A power source for a wideband ac energy meter calibration device

Abstract

The present application belongs to the technical field of low-frequency AC electric energy meter detection equipment, and particularly relates to a power source of a wide-frequency AC electric energy meter detection device. In view of the fact that the existing power-frequency AC electric energy meter detection device cannot meet the requirement of low-frequency AC electric energy meter detection, the present application adopts the following technical scheme: a power source of a wide-frequency AC electric energy meter detection device, comprising: an analog signal generation unit; a power amplifier comprising a voltage amplification unit and a current amplification unit; an output unit; a signal measurement unit; a processor; the controller processes the digital signal from the signal measurement unit, and calculates the fundamental wave voltage, current amplitude and initial phase angle of the output unit in real time; the analog signal generation unit adjusts the analog signal amplitude and phase in real time according to the measurement value; and the voltage amplification unit adopts DC feedback to adjust the gain, thereby eliminating the influence of AC signal on the power amplifier. The present application has the beneficial effect of improving the stability of the voltage amplifier at different frequencies.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of alternating current energy meter detection equipment, and particularly relates to a power source of a wide-frequency alternating current energy meter calibrating device. BACKGROUND

[0002] Low-frequency alternating current transmission technology is a new type of alternating current transmission technology with a frequency between industrial frequency 50Hz or 60Hz alternating current transmission and direct current transmission, and is mainly applied to medium and long distance offshore wind power transmission, land new energy collection and transmission, tidal flow dispersion in direct current drop point areas, multi-island interconnection and cable city network power supply, and long distance power transmission in remote areas. At present, the technology of industrial frequency alternating current energy meter calibrating device is very mature and perfect, and the frequency output range is generally 45Hz-70Hz. However, the industrial frequency alternating current energy meter calibrating device does not match the frequency (for example, 15Hz, 20Hz) used in the current low-frequency alternating current transmission project, and the accuracy is low when applied to low-frequency calibration, which cannot meet the demand of low-frequency electric energy meter measurement performance detection.

[0003] The voltage amplification unit of the power amplifier is greatly affected by the load characteristics when working, especially in the low-frequency state, the inductive or capacitive load will affect the stability of the voltage amplifier. Specifically, the current voltage amplifier mainly adopts the booster plus voltage transformer mode, and the current amplifier adopts the current booster plus current transformer mode, and the working frequency of the transformer is generally 45-75Hz. In order to meet the low-frequency (15Hz-75Hz) voltage and current output, according to the induced electromotive force formula:

[0004] E=4.44*f*W*Bm*S*10 -8

[0005] Wherein, f is the working frequency; W is the number of turns; Bm is the magnetic induction intensity (magnetic flux density); S is the cross-sectional area of the core.

[0006] As can be seen, in the case of reducing the working frequency of the transformer, the number of turns or the cross-sectional area of the core needs to be improved to meet the low-frequency voltage and current output.

[0007] In addition, the current amplification unit of the power amplifier of the existing industrial frequency alternating current energy meter calibrating device, the operational amplifier A1 and the operational amplifier A2 are connected in series through the resistor R5, wherein the capacitor C1 and the resistor R4 are connected in series and are connected in parallel with the resistor R3 to be connected across the "-" input terminal and the output terminal of the operational amplifier A1, and the capacitor C2 and the resistor R7 are connected in series and are connected in parallel with the resistor R6 to be connected across the "-" input terminal and the output terminal of the operational amplifier A2. Due to the existence of the capacitor C1 and the capacitor C2, the output gain of the pre-stage part is inversely proportional to the signal frequency (when the input frequency is 20Hz, the gain of the power amplifier will be increased by 2.5 times, and when the input frequency is 100Hz, the gain of the power amplifier will be reduced by 2 times), which cannot meet the actual application demand of the low-frequency amplifier. SUMMARY

[0008] The present application aims at the deficiency that the power source of the existing power frequency AC electric energy meter calibration device cannot meet the low frequency AC electric energy meter calibration, and provides a power source of a wide frequency AC electric energy meter calibration device, which can effectively ensure the accuracy and stability of the output signal under wide frequency (15-75Hz) AC signal input.

[0009] To achieve the above-mentioned purpose, the present application adopts the following technical scheme: a power source of a wide frequency AC electric energy meter calibration device, comprising:

[0010] an analog signal generating unit;

[0011] a power amplifier comprising a voltage amplification unit and a current amplification unit;

[0012] an output unit;

[0013] a signal measurement unit;

[0014] a processor;

[0015] The signal measurement unit converts the voltage signal and the current signal into digital signals through a D / A conversion circuit, the processor processes the digital signals from the signal measurement unit, and calculates the fundamental wave voltage, the current amplitude and the initial phase angle of the output unit in real time, the processor completes the calculation and interacts with the analog signal generating unit, and the analog signal generating unit adjusts the amplitude and the phase of the analog signal in real time according to the measurement value.

[0016] The voltage amplification unit adopts DC feedback to adjust the gain and eliminate the influence of the AC signal on the power amplifier.

[0017] The power source of the wide frequency AC electric energy meter calibration device of the present application is beneficial to realize the accurate output of the amplifier under different load conditions and in the frequency range through the cooperation of the analog signal generating unit, the power amplifier, the signal measurement unit and the output unit, the voltage amplification unit adopts DC feedback to adjust the gain and eliminate the influence of the AC signal on the power amplifier, and the stability of the voltage amplifier under different frequencies is improved.

[0018] As an improvement, the voltage amplification unit comprises a precision full-wave rectifier circuit for rectifying the AC feedback signal into a DC feedback signal, a PI integrator for integrating and adjusting the deviation between the standard DC small signal and the DC feedback signal, a first operational amplifier A1 for operational amplifying the standard AC small signal, and a multiplier connected to the output ends of the PI integrator and the first operational amplifier A1.

[0019] As an improvement, the precision full-wave rectifier circuit comprises a third operational amplifier A3, a fourth operational amplifier A4 and a plurality of capacitors and resistors.

[0020] As an improvement, the PI integrator comprises a second operational amplifier A2 and a capacitor and a resistor connected in series, and the PI integrator outputs the proportional integral of the control deviation of the DC feedback signal and the standard DC small signal to the multiplier through the second operational amplifier A2.

[0021] As an improvement, the voltage amplification unit further comprises a voltage transformer connected to the input end of the precision full-wave rectifier circuit for feedback sampling, an amplification circuit for proportional amplification of the amplitude-modulated AC signal, a voltage booster for boosting the voltage output by the amplification circuit, and a switching circuit for gear switching.

[0022] As an improvement, the current amplification unit comprises operational amplifiers A1 and A2, resistors R1 to R8, capacitors C1 to C4, and variable resistors VR1 and VR2, the operational amplifiers A1 and A2 are connected in series, and the "+" input terminals of the operational amplifiers A1 and A2 are grounded; the resistors R1 and R2 are connected in parallel and connected to the "-" input terminal of the operational amplifier A1; the capacitor C1 and the resistor R4 are connected in series and connected in parallel with the resistor R3, and are connected across the "-" input terminal and the output terminal of the operational amplifier A1; the resistor R5 is connected to the output terminal of the operational amplifier A1 and the "-" input terminal of the operational amplifier A2, respectively; the variable resistors VR1 and VR2 and the resistor R8 form a T-shaped feedback network resistance, and are connected in parallel with the capacitor C2 and the resistor R7 connected in series, and are connected to the "-" input terminal and the output terminal of the operational amplifier A2, respectively; one end of the resistor R8 is connected to the middle of the variable resistors VR1 and VR2, and the other end is grounded.

[0023] As an improvement, the variable resistors VR1 and VR2 are programmable electronic potentiometers X9921, which have two independent variable resistors, can realize arbitrary adjustment of 0-10K resistance, and can realize 1000 times gain adjustment.

[0024] As an improvement, the gain A2u of the operational amplifier A2 is obtained by the following formula:

[0025]

[0026] As an improvement, the processor is an ARM32 processor, the ARM32 processor feeds back the calculation result to the upper computer for communication, issues a gear adjustment instruction to the programmable electronic potentiometers VR1 and VR2, and realizes adaptive adjustment of the amplifier gain of the power amplifier under the input of an AC signal of 15-75 Hz.

[0027] As an improvement, the voltage loop of the signal measurement unit adopts resistance voltage division sampling, and the current loop adopts feedback mutual inductance sampling, the measurement unit has frequency capture and tracking sampling functions, the voltage signal and the current signal can be converted by the D / A conversion circuit, and the processor processes the digital signal by the FFT algorithm.

[0028] The power source of the wide-frequency AC electric energy meter calibration device has the advantages that: through cooperation of the analog signal generating unit, the power amplifier, the signal measuring unit and the output unit, the power amplifier can accurately output under different load conditions and in a frequency range; the voltage amplification unit adopts DC feedback to adjust the gain, eliminates the influence of AC signal on the power amplifier, and improves the stability of the voltage amplifier at different frequencies. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a structural block diagram of the power source of the embodiment one of the present application.

[0030] Figure 2 is a structural block diagram of the voltage amplification unit of the power source of the embodiment one of the present application.

[0031] Figure 3 is a partial circuit schematic diagram of the voltage amplification unit of the power source of the embodiment one of the present application.

[0032] Figure 4 is a partial circuit schematic diagram of the current amplification unit of the power source of the embodiment one of the present application. DETAILED DESCRIPTION

[0033] The technical solutions of the embodiments of the present application are explained and described below in combination with the drawings of the embodiments of the present application, but the following embodiments are only preferred embodiments of the present application, not all. Based on the embodiments in the embodiments, other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0034] Referring to Figures 1 to 4 , the power source of the wide-frequency AC electric energy meter calibration device comprises:

[0035] an analog signal generating unit;

[0036] a power amplifier comprising a voltage amplification unit and a current amplification unit;

[0037] an output unit;

[0038] a signal measuring unit;

[0039] a processor;

[0040] The signal measurement unit carries out analog-digital conversion on the voltage signal and the current signal through a D / A conversion circuit, the processor processes the digital signal from the signal measurement unit, and calculates the fundamental wave voltage, the current amplitude and the initial phase angle of the output unit in real time, the processor completes the calculation and interacts with the analog signal generation unit, and the analog signal generation unit adjusts the analog signal amplitude and the phase in real time according to the measurement value.

[0041] The voltage amplification unit adopts DC feedback to adjust the gain, so that the influence of the AC signal on the power amplifier is eliminated.

[0042] The power source of the wide-frequency AC electric energy meter calibration device has the advantages that the cooperation of the analog signal generation unit, the power amplifier, the signal measurement unit and the output unit facilitates the accurate output of the amplifier under different load conditions and in the frequency range; the voltage amplification unit adopts DC feedback to adjust the gain, so that the influence of the AC signal on the power amplifier is eliminated, and the stability of the voltage amplifier under different frequencies is improved.

[0043] Embodiment one

[0044] Referring to Figures 1 to 4 The power source of the wide-frequency AC electric energy meter calibration device comprises:

[0045] An analog signal generation unit;

[0046] A power amplifier comprising a voltage amplification unit and a current amplification unit;

[0047] An output unit;

[0048] A signal measurement unit;

[0049] A processor;

[0050] The signal measurement unit carries out analog-digital conversion on the voltage signal and the current signal through a D / A conversion circuit, the processor processes the digital signal from the signal measurement unit, and calculates the fundamental wave voltage, the current amplitude and the initial phase angle of the output unit in real time, the processor completes the calculation and interacts with the analog signal generation unit, and the analog signal generation unit adjusts the analog signal amplitude and the phase in real time according to the measurement value.

[0051] The voltage amplification unit adopts DC feedback to adjust the gain, so that the influence of the AC signal on the power amplifier is eliminated.

[0052] Referring to Figure 2 and Figure 3The voltage amplifier is greatly affected by load characteristics during operation, especially in a low frequency state, and inductive or capacitive load can affect the stability of the voltage amplifier, in order to improve the stability of the voltage amplifier at different frequencies, in the embodiment, the voltage amplifier adopts DC feedback to adjust the gain, and the influence of AC signal on the amplifier is eliminated.

[0053] In the embodiment, the voltage amplification unit comprises:

[0054] AC / DC small signal: standard AC / DC signal, the DC signal is mainly used for amplitude modulation value;

[0055] Multiplier: the multiplier adopts AD734, and the standard AC signal is multiplied with the DC signal output by the integrator to realize the DC signal amplitude modulation function;

[0056] Amplification circuit: the AC signal is proportionally amplified to obtain the required voltage amplitude;

[0057] Switching circuit: the voltage amplifier is built-in four gears to ensure the output accuracy and stability under different voltages;

[0058] Precise full-wave rectifier circuit: the AC feedback signal is rectified into a DC signal;

[0059] Voltage booster: the voltage booster boosts the voltage output by the discharge circuit;

[0060] Voltage transformer: the voltage transformer is mainly used for feedback sampling to ensure the accuracy of the output voltage amplitude;

[0061] PI integrator: the standard DC signal and the feedback DC signal are integrated to adjust and output to the multiplier in a stable state.

[0062] In the embodiment, the precise full-wave rectifier circuit comprises a third operational amplifier A3, a fourth operational amplifier A4 and a plurality of capacitors and resistors.

[0063] In the embodiment, the PI integrator comprises a second operational amplifier A2 and a capacitor and a resistor connected in series, and the PI integrator outputs the proportional integral of the control deviation composed of the DC feedback signal and the standard DC small signal to the multiplier through the second operational amplifier A2.

[0064] In the embodiment, u1 is a standard AC small signal, Udc1 is a standard DC small signal, the AC feedback signal is a small signal obtained by the output voltage after the mutual inductor transformation ratio, and the feedback signal is rectified into a DC signal Udc2 by the precision full-wave rectifier circuit composed of operational amplifiers A3 and A4. The PI integrator is composed of an operational amplifier A2 and a capacitor resistor, a control deviation is formed according to the set value Udc1 and the actual value Udc2, the proportional integral of the deviation is output as Udc3 through the operational amplifier A2. Udc3 and u2 are output as an AC signal u3 through a multiplier, u3 = u2 x Udc3 / 10, the amplitude of u3 is only related to Udc3, and the phase of u3 is only related to u2, so that the phase change caused by the external load characteristic will not cause the change of the pre-stage voltage, the amplification multiple of the voltage amplifier will not be affected by the frequency, and the stability of the voltage amplifier is improved.

[0065] Referring to Figure 4 In the embodiment, the current amplification unit comprises operational amplifiers A1 and A2, resistors R1 to R8, capacitors C1 to C4, and variable resistors VR1 and VR2. The operational amplifiers A1 and A2 adopt a sampling series structure, and the “+” input terminals of the operational amplifiers A1 and A2 are grounded. The resistors R1 and R2 adopt a parallel structure and are connected to the “-” input terminal of the operational amplifier A1. The capacitor C1 and the resistor R4 are connected in series and are connected in parallel with the resistor R3, and are connected across the “-” input terminal and the output terminal of the operational amplifier A1. The resistor R5 is connected to the output terminal of the operational amplifier A1 and the “-” input terminal of the operational amplifier A2 respectively. The variable resistors VR1 and VR2 and the resistor R8 form a T-type feedback network resistor, and are connected in parallel with the capacitor C2 and the resistor R7 in a series structure, and are connected to the “-” input terminal and the output terminal of the operational amplifier A2 respectively. One end of the resistor R8 is connected to the middle of the variable resistors VR1 and VR2, and the other end is grounded.

[0066] In the embodiment, the variable resistors VR1 and VR2 adopt programmable electronic potentiometers X9921, the potentiometers have two independent variable resistors, can realize the arbitrary adjustment of 0-10K resistance, and realize 1000 times gain adjustment.

[0067] In the embodiment, the gain A2u of the operational amplifier A2 is obtained by the following formula:

[0068]

[0069] In the embodiment, the processor is an ARM32 processor, the ARM32 processor feeds back the calculation result to an upper computer for communication, and issues a gear adjustment instruction to the programmable electronic potentiometers VR1 and VR2, so as to realize the adaptive adjustment of the amplifier gain of the power amplifier under the 15-75Hz AC input signal.

[0070] In the embodiment, the voltage circuit of the signal measurement unit adopts resistance voltage sampling, the current circuit is sampled through feedback mutual inductance, the measurement unit has frequency capture and tracking sampling functions, the voltage signal and the current signal can be converted by the D / A conversion circuit, and the processor processes the digital signal through the FFT algorithm.

[0071] The power source of the wideband AC electric energy meter calibration device has the beneficial effects that: through cooperation of the analog signal generation unit, the power amplifier, the signal measurement unit and the output unit, the amplifier can accurately output under different load conditions and in a frequency range; the voltage amplification unit adopts DC feedback to adjust the gain, eliminates the influence of AC signals on the power amplifier, and improves the stability of the voltage amplifier at different frequencies.

[0072] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this, and those skilled in the art should understand that the present application includes but is not limited to the above specific embodiments. Any modification that does not deviate from the functional and structural principles of the present application shall be included in the scope of the claims.

Claims

1. A power source for a wideband AC electric energy meter calibrating device, characterized by: The power source of the wideband AC electric energy meter calibration device comprises: an analog signal generating unit; a power amplifier comprising a voltage amplification unit and a current amplification unit; an output unit; a signal measurement unit; a processor; wherein the signal measurement unit performs analog-digital conversion on the voltage signal and the current signal through a D / A conversion circuit, the processor processes the digital signal from the signal measurement unit, and calculates the fundamental wave voltage, current amplitude and initial phase angle of the output unit in real time, the processor completes the calculation and interacts with the analog signal generating unit, and the analog signal generating unit adjusts the analog signal amplitude and phase in real time according to the measurement value; wherein the voltage amplification unit adopts direct current feedback to adjust the gain and eliminate the influence of alternating current signal on the power amplifier; the current amplification unit comprises operational amplifiers A1 and A2, resistors R1 to R8, capacitors C1 and C2, and variable resistors VR1 and VR2, the operational amplifiers A1 and A2 adopt a sampling series structure, and the "+ " input terminals of the operational amplifiers A1 and A2 are grounded; the resistors R1 and R2 adopt a parallel structure and are connected to the "- " input terminal of the operational amplifier A1; the capacitor C1 is connected in series with the resistor R4 and in parallel with the resistor R3, and is connected across the "- " input terminal and the output terminal of the operational amplifier A1; the resistor R5 is connected to the output terminal of the operational amplifier A1 and the "- " input terminal of the operational amplifier A2 respectively; the variable resistors VR1 and VR2 and the resistor R8 form a T-type feedback network resistor, and are connected in parallel with the capacitor C2 and the resistor R7 in a series structure, and are connected to the "- " input terminal and the output terminal of the operational amplifier A2 respectively; one end of the resistor R8 is connected to the middle of the variable resistors VR1 and VR2, and the other end is grounded.

2. The power source of the wideband AC electric energy meter verification device according to claim 1, characterized in that: The voltage amplification unit comprises a precision full-wave rectifier circuit for rectifying alternating current feedback signals into direct current feedback signals, a PI integrator for integrating and adjusting the deviation between a standard direct current small signal and the direct current feedback signal, a first operational amplifier A1 for operational amplifying a standard alternating current small signal, and a multiplier connected to the output terminals of the PI integrator and the first operational amplifier A1.

3. The power source of the wideband AC electric energy meter testing device according to claim 2, characterized in that: The precision full-wave rectifier circuit comprises a third operational amplifier A3, a fourth operational amplifier A4 and a plurality of capacitors and resistors.

4. The power source of the wideband AC electric energy meter testing device according to claim 2, characterized in that: The PI integrator comprises a second operational amplifier A2 and a capacitor and a resistor connected in series, and outputs the proportional integral of the control deviation between the direct current feedback signal and the standard direct current small signal to the multiplier through the second operational amplifier A2.

5. The power source of the wideband AC electric energy meter testing device according to claim 2, characterized in that: The voltage amplification unit further comprises a voltage transformer connected to the input terminal of the precision full-wave rectifier circuit for feedback sampling, an amplification circuit for proportionally amplifying the amplitude-modulated alternating current signal, a voltage booster for boosting the voltage output by the amplification circuit, and a switching circuit for gear switching.

6. The power source of a wideband AC electric energy meter verification device according to claim 1, characterized in that: The variable resistors VR1 and VR2 adopt a programmable electronic potentiometer X9921, which has two independent variable resistors, realizes arbitrary adjustment of 0-10K resistance, and realizes 1000 times gain adjustment.

7. The power source of the wideband AC electric energy meter testing device according to claim 1, characterized in that: The gain A2u of the operational amplifier A2 is obtained by the following formula: A2u= .

8. The power source of the wideband AC electric energy meter testing device according to claim 1, characterized in that: The processor is an ARM32 processor, the ARM32 processor feeds back a calculation result to a host computer for communication, and issues a gear adjustment instruction to programmable electronic potentiometers VR1 and VR2, so that adaptive adjustment of amplifier gain of a power amplifier under an alternating current input signal of 15-75 Hz is realized.

9. The power source of the wideband AC electric energy meter testing device according to claim 1, characterized in that: The voltage loop of the signal measurement unit adopts resistance voltage division sampling, and the current loop adopts feedback mutual inductance sampling, the signal measurement unit has frequency capture and tracking sampling functions, and the processor processes digital signals through an FFT algorithm.

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