the above (FIG. 11). For those, the same symbols are followed by “D” and detailed description is omitted.
  • a phase correction means 8 is inserted between the Fourier transform means 3 D and the power-related amount calculation means 4 D, and the phase correction means 8 performs a rotation calculation of the absolute phase of the voltage or the current. This corrects the phase difference between the voltage and current for each harmonic.
  • current sensors such as CT
  • voltage sensors such as PT
  • the voltage and current phases are also affected by an analog circuit provided on the input side of the AD converter 1D. Therefore, in order to accurately measure the power-related amount in the power supply line, it is necessary to correct the phase distorted by the analog circuit.
  • the phase of the voltage and current of the nth harmonic has the relationship shown in Fig. 1, and if the phase difference in the power supply line is "0", the voltage is rotated by 0- ⁇ or Alternatively, the rotation calculation of the current may be performed by — ⁇ 0. If the phase difference in the power supply line is not “0”, the rotation calculation may be performed to obtain the phase difference.
  • the new current I n—c mp— new is calculated by the following equation (34). , (34)
  • the new current In-c mp- ⁇ ⁇ w values By performing this correction for each harmonic, the power-related amount can be calculated with high accuracy.
  • active power, active power, reactive power, reactive power, apparent power, strain power, current effective value, voltage effective value, phase difference between current and voltage, and their respective orders It can calculate power-related quantities such as values at higher harmonics, so it can be used in electronic watt-hour meters and power-related quantity calculation circuits not only for household use but also for consumers who need to manage power consumption by time of day. Useful.
  • power-related quantities such as values at higher harmonics
  • By measuring the amount of reactive power not only for customers who manage the power factor, but also for customers who use harmonic generators such as inverters, electronic watt-hour meters and power-related amount calculations Useful for circuits.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Frequencies, Analyzing Spectra (AREA)
  • Measurement Of Current Or Voltage (AREA)
  • Rectifiers (AREA)
  • Inverter Devices (AREA)

Abstract

Selon cette invention, on calcule avec une haute précision une quantité de courant au moyen d'un correcteur de fréquence d'échantillonnage de façon à permettre à la fréquence d'échantillonnage du numériseur de suivre une fréquence dont la valeur représente L fois celle de la fréquence d'alimentation et de l'oscillateur commandé en tension (VCO) afin de contrôler avec une haute précision la fréquence d'échantillonnage du numériseur. On calcule avec une haute précision et à une haute fréquence la puissance réactive utilisée pour capter le rendement de l'alimentation en courant calculée, et on détermine le facteur de puissance utilisé comme indice d'utilisation efficace du courant.
PCT/JP2002/002850 2002-03-25 2002-03-25 Watt-heuremetre electronique et circuit de calcul d'une quantite de courant WO2003081264A1 (fr)

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PCT/JP2002/002850 WO2003081264A1 (fr) 2002-03-25 2002-03-25 Watt-heuremetre electronique et circuit de calcul d'une quantite de courant
CN02805485.7A CN1292259C (zh) 2002-03-25 2002-03-25 电子式电能计和功率关联量运算电路
AU2002239060A AU2002239060B1 (en) 2002-03-25 2002-03-25 Electronic watthour meter and power-associated quantity calculating circuit
JP2003578946A JP4127676B2 (ja) 2002-03-25 2002-03-25 電子式電力量計および電力関連量演算回路

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JP2012032409A (ja) * 2006-06-08 2012-02-16 Shanghai Jiao Tong Univ 電力計及び電力監視システム
JP2016153792A (ja) * 2011-06-09 2016-08-25 玉山 ▲ハオ▼ 交流の物理量を測定及びデータ集録する装置及び方法
CN108919168A (zh) * 2018-05-11 2018-11-30 国网四川省电力公司电力科学研究院 基于数字补偿技术改善高压功率源失真度的方法

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JP4275696B2 (ja) * 2006-11-09 2009-06-10 三菱電機株式会社 サンプリング周波数制御方式および保護継電器
US10816579B2 (en) * 2012-03-13 2020-10-27 Informetis Corporation Sensor, sensor signal processor, and power line signal encoder
CN104502675B (zh) * 2014-12-29 2017-05-24 广东电网有限责任公司电力科学研究院 电力信号的基波幅值测量方法和系统
CN105071792B (zh) * 2015-07-17 2018-03-30 英特尔公司 脉冲密度调制值转换器及其应用
CN108471960A (zh) * 2016-10-21 2018-08-31 华为技术有限公司 血压检测信号采样补偿方法和装置以及血压信号采集系统
CN109116101B (zh) * 2018-08-08 2020-10-27 贵州电网有限责任公司 一种无功计量方法
CN109709390B (zh) * 2018-12-19 2021-10-01 深圳市中电电力技术股份有限公司 一种三相高精度谐波电能表
CN111679236B (zh) * 2020-05-11 2022-07-01 国网江苏省电力有限公司营销服务中心 一种直流暂态阶跃响应延时测试方法、系统及装置

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EP0634662A1 (fr) * 1993-01-06 1995-01-18 Mitsubishi Denki Kabushiki Kaisha Wattheuremetre electronique
JPH0743399A (ja) * 1993-07-30 1995-02-14 Hioki Ee Corp パワーアナライザ装置における測定データ表示方法

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JPH06273461A (ja) * 1993-03-23 1994-09-30 Yokogawa Electric Corp 電力測定装置
JPH0743399A (ja) * 1993-07-30 1995-02-14 Hioki Ee Corp パワーアナライザ装置における測定データ表示方法

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Publication number Priority date Publication date Assignee Title
JP2012032409A (ja) * 2006-06-08 2012-02-16 Shanghai Jiao Tong Univ 電力計及び電力監視システム
JP2016153792A (ja) * 2011-06-09 2016-08-25 玉山 ▲ハオ▼ 交流の物理量を測定及びデータ集録する装置及び方法
CN108919168A (zh) * 2018-05-11 2018-11-30 国网四川省电力公司电力科学研究院 基于数字补偿技术改善高压功率源失真度的方法

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CN1292259C (zh) 2006-12-27
CN1493002A (zh) 2004-04-28

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