Harmonic calibration device and method for current transformer calibrator

Abstract

The invention discloses a harmonic calibration device and method for a current transformer calibrator. The device comprises a control computer, a quantum voltage generation module, a symmetric transconductance amplification module and a differential current feedback correction module. The control computer obtains a harmonic current measurement point and an error point, generates fitting waveforms of the first harmonic voltage and the second harmonic voltage, and outputs corresponding harmonic voltage through the quantum voltage generation module. The symmetrical transconductance amplification module converts the harmonic voltage into corresponding harmonic current, and the differential current feedback correction module performs differential current superposition on the first harmonic current and the second harmonic current to generate third harmonic voltage. The control computer calculates a harmonic error compensation value based on the third harmonic voltage and generates a fourth harmonic voltage fitting waveform. And the quantum voltage generation module outputs fourth and fifth harmonic voltages, the fourth and fifth harmonic voltages are converted into fourth and fifth harmonic currents through the symmetric transconductance amplification module, and the fourth and fifth harmonic currents are finally input to the to-be-calibrated current transformer calibrator for calibration, so that precise compensation of harmonic errors is realized.

Description

Technical Field

[0001] The invention relates to the technical field of current transformer tester detection, and in particular to a harmonic calibration device and method for a current transformer tester. Background Art

[0002] Current transformer testers play a vital role in power systems. They need to verify the error characteristics of current transformers in complex harmonic environments to cope with wide-band interference caused by new energy grid connection and nonlinear loads. With the expansion of the harmonic spectrum of the power grid (such as 2nd to 50th harmonics), the tester must not only maintain high accuracy under fundamental conditions, but also suppress amplitude and phase deviations in real time within the range of higher harmonics, thereby meeting the stringent requirements of smart grids for harmonic measurement.

[0003] However, the existing calibration technology relies on static calibration and manual intervention, lacks a dynamic feedback mechanism, and the traditional method cannot correct the nonlinear distortion and differential current coupling effect in the transconductance conversion in real time, resulting in the difficulty in suppressing the error accumulation under high-order harmonics, which creates an accuracy bottleneck for the current transformer tester. This defect poses a severe challenge to the reliability and standard compliance of the tester under complex working conditions. Summary of the invention

[0004] The embodiment of the present invention provides a harmonic calibration device and method for a current transformer tester. The present invention can solve the problem of error accumulation of the current transformer tester caused by lack of real-time compensation in the prior art.

[0005] An embodiment of the present invention provides a harmonic calibration device for a current transformer tester, the harmonic calibration device comprising a control computer, a quantum voltage generation module, a symmetrical transconductance amplification module and a differential current feedback correction module; the harmonic calibration device is connected to the current transformer tester to be calibrated;

[0006] The control computer is used to obtain harmonic current measurement points and harmonic current error points; and generate a fitting waveform of the first harmonic voltage and a fitting waveform of the second harmonic voltage according to the harmonic current measurement points;

[0007] The quantum voltage generating module is used to output the first harmonic voltage and the second harmonic voltage according to the fitted waveform of the first harmonic voltage and the fitted waveform of the second harmonic voltage;

[0008] The symmetrical transconductance amplification module is used to perform transconductance conversion on the first harmonic voltage and the second harmonic voltage respectively to generate corresponding first harmonic current and second harmonic current;

[0009] The differential current feedback correction module is used to perform differential current superposition on the first harmonic current and the second harmonic current to generate a third harmonic voltage;

[0010] The control computer is further used to calculate and generate a harmonic error compensation value based on the third harmonic voltage and the first harmonic voltage; and to generate a fitting waveform of the fourth harmonic voltage based on the harmonic current measurement point, the harmonic current error point and the harmonic error compensation value;

[0011] The quantum voltage generation module is further used to output a fourth harmonic voltage and a fifth harmonic voltage according to the fitted waveform of the fourth harmonic voltage and the fitted waveform of the first harmonic voltage respectively;

[0012] The symmetrical transconductance amplification module is also used to perform transconductance conversion on the fourth harmonic voltage and the fifth harmonic voltage to generate corresponding fourth harmonic current and fifth harmonic current; and input the fourth harmonic current and the fifth harmonic current into the current transformer calibrator to be calibrated for verification.

[0013] Further, the quantum voltage generation module includes a high-stability clock, a first quantum voltage generator and a second quantum voltage generator;

[0014] The first output terminal of the high-stability clock is connected to the clock input terminal of the first quantum voltage generator;

[0015] The second output terminal of the high-stability clock is connected to the clock input terminal of the second quantum voltage generator;

[0016] The control signal input terminal of the first quantum voltage generator is connected to the first control signal output terminal of the control computer;

[0017] The control signal input terminal of the second quantum voltage generator is connected to the second control signal output terminal of the control computer;

[0018] The voltage output terminal of the first quantum voltage generator is connected to the first input terminal of the symmetrical transconductance amplification module;

[0019] The voltage output terminal of the second quantum voltage generator is connected to the second input terminal of the symmetrical transconductance amplification module;

[0020] The ground terminal of the first quantum voltage generator is grounded;

[0021] The ground terminal of the second quantum voltage generator is grounded.

[0022] Further, the symmetrical transconductance amplification module includes a first precision transconductance amplifier and a second precision transconductance amplifier;

[0023] The first input end of the symmetrical transconductance amplification module is the input end of the first precision transconductance amplifier;

[0024] The second input end of the symmetrical transconductance amplification module is the input end of the second precision transconductance amplifier;

[0025] The ground terminal of the first precision transconductance amplifier is grounded;

[0026] The ground terminal of the second precision transconductance amplifier is grounded;

[0027] The current output terminal of the first precision transconductance amplifier is connected to the first terminal of the standard sampling unit of the digital comparison current transformer tester;

[0028] The current output terminal of the second precision transconductance amplifier is connected to the first terminal of the measured sampling unit of the digital comparison current transformer tester.

[0029] Furthermore, the differential current feedback correction module includes an AC / DC current comparator, a first operational amplifier, a first resistor and a digital multimeter; the AC / DC current comparator includes a standard current input winding, a detected current input winding and a differential current output winding;

[0030] The high potential end of the standard current input winding is connected to the second end of the standard sampling unit of the digital comparator current transformer tester;

[0031] The high potential end of the current input winding to be tested is connected to the second end of the sampling unit to be tested of the digital comparison current transformer tester;

[0032] The low potential end of the standard current input winding is grounded;

[0033] The low potential end of the detected current input winding is grounded;

[0034] The high potential end of the differential current output winding is connected to the positive input terminal of the first operational amplifier;

[0035] The low potential end of the differential current output winding is grounded;

[0036] The negative input terminal of the first operational amplifier is grounded;

[0037] One end of the first resistor is connected to the positive input terminal of the first operational amplifier;

[0038] The other end of the first resistor is connected to the output end of the first operational amplifier;

[0039] The voltage input terminal of the digital multimeter is connected to the output terminal of the first operational amplifier;

[0040] The GPIB interface terminal of the digital multimeter is connected to the GPIB interface terminal of the control computer;

[0041] The ground terminal of the digital multimeter is connected to ground.

[0042] Further, the first precision transconductance amplifier includes a second operational amplifier, a first power amplifier, a second resistor, a third resistor, a fourth resistor, a fifth resistor and a sixth resistor;

[0043] The ground terminal of the first precision transconductance amplifier is one end of the third resistor;

[0044] The input terminal of the first precision transconductance amplifier is the positive input terminal of the second operational amplifier;

[0045] The current output end of the first precision transconductance amplifier is one end of the sixth resistor;

[0046] The negative input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier;

[0047] One end of the second resistor is connected to the output end of the second operational amplifier;

[0048] The positive input terminal of the first power amplifier is connected to the other end of the second resistor;

[0049] The other end of the third resistor is connected to the negative input terminal of the first power amplifier;

[0050] One end of the fourth resistor is connected to the negative input terminal of the first power amplifier;

[0051] One end of the fifth resistor is connected to the positive input terminal of the first power amplifier;

[0052] An output terminal of the first power amplifier is connected to the other end of the fifth resistor;

[0053] The other end of the sixth resistor is connected to the output end of the first power amplifier;

[0054] The other end of the fourth resistor is connected to one end of the sixth resistor.

[0055] Further, the second precision transconductance amplifier includes a third operational amplifier, a second power amplifier, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor and an eleventh resistor;

[0056] The ground terminal of the second precision transconductance amplifier is one end of the eighth resistor;

[0057] The input terminal of the second precision transconductance amplifier is the positive input terminal of the third operational amplifier;

[0058] The current output end of the second precision transconductance amplifier is one end of the eleventh resistor;

[0059] The negative input terminal of the third operational amplifier is connected to the output terminal of the third operational amplifier;

[0060] One end of the seventh resistor is connected to the output end of the third operational amplifier;

[0061] The positive input terminal of the second power amplifier is connected to the other end of the seventh resistor;

[0062] The other end of the eighth resistor is connected to the negative input terminal of the second power amplifier;

[0063] One end of the ninth resistor is connected to the negative input terminal of the second power amplifier;

[0064] One end of the tenth resistor is connected to the positive input terminal of the second power amplifier;

[0065] An output terminal of the second power amplifier is connected to the other end of the tenth resistor;

[0066] The other end of the eleventh resistor is connected to the output end of the second power amplifier;

[0067] The other end of the ninth resistor is connected to one end of the eleventh resistor.

[0068] Further, the harmonic current measurement point includes the rated current value, the harmonic order, and the percentage of the harmonic current to the rated current; and generating the fitting waveform of the first harmonic voltage and the fitting waveform of the second harmonic voltage according to the harmonic current measurement point includes:

[0069] Extracting the rated current value, the harmonic order and the percentage of the harmonic current to the rated current from the harmonic current measurement point;

[0070] Calculating and generating a voltage amplitude according to the rated current value, the percentage of harmonic current to the rated current, and a preset current feedback resistor;

[0071] Calculate and generate harmonic frequencies according to the harmonic order and the preset fundamental frequency;

[0072] The fitting waveform of the first harmonic voltage and the fitting waveform of the second harmonic voltage are generated by the following formula:

[0073] V1=abs(V amp )×sin(2×π×f×t+φ)

[0074] V2=abs(V amp )×sin(2×π×f×t+φ)

[0075] Wherein, V1 is the fitting waveform of the first harmonic voltage; V2 is the fitting waveform of the second harmonic voltage; abs(V amp ) is the absolute value of the voltage amplitude; f is the harmonic frequency; t is the time variable; φ is the initial phase angle.

[0076] Further, the calculating and generating a harmonic error compensation value according to the third harmonic voltage and the first harmonic voltage includes:

[0077] The amplitude error compensation value is calculated using the following formula:

[0078]

[0079]

[0080] Among them, e f is the amplitude error compensation value; is the error vector; is the absolute value of the error vector; is the third harmonic voltage; is the first harmonic voltage; R1 is the first resistor; R6 is the sixth resistor;

[0081] The phase error compensation value is calculated using the following formula:

[0082]

[0083] Among them, e φ is the phase error compensation value; a is the scaling factor; is the imaginary part of the error vector; is the real part of the error vector;

[0084] The amplitude error compensation value and the phase error compensation value are recorded as harmonic error compensation values.

[0085] Furthermore, the harmonic current error points include harmonic current ratio difference and harmonic current phase difference; the fitting waveform of the fourth harmonic voltage is generated by the following formula:

[0086] V4=abs(V amp )×(1-e f )×(1+f ε )×sin(2×π×f×t+φ-e φ +φ e )

[0087] Wherein, V4 is the fitting waveform of the fourth harmonic voltage; f ε is the harmonic current ratio difference; φ e is the harmonic current phase difference.

[0088] An embodiment of the present invention provides a harmonic calibration method for a current transformer tester, which is applicable to a control computer of a harmonic calibration device of a current transformer tester, wherein the harmonic calibration device comprises a control computer, a quantum voltage generation module, a symmetrical transconductance amplification module, and a differential current feedback correction module; the harmonic calibration device is connected to a current transformer tester to be calibrated; the harmonic calibration method comprises:

[0089] Obtain harmonic current measurement points and harmonic current error points;

[0090] Generating a fitting waveform of a first harmonic voltage and a fitting waveform of a second harmonic voltage according to the harmonic current measurement point;

[0091] The driving quantum voltage generation module outputs a first harmonic voltage and a second harmonic voltage according to the fitting waveform of the first harmonic voltage and the fitting waveform of the second harmonic voltage respectively;

[0092] After collecting the first harmonic voltage and the second harmonic voltage and inputting them into the symmetrical transconductance amplification module to convert them into the corresponding first harmonic current and second harmonic current, the first harmonic current and the second harmonic current are input into the differential current feedback correction module to perform differential current superposition to obtain the third harmonic voltage;

[0093] Calculating and generating a harmonic error compensation value according to the third harmonic voltage and the first harmonic voltage;

[0094] Generate a fitting waveform of the fourth harmonic voltage according to the harmonic current measurement point, the harmonic current error point and the harmonic error compensation value;

[0095] The driving quantum voltage generation module outputs a fourth harmonic voltage and a fifth harmonic voltage according to the fitting waveform of the fourth harmonic voltage and the fitting waveform of the first harmonic voltage respectively;

[0096] driving the symmetrical transconductance amplification module to convert the fourth harmonic voltage and the fifth harmonic voltage into corresponding fourth harmonic current and fifth harmonic current;

[0097] The fourth harmonic current and the fifth harmonic current are input into a current transformer tester to be calibrated for verification.

[0098] Compared with the prior art, the present invention has the following beneficial effects:

[0099] The embodiment of the present invention provides a harmonic calibration device and method for a current transformer tester. The device accurately generates and outputs multiple harmonic current signals by cooperating with each other through a control computer, a quantum voltage generation module, a symmetrical transconductance amplification module and a differential current feedback correction module. The control computer generates a fitting waveform according to the harmonic current measurement point and the error point, generates a compensation voltage using the differential current feedback correction module, and outputs the corresponding harmonic voltage signal through the quantum voltage generation module. Through the transconductance conversion of the symmetrical transconductance amplification module, the corresponding harmonic current is generated, and finally the generated current signal is input into the current transformer tester to be calibrated for verification.

[0100] The present invention detects the difference current between the standard current (first harmonic current) and the calibrated current (second harmonic current) in real time through the difference current feedback correction module and generates the third harmonic voltage. It combines the high-precision reference signal of the quantum voltage generation module with the dynamic compensation algorithm of the control computer to form a closed-loop correction link, accurately compensates for the phase difference and amplitude difference of the harmonics, and solves the error accumulation problem of the current transformer calibrator caused by the lack of real-time compensation in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0101] Figure 1 The present invention is a schematic diagram of the structure of a harmonic calibration device for a current transformer tester provided in one embodiment of the present invention.

[0102] Figure 2 It is a structural schematic diagram of a first precision transconductance amplifier provided in one embodiment of the present invention.

[0103] Figure 3 It is a structural schematic diagram of a second precision transconductance amplifier provided in one embodiment of the present invention.

[0104] Figure 4 The present invention is a flowchart of a harmonic calibration method for a current transformer tester provided in an embodiment of the present invention.

[0105] Description of reference numerals:

[0106] 1. High-stability clock; 2. First quantum voltage generator; 3. Second quantum voltage generator; 4. First precision transconductance amplifier; 5. Second precision transconductance amplifier; 6. AC / DC current comparator; 7. First operational amplifier; 8. First resistor; 9. Digital multimeter; 10. Control computer; 11. Current transformer tester; 12. Second operational amplifier; 13. Second resistor; 14. Third resistor; 15. Fourth resistor; 16. First power amplifier; 17. Fifth resistor; 18. Sixth resistor; 19. Third operational amplifier; 20. Seventh resistor; 21. Eighth resistor; 22. Ninth resistor; 23. Second power amplifier; 24. Tenth resistor; 25. Eleventh resistor. DETAILED DESCRIPTION

[0107] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0108] like Figure 1As shown, an embodiment of the present invention provides a harmonic calibration device for a current transformer tester, the harmonic calibration device comprising a control computer, a quantum voltage generation module, a symmetrical transconductance amplification module and a differential current feedback correction module; the harmonic calibration device is connected to the current transformer tester to be calibrated;

[0109] The control computer is used to obtain harmonic current measurement points and harmonic current error points; and generate a fitting waveform of the first harmonic voltage and a fitting waveform of the second harmonic voltage according to the harmonic current measurement points;

[0110] Specifically, the control computer is used for waveform fitting of harmonic voltage, modulates the desired synthesized waveform into a series of digital code patterns, and sends them to the quantum voltage generation module. Based on the harmonic current measurement point parameters in the JJG 1176 specification (such as rated current value, harmonic order and proportion), the corresponding harmonic current measurement points are extracted from the preset standard library, and then the measurement point parameters are converted into the time domain fitting waveforms of the first and second harmonic voltages through the digital signal reconstruction algorithm, where the first waveform corresponds to the reference signal of the standard current, and the second waveform is used as the initial calibrated signal, and the frequency, amplitude and phase of the two are strictly synchronized; the measurement points of the harmonic current can be selected according to the following table:

[0111]

[0112] The harmonic current error point can be selected according to the following table:

[0113]

[0114] The quantum voltage generating module is used to output the first harmonic voltage and the second harmonic voltage according to the fitted waveform of the first harmonic voltage and the fitted waveform of the second harmonic voltage;

[0115] Specifically, the quantum voltage generation module is based on the Josephson array technology, and generates a high-precision reference signal with natural constant traceability characteristics by controlling the harmonic voltage fitting waveform input by the computer. Specifically, the module converts the digital waveform instruction into a quantized voltage output using the superconducting quantum interference effect based on the first harmonic voltage fitting waveform (the reference signal representing the standard current) and the second harmonic voltage fitting waveform (the initial calibrated signal). Its amplitude uncertainty is ≤5ppm and the phase synchronization error is ≤0.1μs, ensuring the strict synchronization of the two voltage signals in the wide frequency domain (2nd 50th harmonics). By dynamically adapting the frequency and amplitude parameters of the harmonic characteristics, the module can generate harmonic voltages with a frequency of up to 2.5kHz and an amplitude covering the range of 10mV10V in real time, while eliminating the temperature drift and time base jitter interference of the traditional signal source, and providing a stable voltage-current conversion reference for the symmetrical transconductance amplifier module.

[0116] The symmetrical transconductance amplification module is used to perform transconductance conversion on the first harmonic voltage and the second harmonic voltage respectively to generate corresponding first harmonic current and second harmonic current;

[0117] Specifically, the symmetrical transconductance amplification module is used to perform transconductance conversion on the first harmonic voltage and the second harmonic voltage respectively to generate corresponding first harmonic current and second harmonic current; the module adopts a high-linearity transconductance amplifier to accurately convert the input harmonic voltage signal into a current signal that is linearly related to the voltage amplitude and phase, thereby simulating the harmonic current characteristics under real working conditions; at the same time, the symmetrical transconductance amplification module has positive and negative symmetrical transconductance characteristics, which can effectively suppress the influence of even harmonic components and DC bias on the output current, ensuring that the generated first harmonic current and second harmonic current are not only accurate in amplitude, but also accurate in phase, thereby laying a stable and reliable current input condition for subsequent differential current feedback correction and harmonic error compensation.

[0118] The differential current feedback correction module is used to perform differential current superposition on the first harmonic current and the second harmonic current to generate a third harmonic voltage;

[0119] Specifically, the differential current feedback correction module realizes the differential current detection and error signal generation between the standard current and the calibrated current through a high-sensitivity AC / DC comparator and a precision I / V conversion circuit. Specifically, the module adopts the principle of magnetic potential balance, inputs the standard current and the calibrated current into the symmetrical winding of the comparator respectively, generates an induced current through the core magnetic flux difference, and then converts it into the third harmonic voltage through the first operational amplifier and the first resistor. The module has a built-in high-speed ADC and digital filtering unit to synchronously sample and separate the third harmonic voltage, extract the real part (ratio difference component) and imaginary part (angle difference component) of the error vector through the FFT algorithm, and input them into the control computer to generate dynamic compensation parameters.

[0120] The control computer is further used to calculate and generate a harmonic error compensation value based on the third harmonic voltage and the first harmonic voltage; and to generate a fitting waveform of the fourth harmonic voltage based on the harmonic current measurement point, the harmonic current error point and the harmonic error compensation value;

[0121] The quantum voltage generation module is further used to output a fourth harmonic voltage and a fifth harmonic voltage according to the fitted waveform of the fourth harmonic voltage and the fitted waveform of the first harmonic voltage respectively;

[0122] Specifically, the control computer is also used to calculate and generate a harmonic error compensation value based on the third harmonic voltage and the first harmonic voltage; wherein the control computer receives the third harmonic voltage output by the differential current feedback correction module, and performs amplitude and phase difference analysis on it and the first harmonic voltage, and uses the harmonic error model to compare and calculate key error information such as ratio difference and angle difference, and generates a corresponding harmonic error compensation value. Subsequently, the control computer corrects the deviation of the original harmonic voltage waveform in combination with the harmonic current measurement point, the harmonic current error point and the calculated harmonic error compensation value, and dynamically adjusts the voltage amplitude and phase relationship, thereby generating a fitting waveform of the fourth harmonic voltage. The fitting waveform fully considers the real-time compensation result of the harmonic error, so that the harmonic current outputted subsequently can more accurately reflect the harmonic characteristics under ideal calibration conditions, laying a foundation for improving the detection accuracy of the current transformer tester under harmonic conditions.

[0123] The symmetrical transconductance amplification module is also used to perform transconductance conversion on the fourth harmonic voltage and the fifth harmonic voltage to generate corresponding fourth harmonic current and fifth harmonic current; and input the fourth harmonic current and the fifth harmonic current into the current transformer calibrator to be calibrated for verification.

[0124] Specifically, the symmetrical transconductance amplification module is also used to perform transconductance conversion on the fourth harmonic voltage and the fifth harmonic voltage to generate the corresponding fourth harmonic current and fifth harmonic current; wherein, the symmetrical transconductance amplification module receives the fourth harmonic voltage and the fifth harmonic voltage output by the quantum voltage generation module, and accurately converts the input voltage signal into the corresponding harmonic current signal according to the linear response characteristics of the transconductance amplification. This module can ensure the stability of the transconductance ratio, ensure that the amplitude and phase of the current output accurately reflect the harmonic characteristics of the input voltage, and avoid harmonic distortion caused by transconductance distortion. Subsequently, the generated fourth harmonic current and fifth harmonic current are synchronously input to the current transformer tester to be calibrated for verification, so as to simulate the real working conditions under complex harmonic conditions, realize the harmonic error test of the current transformer tester, thereby evaluating its ratio difference and angle difference accuracy in a high-order harmonic environment, and provide reliable measurement data support for further implementation of harmonic error compensation.

[0125] In a preferred embodiment, the quantum voltage generation module includes a high-stable clock 1, a first quantum voltage generator 2 and a second quantum voltage generator 3;

[0126] The first output terminal of the high-stable clock 1 is connected to the clock input terminal of the first quantum voltage generator 2;

[0127] The second output terminal of the high stable clock 1 is connected to the clock input terminal of the second quantum voltage generator 3;

[0128] The control signal input terminal of the first quantum voltage generator 2 is connected to the first control signal output terminal of the control computer 10;

[0129] The control signal input terminal of the second quantum voltage generator 3 is connected to the second control signal output terminal of the control computer 10;

[0130] The voltage output terminal of the first quantum voltage generator 2 is connected to the first input terminal of the symmetrical transconductance amplifier module;

[0131] The voltage output terminal of the second quantum voltage generator 3 is connected to the second input terminal of the symmetrical transconductance amplification module;

[0132] The ground terminal of the first quantum voltage generator 2 is grounded;

[0133] The ground terminal of the second quantum voltage generator 3 is grounded.

[0134] Specifically, the first quantum voltage generator and the second quantum voltage generator are controlled by the same high-stability clock, and are composed of a Josephson array chip, microwaves, a cryogenic refrigerator, a pulse code generator, a low-pass filter, etc., and are used to generate a precise current signal source based on the Josephson quantum effect. Since the voltage value output by the quantum voltage generator is only related to the basic physical constants, it has extremely high stability and accuracy. The quantum voltage generator has a wide-band output capability: it can synthesize harmonic signal sources generated by AC quantum voltages of various frequencies and amplitudes that are close to the ideal waveform, with ultra-low noise and distortion. Compared with the signal source developed by traditional semiconductor devices, the amplitude of the synthesized signal of the quantum voltage generator can be traced back to natural constants, and its output waveform has the advantages of ultra-low noise and ultra-low distortion, and its uncertainty is better than 5ppm at 50kHZ~10kHz.

[0135] In a preferred embodiment, the symmetrical transconductance amplification module includes a first precision transconductance amplifier 4 and a second precision transconductance amplifier 5;

[0136] The first input end of the symmetrical transconductance amplification module is the input end of the first precision transconductance amplifier 4;

[0137] The second input end of the symmetrical transconductance amplification module is the input end of the second precision transconductance amplifier 5;

[0138] The ground terminal of the first precision transconductance amplifier 4 is grounded;

[0139] The ground terminal of the second precision transconductance amplifier 5 is grounded;

[0140] The current output terminal of the first precision transconductance amplifier 4 is connected to the first terminal of the standard sampling unit of the digital comparison current transformer tester 11;

[0141] The current output terminal of the second precision transconductance amplifier 5 is connected to the first terminal of the measured sampling unit of the digital comparison current transformer tester 11 .

[0142] In a preferred embodiment, the differential current feedback correction module includes an AC / DC current comparator 6, a first operational amplifier 7, a first resistor 8 and a digital multimeter 9; the AC / DC current comparator 6 includes a standard current input winding, a detected current input winding and a differential current output winding;

[0143] The high potential end of the standard current input winding is connected to the second end of the standard sampling unit of the digital comparison current transformer tester 11;

[0144] The high potential end of the current input winding to be tested is connected to the second end of the tested sampling unit of the digital comparator current transformer tester 11;

[0145] The low potential end of the standard current input winding is grounded;

[0146] The low potential end of the detected current input winding is grounded;

[0147] The high potential end of the differential current output winding is connected to the positive input terminal of the first operational amplifier 7;

[0148] The low potential end of the differential current output winding is grounded;

[0149] The negative input terminal of the first operational amplifier 7 is grounded;

[0150] One end of the first resistor 8 is connected to the positive input terminal of the first operational amplifier 7;

[0151] The other end of the first resistor 8 is connected to the output end of the first operational amplifier 7;

[0152] The voltage input terminal of the digital multimeter 9 is connected to the output terminal of the first operational amplifier 7;

[0153] The GPIB interface end of the digital multimeter 9 is connected to the GPIB interface end of the control computer 10;

[0154] The ground terminal of the digital multimeter 9 is grounded.

[0155] like Figure 2 As shown, in a preferred embodiment, the first precision transconductance amplifier 4 includes a second operational amplifier 12, a first power amplifier 16, a second resistor 13, a third resistor 14, a fourth resistor 15, a fifth resistor 17 and a sixth resistor 18;

[0156] The ground terminal of the first precision transconductance amplifier 4 is one end of the third resistor 14;

[0157] The input terminal of the first precision transconductance amplifier 4 is the positive input terminal of the second operational amplifier 12;

[0158] The current output end of the first precision transconductance amplifier 4 is one end of the sixth resistor 18;

[0159] The negative input terminal of the second operational amplifier 12 is connected to the output terminal of the second operational amplifier 12;

[0160] One end of the second resistor 13 is connected to the output end of the second operational amplifier 12;

[0161] The positive input terminal of the first power amplifier 16 is connected to the other end of the second resistor 13;

[0162] The other end of the third resistor 14 is connected to the negative input terminal of the first power amplifier 16;

[0163] One end of the fourth resistor 15 is connected to the negative input terminal of the first power amplifier 16;

[0164] One end of the fifth resistor 17 is connected to the positive input terminal of the first power amplifier 16;

[0165] The output end of the first power amplifier 16 is connected to the other end of the fifth resistor 17;

[0166] The other end of the sixth resistor 18 is connected to the output end of the first power amplifier 16;

[0167] The other end of the fourth resistor 15 is connected to one end of the sixth resistor 18 .

[0168] like Figure 3 As shown, in a preferred embodiment, the second precision transconductance amplifier 5 includes a third operational amplifier 19, a second power amplifier 23, a seventh resistor 20, an eighth resistor 21, a ninth resistor 22, a tenth resistor 24 and an eleventh resistor 25;

[0169] The ground terminal of the second precision transconductance amplifier 5 is one end of the eighth resistor 21;

[0170] The input terminal of the second precision transconductance amplifier 5 is the positive input terminal of the third operational amplifier 19;

[0171] The current output end of the second precision transconductance amplifier 5 is one end of the eleventh resistor 25;

[0172] The negative input terminal of the third operational amplifier 19 is connected to the output terminal of the third operational amplifier 19;

[0173] One end of the seventh resistor 20 is connected to the output end of the third operational amplifier 19;

[0174] The positive input terminal of the second power amplifier 23 is connected to the other end of the seventh resistor 20;

[0175] The other end of the eighth resistor 21 is connected to the negative input end of the second power amplifier 23;

[0176] One end of the ninth resistor 22 is connected to the negative input end of the second power amplifier 23;

[0177] One end of the tenth resistor 24 is connected to the positive input terminal of the second power amplifier 23;

[0178] The output end of the second power amplifier 23 is connected to the other end of the tenth resistor 24;

[0179] The other end of the eleventh resistor 25 is connected to the output end of the second power amplifier 23;

[0180] The other end of the ninth resistor 22 is connected to one end of the eleventh resistor 25 .

[0181] In a preferred embodiment, the harmonic current measurement point includes the rated current value, the harmonic order, and the percentage of the harmonic current to the rated current; the generating of the fitting waveform of the first harmonic voltage and the fitting waveform of the second harmonic voltage according to the harmonic current measurement point includes:

[0182] Extracting the rated current value, the harmonic order and the percentage of the harmonic current to the rated current from the harmonic current measurement point;

[0183] Calculating and generating a voltage amplitude according to the rated current value, the percentage of harmonic current to the rated current, and a preset current feedback resistor;

[0184] Calculate and generate harmonic frequencies according to the harmonic order and the preset fundamental frequency;

[0185] The fitting waveform of the first harmonic voltage and the fitting waveform of the second harmonic voltage are generated by the following formula:

[0186] V1=abs(V amp )×sin(2×π×f×t+φ)

[0187] V2=abs(V amp )×sin(2×π×f×t+φ)

[0188] Wherein, V1 is the fitting waveform of the first harmonic voltage; V2 is the fitting waveform of the second harmonic voltage; abs(V amp ) is the absolute value of the voltage amplitude; f is the harmonic frequency; t is the time variable; φ is the initial phase angle.

[0189] Specifically, the voltage amplitude is calculated based on the rated current value, the percentage of harmonic current in the rated current, and the preset current feedback resistor; wherein the rated current value is used to determine the reference current size of the current transformer under the rated working state, the percentage of harmonic current in the rated current reflects the proportion of harmonic components in the overall current, and the preset current feedback resistor is used as a mapping relationship parameter between current and voltage during the transconductance conversion process; based on the above parameters, the control computer calculates the corresponding voltage amplitude to further generate an accurate harmonic voltage fitting waveform, thereby providing accurate voltage input conditions for subsequent harmonic error compensation and current transformer calibration. The current feedback resistor can be flexibly adjusted according to the situation.

[0190] In a preferred embodiment, the calculating and generating the harmonic error compensation value according to the third harmonic voltage and the first harmonic voltage includes:

[0191] The amplitude error compensation value is calculated using the following formula:

[0192]

[0193] Among them, e f is the amplitude error compensation value; is the error vector; is the absolute value of the error vector; is the third harmonic voltage; is the first harmonic voltage; R1 is the first resistor; R6 is the sixth resistor;

[0194] The phase error compensation value is calculated using the following formula:

[0195]

[0196] Among them, e φ is the phase error compensation value; a is the scaling factor; is the imaginary part of the error vector; is the real part of the error vector;

[0197] The amplitude error compensation value and the phase error compensation value are recorded as harmonic error compensation values.

[0198] In a preferred embodiment, the harmonic current error points include harmonic current ratio difference and harmonic current phase difference; the fitting waveform of the fourth harmonic voltage is generated by the following formula:

[0199] V4=abs(V amp )×(1-e f )×(1+f ε )×sin(2×π×f×t+φ-e φ +φ e)

[0200] Wherein, V4 is the fitting waveform of the fourth harmonic voltage; f ε is the harmonic current ratio difference; φ e is the harmonic current phase difference.

[0201] like Figure 4 As shown, an embodiment of the present invention provides a harmonic calibration method for a current transformer tester, which is applicable to a control computer of a harmonic calibration device of a current transformer tester, wherein the harmonic calibration device includes a control computer, a quantum voltage generation module, a symmetrical transconductance amplification module, and a differential current feedback correction module; the harmonic calibration device is connected to the current transformer tester to be calibrated; the harmonic calibration method at least includes:

[0202] Step S1, obtaining harmonic current measurement points and harmonic current error points;

[0203] Specifically, the harmonic current measurement points are used to reflect the current response of the current transformer to be calibrated at different harmonic frequencies, including the amplitude and phase information corresponding to each harmonic; the harmonic current error points are used to quantify the ratio difference and angle difference of the current transformer to be calibrated at each harmonic frequency, thereby characterizing the accuracy of its harmonic response. The control computer extracts the current measurement values ​​and their corresponding error data at different harmonic frequencies through data interaction with the current transformer tester to be calibrated, laying the foundation for the subsequent fitting calculation and error compensation of the harmonic voltage.

[0204] Step S2, generating a fitting waveform of the first harmonic voltage and a fitting waveform of the second harmonic voltage according to the harmonic current measurement point;

[0205] Specifically, according to the harmonic current measurement points, a fitting waveform of the first harmonic voltage and a fitting waveform of the second harmonic voltage are generated; wherein, the control computer models and calculates harmonic currents of different frequencies through a mathematical fitting algorithm based on the extracted harmonic current measurement points, including the amplitude, phase and other data of each harmonic current, to generate corresponding harmonic voltage waveforms. The fitting waveform of the first harmonic voltage corresponds to the voltage conversion result of the fundamental current, which is used to reflect the voltage response characteristics of the current transformer to be calibrated under fundamental conditions; the fitting waveform of the second harmonic voltage corresponds to the voltage conversion result of a specific harmonic current, which is used to simulate the voltage response of the current transformer to be calibrated at the harmonic frequency. These fitting waveforms not only accurately depict the nonlinear relationship between harmonic current and voltage, but also provide a reliable data basis for the voltage output of the subsequent quantum voltage generation module.

[0206] Step S3, driving the quantum voltage generation module to output the first harmonic voltage and the second harmonic voltage according to the fitting waveform of the first harmonic voltage and the fitting waveform of the second harmonic voltage respectively;

[0207] Specifically, the control computer sends a control signal to the quantum voltage generation module, so that it receives and analyzes the fitting waveform data of the first harmonic voltage and the second harmonic voltage. The quantum voltage generation module accurately converts the fitting waveform into an analog voltage signal based on its internal high-precision digital-to-analog conversion unit (DAC) and voltage stabilization control circuit, thereby outputting the first harmonic voltage corresponding to the fundamental current and the second harmonic voltage corresponding to the specific subharmonic current. This voltage generation method based on the quantum voltage standard effectively reduces the amplitude error and phase deviation of the output voltage, and provides a highly stable and accurate voltage source for subsequent transconductance conversion and differential current feedback correction. In addition, through the synchronous control mechanism of the quantum voltage generation module, the first harmonic voltage and the second harmonic voltage are accurately aligned in the time domain, thereby avoiding the influence of phase drift on the subsequent harmonic error compensation calculation.

[0208] Step S4, collecting and inputting the first harmonic voltage and the second harmonic voltage into the symmetrical transconductance amplification module to convert into the corresponding first harmonic current and second harmonic current, and then inputting the first harmonic current and the second harmonic current into the differential current feedback correction module to perform differential current superposition to obtain the third harmonic voltage;

[0209] Specifically, the signal after the first harmonic voltage and the second harmonic voltage are input to the symmetrical transconductance amplification module is collected and processed to convert the first harmonic voltage and the second harmonic voltage into the corresponding first harmonic current and the second harmonic current respectively; wherein, the symmetrical transconductance amplification module linearly converts the input harmonic voltage signal into a proportional harmonic current signal through a precision transconductance unit according to the transconductance amplification principle, ensuring that the amplitude proportional relationship and phase characteristics in the voltage-current conversion process remain consistent. After obtaining the first harmonic current and the second harmonic current, the two harmonic currents are input to the differential current feedback correction module for differential current superposition operation; the differential current feedback correction module generates and outputs the third harmonic voltage by real-time detection and calculation of the amplitude difference and phase offset of the input current, thereby reflecting the difference between the first harmonic current and the second harmonic current in the harmonic response. The collected third harmonic voltage not only contains the error component introduced by the current transformer, but also superimposes the voltage distortion component caused by the interaction of harmonics, providing key data support for the subsequent harmonic error compensation calculation.

[0210] Step S5, calculating and generating a harmonic error compensation value according to the third harmonic voltage and the first harmonic voltage;

[0211] Specifically, a harmonic error compensation value is calculated and generated according to the third harmonic voltage and the first harmonic voltage; wherein the third harmonic voltage reflects the comprehensive effect of the first harmonic current and the second harmonic current after the differential current is superimposed, including the harmonic error component and the nonlinear response error introduced by the current transformer under harmonic conditions. The first harmonic voltage is used as a reference signal to identify the reference value of the harmonic voltage under ideal conditions. By comparing and analyzing the third harmonic voltage with the first harmonic voltage, extracting the amplitude deviation and phase offset between the two, and calculating in combination with a mathematical fitting model, a harmonic error compensation value is generated. This compensation value not only takes into account the ratio error of the current transformer under harmonic conditions, but also further corrects the angle difference error, ensuring that the subsequently generated harmonic voltage waveform can accurately reflect the measurement results under ideal harmonic conditions, thereby improving the accuracy and reliability of the calibrator in high-order harmonic detection.

[0212] Step S6, generating a fitting waveform of the fourth harmonic voltage according to the harmonic current measurement point, the harmonic current error point and the harmonic error compensation value;

[0213] Specifically, according to the harmonic current measurement points, harmonic current error points and harmonic error compensation values, a fitting waveform of the fourth harmonic voltage is generated; wherein, the harmonic current measurement points are used to identify the actual measurement results of the current transformer tester to be calibrated at different harmonic frequencies, the harmonic current error points reflect the deviation between the current measurement value and the theoretical value, and the harmonic error compensation value is used to correct the measurement error introduced by the unbalanced harmonic response. Based on the above data, the control computer performs nonlinear fitting on each measurement point, and uses mathematical models such as interpolation algorithms or least squares methods to construct a continuous and smooth fourth harmonic voltage fitting waveform. The fitting waveform can not only truly reflect the dynamic changes of the harmonic current at different measurement points, but also fully consider the error compensation of the ratio difference and the angle difference, so that the generated fourth harmonic voltage is closer to the harmonic voltage signal under the ideal state, which lays a precise voltage foundation for the subsequent transconductance conversion and current output, thereby improving the reliability and accuracy of the verification results.

[0214] Step S7, driving the quantum voltage generation module to output the fourth harmonic voltage and the fifth harmonic voltage according to the fitted waveform of the fourth harmonic voltage and the fitted waveform of the first harmonic voltage respectively;

[0215] Step S8, driving the symmetrical transconductance amplification module to convert the fourth harmonic voltage and the fifth harmonic voltage into corresponding fourth harmonic current and fifth harmonic current;

[0216] Step S9: input the fourth harmonic current and the fifth harmonic current into a current transformer tester to be calibrated for verification.

[0217] Specifically, the fourth harmonic current and the fifth harmonic current are input into the current transformer calibrator to be calibrated for calibration; wherein, the fourth harmonic current carries the calibration information after harmonic error compensation, which is used to simulate the current signal in a complex harmonic environment, and the fifth harmonic current is used as a reference current to provide a benchmark basis for subsequent error comparison. These two harmonic currents are synchronously input into the current transformer calibrator to be calibrated after high-precision transconductance conversion, triggering the ratio difference and angle difference measurement module inside the calibrator to perform real-time calibration of the input harmonic current. During the calibration process, the control computer can continuously monitor the response data of the calibrator, extract the error information of the output signal, and dynamically adjust the input signal in combination with the pre-calculated harmonic error compensation value to ensure the consistency of the calibration conditions and the accuracy of the measurement results. Finally, the accurate calibration of the current transformer calibrator to be calibrated under harmonic conditions is achieved, providing technical guarantee for improving the reliability of harmonic measurement in power systems.

[0218] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0219] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A harmonic calibration device for a current transformer tester, characterized in that: The harmonic calibration device includes a control computer, a quantum voltage generation module, a symmetrical transconductance amplification module and a differential current feedback correction module; The harmonic calibration device is connected to a current transformer tester to be calibrated; The control computer is used to obtain harmonic current measurement points and harmonic current error points; and generate a fitting waveform of the first harmonic voltage and a fitting waveform of the second harmonic voltage according to the harmonic current measurement points; The quantum voltage generating module is used to output the first harmonic voltage and the second harmonic voltage according to the fitted waveform of the first harmonic voltage and the fitted waveform of the second harmonic voltage; The symmetrical transconductance amplification module is used to perform transconductance conversion on the first harmonic voltage and the second harmonic voltage respectively to generate corresponding first harmonic current and second harmonic current; The differential current feedback correction module is used to perform differential current superposition on the first harmonic current and the second harmonic current to generate a third harmonic voltage; The control computer is further used to calculate and generate a harmonic error compensation value based on the third harmonic voltage and the first harmonic voltage; and to generate a fitting waveform of the fourth harmonic voltage based on the harmonic current measurement point, the harmonic current error point and the harmonic error compensation value; The quantum voltage generation module is further used to output a fourth harmonic voltage and a fifth harmonic voltage according to the fitted waveform of the fourth harmonic voltage and the fitted waveform of the first harmonic voltage respectively; The symmetrical transconductance amplification module is also used to perform transconductance conversion on the fourth harmonic voltage and the fifth harmonic voltage to generate corresponding fourth harmonic current and fifth harmonic current; and input the fourth harmonic current and the fifth harmonic current into the current transformer calibrator to be calibrated for verification.

2. The harmonic calibration device for a current transformer tester according to claim 1, characterized in that: The quantum voltage generation module includes a high-stability clock, a first quantum voltage generator and a second quantum voltage generator; The first output terminal of the high-stability clock is connected to the clock input terminal of the first quantum voltage generator; The second output terminal of the high-stability clock is connected to the clock input terminal of the second quantum voltage generator; The control signal input terminal of the first quantum voltage generator is connected to the first control signal output terminal of the control computer; The control signal input terminal of the second quantum voltage generator is connected to the second control signal output terminal of the control computer; The voltage output terminal of the first quantum voltage generator is connected to the first input terminal of the symmetrical transconductance amplification module; The voltage output terminal of the second quantum voltage generator is connected to the second input terminal of the symmetrical transconductance amplification module; The ground terminal of the first quantum voltage generator is grounded; The ground terminal of the second quantum voltage generator is grounded.

3. The harmonic calibration device for a current transformer tester as claimed in claim 2, characterized in that: The symmetrical transconductance amplification module includes a first precision transconductance amplifier and a second precision transconductance amplifier; The first input end of the symmetrical transconductance amplification module is the input end of the first precision transconductance amplifier; The second input end of the symmetrical transconductance amplification module is the input end of the second precision transconductance amplifier; The ground terminal of the first precision transconductance amplifier is grounded; The ground terminal of the second precision transconductance amplifier is grounded; The current output terminal of the first precision transconductance amplifier is connected to the first terminal of the standard sampling unit of the digital comparison current transformer tester; The current output terminal of the second precision transconductance amplifier is connected to the first terminal of the measured sampling unit of the digital comparison current transformer tester.

4. The harmonic calibration device for a current transformer tester as claimed in claim 3, characterized in that: The differential current feedback correction module includes an AC / DC current comparator, a first operational amplifier, a first resistor and a digital multimeter; the AC / DC current comparator includes a standard current input winding, a detected current input winding and a differential current output winding; The high potential end of the standard current input winding is connected to the second end of the standard sampling unit of the digital comparator current transformer tester; The high potential end of the current input winding to be tested is connected to the second end of the sampling unit to be tested of the digital comparison current transformer tester; The low potential end of the standard current input winding is grounded; The low potential end of the detected current input winding is grounded; The high potential end of the differential current output winding is connected to the positive input terminal of the first operational amplifier; The low potential end of the differential current output winding is grounded; The negative input terminal of the first operational amplifier is grounded; One end of the first resistor is connected to the positive input terminal of the first operational amplifier; The other end of the first resistor is connected to the output end of the first operational amplifier; The voltage input terminal of the digital multimeter is connected to the output terminal of the first operational amplifier; The GPIB interface terminal of the digital multimeter is connected to the GPIB interface terminal of the control computer; The ground terminal of the digital multimeter is connected to ground.

5. The harmonic calibration device for a current transformer tester as claimed in claim 4, characterized in that: The first precision transconductance amplifier includes a second operational amplifier, a first power amplifier, a second resistor, a third resistor, a fourth resistor, a fifth resistor and a sixth resistor; The ground terminal of the first precision transconductance amplifier is one end of the third resistor; The input terminal of the first precision transconductance amplifier is the positive input terminal of the second operational amplifier; The current output end of the first precision transconductance amplifier is one end of the sixth resistor; The negative input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier; One end of the second resistor is connected to the output end of the second operational amplifier; The positive input terminal of the first power amplifier is connected to the other end of the second resistor; The other end of the third resistor is connected to the negative input terminal of the first power amplifier; One end of the fourth resistor is connected to the negative input terminal of the first power amplifier; One end of the fifth resistor is connected to the positive input terminal of the first power amplifier; An output terminal of the first power amplifier is connected to the other end of the fifth resistor; The other end of the sixth resistor is connected to the output end of the first power amplifier; The other end of the fourth resistor is connected to one end of the sixth resistor.

6. The harmonic calibration device for a current transformer tester as claimed in claim 5, characterized in that: The second precision transconductance amplifier includes a third operational amplifier, a second power amplifier, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor and an eleventh resistor; The ground terminal of the second precision transconductance amplifier is one end of the eighth resistor; The input terminal of the second precision transconductance amplifier is the positive input terminal of the third operational amplifier; The current output end of the second precision transconductance amplifier is one end of the eleventh resistor; The negative input terminal of the third operational amplifier is connected to the output terminal of the third operational amplifier; One end of the seventh resistor is connected to the output end of the third operational amplifier; The positive input terminal of the second power amplifier is connected to the other end of the seventh resistor; The other end of the eighth resistor is connected to the negative input terminal of the second power amplifier; One end of the ninth resistor is connected to the negative input terminal of the second power amplifier; One end of the tenth resistor is connected to the positive input terminal of the second power amplifier; An output terminal of the second power amplifier is connected to the other end of the tenth resistor; The other end of the eleventh resistor is connected to the output end of the second power amplifier; The other end of the ninth resistor is connected to one end of the eleventh resistor.

7. The harmonic calibration device for a current transformer tester according to claim 6, characterized in that: The harmonic current measurement points include the rated current value, the harmonic order, and the percentage of the harmonic current to the rated current; and the generating of the fitting waveform of the first harmonic voltage and the fitting waveform of the second harmonic voltage according to the harmonic current measurement points includes: Extracting the rated current value, the harmonic order and the percentage of the harmonic current to the rated current from the harmonic current measurement point; Calculating and generating a voltage amplitude according to the rated current value, the percentage of harmonic current to the rated current, and a preset current feedback resistor; Calculate and generate harmonic frequencies according to the harmonic order and the preset fundamental frequency; The fitting waveform of the first harmonic voltage and the fitting waveform of the second harmonic voltage are generated by the following formula: V1=abs(V amp )×sin(2×π×f×t+φ) V2=abs(V amp )×sin(2×π×f×t+φ) Wherein, V1 is the fitting waveform of the first harmonic voltage; V2 is the fitting waveform of the second harmonic voltage; abs(V amp ) is the absolute value of the voltage amplitude; f is the harmonic frequency; t is the time variable; φ is the initial phase angle.

8. The harmonic calibration device for a current transformer tester as claimed in claim 7, characterized in that: The calculating and generating a harmonic error compensation value according to the third harmonic voltage and the first harmonic voltage includes: The amplitude error compensation value is calculated using the following formula: Among them, e f is the amplitude error compensation value; is the error vector; is the absolute value of the error vector; is the third harmonic voltage; is the first harmonic voltage; R1 is the first resistor; R6 is the sixth resistor; The phase error compensation value is calculated using the following formula: Among them, e φ is the phase error compensation value; a is the scaling factor; is the imaginary part of the error vector; is the real part of the error vector; The amplitude error compensation value and the phase error compensation value are recorded as harmonic error compensation values.

9. The harmonic calibration device for a current transformer tester as claimed in claim 8, characterized in that: The harmonic current error points include harmonic current ratio difference and harmonic current phase difference; The fitted waveform of the fourth harmonic voltage is generated by the following formula: V4=abs(V amp )×(1st f )×(1+f ε )×sin(2×π×f×t+φ-e φ +φ e ) Wherein, V4 is the fitting waveform of the fourth harmonic voltage; f ε is the harmonic current ratio difference; φ e is the harmonic current phase difference.

10. A harmonic calibration method for a current transformer tester, applicable to a control computer of a harmonic calibration device of a current transformer tester, characterized in that: The harmonic calibration device includes a control computer, a quantum voltage generation module, a symmetrical transconductance amplification module and a differential current feedback correction module; The harmonic calibration device is connected to a current transformer tester to be calibrated; The harmonic calibration method comprises: Obtain harmonic current measurement points and harmonic current error points; Generating a fitting waveform of a first harmonic voltage and a fitting waveform of a second harmonic voltage according to the harmonic current measurement point; The driving quantum voltage generation module outputs a first harmonic voltage and a second harmonic voltage according to the fitting waveform of the first harmonic voltage and the fitting waveform of the second harmonic voltage respectively; After collecting the first harmonic voltage and the second harmonic voltage and inputting them into the symmetrical transconductance amplification module to convert them into the corresponding first harmonic current and second harmonic current, the first harmonic current and the second harmonic current are input into the differential current feedback correction module to perform differential current superposition to obtain the third harmonic voltage; Calculating and generating a harmonic error compensation value according to the third harmonic voltage and the first harmonic voltage; Generate a fitting waveform of the fourth harmonic voltage according to the harmonic current measurement point, the harmonic current error point and the harmonic error compensation value; The driving quantum voltage generation module outputs a fourth harmonic voltage and a fifth harmonic voltage according to the fitting waveform of the fourth harmonic voltage and the fitting waveform of the first harmonic voltage respectively; driving the symmetrical transconductance amplification module to convert the fourth harmonic voltage and the fifth harmonic voltage into corresponding fourth harmonic current and fifth harmonic current; The fourth harmonic current and the fifth harmonic current are input into a current transformer tester to be calibrated for verification.

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