CN104280609B - Ultra-wide-range impact load electric energy meter - Google Patents
Ultra-wide-range impact load electric energy meter Download PDFInfo
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Abstract
The invention discloses an ultra-wide-range impact load electric energy meter, and belongs to the technical field of electric energy measurement. The energy meter is composed of an A-phase multirange input module, a B-phase multirange input module, a C-phase multirange input module, an analog-digital converter (ADC), a digital signal processor (DSP) and an electric energy data output module. According to the electric energy meter, the 0.5s level or the 0.2s level of nominal accuracy within 0.05In to 360In can be achieved. The electric energy meter can measure high-precision large current and small current as well.
Description
Technical Field
The invention belongs to the technical field of electric energy metering, and particularly relates to a range impact load electric energy meter.
Background
Impact load refers to a load with widely varying load current (e.g., arc furnace, rolling mill, etc.), and the peak value of impact current may be several or ten times the average load current.
Ordinary people pay more attention to the nominal precision of the electric energy meter, but do not pay much attention to the range of the electric energy meter. In fact, the nominal accuracy of the electric energy meter is onlyCan be ensured within the range of the temperature,is the maximum current (effective value) of the electric energy meter which guarantees the nominal precision,is the minimum current (effective value) of the electric energy meter for ensuring the nominal precision, and the electric energy meter also has an important parameter, namely basic current(effective value), the basic current is the most basic operating current for calibrating the accuracy of the electric energy meter.
National standard regulation of the electric energy meter: under normal circumstancesAnd n is called overload multiple, the overload multiple of the conventional electric energy meter is 4 times and 6 times, the electric energy meter with wide measuring range is obtained when the overload multiple reaches 8 times and 10 times, and the overload multiple is more than 10 times, because the high-current measurement precision and the low-current measurement precision are difficult to combine.
Some of the current peaks due to shock loading may exceedTherefore, the conventional electric energy meter measures the impact load electric energy inaccurately, sometimes even "loses" the impact load electric energy.
The national grid company 'intelligent electric energy meter type standard article explanation' explicitly indicates that: the wide range and the high reliability are a development trend of the electric energy meter, and the higher the overload multiple of the electric energy meter is, the wider the load range which can meet the accurate measurement of the grade index is. In addition, if the load of the user is increased in the future, the workload of replacing the electric energy meter can be reduced.
Disclosure of Invention
The invention provides an ultra-wide range impact load electric energy meter, the overload multiple of which can reach 360 times, namely that of the electric energy meterThe nominal precision of the electric energy meter in the range can be 0.5s or even 0.2 s.
The invention is composed of A, B, C phase multi-range input module, ADC, DSP and power data output module;
each phase multi-range input module comprises a voltage transformer PTxA first current transformer CTx1 and a second current transformer CTx2. A voltage signal conditioning link, a first current signal conditioning link and a second current signal conditioning link;
voltage transformer PT of each phase multi-range input modulexWill be the voltage signal of the corresponding phaseConversion to low voltage signalsAnd will low voltage signalSending the voltage signal to a voltage signal conditioning link, and sending the voltage signal to a first current transformer CT of each phase multi-range input modulex1 according to current transformation ratioCurrent signals of the respective phasesConverted to a first low current signalAnd sends the first low current signalSending to a first current signal conditioning link and a second current transformer CTx2 according to current transformation ratioCurrent signals of the respective phasesConverted to a second low current signalAnd the second low current signalSending to a second current signal conditioning stageK i2＜K i1；
The voltage signal conditioning link, the first current signal conditioning link and the second current signal conditioning link of the multi-range input module of each phase respectively condition the low voltage signal after regulationA first low current signalAnd a second low current signalConverting the low voltage digital signal into a low voltage digital signal by an analog-to-digital converter (ADC)The first stepA low current digital signalAnd a second low current digital signal；
Low voltage digital signalA first low current digital signalAnd a second low current digital signalLow voltage digital signal to each item via digital signal processor DSPA first low current digital signalAnd a second low current digital signalCarrying out digital integration to obtain three-phase electric energy data and transmitting the three-phase electric energy data to an electric energy data output module;
the formula of the digital signal processor DSP for digital integration is as follows:
in the above formula, the first and second carbon atoms are,is the firstThe time of one calculation cycle is,is the variable ratio constant of the voltage input link,is the firstThe transformation ratio of the current input link in each calculation period,phase current digital signals used for calculating corresponding phase active electric energy;
the digital signal processor DSP contains a current channel automatic selector in the secondIn each calculation period, the selection principle of the current channel automatic selector is as follows:
wherein,andrespectively, a digital signal processor DSP is inThe current digital quantity and the current transformation ratio used for calculating the electric energy of the corresponding phase in each calculation period,andrespectively a positive maximum digital quantity and a negative minimum digital quantity for linear analog-to-digital conversion by the analog-to-digital converter ADC.
The electric energy data output mode of the electric energy data output module can be three types: and displaying on a panel of the display, testing active pulses and testing idle pulses, and outputting data through a communication interface.
The conventional methods for calculating, displaying, uploading and calibrating the active electric energy and the reactive electric energy are not repeated herein, and the invention is characterized in that:
phase signal of each phaseThe input path has two paths, one is a conventional path-via the first current transformer CTx1 according to current transformation ratioSent to ADC to be converted into current digital quantityOne is an impact path-via the second current transformer CTx2 according to current transformation ratioSent to ADC to be converted into current digital quantity，。
Let the basic current corresponding to the conventional path beMaximum current ofMinimum current ofThe overload multiple is n1(ii) a The impact path corresponds to a basic current ofMaximum current ofMinimum current ofThe overload multiple is n2。
Thus, the key elements of the invention are: how to determine the conventional path、、、How to determine the path of the impact、、、How to switch when the DSP calculates the electric energyThe two paths are switched.
If the analog-to-digital converter ADC is in the range of linear analog-to-digital conversion corresponding to the digital quantity，Andrespectively positive maximum digital quantity and negative minimum digital quantity of linear analog-to-digital conversion of analog-to-digital converter ADC, and is generally taken in electric energy meter. Numerical quantityAnalog voltage value corresponding to ADC input terminalThen determining the current transformation ratioThe principle of (1) is as follows:
（1）
wherein,is the current form factor.
Current transformation ratioAfter determination, the current transformation ratio can be determinedDeterminingThe principle of (1) is as follows:
（2）
here, the。
The DSP contains a current channel automatic selection mechanism, and in the nth calculation period, the selection principle of the selection mechanism is as follows:
（3）
（4）
wherein,andrespectively, a digital signal processor DSP is inThe current digital quantity and the current transformation ratio for calculating the electric energy (digital integral) of the corresponding phase in each calculation period,andrespectively a positive maximum digital quantity and a negative minimum digital quantity for linear analog-to-digital conversion by the analog-to-digital converter ADC.
Formulae (1) to (4) mean: when the current signalIs less thanCalculating data of conventional path for electric energy when current signalIs greater than or equal toAnd calculating the data of the impact path for the electric energy.
Get It is apparent that the range of conventional and impulse paths is inThe range is continuously covered.
In summary, the indexes of the whole ultra-wide range impact load electric energy meter are as follows: basic currentMinimum current ofMaximum current ofThat is to say, inThe nominal precision of the electric energy meter in the range can be ensured.
It can be seen that the invention can be regarded as a seamless butt joint of two electric energy meters with 6-time overload times, and the realization of 0.5s level or 0.2s level of each 6-time electric energy meter is a mature technology, so the invention is used for solving the problems that the prior art has high cost and high reliabilityThe standard precision within the range is not problematic to be 0.5s or 0.2s, namely the invention can measure high current and low current with high precision.
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Fig. 1 is a schematic block diagram of the present invention.
Detailed Description
As shown in fig. 1, the invention is composed of A, B, C three-phase multi-range input module 1, analog-to-digital converter ADC 2, digital signal processor DSP 3 and power data output module 4.
The DSP contains a current channel automatic selector, and in the first calculation period, the selection principle of the current channel automatic selector is as follows:
wherein,andrespectively, a digital signal processor DSP is inThe current digital quantity and the current transformation ratio for calculating the electric energy (digital integral) of the corresponding phase in each calculation period,andrespectively a positive maximum digital quantity and a negative minimum digital quantity for linear analog-to-digital conversion by the analog-to-digital converter ADC.
Each phase multi-range input module 1 comprises a voltage transformer PTx11. First current transformer CTx112 and a second current transformer CTx213. A voltage signal conditioning link 14, a first current signal conditioning link 15 and a second current signal conditioning link 16.
Voltage transformer PT of each-phase multi-range input module 1x11 will correspond to the phase voltage signalConversion to low voltage signalsAnd will low voltage signalSending to a voltage signal conditioning link 14, and a first current transformer CT of each phase multi-range input module 1x112 in current transformation ratioCurrent signals of the respective phasesConverted to a first low current signalAnd sends the first low current signalSending to a first current signal conditioning link 15 and a second current transformer CTx213 according to current transformation ratioCurrent signals of the respective phasesConverted to a second low current signalAnd the second low current signalTo a second current signal conditioning stage 16, andK i2＜K i1。
the voltage signal conditioning link 14, the first current signal conditioning link 15 and the second current signal conditioning link 16 of the multi-range input module 1 of each phase respectively condition the low voltage signal after regulationA first low current signalAnd a second low current signalConverting the low voltage digital signal into a low voltage digital signal by an analog-to-digital converter (ADC)A first low current digital signalAnd a second low current digital signal。
Low voltage digital signalA first low current digital signalAnd a second low current digital signalLow voltage digital signals of each phase are respectively processed by a digital signal processor DSP according to the following formulaA first low current digital signalAnd a second low current digital signalAnd carrying out digital integration to obtain three-phase electric energy data and transmitting the three-phase electric energy data to the electric energy data output module.
The formula for the digital signal processor DSP to perform digital integration is:
in the above formula, the first and second carbon atoms are,is the firstThe time of one calculation cycle is,is the variable ratio constant of the voltage input link,is the firstThe transformation ratio of the current input link in each calculation period,phase current digital signals used for calculating corresponding phase active electric energy;
the three-phase input circuit of the invention is symmetrical, and the voltage transformer PTxPreferably, 11 is a resistance voltage division type PT, each current transformer is an electromagnetic type CT, and the transformation ratios of the CTs used by the two current paths are different: the current transformation ratio of the conventional path CT1 plus the signal conditioning element isCurrent transformation ratio of impulse path CT2 plus signal conditioning elementIs thatThe ratio of the total amount of the active carbon to the total amount of the active carbon is 60 times that of the active carbon,selected according to formula (1).
The signal conditioning links are conventional circuits, 16-bit ADCs are recommended for the analog-to-digital converters, 32-bit DSPs (such as TMS320F 2812) are recommended for the digital signal processors, and displays, communication ports, pulse output and the like are the same as those of conventional electric energy meters.
Claims (1)
1. An ultra-wide range impact load electric energy meter is composed of an A, B, C-phase multi-range input module, an analog-to-digital converter (ADC), a Digital Signal Processor (DSP) and an electric energy data output module; the method is characterized in that:
each phase multi-range input module comprises a voltage transformer PTxA first current transformer CTx1 and a second current transformer CTx2. A voltage signal conditioning link, a first current signal conditioning link and a second current signal conditioning link;
voltage transformer PT of each phase multi-range input modulexWill be corresponding toVoltage signal of phaseConversion to low voltage signalsAnd will low voltage signalSending the voltage signal to a voltage signal conditioning link, and sending the voltage signal to a first current transformer CT of each phase multi-range input modulex1 according to current transformation ratioCurrent signals of the respective phasesConverted to a first low current signalAnd sends the first low current signalSending to a first current signal conditioning link and a second current transformer CTx2 according to current transformation ratioCurrent signals of the respective phasesConverted to a second low current signalAnd the second low current signalSending to a second current signal conditioning stageK i2＜K i1；
The voltage signal conditioning link, the first current signal conditioning link and the second current signal conditioning link of the multi-range input module of each phase respectively condition the low voltage signal after regulationA first low current signalAnd a second low current signalConverting the low voltage digital signal into a low voltage digital signal by an analog-to-digital converter (ADC)A first low current digital signalAnd a second low current digital signal；
Low voltage digital signalA first low current digital signalAnd a second low current digital signalLow voltage digital signal for each phase via digital signal processor DSPA first low current digital signalAnd a second low current digital signalCarrying out digital integration to obtain three-phase electric energy data and transmitting the three-phase electric energy data to an electric energy data output module;
the formula of the digital signal processor DSP for digital integration is as follows:
in the above formula, the first and second carbon atoms are,is the firstThe time of one calculation cycle is,is the variable ratio constant of the voltage input link,is the firstThe transformation ratio of the current input link in each calculation period,phase current digital signals used for calculating corresponding phase active electric energy;
the digital signal processor DSP contains a current channel automatic selector in the secondIn each calculation period, the selection principle of the current channel automatic selector is as follows:
wherein,andrespectively, a digital signal processor DSP is inThe current digital quantity and the current transformation ratio used for calculating the electric energy of the corresponding phase in each calculation period,andrespectively a positive maximum digital quantity and a negative minimum digital quantity for linear analog-to-digital conversion by the analog-to-digital converter ADC.
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Citations (3)
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| CN201191304Y (en) * | 2008-04-25 | 2009-02-04 | 四川启明星蜀达电气有限公司 | Electrical energy meter of ultra-wide metering range |
| CN201355376Y (en) * | 2009-02-27 | 2009-12-02 | 四川启明星蜀达电气有限公司 | Ultra-wide range single-phase multi-rate watt-hour meter |
| CN102981083A (en) * | 2012-12-05 | 2013-03-20 | 江苏中凌高科技有限公司 | Self-calibration electric energy quality monitoring device |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201191304Y (en) * | 2008-04-25 | 2009-02-04 | 四川启明星蜀达电气有限公司 | Electrical energy meter of ultra-wide metering range |
| CN201355376Y (en) * | 2009-02-27 | 2009-12-02 | 四川启明星蜀达电气有限公司 | Ultra-wide range single-phase multi-rate watt-hour meter |
| CN102981083A (en) * | 2012-12-05 | 2013-03-20 | 江苏中凌高科技有限公司 | Self-calibration electric energy quality monitoring device |
Non-Patent Citations (1)
| Title |
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| 基于PSOC的宽量程电能计量模块;梅永 等;《江苏电机工程》;20050331;第24卷(第2期);第48-50页 * |
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