A method and system for realizing AC quantity acquisition and calibration of electric power comprehensive tester

Abstract

The present invention discloses a method and system for realizing AC quantity acquisition and calibration of a comprehensive electric power tester, which belongs to the technical field of electric power instruments and meters, and includes: obtaining an external voltage and current input signal, and preprocessing the external voltage and current input signal to obtain a small voltage signal and use it as an input signal of an AD sampling module; performing continuous cycle sampling on the input signal of the AD sampling module according to a set sampling frequency, and performing DFT calculation on the sampling point to obtain the amplitude and phase angle of the three-phase voltage and current; in a calibration mode, calculating the amplitude and phase angle of the three-phase voltage and current with the standard value of the three-phase voltage and current under different gears to obtain the calibration coefficient under each gear; calculating the current voltage and current acquisition actual value according to the calibration coefficient of the current gear and the actual input value, and automatically adjusting the gear. Compared with traditional test instruments, the present invention solves the defect that the acquisition accuracy cannot be improved under a wide range.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power instruments and meters, and in particular to a method and system for realizing AC quantity collection and calibration of an electric power comprehensive tester. Background Art

[0002] With the rapid development of the electric power industry, "smart grid" is gradually being used in the power system to solve many problems in the use of electric energy. As the monitoring unit at the end of the smart grid, the smart power meter is mainly used to collect basic power information such as voltage, current, frequency, phase, power and electric energy to improve the utilization rate of power resources. The current widespread application of large-scale integrated circuits has enabled power meters to develop from simple components to integrated components that integrate multiple functions. The power industry's rich functional requirements have also given power meters more functions, and the requirements for the accuracy of power meter collection are also getting higher and higher. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the above-mentioned background technology and solve the defect in the prior art that the acquisition accuracy cannot be improved under a wide range.

[0004] To achieve the above purpose, a method for collecting and calibrating AC quantities of a comprehensive power tester is adopted, which includes the following steps:

[0005] Obtaining external voltage and current input signals, and preprocessing the external voltage and current input signals to obtain a small voltage signal as an input signal of an AD sampling module;

[0006] The input signal of the AD sampling module is sampled continuously at the set sampling frequency, and DFT calculation is performed on the sampling points to obtain the amplitude and phase angle of the three-phase voltage and current;

[0007] In the calibration mode, the amplitude and phase angle of the three-phase voltage and current are calculated with the standard values ​​of the three-phase voltage and current at different gears to obtain the calibration coefficient at each gear, which includes the amplitude calibration coefficient and the angle calibration coefficient;

[0008] In the acquisition mode, the actual acquisition value of the current voltage and current is calculated according to the calibration coefficient and the actual input value in the current gear;

[0009] The input gear of the AD sampling module is adjusted according to the actual collected values ​​of the current voltage and current.

[0010] Furthermore, the external voltage and current input signals are obtained, and the external voltage and current input signals are preprocessed to obtain a small voltage signal as an input signal of the AD sampling module, including:

[0011] Perform PT and CT ratio processing on the external voltage and current input signals to obtain small voltage and current signals;

[0012] Use voltage dividing resistors and sampling resistors to process the small voltage and current signals respectively to obtain processed voltage and current signals;

[0013] Use conditioning circuits and programmable amplifiers with different gears to process the processed voltage and current signals, and convert the processed voltage signal into a small voltage signal within a corresponding range;

[0014] Take the small voltage signal within the corresponding range as the input signal of the AD sampling module.

[0015] Further, the corresponding relationship between the amplification factors of the conditioning circuits and programmable amplifiers with different gears is as follows:

[0016] For the range 0V < U ≤ 3V, 200 - fold sampling is adopted, and the upper limit of the AD input voltage is 3 / 101×200 ≈ 6V;

[0017] For the range 3V < U ≤ 30V, 20 - fold sampling is adopted, and the upper limit of the AD input voltage is 30 / 101×20 ≈ 6V;

[0018] For the range 0V < U ≤ 3V, 2 - fold sampling is adopted, and the upper limit of the AD input voltage is 450 / 101×2 ≈ 9V;

[0019] For the range 0A < I ≤ 1A, 200 - fold sampling is adopted, and the upper limit of the AD input voltage is 1 / 4000×120×200 ≈ 6V;

[0020] For the range 1A < I ≤ 10A, 20 - fold sampling is adopted, and the upper limit of the AD input voltage is 10 / 4000×120×20 ≈ 6V;

[0021] For the range 10A < I ≤ 100A, 2 - fold sampling is adopted, and the upper limit of the AD input voltage is 100 / 4000×120×20 ≈ 6V.

[0022] Further, continuously sample the input signal of the AD sampling module at a set sampling frequency for consecutive cycles, and perform DFT calculation on the sampling points to obtain the amplitudes and phase angles of the three - phase voltage and current, including:

[0023] Continuously sample the input signal of the AD sampling module at the set sampling frequency and the number of sampling points per cycle;

[0024] Perform Fourier transform on the signal collected in each cycle, and calculate the fundamental wave effective value and phase angle of the voltage and current signals according to the result of the Fourier transform;

[0025] The fundamental effective value and phase angle calculated for N cycles are averaged to obtain the amplitude and phase angle of the three-phase voltage and current.

[0026] Further, in the calibration mode, the amplitude and phase angle of the three-phase voltage and current are calculated with the standard values ​​of the three-phase voltage and current at different gears to obtain the calibration coefficient at each gear, the calibration coefficient includes the amplitude calibration coefficient and the angle calibration coefficient, and the standard values ​​of the three-phase voltage and current include the standard values ​​of the three-phase voltage, current, active power and reactive power, including:

[0027] The calculation formula for the amplitude calibration coefficient of each acquisition channel is:

[0028] Kni=Sni / Xni(i=0,1,2…represents Ua,Ub,Uc,Ia,Ib,Ic respectively)

[0029] Where: Kni is the calibration coefficient of the ith channel at the nth gear, Xni is the effective amplitude of the fundamental wave calculated by the current channel, and Sni is the standard applied value of the current acquisition channel;

[0030] The angle of the acquisition channel Ua is always set to 0 degrees, and the phase angle values ​​of other acquisition channels are the angles with Ua. In the calibration mode, the three-phase voltage standard values ​​are output with a fixed phase sequence, and the angle calibration coefficient of the voltage channel is calculated.

[0031] Furthermore, the calculation process of the angle calibration coefficient of the voltage channel includes:

[0032] KθnUa=0,

[0033] KθnUb=240-(XθnUb-XθnUa),

[0034] KθnUc=120-(XθnUc-XθnUa),

[0035] Among them: KθnUa, KθnUb, KθnUc are the calibration coefficients of the three channel angles Ua, Ub, Uc in gear n, respectively; XθnUa, XθnUb, XθnUc are the calculated values ​​of the DFT angles of each channel at present;

[0036] Then, according to the standard values ​​of active power and reactive power, the angle between voltage and current is calculated:

[0037] Ang_nIa=atan(Qa_n / Pa_n),

[0038] Ang_nIb=atan(Qb_n / Pb_n),

[0039] Ang_nIc=atan(Qc_n / Pc_n),

[0040] KθnIa=0-Ang_nIa-XθnIa+XθnUa,

[0041] KθnIb=240-Ang_nIb-XθnIb+XθnUa,

[0042] KθnIc=120-Ang_nIc-XθnIc+XθnUa,

[0043] Among them: KθnIa, KθnIb, KθnIc are the calibration coefficients of the three channel angles Ia, Ib, Ic in gear n respectively, and XθnIa, XθnIb, XθnIc are the calculated values ​​of the DFT angles of each current channel.

[0044] Furthermore, in the acquisition mode, the actual acquisition value of the current voltage and current is calculated according to the calibration coefficient and the actual input value in the current gear, including:

[0045] In the acquisition mode, the amplitude and phase angle of the voltage and current acquisition calculation values ​​are calculated according to the calibration coefficients in the current gear, where:

[0046] Yni=Kni×Xni(i=0,1,2…represents Ua,Ub,Uc,Ia,Ib,Ic respectively),

[0047] Where: Kni is the amplitude calibration coefficient of the ith channel in gear n, Xni is the effective amplitude of the fundamental wave calculated by the current channel, and Yni is the voltage or current acquisition calculation value of the current acquisition channel;

[0048] YθnUa=0,

[0049] YθnUb=XθnUb+KθnUb–XθnUa-KθnUa,

[0050] YθnUc=XθnUc+KθnUc–XθnUa-KθnUa,

[0051] Among them: KθnUa, KθnUb, KθnUc are the calibration coefficients of the three channel angles Ua, Ub, Uc in gear n, XθnUa, XθnUb, XθnUc are the calculated values ​​of the DFT angles of each current channel, YθnUa, YθnUb, YθnUc are the calculated values ​​of the voltage or current angles of the current acquisition channel.

[0052] On the other hand, a power comprehensive tester AC quantity collection and calibration implementation system is adopted, including: a preprocessing module, an AD sampling module and a core control module, wherein:

[0053] The preprocessing module is used to obtain external voltage and current input signals, and preprocess the external voltage and current input signals to obtain small voltage signals as input signals of the AD sampling module;

[0054] The core control module continuously samples the input signal of the AD sampling module according to the set sampling frequency, and performs DFT calculation on the sampling points to obtain the amplitude and phase angle of the three-phase voltage and current;

[0055] In the calibration mode, the core control module calculates the amplitude and phase angle of the three-phase voltage and current with the standard values ​​of the three-phase voltage and current at different gears to obtain the calibration coefficient at each gear, which includes the amplitude calibration coefficient and the angle calibration coefficient;

[0056] In the acquisition mode, the core control module calculates the actual acquisition value of the current voltage and current according to the calibration coefficient and the actual input value under the current gear, and adjusts the input gear of the AD sampling module according to the actual acquisition value of the current voltage and current.

[0057] Furthermore, the preprocessing module includes a voltage transformer, a current transformer, a voltage dividing resistor, a sampling resistor, a conditioning circuit and a programmable amplifier, wherein:

[0058] The voltage transformer and the current transformer perform PT and CT ratio processing on the external voltage and current input signals respectively to obtain small voltage and current signals;

[0059] The voltage divider resistor and the sampling resistor process the small voltage and current signals respectively to obtain processed voltage and current signals;

[0060] The conditioning circuits and program-controlled amplifiers of different gears process the processed voltage and current signals, and convert the processed voltage signals into small voltage signals of corresponding intervals as input signals of the AD sampling module.

[0061] Further, the core control module includes a calibration coefficient calculation module, which includes an amplitude calibration coefficient calculation unit and an angle calibration coefficient calculation unit, wherein:

[0062] The amplitude calibration coefficient calculation unit is used to calculate the amplitude calibration coefficient of each acquisition channel. The calculation formula is:

[0063] Kni=Sni / Xni(i=0,1,2…represents Ua,Ub,Uc,Ia,Ib,Ic respectively)

[0064] Where: Kni is the calibration coefficient of the ith channel at the nth gear, Xni is the effective amplitude of the fundamental wave calculated by the current channel, and Sni is the standard applied value of the current acquisition channel;

[0065] The angle calibration coefficient calculation unit is used to set the angle of the acquisition channel Ua to always be 0 degrees, and the phase angle values ​​of other acquisition channels are the angles between them and Ua. In the calibration mode, the three-phase voltage standard values ​​are output with a fixed phase sequence to calculate the angle calibration coefficient of the voltage channel.

[0066] Compared with the prior art, the present invention has the following technical effects: the present invention automatically switches the programmable amplifier to different gears according to the range of voltage and current input values ​​to ensure the sampling accuracy of AD, and then further improves the acquisition accuracy by calibrating the amplitude and phase angle at different gears, thereby improving the acquisition accuracy even in a wide range. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings:

[0068] Figure 1 The present invention is a flow chart of a method for realizing AC quantity collection and calibration of a comprehensive power tester;

[0069] Figure 2 The present invention is a structural diagram of an AC quantity acquisition and calibration implementation system of an electric power comprehensive tester. DETAILED DESCRIPTION

[0070] In order to further illustrate the features of the present invention, please refer to the following detailed description and drawings of the present invention. The drawings are for reference and illustration only and are not intended to limit the scope of protection of the present invention.

[0071] like Figure 1 As shown, this embodiment discloses a method for collecting and calibrating AC quantities of a comprehensive power tester, including the following steps:

[0072] S1, obtaining an external voltage and current input signal, and preprocessing the external voltage and current input signal to obtain a small voltage signal as an input signal of an AD sampling module;

[0073] S2. Continuously sample the input signal of the AD sampling module according to the set sampling frequency, and perform DFT calculation on the sampling points to obtain the amplitude and phase angle of the three-phase voltage and current;

[0074] S3. In the calibration mode, the amplitude and phase angle of the three-phase voltage and current are calculated with the standard values ​​of the three-phase voltage and current at different gears to obtain the calibration coefficient at each gear, which includes the amplitude calibration coefficient and the angle calibration coefficient;

[0075] S4. In the acquisition mode, the actual acquisition value of the current voltage and current is calculated according to the calibration coefficient and the actual input value in the current gear;

[0076] S5. Adjust the input range of the AD sampling module according to the actual collected values of the current voltage and current.

[0077] It should be noted that in the normal sampling mode of this embodiment, the actual values of the voltage and current collected in real time are obtained according to the calculated calibration coefficient. According to the range division, the amplification coefficient of the corresponding range is switched so that the input voltage of the AD sampling is preferably within the full-scale range, thereby ensuring the sampling accuracy.

[0078] As a further preferred solution, the above step S1: Obtain the external voltage and current input signals, and preprocess the external voltage and current input signals to obtain a small voltage signal and use it as the input signal of the AD sampling module, including the following sub-steps S11 to S14:

[0079] S11. Perform PT and CT transformation ratio processing on the external voltage and current input signals to obtain small voltage and current signals;

[0080] It should be noted that in this embodiment, high-precision PT and CT with an accuracy of 0.01 level are used. After the external input voltage and current signals pass through the high-precision PT and CT, they are transformed into small voltage and current signals.

[0081] S12. Use voltage dividing resistors and sampling resistors to process the small voltage and current signals respectively to obtain the processed voltage and current signals;

[0082] S13. Use conditioning circuits and programmable amplifiers with different ranges to process the processed voltage and current signals, and convert the processed voltage signal into a small voltage signal within the corresponding range;

[0083] S14. Use the small voltage signal within the corresponding range as the input signal of the AD sampling module.

[0084] As a further preferred solution, the voltage input range of the AD sampling module is -10V to 10V, and the corresponding relationship between the amplification multiples of the conditioning circuits and programmable amplifiers with different ranges is as follows:

[0085] For the voltage acquisition range of 0V to 450V, the PT resistor voltage division ratio is 100:1, and the sampling resistor uses 3 200K resistors in series and a 6K resistor for voltage division:

[0086] In the range of 0V < U ≤ 3V, 200-fold sampling is used, and the upper limit value of the AD input voltage is 3 / 101 × 200 ≈ 6V;

[0087] In the range of 3V < U ≤ 30V, 20-fold sampling is used, and the upper limit value of the AD input voltage is 30 / 101 × 20 ≈ 6V;

[0088] When the range is 0V < U ≤ 3V, 2 - fold sampling is adopted, and the upper limit value of the AD input voltage is 450 / 101 * 2 ≈ 9V;

[0089] The current acquisition range is 0 - 100A, the number of turns of the CT coil is 4000T, and the sampling resistance is 120Ω:

[0090] When the range is 0A < I ≤ 1A, 200 - fold sampling is adopted, and the upper limit value of the AD input voltage is 1 / 4000 × 120 × 200 ≈ 6V;

[0091] When the range is 1A < I ≤ 10A, 20 - fold sampling is adopted, and the upper limit value of the AD input voltage is 10 / 4000 × 120 × 20 ≈ 6V;

[0092] When the range is 10A < I ≤ 100A, 2 - fold sampling is adopted, and the upper limit value of the AD input voltage is 100 / 4000 × 120 × 20 ≈ 6V.

[0093] As a further preferred solution, in the above - mentioned step S2: Continuously sample the input signal of the AD sampling module at a set sampling frequency for continuous cycle sampling, and perform DFT calculation on the sampling points to obtain the amplitudes and phase angles of the three - phase voltage and current, including the following sub - steps S21 to S23:

[0094] S21. Continuously sample the input signal of the AD sampling module at a set sampling frequency and the number of sampling points per cycle;

[0095] S22. Perform Fourier transform on the collected signal for each cycle, and calculate the fundamental effective value and phase angle of the voltage and current signals according to the result of the Fourier transform;

[0096] S23. Take the average of the fundamental effective values and phase angles calculated for N cycles to obtain the amplitudes and phase angles of the three - phase voltage and current.

[0097] It should be noted that in this embodiment, the device collects external voltage and current signals in real - time at a sampling frequency of 50HZ and 1024 sampling points per cycle, performs a discrete Fourier transform DFT calculation on the collected signal for each cycle, and obtains the fundamental effective value and phase angle of the voltage and current signals according to the result of the discrete Fourier transform DFT, and then takes the average of the calculated values for N cycles to obtain the amplitudes and phase angles of the voltage and current.

[0098] As a further preferred solution, in the above - mentioned step S3: In the calibration mode, calculate the amplitudes and phase angles of the three - phase voltage and current with the standard values of the three - phase voltage and current at different gears to obtain the calibration coefficients at each gear. The calibration coefficients include amplitude calibration coefficients and angle calibration coefficients. Among them, the standard values of the three - phase voltage and current include the standard values of three - phase voltage, current, active power, and reactive power, including:

[0099] The calculation formula for the amplitude calibration coefficient of each acquisition channel is:

[0100] Kni=Sni / Xni(i=0,1,2…represents Ua,Ub,Uc,Ia,Ib,Ic respectively)

[0101] Among them: Kni is the calibration coefficient of the ith channel in the nth gear, Xni is the effective amplitude of the fundamental wave calculated by the current channel, and Sni is the standard applied value of the current acquisition channel, which is issued by the host computer;

[0102] The angle of the acquisition channel Ua is always set to 0 degrees, and the phase angle values ​​of other acquisition channels are the angles with Ua. In the calibration mode, the three-phase voltage standard values ​​are output with a fixed phase sequence, and the angle calibration coefficient of the voltage channel is calculated.

[0103] Specifically, due to the crystal oscillator error and timer error, the absolute angle calculated by DFT after sampling each channel for each cycle is changing, but the relative angle difference of each channel is constant, so the angle of channel Ua is always set to 0 degrees, and the phase angle values ​​of other channels are the angles between Ua and the phase angle. When calibrating, a three-phase voltage is applied with a fixed phase sequence (0°, 240°, 120°) to output, and the angle calibration coefficient of the voltage channel is obtained as follows:

[0104] KθnUa=0,

[0105] KθnUb=240-(XθnUb-XθnUa),

[0106] KθnUc=120-(XθnUc-XθnUa),

[0107] Among them: KθnUa, KθnUb, KθnUc are the calibration coefficients of the three channel angles Ua, Ub, Uc in gear n, respectively; XθnUa, XθnUb, XθnUc are the calculated values ​​of the DFT angles of each channel at present;

[0108] Then, according to the standard values ​​of active power and reactive power, the angle between voltage and current is calculated:

[0109] Ang_nIa=atan(Qa_n / Pa_n),

[0110] Ang_nIb=atan(Qb_n / Pb_n),

[0111] Ang_nIc=atan(Qc_n / Pc_n),

[0112] KθnIa=0-Ang_nIa-XθnIa+XθnUa,

[0113] KθnIb=240-Ang_nIb-XθnIb+XθnUa,

[0114] KθnIc=120-Ang_nIc-XθnIc+XθnUa,

[0115] Among them: KθnIa, KθnIb, KθnIc are the calibration coefficients of the three channel angles Ia, Ib, Ic in gear n respectively, and XθnIa, XθnIb, XθnIc are the calculated values ​​of the DFT angles of each current channel.

[0116] As a further preferred solution, the above step S4: in the acquisition mode, according to the calibration coefficient and the actual input value in the current gear, the actual acquisition value of the current voltage and current is calculated, including:

[0117] In the acquisition mode, the amplitude and phase angle of the voltage and current acquisition calculation values ​​are calculated according to the calibration coefficients in the current gear, where:

[0118] Yni=Kni×Xni(i=0,1,2…represents Ua,Ub,Uc,Ia,Ib,Ic respectively),

[0119] Where: Kni is the amplitude calibration coefficient of the ith channel in gear n, Xni is the effective amplitude of the fundamental wave calculated by the current channel, and Yni is the voltage or current acquisition calculation value of the current acquisition channel;

[0120] YθnUa=0,

[0121] YθnUb=Xθ'nUb+KθnUb–Xθ'nUa-KθnUa,

[0122] YθnUc=Xθ'nUc+KθnUc–Xθ'nUa-KθnUa,

[0123] Among them: KθnUa, KθnUb, KθnUc are the calibration coefficients of the three channel angles Ua, Ub, Uc in gear n, XθnUa, XθnUb, XθnUc are the calculated values ​​of the DFT angles of each current channel, YθnUa, YθnUb, YθnUc are the calculated values ​​of the voltage or current angles of the current acquisition channel.

[0124] As a further preferred solution, the above step S5: adjusting the input gear of the AD sampling module according to the actual collected values ​​of the current voltage and current, includes:

[0125] In normal acquisition mode, the actual values ​​of voltage and current collected in real time are obtained based on the calculated calibration coefficients. According to the gear division, the programmable amplifier is switched to the amplification factor of the corresponding gear, so that the input voltage of AD sampling is as close to the full scale as possible, thereby ensuring the sampling accuracy.

[0126] As Figure 2 shown, this embodiment discloses an AC quantity acquisition and calibration implementation system for a power comprehensive tester, including: a preprocessing module 10, an AD sampling module 20, and a core control module 30, where:

[0127] The preprocessing module 10 is used to obtain an external voltage and current input signal, preprocess the external voltage and current input signal to obtain a small voltage signal, and use it as the input signal of the AD sampling module;

[0128] The core control module 30 continuously samples the input signal of the AD sampling module at a set sampling frequency, and performs DFT calculation on the sampling points to obtain the amplitudes and phase angles of the three-phase voltage and current;

[0129] In the calibration mode, the core control module 30 calculates the amplitudes and phase angles of the three-phase voltage and current with the standard values of the three-phase voltage and current at different gears to obtain the calibration coefficients at each gear. The calibration coefficients include amplitude calibration coefficients and angle calibration coefficients;

[0130] In the acquisition mode, the core control module 30 calculates the actual acquisition values of the current voltage and current according to the calibration coefficients and the actual input values at the current gear, and adjusts the input gear of the AD sampling module 20 according to the actual acquisition values of the current voltage and current.

[0131] As a further preferred solution, the preprocessing module 10 includes a voltage transformer, a current transformer, a voltage-dividing resistor, a sampling resistor, a conditioning circuit, and a programmable gain amplifier, where:

[0132] The voltage transformer and the current transformer respectively perform PT and CT ratio processing on the external voltage and current input signals to obtain small voltage and current signals;

[0133] The voltage-dividing resistor and the sampling resistor respectively process the small voltage and current signals to obtain processed voltage and current signals;

[0134] The conditioning circuits and programmable gain amplifiers at different gears process the processed voltage and current signals, and convert the processed voltage signal into a small voltage signal within a corresponding range as the input signal of the AD sampling module 20.

[0135] The corresponding relationship of the amplification multiples of the conditioning circuits and programmable gain amplifiers at different gears is:

[0136] In the range of 0V < U ≤ 3V, 200 times sampling is adopted, and the upper limit value of the AD input voltage is 3 / 101×200≈6V;

[0137] When 3V < U ≤ 30V, 20 - fold sampling is adopted, and the upper limit value of the AD input voltage is 30 / 101×20 ≈ 6V;

[0138] When 0V < U ≤ 3V, 2 - fold sampling is adopted, and the upper limit value of the AD input voltage is 450 / 101×2 ≈ 9V;

[0139] When 0A < I ≤ 1A, 200 - fold sampling is adopted, and the upper limit value of the AD input voltage is 1 / 4000×120×200 ≈ 6V;

[0140] When 1A < I ≤ 10A, 20 - fold sampling is adopted, and the upper limit value of the AD input voltage is 10 / 4000×120×20 ≈ 6V;

[0141] When 10A < I ≤ 100A, 2 - fold sampling is adopted, and the upper limit value of the AD input voltage is 100 / 4000×120×20 ≈ 6V.

[0142] As a further preferred solution, the core control module 30 includes a calibration coefficient calculation module, and the calibration coefficient calculation module includes an amplitude calibration coefficient calculation unit and an angle calibration coefficient calculation unit, where:

[0143] The amplitude calibration coefficient calculation unit is used to calculate the amplitude calibration coefficient of each acquisition channel, and the calculation formula is:

[0144] Kni = Yn i / Sni (i = 0, 1, 2... respectively represent Ua, Ub, Uc, Ia, Ib, Ic)

[0145] Where: Kni is the calibration coefficient of the i - th channel in the n - th gear, Xni is the effective fundamental amplitude calculated by the current channel, and Sni is the standard applied value of the current acquisition channel;

[0146] The angle calibration coefficient calculation unit is used to set the angle of the acquisition channel Ua to be always 0 degrees, and the phase angle values of other acquisition channels are the included angles with Ua. In the calibration mode, the standard three - phase voltage values are output in a fixed phase sequence, and the angle calibration coefficient of the voltage channel is calculated.

[0147] As a further preferred solution, the angle calibration coefficient calculation unit is specifically used for:

[0148] KθnUa = 0,

[0149] KθnUb = 240 - (XθnUb - XθnUa),

[0150] KθnUc = 120 - (XθnUc - XθnUa),

[0151] Among them: KθnUa, KθnUb, KθnUc are the calibration coefficients of the three channel angles Ua, Ub, Uc in gear n, respectively; XθnUa, XθnUb, XθnUc are the calculated values ​​of the DFT angles of each channel at present;

[0152] Then, according to the standard values ​​of active power and reactive power, the angle between voltage and current is calculated:

[0153] Ang_nIa=atan(Qa_n / Pa_n),

[0154] Ang_nIb=atan(Qb_n / Pb_n),

[0155] Ang_nIc=atan(Qc_n / Pc_n),

[0156] KθnIa=0-Ang_nIa-XθnIa+XθnUa,

[0157] KθnIb=240-Ang_nIb-XθnIb+XθnUa,

[0158] KθnIc=120-Ang_nIc-XθnIc+XθnUa,

[0159] Among them: KθnIa, KθnIb, KθnIc are the calibration coefficients of the three channel angles Ia, Ib, Ic in gear n respectively, and XθnIa, XθnIb, XθnIc are the calculated values ​​of the DFT angles of each current channel.

[0160] As a further preferred solution, the core control module 30 is specifically used to calculate the amplitude and phase angle of the voltage and current acquisition calculation value according to the calibration coefficient under the current gear in the acquisition mode, wherein:

[0161] Yni=Kni×Sni(i=0,1,2…represents Ua,Ub,Uc,Ia,Ib,Ic respectively),

[0162] Where: Kni is the calibration coefficient of the ith channel in gear n, Sni is the effective amplitude of the fundamental wave calculated by the current channel, and Yni is the voltage or current acquisition calculation value of the current acquisition channel;

[0163] YθnUa=0,

[0164] YθnUb=XθnUb+KθnUb–XθnUa-KθnUa,

[0165] YθnUc=XθnUc+KθnUc–XθnUa-KθnUa,

[0166] Among them: KθnUa, KθnUb, KθnUc are the calibration coefficients of the three channel angles Ua, Ub, Uc in gear n, XθnUa, XθnUb, XθnUc are the calculated values ​​of the DFT angles of each current channel, YθnUa, YθnUb, YθnUc are the calculated values ​​of the voltage or current angles of the current acquisition channel.

[0167] It should be noted that after the acquisition value is calculated by the above formula, the core control module 30 automatically switches the AD input gear according to the size of the acquisition value. For example, at the current 2x amplification factor gear, the voltage obtained by the acquisition calculation is 20V. According to the above gear division, the amplification factor of the programmable amplifier is controlled to switch from 2x to 20x to ensure the sampling accuracy of the AD.

[0168] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for collecting and calibrating AC quantities of a comprehensive power tester, characterized in that: include: S1, obtaining an external voltage and current input signal, and preprocessing the external voltage and current input signal to obtain a small voltage signal as an input signal of an AD sampling module; S2. Continuously sample the input signal of the AD sampling module according to the set sampling frequency, and perform DFT calculation on the sampling points to obtain the amplitude and phase angle of the three-phase voltage and current; S3. In the calibration mode, the amplitude and phase angle of the three-phase voltage and current are calculated with the standard values ​​of the three-phase voltage and current at different gears to obtain the calibration coefficient at each gear, wherein the calibration coefficient includes an amplitude calibration coefficient and an angle calibration coefficient, and the standard values ​​of the three-phase voltage and current include standard values ​​of the three-phase voltage, current, active power and reactive power; S4. In the acquisition mode, the actual acquisition value of the current voltage and current is calculated according to the calibration coefficient and the actual input value in the current gear; S5. Adjust the input gear of the AD sampling module according to the actual collected values ​​of the current voltage and current; Step S3 specifically includes: The calculation formula for the amplitude calibration coefficient of each acquisition channel is: Kni=Sni / Xni,i=0,1,2…represent Ua,Ub,Uc,Ia,Ib,Ic respectively Where: Kni is the calibration coefficient of the ith channel at the nth gear, Xni is the effective amplitude of the fundamental wave calculated by the current channel, and Sni is the standard applied value of the current acquisition channel; The angle of the acquisition channel Ua is always set to 0 degrees, and the phase angle values ​​of other acquisition channels are the angles between them and Ua. In the calibration mode, the three-phase voltage standard values ​​are output in a fixed phase sequence, and the angle calibration coefficient of the voltage channel is calculated; The calculation process of the angle calibration coefficient of the voltage channel includes: KθnUa=0, KθnUb=240-(XθnUb-XθnUa), KθnUc=120-(XθnUc-XθnUa), Among them: KθnUa, KθnUb, KθnUc are the calibration coefficients of the three channel angles Ua, Ub, Uc in gear n, respectively; XθnUa, XθnUb, XθnUc are the calculated values ​​of the DFT angles of each channel at present; Then, according to the standard values ​​of active power and reactive power, the angle between voltage and current is calculated: Ang_nIa=atan(Qa_n / Pa_n), Ang_nIb=atan(Qb_n / Pb_n), Ang_nIc=atan(Qc_n / Pc_n), KθnIa=0-Ang_nIa-XθnIa+XθnUa, KθnIb=240-Ang_nIb-XθnIb+XθnUa, KθnIc=120-Ang_nIc-XθnIc+XθnUa, Among them: KθnIa, KθnIb, KθnIc are the calibration coefficients of the three channel angles Ia, Ib, Ic in gear n respectively, and XθnIa, XθnIb, XθnIc are the calculated values ​​of the DFT angles of each current channel.

2. The method for realizing AC quantity collection and calibration of a comprehensive electric power tester according to claim 1, characterized in that: The method of obtaining an external voltage and current input signal and preprocessing the external voltage and current input signal to obtain a small voltage signal as an input signal of an AD sampling module includes: Perform PT and CT ratio processing on the external voltage and current input signals to obtain small voltage and current signals; Use voltage dividing resistors and sampling resistors to process the small voltage and current signals respectively to obtain processed voltage and current signals; Use conditioning circuits and programmable amplifiers with different gears to process the processed voltage and current signals, and convert the processed voltage signal into a small voltage signal within the corresponding range; Use the small voltage signal within the corresponding range as the input signal of the AD sampling module.

3. The method for realizing AC quantity collection and calibration of a comprehensive electric power tester according to claim 2, characterized in that: The corresponding relationship between the amplification factors of the conditioning circuits and programmable amplifiers with different gears is as follows: For voltage acquisition range 0 - 450V, the PT resistor voltage division ratio is 100:1, and the sampling resistor uses 3 200K in series and 6K for voltage division; In the range of 0V < U ≤ 3V, 200 - fold sampling is used, and the upper limit of the AD input voltage is 3 / 101×200 ≈ 6V; In the range of 3V < U ≤ 30V, 20 - fold sampling is used, and the upper limit of the AD input voltage is 30 / 101×20 ≈ 6V; In the range of 0V < U ≤ 450V, 2 - fold sampling is used, and the upper limit of the AD input voltage is 450 / 101×2 ≈ 9V; For current acquisition range 0 - 100A, the CT coil turns are 4000T, and the sampling resistor is 120Ω; In the range of 0A < I ≤ 1A, 200 - fold sampling is used, and the upper limit of the AD input voltage is 1 / 4000×120×200 ≈ 6V; In the range of 1A < I ≤ 10A, 20 - fold sampling is used, and the upper limit of the AD input voltage is 10 / 4000×120×20 ≈ 6V; In the range of 10A < I ≤ 100A, 2 - fold sampling is used, and the upper limit of the AD input voltage is 100 / 4000×120×20 ≈ 6V.

4. The method for realizing AC quantity collection and calibration of a comprehensive electric power tester according to claim 1, characterized in that: Perform continuous cycle sampling on the input signal of the AD sampling module according to the set sampling frequency, and perform DFT calculation on the sampling points to obtain the amplitudes and phase angles of the three - phase voltage and current, including: Perform continuous cycle sampling on the input signal of the AD sampling module according to the set sampling frequency and the number of sampling points per cycle; Perform Fourier transform on the signal collected in each cycle, and calculate the fundamental wave effective value and phase angle of the voltage and current signals according to the result of the Fourier transform; Take the average value of the fundamental wave effective values and phase angles calculated for N cycles to obtain the amplitudes and phase angles of the three - phase voltage and current.

5. The method for realizing AC quantity collection and calibration of a comprehensive electric power tester according to claim 1, characterized in that: In the acquisition mode, calculate the actual acquisition values of the current voltage and current according to the calibration coefficient and the actual input value at the current gear, including: In the acquisition mode, calculate the amplitude and phase angle of the voltage and current acquisition calculation values according to the calibration coefficient at the current gear, where: Yni = Kni×Xni, i = 0, 1, 2... respectively represent Ua, Ub, Uc, Ia, Ib, Ic, where: Kni is the calibration coefficient of the i - th channel at the n - th gear, Xni is the fundamental wave effective amplitude calculated by the current channel, and Yn i is the voltage or current acquisition calculation value of the current acquisition channel; YθnUa = 0, YθnUb = Xθ’nUb + KθnUb – Xθ’nUa - KθnUa, YθnUc=Xθ'nUc+KθnUc–Xθ'nUa-KθnUa, Among them: KθnUa, KθnUb, KθnUc are the calibration coefficients of the three channel angles Ua, Ub, Uc in gear n, Xθ'nUa, Xθ'nUb, Xθ'nUc are the calculated values ​​of the DFT angles of each current channel, YθnUa, YθnUb, YθnUc are the calculated values ​​of the voltage or current angles of the current acquisition channel.

6. A system for collecting and calibrating AC quantities of a comprehensive power tester, characterized in that: include: Preprocessing module, AD sampling module and core control module, including: The preprocessing module is used to obtain external voltage and current input signals, and preprocess the external voltage and current input signals to obtain small voltage signals as input signals of the AD sampling module; The core control module continuously samples the input signal of the AD sampling module according to the set sampling frequency, and performs DFT calculation on the sampling points to obtain the amplitude and phase angle of the three-phase voltage and current; In the calibration mode, the core control module calculates the amplitude and phase angle of the three-phase voltage and current with the standard values ​​of the three-phase voltage and current at different gears to obtain the calibration coefficient at each gear, the calibration coefficient including the amplitude calibration coefficient and the angle calibration coefficient, and the standard values ​​of the three-phase voltage and current include the standard values ​​of the three-phase voltage, current, active power and reactive power; In the acquisition mode, the core control module calculates the actual acquisition value of the current voltage and current according to the calibration coefficient and the actual input value under the current gear, and adjusts the input gear of the AD sampling module according to the actual acquisition value of the current voltage and current; The core control module is specifically used for: The calculation formula for the amplitude calibration coefficient of each acquisition channel is: Kni=Sni / Xni,i=0,1,2…represents Ua,Ub,Uc,Ia,Ib,Ic respectively Where: Kni is the calibration coefficient of the ith channel at the nth gear, Xni is the effective amplitude of the fundamental wave calculated by the current channel, and Sni is the standard applied value of the current acquisition channel; The angle of the acquisition channel Ua is always set to 0 degrees, and the phase angle values ​​of other acquisition channels are the angles between them and Ua. In the calibration mode, the three-phase voltage standard values ​​are output in a fixed phase sequence, and the angle calibration coefficient of the voltage channel is calculated; The calculation process of the angle calibration coefficient of the voltage channel includes: KθnUa=0, KθnUb=240-(XθnUb-XθnUa), KθnUc=120-(XθnUc-XθnUa), Among them: KθnUa, KθnUb, KθnUc are the calibration coefficients of the three channel angles Ua, Ub, Uc in gear n, respectively; XθnUa, XθnUb, XθnUc are the calculated values ​​of the DFT angles of each channel at present; Then, according to the standard values ​​of active power and reactive power, the angle between voltage and current is calculated: Ang_nIa=atan(Qa_n / Pa_n), Ang_nIb=atan(Qb_n / Pb_n), Ang_nIc=atan(Qc_n / Pc_n), KθnIa=0-Ang_nIa-XθnIa+XθnUa, KθnIb=240-Ang_nIb-XθnIb+XθnUa, KθnIc=120-Ang_nIc-XθnIc+XθnUa, Among them: KθnIa, KθnIb, KθnIc are the calibration coefficients of the three channel angles Ia, Ib, Ic in gear n respectively, and XθnIa, XθnIb, XθnIc are the calculated values ​​of the DFT angles of each current channel.

7. The AC quantity collection and calibration implementation system of the electric power comprehensive tester according to claim 6, characterized in that: The preprocessing module includes a voltage transformer, a current transformer, a voltage dividing resistor, a sampling resistor, a conditioning circuit and a programmable amplifier, wherein: The voltage transformer and the current transformer perform PT and CT ratio processing on the external voltage and current input signals respectively to obtain small voltage and current signals; The voltage divider resistor and the sampling resistor process the small voltage and current signals respectively to obtain processed voltage and current signals; The conditioning circuits and program-controlled amplifiers of different gears process the processed voltage and current signals, and convert the processed voltage signals into small voltage signals of corresponding intervals as input signals of the AD sampling module.

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