阅读说明：本技术 一种具有谐波测量的高准确度三相标准电能表 (A kind of high accuracy three-phase standard electric energy meter with harmonic measure ) 是由 徐燕明 冷学道 顾葳 姜文辉 姚元其 吴彦奇 周焱磊 王驰予 于 2019-09-26 设计创作，主要内容包括：本发明提出了一种具有谐波测量的高准确度三相标准电能表,其三相电压信号取样电路、三相电流信号取样电路分别经过信号隔离电路与采样部分CPU的输入端相连,所述三相电流信号取样电路包括有源补偿电流互感器和程控运放电路,所述采样部分CPU的输出端分别与误差计算器、标准表脉冲输出电路相连,所述人机界面CPU、误差计算器通过过串口转RS-485通信线与采样部分CPU连接,所述人机界面CPU与显示单元,键盘单元相连,所述被检表脉冲输入电路的输出端与误差计算器相连。该三相标准电能表扩展了小电流量程,能够提高小电流的测量精度,并且能够产生基波或谐波电能,可作为谐波电能表检验基波电能或谐波电能的标准。(The invention proposes a kind of high accuracy three-phase standard electric energy meter with harmonic measure, its three-phase voltage signal sample circuit, three-phase current signal sample circuit passes through signal isolation circuit respectively and is connected with the input terminal of sampling section CPU, the three-phase current signal sample circuit includes active compensation current transformer and program-controlled operational amplifier circuit, the output end of the sampling section CPU respectively with Error Calculator, standard scale impulse output circuit is connected, the man-machine interface CPU, Error Calculator passed through serial ports and turns RS-485 communication line to be connect with sampling section CPU, the man-machine interface CPU and display unit, keyboard unit is connected, the output end of the checklist pulse input circuit is connected with Error Calculator.The three-phase standard electric energy meter extends low current range, can be improved the measurement accuracy of low current, and can generate fundamental wave or harmonic electric energy, can be used as the standard that harmonic electric energy meter examines fundamental energy or harmonic electric energy.)

1. a kind of high accuracy three-phase standard electric energy meter with harmonic measure, it is characterised in that: taken including three-phase voltage signal Sample circuit (1), three-phase current signal sample circuit (2), signal isolation circuit (3), sampling section CPU(4), man-machine interface CPU (5), display unit (6), keyboard unit (7), Error Calculator (8), checklist pulse input circuit (9), standard scale pulse are defeated Circuit (10) out, the three-phase voltage signal sample circuit (1), three-phase current signal sample circuit (2) respectively by signal every It is connected from circuit (3) with the input terminal of sampling section CPU(4), three-phase voltage signal and three-phase current signal are separately input to three In phase voltage signal sample circuit (1), three-phase current signal sample circuit (2), three-phase current signal sample circuit (2) packet Active compensation current transformer and program-controlled operational amplifier circuit are included, active compensation current transformer includes first winding N, secondary winding N1 With N2, compensative winding N3 and excitation winding N4, the first winding N is connected with current input terminal, and secondary winding N1 and N2 are logical Cross relay switching and be connected with sampling resistor R, sampled signal inputs program-controlled operational amplifier circuit, compensative winding N3 and excitation winding N4 it Between be connected with a compensation circuit, the sampling section CPU(4) output end respectively with Error Calculator (8), standard scale pulse Output circuit (10) is connected, the man-machine interface CPU(5), Error Calculator (8) passed through serial ports and turns RS-485 communication line and adopt Sample part CPU(4) connection, the man-machine interface CPU(5) and display unit (6), keyboard unit (7) is connected, the checklist arteries and veins The output end for rushing input circuit (9) is connected with Error Calculator (8).

2. a kind of high accuracy three-phase standard electric energy meter with harmonic measure as described in claim 1, it is characterised in that: institute Stating three-phase voltage signal sample circuit (1) includes resistor voltage divider circuit, program-controlled operational amplifier circuit, ADC conversion circuit and ADC benchmark electricity Volt circuit, the signal after partial pressure realizes the amplification of signal by program-controlled operational amplifier circuit, defeated with the full scale for adapting to ADC input signal Enter.

3. a kind of high accuracy three-phase standard electric energy meter with harmonic measure as claimed in claim 2, it is characterised in that: institute Stating three-phase current signal sample circuit (2) further includes ADC conversion circuit and ADC reference voltage circuit.

4. a kind of high accuracy three-phase standard electric energy meter with harmonic measure as claimed in claim 3, it is characterised in that: institute The sampling resistor R of the resistance, three-phase current signal sample circuit (2) of stating three-phase voltage signal sample circuit (1) is all made of The Low Drift Temperature foil resistance of VISHAY company production, temperature coefficient are 0.05ppm/ DEG C, and ADC conversion circuit uses 18 AD conversion Chip AD7634, data width 18-bit；The LM399H that ADC reference voltage circuit selects temperature drift extremely low, temperature drift parameter are 0.5ppm /℃。

5. a kind of high accuracy three-phase standard electric energy meter with harmonic measure as described in claim 1, it is characterised in that: institute The number of turns for stating secondary winding N1 is 200, the number of turns of N2 is 1800.

6. a kind of high accuracy three-phase standard electric energy meter with harmonic measure as described in claim 1, it is characterised in that: institute Signal isolation circuit (3) are stated for reducing signal interference between analog circuit and digital circuit, three-phase voltage, three-phase current Input circuit is worked using individual power supply, to reduce signal interference between phase and phase.

7. a kind of high accuracy three-phase standard electric energy meter with harmonic measure as described in claim 1, it is characterised in that: institute State sampling section CPU(4) there is single-precision floating point arithmetic element, to shorten operation time when discrete Fourier transform.

8. a kind of high accuracy three-phase standard electric energy meter with harmonic measure as described in claim 1, it is characterised in that: three Phase voltage signal and three-phase current signal are input to three-phase voltage signal sample circuit (1), three-phase current signal sample circuit (2) In, sampling section CPU(4) according to the generation sampling time sequence pulse of the sampling number of the frequency input signal captured and a cycle To control ADC conversion rate；Sampling section CPU(4) according to sampling time sequence, three road voltages and three are read in external interrupt routine The sample point data of road electric current is stored to respectively in six arrays；In main circulating program, distinguished with the data in six arrays Calculate voltage, electric current, active power, reactive power, phase.

9. a kind of high accuracy three-phase standard electric energy meter with harmonic measure as claimed in claim 8, it is characterised in that: should The method that high accuracy three-phase standard scale carries out frequency analysis to harmonic electric energy meter are as follows: the data point sampled is carried out discrete Fu In leaf transformation, the virtual value RMS and phase Phase of the waveform signal fundamental wave and each harmonic is calculated；According to being calculated Voltage harmonic virtual valueAnd phase, current harmonics virtual valueAnd phaseCalculate harmonic wave wattful power Rate and reactive power；Calculation formula is as follows:

Active power virtual value

Reactive power virtual value,

The high accuracy three-phase standard scale by power be converted into standard electrical energy pulse by standard scale impulse output circuit (10) it is defeated Out, the standard verification as tested electric energy meter；The high accuracy three-phase standard scale calculates tested electric energy by Error Calculator (8) The electric energy error of table, the calibrating of achievable fundamental energy, harmonic electric energy to harmonic electric energy meter.

Technical field

The present invention relates to the technical field of three-phase electric energy meter, especially a kind of high accuracy three-phase mark with harmonic measure Quasi- electric energy meter.

Background technique

The advanced high-grade three-phase standard electric energy meter of Technical comparing is based on digital sampling, according to the frequency captured at present Sample frequency occurs for the sampling number of rate and a cycle, passes through the wave of sampling time sequence CPU sampling three-phase voltage and three-phase current The electricity such as voltage, electric current, active power, reactive power, power factor, phase are obtained by calculation in form point.It calculated at this Electricity obtained in journey is all all-wave, is unable to get the electricity of fundamental wave and each harmonic.For making for various harmonic electric energy meters With this kind of standard electric energy meter can not be as the standard of calibrating harmonic electric energy meter, it is proposed that a kind of Gao Zhun with harmonic measure Exactness three-phase standard electric energy meter.

Summary of the invention

The object of the invention is to solve the problems of the prior art, a kind of high accuracy three with harmonic measure is proposed Phase standard electric energy meter extends low current range, can be improved the measurement accuracy of low current, and can generate fundamental wave or harmonic wave Electric energy can be used as the standard that harmonic electric energy meter examines fundamental energy or harmonic electric energy.

To achieve the above object, the invention proposes a kind of high accuracy three-phase standard electric energy meter with harmonic measure, Including three-phase voltage signal sample circuit, three-phase current signal sample circuit, signal isolation circuit, sampling section CPU, man-machine boundary Face CPU, display unit, keyboard unit, Error Calculator, checklist pulse input circuit, standard scale impulse output circuit are described Three-phase voltage signal sample circuit, three-phase current signal sample circuit pass through signal isolation circuit and sampling section CPU's respectively Input terminal is connected, and three-phase voltage signal and three-phase current signal are separately input to three-phase voltage signal sample circuit, three-phase current In signal sampling circuit, the three-phase current signal sample circuit includes active compensation current transformer and program-controlled operational amplifier circuit, Active compensation current transformer includes first winding N, secondary winding N1 and N2, compensative winding N3 and excitation winding N4, and described one Secondary winding N is connected with current input terminal, and secondary winding N1 and N2 is connected with sampling resistor R, sampling letter by relay switching Number program-controlled operational amplifier circuit of input, is connected with a compensation circuit, the sampling section between compensative winding N3 and excitation winding N4 The output end of CPU is connected with Error Calculator, standard scale impulse output circuit respectively, the man-machine interface CPU, Error Calculator Turn RS-485 communication line by serial ports excessively to connect with sampling section CPU, the man-machine interface CPU and display unit, keyboard unit It is connected, the output end of the checklist pulse input circuit is connected with Error Calculator.

Preferably, the three-phase voltage signal sample circuit includes resistor voltage divider circuit, program-controlled operational amplifier circuit, ADC turns Circuit and ADC reference voltage circuit are changed, the signal after partial pressure realizes the amplification of signal by program-controlled operational amplifier circuit, to adapt to ADC The full scale of input signal inputs.

Preferably, the three-phase current signal sample circuit further includes ADC conversion circuit and ADC reference voltage circuit.

Preferably, the sampling electricity of the resistance of the three-phase voltage signal sample circuit, three-phase current signal sample circuit Resistance R is all made of the Low Drift Temperature foil resistance of VISHAY company production, and temperature coefficient is 0.05ppm/ DEG C, and ADC conversion circuit uses 18 Position AD conversion chip AD7634, data width 18-bit；The LM399H that ADC reference voltage circuit selects temperature drift extremely low, temperature drift Parameter be 0.5ppm/DEG C.

Preferably, the number of turns of the secondary winding N1 is 200, the number of turns of N2 is 1800.

Preferably, the signal isolation circuit is used to reduce signal interference between analog circuit and digital circuit, three Phase voltage, three-phase current input circuit worked using individual power supply, to reduce signal interference between phase and phase.

Preferably, the sampling section CPU has single-precision floating point arithmetic element, to shorten discrete Fourier transform When operation time.

Preferably, three-phase voltage signal and three-phase current signal are input to three-phase voltage signal sample circuit, three-phase electricity It flows in signal sampling circuit, sampling section CPU occurs according to the sampling number of the frequency input signal captured and a cycle Sampling time sequence pulse controls ADC conversion rate；Sampling section CPU reads three in external interrupt routine according to sampling time sequence The sample point data of road voltage and three road electric currents is stored to respectively in six arrays；In main circulating program, in six arrays Data calculate separately voltage, electric current, active power, reactive power, phase.

Preferably, the method that the high accuracy three-phase standard scale carries out frequency analysis to harmonic electric energy meter are as follows: sampling The data point arrived carries out discrete Fourier transform, and the virtual value RMS and phase of the waveform signal fundamental wave and each harmonic is calculated Position Phase；According to the voltage harmonic virtual value being calculatedAnd phase, current harmonics virtual valueAnd phaseCalculate harmonic wave active power and reactive power；Calculation formula is as follows:

Active power virtual value

Reactive power virtual value,

The high accuracy three-phase standard scale converts standard electrical energy pulse for power and is exported by standard scale impulse output circuit, makees For the standard verification for being detected electric energy meter；The high accuracy three-phase standard scale calculates the electric energy of tested electric energy meter by Error Calculator Error, the calibrating of achievable fundamental energy, harmonic electric energy to harmonic electric energy meter.

Beneficial effects of the present invention: the present invention passes through the switching of secondary winding in current transformer the number of turns, extends low current Range, and fundamental wave and each harmonic electricity can be calculated by discrete Fourier transform, fundamental wave or harmonic electric energy are generated, It can be used as the standard that harmonic electric energy meter examines fundamental energy or harmonic electric energy.

Feature and advantage of the invention will be described in detail by embodiment combination attached drawing.

Detailed description of the invention

Fig. 1 is a kind of functional block diagram of the high accuracy three-phase standard electric energy meter with harmonic measure of the present invention；

Fig. 2 is a kind of electricity mutual inductor principle of the high accuracy three-phase standard electric energy meter with harmonic measure of the present invention.

Specific embodiment

Refering to fig. 1 with a kind of high accuracy three-phase standard electric energy meter with harmonic measure of Fig. 2 present invention, including three-phase electricity Press signal sampling circuit 1, three-phase current signal sample circuit 2, signal isolation circuit 3, sampling section CPU4, man-machine interface CPU5, display unit 6, keyboard unit 7, Error Calculator 8, checklist pulse input circuit 9, standard scale impulse output circuit 10, the three-phase voltage signal sample circuit 1, three-phase current signal sample circuit 2 are respectively by signal isolation circuit 3 and sampling The input terminal of part CPU4 is connected, and three-phase voltage signal and three-phase current signal are separately input to three-phase voltage signal sample circuit 1, in three-phase current signal sample circuit 2, the three-phase current signal sample circuit 2 includes active compensation current transformer and journey Control operational amplifier circuit, active compensation current transformer include first winding N, secondary winding N1 and N2, compensative winding N3 and excitation around N4 is organized, the first winding N is connected with current input terminal, and secondary winding N1 and N2 is connected with sampling electricity by relay switching R is hindered, sampled signal inputs program-controlled operational amplifier circuit, a compensation circuit is connected between compensative winding N3 and excitation winding N4, uses Excitation winding extracts exciting current and generates compensation electric current appropriate, injecting compensating winding by compensation circuit.Compensation electric current exists Magnetic flux is generated in auxiliary iron core, and main iron core is made to reach Zero flux, thus reduce error, the output end point of the sampling section CPU4 It is not connected with Error Calculator 8, standard scale impulse output circuit 10, the man-machine interface CPU5, Error Calculator 8 passed through string Mouth turns RS-485 communication line and connect with sampling section CPU4, and the man-machine interface CPU5 and display unit 6, keyboard unit 7 are connected, The output end of the checklist pulse input circuit 9 is connected with Error Calculator 8.

Further, the three-phase voltage signal sample circuit 1 includes resistor voltage divider circuit, program-controlled operational amplifier circuit, ADC turns Circuit and ADC reference voltage circuit are changed, the signal after partial pressure realizes the amplification of signal by program-controlled operational amplifier circuit, to adapt to ADC The full scale of input signal inputs, and improves sampling accuracy.

Further, the three-phase current signal sample circuit 2 further includes ADC conversion circuit and ADC reference voltage circuit.

Further, the sampling of the resistance, three-phase current signal sample circuit 2 of the three-phase voltage signal sample circuit 1 Resistance R is all made of the Low Drift Temperature foil resistance of VISHAY company production, and temperature coefficient is 0.05ppm/ DEG C, and ADC conversion circuit uses 18 AD conversion chip AD7634, data width 18-bit；The LM399H that ADC reference voltage circuit selects temperature drift extremely low, temperature Drift parameter be 0.5ppm/DEG C.The stability that ensure that analog input signal improves the resolution of the digital signal of ADC conversion Rate improves the stability and accuracy of standard electric energy meter measurement.

Further, referring to Fig.2, the number of turns of the secondary winding N1 is 200, the number of turns of N2 is 1800.Conventional current amount The K1 of secondary winding N1 is connected to resistance R when journey, and the K2 of N1 is connected to the K3 of N2 by S1 switching, and the K4 of N2 is connected to by S1 switching to be adopted Sample resistance R, sampling resistor R connect at the K1 of N1 and at the K2 of N2 (2000T).When low current 20mA range, sampling resistor R passes through The switching of S1 and S2 connects at the K1 and K2 of N1 (200), the voltage signal got on sampling resistor R when improving small current measurement, To adapt to the full scale input of ADC input signal, sampling accuracy is improved.

Further, the signal isolation circuit 3 is used to reduce signal interference between analog circuit and digital circuit, and three Phase voltage, three-phase current input circuit worked using individual power supply, to reduce signal interference between phase and phase.

Further, the sampling section CPU4 selects STM32F4xx series A RM core, and dominant frequency is up to 168 MHz, 32 multipliers of interior band and divider have single-precision floating point arithmetic element.Discrete Fourier transform needs are largely floated Point processing, operation time when there is CPU FPU Float Point Unit to substantially reduce discrete Fourier transform.

The course of work of the present invention:

Three-phase voltage signal and three-phase current signal are input to three-phase voltage signal sample circuit 1, three-phase current signal takes In sample circuit 2, when sampling section CPU4 is sampled according to the sampling number of the frequency input signal captured and a cycle Serial vein brings control ADC conversion rate；Sampling section CPU4 reads three road voltages according to sampling time sequence in external interrupt routine With the sample point data of three road electric currents, it is stored in six arrays respectively；In main circulating program, with the data in six arrays come Calculate separately the electricity such as voltage, electric current, active power, reactive power, phase.

When needing to carry out frequency analysis, the data point sampled is carried out discrete Fourier transform, the wave is calculated The virtual value RMS and phase Phase of shape signal fundamental wave and each harmonic；According to the voltage harmonic virtual value being calculated And phase, current harmonics virtual valueAnd phaseCalculate harmonic wave active power and reactive power；Calculation formula It is as follows:

Active power virtual value

Reactive power virtual value,

The high accuracy three-phase standard scale converts standard electrical energy pulse for power and is exported by standard scale impulse output circuit 10, As the standard verification of tested electric energy meter, standard electrical energy pulse output may be selected to be all-wave active energy pulse output, all-wave without The sides such as the output of function electrical energy pulse, the output of fundamental active electrical energy pulse, the output of fundamental wave reactive power electrical energy pulse, harmonic electric energy pulse output Formula.The high accuracy three-phase standard scale calculates the electric energy error of tested electric energy meter by Error Calculator 8, achievable to harmonic wave electricity The calibrating of the fundamental energy, harmonic electric energy of energy table.

This high accuracy three-phase standard scale extends low current range (20mA), improves the measurement accuracy of low current.

This high accuracy three-phase standard scale generates fundamental wave or harmonic electric energy, can be used as harmonic electric energy meter examine fundamental energy or The standard of harmonic electric energy.

Above-described embodiment is the description of the invention, is not limitation of the invention, after any pair of simple transformation of the present invention Scheme all belong to the scope of protection of the present invention.