CN103472426A - Sinusoidal active power calibration system based on current comparator - Google Patents

Abstract

The invention provides a sinusoidal active power calibration system based on a current comparator. The sinusoidal active power calibration system comprises a voltage calibration end and a current calibration end, wherein the voltage calibration end comprises an alternating current voltage source and a direct current voltage source which are respectively connected with an alternating current and direct current conversion standard device; the current calibration end comprises a quadrature current source circuit, a detection amplifier, a transconductance amplifier and a precise current transformer, and the quadrature current source circuit, the detection amplifier, the transconductance amplifier and the precise current transformer are connected sequentially. The precise current transformer comprises a first-stage transformer and a second-stage transformer, a voltage circuit of a meter to be tested is connected with the output end of the alternating current voltage source, and a current circuit of the meter to be tested is connected with the first-stage transformer. Compared with the prior art, the sinusoidal active power calibration system based on the current comparator effectively improves accuracy and stability of power calibration and can meet different needs of laboratory and field measurement.

Description

Sine Active Power Calibration System Based on Current Comparator

technical field

The invention relates to a power calibration system, in particular to a sinusoidal active power calibration system based on a current comparator.

Background technique

With the development of the power industry, the evaluation and measurement of active power is becoming more and more important. The electrical basic unit of active power in the prior art is derived as follows: based on the power consumption of the resistor, when a known AC voltage U is applied to the resistor R, the resulting power consumption is U ² /R, and the AC The effective value of the voltage is determined by the DC flow with the same thermoelectric effect, and the DC standard value is transferred to the AC by means of thermoelectric conversion, so that the power unit can be derived from the DC voltage standard and resistance standard, and then the standard power can be extended in time Electric energy can be obtained; however, since high-power precision resistors are not easy to design and manufacture, current comparison ceremony power bridge technology is often used for the research and development of active power measurement functions; The active power calibration system of the comparator is particularly important.

Contents of the invention

In order to meet the needs of the prior art, the present invention provides a sinusoidal active power calibration system based on a current comparator, the system includes a voltage calibration terminal and a current calibration terminal, and the voltage calibration terminal includes an AC-DC conversion standard A connected AC voltage source and a DC voltage source; the current calibration terminal includes a sequentially connected orthogonal current source circuit, a detection amplifier, a transconductance amplifier and a precision current transformer; the precision current transformer includes a first-stage transformer and The second stage transformer; the voltage loop of the meter to be tested is connected to the output end of the AC voltage source; the current loop of the meter to be tested is connected to the first stage transformer.

Preferably, the 100V DC voltage output by the DC voltage source is divided into 10V voltage by a voltage divider; the digital multimeter compares the collected 10V voltage with a solid-state voltage standard to obtain the actual value of the 10V voltage; according to the Adjusting the set value of the DC voltage source with the actual value traces the 100V DC voltage to the DC voltage working reference;

Preferably, the AC voltage source is respectively connected to the AC-DC conversion standard and the quadrature current source circuit through a current comparator high voltage divider; the AC voltage output by the AC voltage source is passed through the current comparator The high-voltage divider will be divided into 100V AC voltage; the 100V AC voltage and the 100V DC voltage are respectively connected to the two input terminals of the AC-DC conversion standard; the AC-DC conversion standard converts the 100V AC The voltage is traced to the DC voltage working reference;

Preferably, one output branch line of the quadrature current source circuit is directly connected to the detection amplifier, and the AC voltage generated by the quadrature current source circuit is input to the detection amplifier as a reference voltage; the other output branch line passes the current The comparison ceremony power bridge is connected to the precision current transformer; the detection amplifier drives the transconductance amplifier to output a correction current, and the correction current is input to the current loop of the meter under test through the first-stage transformer;

Preferably, the current comparator power bridge includes a winding _NR , a winding _NC , a winding _NX and a winding _ND ; the in-phase current I _R and the quadrature current I _C output by the quadrature current source circuit are respectively input to the The winding _NR and the winding _NC ; the winding _NX is connected to the second-stage transformer; the winding _ND is connected to the detection amplifier;

Preferably, the second-level transformer converts the corrected current proportionally to obtain a balance current I _X ; the value of the balance current I _X is less than 1A; judge the balance current I _X , the in-phase current I _R and Whether the quadrature current _IC satisfies the balance condition of the power bridge of the current comparison formula _; The correction current input by the first stage transformer to the current loop of the meter under test;

Preferably, the equilibrium condition is ${\stackrel{\·}{I}}_R{N}_R+{\stackrel{\&Center\; Dot;}{I}}_C{N}_C={\stackrel{\&Center\; Dot;}{I}}_x{N}_x;$

Preferably, the voltage calibration range of the system is 57V-480V; the current calibration range is 0.5A-100A; the power factor range is 0(L)-1.0-0(C).

Compared with prior art, the excellent effect of the present invention is:

1. In the technical scheme of the present invention, the current comparator power bridge is used to realize the correction current tracking AC voltage; in the orthogonal current source circuit, with the help of the capacitance bridge structure of the current comparator principle, the large-capacity working capacitor C can directly and low-loss , Small-capacity standard air capacitance Cs with good stability is compared to obtain calibration; through the current comparison ceremony power bridge, the dynamic compensation of the working capacitance C can be realized, so that its performance index is greatly improved, so as to obtain pure and stable quadrature current I _C , to ensure the accuracy of power measurement;

2. In the technical solution of the present invention, the voltage and current range settings of the sinusoidal active power calibration system cover the range ranges of various types of standard meters currently used in China, wherein the voltage calibration range is 57V to 480V; the current calibration range is 0.5A ～100A; the power factor range is 0(L)～1.0～0(C); it not only ensures the highest accuracy and stability in the basic range, but also takes into account a wide range of measurement, which can meet the requirements of laboratory and field Different needs for measurement;

3. In the technical solution of the present invention, the standard resistance and the standard capacitance inside the orthogonal current source circuit generate 10mA in-phase current I _R and 10mA orthogonal current I _C respectively; The conductor amplifier outputs the correction current, and the current correction is performed on the meter to be tested; the uncertainty caused by the intermediate link transmission is greatly reduced, and the accuracy index of the entire system is greatly improved;

4. In the technical solution of the present invention, the detection amplifier adjusts the driving voltage of the driving transconductance amplifier according to the unbalanced current detected by the winding _ND of the current comparison ceremony power bridge, thereby constantly changing the first-stage transformer input to the current loop of the meter under test The correction current of the current comparator is repeated until the current comparator is balanced; so that the correction current can automatically track the AC voltage under the action of the automatic balance and feedback loop of the current comparator;

5. In the technical solution of the present invention, the AC-DC conversion standard is used to directly compare the AC voltage with a more accurate DC voltage, thereby ensuring the accuracy of the output AC voltage

6. In the technical solution of the present invention, the current comparison high-voltage divider is used to accurately convert the working voltage into 100V AC voltage output. Compared with other magnetic induction voltage dividers, resistance dividers and capacitors, the current comparison high-voltage divider The transformation uncertainty of the voltage divider is smaller.

7. In the technical solution of the present invention, the current transformer includes two stages to expand the calibration current of the system, and can output a maximum current of 100A.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings.

Fig. 1 is: the structural diagram of the sinusoidal active power calibration system based on the current comparator in the embodiment of the present invention;

Fig. 2 is a circuit diagram of an orthogonal current source in an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

Fig. 1 shows the structural diagram of the sinusoidal active power calibration system based on the current comparator in this embodiment; the calibration system includes two parts, the voltage calibration terminal and the current calibration terminal, and the calibration of the active power is realized through the voltage and current calibration of the meter to be tested. calibration;

1. The voltage calibration terminal includes an AC voltage source, a DC voltage source and an AC-DC conversion standard device; the voltage circuit of the meter to be tested is connected to the output terminal of the AC voltage source;

The AC voltage source is connected to the AC-DC conversion standard device through the current comparison high-voltage divider, and the DC voltage source is directly connected to the AC-DC conversion standard device; the 100V DC voltage output by the DC voltage source is divided into 10V voltage by the voltage divider; the digital multimeter Compare the collected 10V voltage with the solid-state voltage standard to obtain the actual value of the 10V voltage; multiply the actual value by the voltage division coefficient to obtain the actual voltage value of the 100V DC voltage; continuously adjust the setting value of the DC voltage source according to the actual voltage value The 100V DC voltage is traced to the DC voltage working reference; the AC voltage output by the AC voltage source will be divided into 100V AC voltage by the high voltage divider of the current comparison ceremony; An input terminal; the AC-DC conversion standard traces the 100V AC voltage to the DC voltage working reference.

2. The current calibration terminal includes an orthogonal current source circuit, a detection amplifier, a transconductance amplifier, and a precision current transformer connected in sequence; the AC voltage source is connected to the orthogonal current source circuit through a current comparison ceremony high-voltage divider; the precision current transformer Including the first-level transformer and the second-level transformer; the current loop of the meter to be tested is connected to the first-level transformer;

An output branch line of the quadrature current source circuit is directly connected to the detection amplifier, and the AC voltage generated by the quadrature current source circuit is input to the detection amplifier as a reference voltage, and the detection amplifier generates a drive voltage with a certain phase with the reference voltage to drive the transconductance amplifier to generate Correction current, the correction current is input to the current circuit of the meter under test through the first-level transformer; the other output branch line is connected to the second-level transformer of the precision current transformer through the current comparison ceremony power bridge;

As shown in Figure 2, the quadrature current source circuit diagram, the quadrature current source circuit outputs the in-phase current I _R and the quadrature current I _C respectively on the standard resistance and the standard capacitance; among them, the capacitor C is a large-capacity working capacitor, and the capacitor Cs is a small-capacity Standard air capacitance; the in-phase current I _R and the quadrature current I _C are respectively input to the winding _NR and winding N _C of the power bridge of the current comparison ceremony; the winding N _X is connected to the second-level transformer, and the second-level transformer corrects the current Perform proportional conversion to obtain the balanced current I _X and return it to the winding N _X ; the value of the balanced current I _X is less than 1A; the winding N _D is connected to the detection amplifier;

检测放大器依据绕组N_D检测到的不平衡电流调整驱动跨导放大器的驱动电压，从而改变第一级互感器输入到待测表电流回路的校正电流。Judging whether the balanced current I _X , the in-phase current I _R and the quadrature current I _C meet the balance conditions of the current comparison ceremony power bridge

The detection amplifier adjusts the driving voltage for driving the transconductance amplifier according to the unbalanced current detected by the winding _ND , thereby changing the correction current input from the first stage transformer to the current loop of the meter under test.

The range of the sinusoidal active power calibration system based on the current comparator provided by the present invention is: voltage calibration range: 57V～480V; current calibration range: 0.5A～100A; power factor range: 0(L)～1.0～0(C) .

Finally, it should be noted that the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

Claims (8)

1. A sinusoidal active power calibration system based on a current comparator, said system comprising a voltage calibration terminal and a current calibration terminal, characterized in that said voltage calibration terminal comprises an AC voltage source and a DC voltage source; the current calibration terminal includes an orthogonal current source circuit, a detection amplifier, a transconductance amplifier and a precision current transformer connected in sequence; the precision current transformer includes a first-level transformer and a second-level transformer; The voltage circuit of the meter to be tested is connected with the output terminal of the AC voltage source; the current circuit of the meter to be tested is connected with the first-stage transformer. 2. a kind of sinusoidal active power calibration system based on current comparator as claimed in claim 1, is characterized in that, the 100V DC voltage of described DC voltage source output is divided into 10V voltage through voltage divider; Digital multimeter will collect The 10V voltage is compared with the solid-state voltage standard to obtain the actual value of the 10V voltage; the setting value of the DC voltage source is adjusted according to the actual value to trace the 100V DC voltage to the DC voltage working reference. 3. A kind of sinusoidal active power calibration system based on current comparator as claimed in claim 1 or 2, is characterized in that, described AC voltage source is respectively connected with described AC-DC conversion standard device by current comparator high voltage divider Connected to the orthogonal current source circuit; the AC voltage output by the AC voltage source will be divided into 100V AC voltage by the high voltage divider of the current comparison ceremony; the 100V AC voltage and the 100V DC voltage are respectively connected The two input terminals of the AC-DC conversion standard; the AC-DC conversion standard traces the 100V AC voltage to the DC voltage working reference. 4. a kind of sinusoidal active power calibration system based on current comparator as claimed in claim 1, is characterized in that, an output branch line of described quadrature current source circuit is directly connected with described detection amplifier, described quadrature The AC voltage generated by the current source circuit is input to the detection amplifier as a reference voltage; another output branch line is connected to the precision current transformer through a current comparator power bridge; the detection amplifier drives the transconductance amplifier to output a correction current, The correction current is input to the current loop of the meter under test through the first stage transformer. 5. A kind of sinusoidal active power calibration system based on current comparator as claimed in claim 1 or 4, is characterized in that, described current comparator power bridge comprises winding N _R , winding N _C , winding N _X and winding N _D ; the in-phase current I _R and the quadrature current I _C output by the quadrature current source circuit are input to the winding _NR and the winding _NC respectively; the winding _NX is connected to the second-level transformer ; The winding _ND is connected to the detection amplifier. 6. A kind of sinusoidal active power calibration system based on current comparator as claimed in claim 5, is characterized in that, described second stage transformer carries out proportional conversion to described correction current and obtains balance current I _X ; The value of the current I _X is less than 1A; judging whether the balance current I _X , the in-phase current I _R and the quadrature current I _C satisfy the balance condition of the power bridge of the current comparison ceremony; the detection amplifier is based on the The unbalanced current detected by the winding _ND adjusts the driving voltage for driving the transconductance amplifier, thereby changing the correction current input by the first stage transformer to the current loop of the meter under test. 7. a kind of sinusoidal active power calibration system based on current comparator as claimed in claim 6, is characterized in that, described balance condition is ${\stackrel{\&Center\; Dot;}{I}}_R{N}_R+{\stackrel{\&Center\; Dot;}{I}}_C{N}_C={\stackrel{\&Center\; Dot;}{I}}_x{N}_x.$ 8. A kind of sinusoidal active power calibration system based on current comparator as claimed in claim 1, is characterized in that, the voltage calibration range of described system is 57V～480V; The current calibration range is 0.5A～100A; The range is 0(L)～1.0～0(C).

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