Square-wave-based standard electronic transformer angular difference traceability device and method

Abstract

The present application provides a standard electronic transformer angular difference traceability device and method based on a square wave, belonging to the technical field of power system measurement. A delay phase determination module is used to determine the fundamental wave delay phase corresponding to the square wave voltage signal according to the rising time or falling time of the square wave voltage signal. A standard analog-to-digital conversion mutual inductance module is used to filter and perform analog-to-digital conversion sampling on the square wave voltage signal according to the clock synchronization signal to obtain a digital voltage signal. A calibrated angular difference determination module is used to perform a discrete Fourier transform on the digital voltage signal to obtain the fundamental wave phase corresponding to the digital voltage signal, and calculate the calibrated angular difference obtained according to the fundamental wave phase and the fundamental wave delay phase, and perform angular difference traceability on the electronic transformer under test. Through the device and method provided by the present application, the calibrated angular difference of the standard analog-to-digital conversion mutual inductance module can be accurately obtained, and angular difference traceability is performed on the electronic transformer under test, improving the accuracy of angular difference traceability and solving the problem of low accuracy.

Description

Technical Field

[0001] This application belongs to the technical field of power system measurement, and particularly relates to a square-wave-based angular difference traceability device and method for a standard electronic current transformer. Background Art

[0002] An electronic current transformer is a device used to measure current and voltage in a power system. In an electronic current transformer, the angular difference refers to the phase difference between the primary input signal and the secondary output signal. The electronic current transformer (or analog input merging unit) is implemented by an electronic current transformer calibrator, and the electronic current transformer calibrator is calibrated by a standard electronic current transformer. The angular difference traceability of the standard electronic current transformer is the key to the traceability of the electronic current transformer.

[0003] Through the angular difference traceability of the electronic current transformer, the measurement result of the angular difference of the current transformer can be linked to the national measurement standard or internationally recognized measurement standards. However, in traditional technologies, due to the limitations and uncertainties of the equipment itself in traditional devices, the accuracy of angular difference traceability is relatively low. Summary of the Invention

[0004] The purpose of this application is to provide a square-wave-based angular difference traceability device and method for a standard electronic current transformer, aiming to solve the problem of relatively low accuracy existing in traditional technologies.

[0005] This application provides a square-wave-based angular difference traceability device for a standard electronic current transformer, including:

[0006] A signal generation module, configured to generate a square-wave voltage signal and a clock synchronization signal;

[0007] A delay phase determination module, connected to the signal generation module, configured to determine the fundamental wave delay phase corresponding to the square-wave voltage signal according to the rising time or falling time of the square-wave voltage signal;

[0008] A standard analog-to-digital conversion mutual inductance module, connected to the signal generation module, configured to filter and perform analog-to-digital conversion sampling on the square-wave voltage signal according to the clock synchronization signal to obtain a digital voltage signal;

[0009] A calibrated angular difference determination module, connected to the standard analog-to-digital conversion mutual inductance module and the delay phase determination module, configured to perform a discrete Fourier transform on the digital voltage signal to obtain the fundamental wave phase corresponding to the digital voltage signal, and perform angular difference traceability on the electronic current transformer to be measured according to the calibrated angular difference calculated based on the fundamental wave phase and the fundamental wave delay phase.

[0010] In one embodiment, the signal generation module includes:

[0011] A signal processing module, configured to generate a switch control signal and the clock synchronization signal, the signal processing module being connected to the standard analog-to-digital conversion mutual inductance module for sending the clock synchronization signal to the standard analog-to-digital conversion mutual inductance module; wherein, the switch control signal is synchronized with the clock synchronization signal;

[0012] A voltage generation module, configured to generate a positive voltage signal and a negative voltage signal;

[0013] An analog switch module, respectively connected to the signal processing module and the voltage generation module, configured to switch and output the positive voltage signal and the negative voltage signal according to the switch control signal to form the square wave voltage signal.

[0014] In one embodiment, the signal generation module further includes:

[0015] A first operational amplifier module, connected to the analog switch module and the standard analog-to-digital conversion mutual inductance module, configured to amplify the positive voltage signal and the negative voltage signal and output the square wave voltage signal to the standard analog-to-digital conversion mutual inductance module.

[0016] In one embodiment, the standard analog-to-digital conversion mutual inductance module includes:

[0017] An analog-to-digital conversion sampling module, connected to the first operational amplifier module, configured to filter and perform analog-to-digital conversion sampling on the square wave voltage signal to obtain a digital sampling signal.

[0018] In one embodiment, the standard analog-to-digital conversion mutual inductance module further includes:

[0019] A protocol conversion control module, connected to the signal processing module and the analog-to-digital conversion sampling module, configured to control the analog-to-digital conversion sampling module to perform analog-to-digital conversion sampling on the square wave voltage signal according to the clock synchronization signal, perform protocol conversion on the digital sampling signal to obtain the digital voltage signal, and send it to the calibration angle difference determination module in the form of message data.

[0020] In one embodiment, the delay phase determination module is connected to the first operational amplifier module, configured to determine the fundamental wave delay phase corresponding to the square wave voltage signal according to the rising time of the square wave voltage signal.

[0021] In one embodiment, the voltage generation module includes:

[0022] A positive voltage generation module, configured to output the positive voltage signal;

[0023] The positive voltage generation module is connected to the analog switch module for sending the positive voltage signal to the analog switch module.

[0024] In one embodiment, the voltage generation module further includes:

[0025] A first resistor module, one end of the first resistor module is connected to the positive voltage generation module;

[0026] A second operational amplifier module, the inverting input terminal of the second operational amplifier module is connected to the other end of the first resistor module, the non-inverting input terminal of the second operational amplifier module is grounded, and the output terminal of the second operational amplifier module is connected to the analog switch module for sending the negative voltage signal to the analog switch module;

[0027] A second resistor module, one end of the second resistor module is connected to the other end of the first resistor module, and the other end of the second resistor module is connected to the output terminal of the second operational amplifier module.

[0028] The present application provides a method for angular difference traceability of a standard electronic current transformer based on a square wave, including:

[0029] Sending a square wave voltage signal and a clock synchronization signal through a signal generation module;

[0030] Receiving the square wave voltage signal through a delay phase determination module, and determining the fundamental wave delay phase corresponding to the square wave voltage signal according to the rising time or the falling time of the square wave voltage signal;

[0031] Receiving the clock synchronization signal through a standard analog-to-digital conversion mutual inductance module, and performing analog-to-digital conversion sampling on the square wave voltage signal according to the clock synchronization signal to obtain a digital voltage signal;

[0032] Performing a discrete Fourier transform on the digital voltage signal to obtain the fundamental wave phase corresponding to the digital voltage signal, and performing angular difference traceability on the measured electronic current transformer according to the calibrated angular difference calculated from the fundamental wave phase and the fundamental wave delay phase.

[0033] In one embodiment, the step of performing angular difference traceability on the measured electronic current transformer according to the calibrated angular difference calculated from the fundamental wave phase and the fundamental wave delay phase includes:

[0034] Obtaining a measured angular difference measured by the measured electronic current transformer for the input signal;

[0035] Determining the actual angular difference of the measured electronic current transformer according to the measured angular difference and the calibrated angular difference.

[0036] The beneficial effects of the embodiments of the present invention compared with the prior art are:

[0037] The angular difference traceability device of the standard electronic current transformer based on square wave provided by this application generates a square wave voltage signal and a clock synchronization signal through a signal generation module, realizes the starting position synchronization, can realize the time synchronization between the standard analog-to-digital conversion mutual inductance module and the signal generation module, and ensures the accuracy of subsequent signal data transmission. By determining the delay phase corresponding to the fundamental wave signal during the transmission process of the square wave voltage signal through a delay phase determination module, the delay phase existing before inputting to the standard analog-to-digital conversion mutual inductance module can be known, and the delay corresponding to the analog quantity is determined.

[0038] Under the control of the clock synchronization signal, the square wave voltage signal outputs a digital voltage signal after passing through the standard analog-to-digital conversion mutual inductance module. According to the fundamental wave phase corresponding to the digital voltage signal and the fundamental wave delay phase existing before inputting to the standard analog-to-digital conversion mutual inductance module, the calibration angular difference of the standard analog-to-digital conversion mutual inductance module can be accurately obtained. The calibration angular difference of the standard analog-to-digital conversion mutual inductance module, as the key reference for traceability, can be used as the calibration basis and the error correction foundation to accurately trace the angular difference of the electronic current transformer to be measured (such as electronic current transformer calibrators and other transformers to be calibrated).

[0039] Therefore, compared with the traditional technology, through the angular difference traceability device of the standard electronic current transformer based on square wave provided by this application, after calibrating the standard analog-to-digital conversion mutual inductance module according to the calibration angular difference calculated from the fundamental wave phase and the fundamental wave delay phase, the standard analog-to-digital conversion mutual inductance module can be used as a standard electronic current transformer to trace the angular difference of the electronic current transformer to be measured (such as electronic current transformer calibrators and other transformers to be calibrated), improving the accuracy of angular difference traceability, having high traceability, and helping to maintain the long-term stability of the measuring equipment during the actual application process. Description of the Drawings

[0040] In order to more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for use in the embodiments or exemplary technical descriptions. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0041] Figure 1 It is a schematic structural diagram of the angular difference traceability device of the standard electronic current transformer based on square wave in some embodiments provided by this application.

[0042] Figure 2 It is a schematic structural diagram of the signal generation module in some embodiments provided by this application.

[0043] Figure 3Schematic diagram of comparison between the voltage signal in the ideal state and the square-wave voltage signal in the actual state provided by some embodiments of the present application.

[0044] Figure 4 Schematic diagram of the waveform of the clock synchronization signal of the number of pulses per second (Pulse Per Second, PPS) provided by some embodiments of the present application.

[0045] Figure 5 Schematic diagram of the structure of the standard analog-to-digital conversion mutual inductance module provided by some embodiments of the present application.

[0046] Figure 6 Spectrum characteristics inside the analog-to-digital conversion sampling module provided by some embodiments of the present application.

[0047] Figure 7 Schematic diagram of the step flow of the angle difference traceability method of the standard electronic current transformer based on square wave provided by some embodiments of the present application. Detailed implementation manners

[0048] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0049] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0050] It should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application.

[0051] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, "a plurality" means two or more unless otherwise specifically defined.

[0052] Please refer toFigure 1 In this application, a square-wave-based standard electronic current transformer angular difference traceability device 100 is provided. The square-wave-based standard electronic current transformer angular difference traceability device 100 includes a signal generation module 10, a delay phase determination module 20, a standard analog-to-digital conversion mutual inductance module 30, and a calibration angular difference determination module 40. The signal generation module 10 is used to generate a square-wave voltage signal and a clock synchronization signal. The delay phase determination module 20 is connected to the signal generation module 10 and is used to determine the fundamental wave delay phase corresponding to the square-wave voltage signal according to the rising time or falling time of the square-wave voltage signal.

[0053] The standard analog-to-digital conversion mutual inductance module 30 is connected to the signal generation module 10 and is used to filter and perform analog-to-digital conversion sampling on the square-wave voltage signal according to the clock synchronization signal to obtain a digital voltage signal. The calibration angular difference determination module 40 is connected to the standard analog-to-digital conversion mutual inductance module 30 and the delay phase determination module 20 and is used to perform a discrete Fourier transform on the digital voltage signal to obtain the fundamental wave phase corresponding to the digital voltage signal, and perform angular difference traceability on the electronic current transformer to be measured according to the calibration angular difference calculated from the fundamental wave phase and the fundamental wave delay phase.

[0054] In this embodiment, the square-wave voltage signal and the clock synchronization signal generated by the signal generation module 10 are used to calibrate the standard analog-to-digital conversion mutual inductance module 30. The clock synchronization signal is used to achieve time synchronization between the standard analog-to-digital conversion mutual inductance module 30 and the signal generation module 10. The clock synchronization signal and the square-wave voltage signal are input into the standard analog-to-digital conversion mutual inductance module 30.

[0055] The square-wave voltage signal serves as the input analog signal of the standard analog-to-digital conversion mutual inductance module 30. After the delay phase determination module 20 obtains the square-wave voltage signal, it analyzes the rising time or falling time of the square-wave voltage signal to determine the fundamental wave delay phase corresponding to the square-wave voltage signal. The fundamental wave delay phase can be understood as the delay phase existing before being input into the standard analog-to-digital conversion mutual inductance module 30. Under the control of the clock synchronization signal, the standard analog-to-digital conversion mutual inductance module 30 filters and performs analog-to-digital conversion sampling on the square-wave voltage signal to obtain the corresponding digital voltage signal. The digital voltage signal serves as the digital signal output by the standard analog-to-digital conversion mutual inductance module 30.

[0056] The calibration angular difference determination module 40 performs a discrete Fourier transform (Discrete Fourier Transform, DFT) on the digital voltage signal to obtain the fundamental wave phase corresponding to the digital voltage signal. Furthermore, according to the calibration angular difference of the standard analog-to-digital conversion mutual inductance module 30 calculated from the fundamental wave phase and the fundamental wave delay phase, the phase relationship between the analog quantity and the digital quantity is established.

[0057] The calibration angle difference determination module 40 calculates the calibration angle difference between the fundamental wave phase corresponding to the digital voltage signal output by the standard analog-to-digital conversion mutual inductance module 30 and the fundamental wave delay phase corresponding to the square wave voltage signal input to the standard analog-to-digital conversion mutual inductance module 30, which is the angle difference between the input and output sides of the standard analog-to-digital conversion mutual inductance module 30. The calibration of the standard analog-to-digital conversion mutual inductance module 30 can be achieved through the calibration angle difference. Furthermore, based on the calibration angle difference of the standard analog-to-digital conversion mutual inductance module 30, the angle difference of the electronic current transformer under test can be traced back.

[0058] The square wave voltage signal and the clock synchronization signal generated by the signal generation module 10 of the standard electronic current transformer angle difference tracing device 100 provided in this application achieve starting position synchronization, enabling time synchronization between the standard analog-to-digital conversion mutual inductance module 30 and the signal generation module 10, and ensuring the accuracy of subsequent signal data transmission. The delay phase determination module 20 determines the delay phase corresponding to the fundamental wave signal during the transmission of the square wave voltage signal, enabling the delay phase existing before the input to the standard analog-to-digital conversion mutual inductance module 30 to be known and the delay corresponding to the analog quantity to be determined.

[0059] Under the control of the clock synchronization signal, the square wave voltage signal outputs a digital voltage signal after passing through the standard analog-to-digital conversion mutual inductance module 30. Based on the fundamental wave phase corresponding to the digital voltage signal and the fundamental wave delay phase existing before the input to the standard analog-to-digital conversion mutual inductance module 30, the calibration angle difference of the standard analog-to-digital conversion mutual inductance module 30 can be accurately obtained. The calibration angle difference of the standard analog-to-digital conversion mutual inductance module 30, as the key reference for tracing back, can be used as the calibration basis and the error correction foundation to accurately trace back the angle difference of the electronic current transformer under test (such as electronic current transformer calibrators and other transformers that need to be calibrated).

[0060] Therefore, compared with the traditional technology, through the standard electronic current transformer angle difference tracing device 100 based on square waves provided in this application, after calibrating the standard analog-to-digital conversion mutual inductance module 30 according to the calibration angle difference calculated from the fundamental wave phase and the fundamental wave delay phase, the standard analog-to-digital conversion mutual inductance module 30 can be used as a standard electronic current transformer to trace back and calibrate the electronic current transformer under test (such as electronic current transformer calibrators and other transformers that need to be calibrated), improving the accuracy of angle difference tracing, having high traceability, and contributing to maintaining the long-term stability of measurement equipment during actual application.

[0061] Please refer to Figure 2, in one embodiment, the signal generation module 10 includes a signal processing module 110, a voltage generation module 120, and an analog switch module 130. The signal processing module 110 is configured to generate a switch control signal and a clock synchronization signal. The signal processing module 110 is connected to the standard analog-to-digital conversion mutual inductance module 30 and is configured to send the clock synchronization signal to the standard analog-to-digital conversion mutual inductance module 30. Among them, the switch control signal is synchronized with the clock synchronization signal. The voltage generation module 120 is configured to generate a positive voltage signal and a negative voltage signal. The analog switch module 130 is respectively connected to the signal processing module 110 and the voltage generation module 120, and is configured to switch and output the positive voltage signal and the negative voltage signal according to the switch control signal.

[0062] In this embodiment, the starting positions of the switch control signal and the clock synchronization signal generated by the signal processing module 110 are synchronized. The switch control signal controls the switching order of the positive voltage signal and the negative voltage signal output by the analog switch module 130 to obtain positive and negative voltage signals with high stability, so as to form a square wave signal with high stability. The two output terminals of the voltage generation module 120 can output a positive voltage signal and a negative voltage signal, which are output to the S1 terminal and the S2 terminal of the analog switch module 130. The switch control signal is input to the A0 terminal of the analog switch module 130.

[0063] Under the control of the switch control signal, the analog switch module 130 is controlled to switch and output the positive voltage signal and the negative voltage signal to form a square wave voltage signal with the positive voltage signal and the negative voltage signal crossing each other. The analog switch module 130 has the advantages of low on-resistance, low charge injection, low off-capacitance, and multi-channel multiplexing, and can perform well in data acquisition and sample-and-hold applications when low glitches and fast settling times are required. Furthermore, under the control of the switch control signal, the analog switch module 130 can switch and output the positive voltage signal and the negative voltage signal at high speed, reducing the delay time of the signal generation module 10 itself, and forming a square wave voltage signal at high speed, which is beneficial to improving the accuracy of the standard electronic current transformer angular difference traceability device 100 based on the square wave.

[0064] In one embodiment, the clock synchronization signal is a second pulse synchronization signal of Pulse Per Second (PPS), which generates an accurate pulse signal per second for realizing time synchronization between different modules.

[0065] In one embodiment, the signal processing module 110 can be a high-performance dual-core fixed-point digital signal processor of ADSP-BF609, integrated with multiple peripherals and multiple timers or / and counters, supporting the Pulse-Width Modulation (PWM) function, and capable of meeting different application requirements. The period of one timer of the signal processing module 110 is 20 ms, and the pulse width is 10 ms, which is used to form a switch control signal to assist in forming a positive voltage signal and a negative voltage signal subsequently. The period of another timer of the signal processing module 110 is 1 s, and the pulse width is 10 ms, which is used to form a clock synchronization signal. The starting position of the clock synchronization signal is synchronized with the starting position of the switch control signal, and the initial moment of the clock synchronization signal corresponds to the initial position of the square wave voltage signal.

[0066] In one embodiment, the analog switch module 130 can be ADG1208, with a switching time of no more than 125 ns, capable of meeting the requirements for fast signal switching in high-speed application scenarios, ensuring accurate selection and transmission of the required analog signals in a short time, and improving the working efficiency and signal processing speed.

[0067] In one embodiment, the signal generation module 10 further includes a first operational amplifier module 140. The first operational amplifier module 140 is connected to the analog switch module 130 and the standard analog-to-digital conversion mutual inductance module 30, and is used to amplify the positive voltage signal and the negative voltage signal, and output a square wave voltage signal to the standard analog-to-digital conversion mutual inductance module 30.

[0068] In this embodiment, the switch control signal is used to control the analog switch module 130 to switch the output order of the positive voltage signal and the negative voltage signal. The first operational amplifier module 140 amplifies the positive voltage signal and the negative voltage signal to form a square wave voltage signal. The square wave voltage signal is output to the standard analog-to-digital conversion mutual inductance module 30. By amplifying the positive voltage signal and the negative voltage signal through the first operational amplifier module 140, square wave voltage signals with different amplitudes can be obtained to adapt to the standard analog-to-digital conversion mutual inductance module 30.

[0069] In one embodiment, the first operational amplifier module 140 can be ADA4807-1, a high-performance amplifier with low power consumption, low noise, high speed, and DC precision performance. Under the condition that the gain is +1 and the peak-to-peak output voltage is 20 mV, the -3dB bandwidth of the first operational amplifier module 140 is as high as 180 MHz, the slew rate is 225 V / μs, and the 0.1% settling time is 47 ns (4 V step).

[0070] In one embodiment, the voltage generation module 120 includes a positive voltage generation module 121. The positive voltage generation module 121 is configured to output a positive voltage signal. The positive voltage generation module 121 is connected to the analog switch module 130 and is used to send the positive voltage signal to the analog switch module 130.

[0071] In this embodiment, the positive voltage generation module 121 is connected to the S1 port of the analog switch module 130 and is used to send the positive voltage signal to the analog switch module 130. Further, based on the control sequence of the switch control signal, the analog switch module 130 alternately outputs the positive voltage signal and the negative voltage signal to form a square wave voltage signal.

[0072] In one embodiment, the positive voltage generation module 121 can be an EVAL-ADR1001, which has characteristics such as high precision, high stability, and low noise, provides a stable reference voltage, ensures the accuracy of the voltage signals converted in subsequent modules, and is conducive to reducing the error of the entire device.

[0073] In one embodiment, the positive voltage signal output by the positive voltage generation module 121 can be a voltage with different amplitudes such as 5V, has an excellent peak-to-peak (Vp-p) noise of 1.2μ, and a low noise level, which helps to maintain the integrity of the positive voltage signal, makes the positive voltage signal more stable and pure, and ensures the accuracy and reliability of the positive voltage signal during transmission and processing.

[0074] In one embodiment, the voltage generation module 120 further includes a first resistor module 122, a second operational amplifier module 123, and a second resistor module 124. One end of the first resistor module 122 is connected to the positive voltage generation module 121. The inverting input terminal of the second operational amplifier module 123 is connected to the other end of the first resistor module 122.

[0075] The non-inverting input terminal of the second operational amplifier module 123 is grounded. The output terminal of the second operational amplifier module 123 is connected to the analog switch module 130 and is used to send the negative voltage signal to the analog switch module 130. One end of the second resistor module 124 is connected to the other end of the first resistor module 122. The other end of the second resistor module 124 is connected to the output terminal of the second operational amplifier module 123.

[0076] In this embodiment, the first resistor module 122, the second operational amplifier module 123, and the second resistor module 124 form an inverting proportional amplification module. The positive voltage signal input to the inverting input terminal of the second operational amplifier module 123 is processed by the second operational amplifier module 123 and then outputs a negative voltage signal. The positive voltage signal and the negative voltage signal are opposite, realizing the inverting amplification of the signal. The resistance values of the first resistor module 122 and the second resistor module 124 are equal. Furthermore, the first resistor module 122, the second operational amplifier module 123, and the second resistor module 124 form an inverting proportional amplification module with equal ratio, making the phase of the negative voltage signal opposite to that of the positive voltage signal and the magnitudes equal to form a square wave voltage signal.

[0077] In one embodiment, the second operational amplifier module 123 uses the low-offset ADA4522, which has characteristics such as high-precision amplification, low-noise performance, high gain-bandwidth product, and slew rate. The typical value of the offset voltage of the ADA4522 is 1.5 uV. Both the first resistor module 122 and the second resistor module 124 include at least one resistor. The resistor is a 1-ppm precision resistor.

[0078] In one embodiment, the delay phase determination module 20 is connected to the first operational amplifier module 140 and is used to determine the fundamental wave delay phase corresponding to the square wave voltage signal according to the rising time of the square wave voltage signal.

[0079] In this embodiment, for the convenience of understanding, the Fourier series corresponding to the square wave voltage signal can be expressed as:

[0080] .

[0081] Among them, k is an odd number, A is the amplitude, and ω is the angular velocity.

[0082] It can be seen from the above formula that the initial phase of the fundamental wave signal corresponding to the square wave voltage signal and the initial phases of each odd harmonic signal correspond to the starting position of the square wave voltage signal.

[0083] By using the clock synchronization signal and the rising edge of the square wave voltage signal, the synchronization relationship between the two signals is determined, thereby determining the phase relationship between the square wave voltage signal before entering the standard analog-to-digital conversion mutual inductance module 30 and the digital voltage signal after outputting from the standard analog-to-digital conversion mutual inductance module 30 during the signal transmission process.

[0084] Due to the slew rate of the analog switch module 130 and the first operational amplifier module 140, it can also be understood that the rising edge or falling edge of the square wave voltage signal in the actual state cannot achieve a 0-second rise and a 0-second fall. Furthermore, there will be a rising and falling time, as Figure 3 shown. Figure 3The middle waveform a represents the voltage waveform that rises at 0 seconds and falls at 0 seconds under ideal conditions, and the waveform b represents the square-wave voltage signal under actual conditions.

[0085] Furthermore, for the sake of easy understanding, as Figure 3 shown, the Fourier series corresponding to the square-wave voltage signal under actual conditions can be expressed as:

[0086] .

[0087] Among them, k is odd, A is the amplitude, and ω is the angular velocity.

[0088] When the delay time td (which can also be understood as the rise or fall time td) approaches 0, in the Fourier series formula corresponding to the square-wave voltage signal under actual conditions, there is:

[0089] .

[0090] The formula of the Fourier series corresponding to the square-wave voltage signal under actual conditions is equivalent to the formula of the Fourier series corresponding to the square-wave voltage signal.

[0091] Furthermore, according to the formula of the Fourier series corresponding to the square-wave voltage signal under actual conditions and the formula of the Fourier series corresponding to the square-wave voltage signal, it can be known that the fundamental wave phase of the square-wave voltage signal under actual conditions is consistent with the fundamental wave phase of the square-wave voltage signal.

[0092] Thus, the delay time corresponding to the square-wave voltage signal from 0 to the positive actual state is td / 2, which can be converted into the corresponding fundamental wave delay phase and can be expressed as:

[0093] .

[0094] The square-wave voltage signal with the fundamental wave delay phase is input into the standard analog-to-digital conversion mutual inductance module 30. Through the fundamental wave delay phase in this embodiment, the delay phase existing in the input signal before entering the standard analog-to-digital conversion mutual inductance module 30 can be known, so as to facilitate the subsequent calibration of the angular difference of the standard analog-to-digital conversion mutual inductance module 30.

[0095] In one embodiment, due to the high speed of the analog switch module 130 and the first operational amplifier module 140, the actual delay time td (which can also be understood as the rise or fall time td) is less than 100 ns, and the td / 2 delay is less than 50 ns. Then, the fundamental wave delay phase corresponding to the square-wave voltage signal is:

[0096] .

[0097] Thus, the square-wave voltage signal can establish a relative to the PPS second pulse synchronization signal (such asFigure 4 The phase of the clock synchronization signal shown in the figure is the fundamental wave delay phase of -0.054 minutes.

[0098] In one embodiment, the delay phase determination module 20 includes an oscilloscope.

[0099] In one embodiment, the standard analog-to-digital conversion mutual inductance module 30 can be a standard electronic transformer or analog input merging unit for sigma-delta based analog-to-digital conversion.

[0100] Please refer to Figure 5 , in one embodiment, the standard analog-to-digital conversion mutual inductance module 30 includes an analog-to-digital conversion sampling module 310. The analog-to-digital conversion sampling module 310 is connected to the first operational amplifier module 140 and is used to filter and perform analog-to-digital conversion sampling on the square wave voltage signal to obtain a digital sampling signal.

[0101] In this embodiment, by filtering the square wave voltage signal through the analog-to-digital conversion sampling module 310, the problem of spectral aliasing caused by the infinite spectrum of the square wave voltage signal can be solved, and the accuracy of fundamental wave measurement can be improved. As can be seen from Figure 6 , for frequencies greater than 0.5f IN Input signal frequency / f DATA The attenuation of the sampling rate frequency reaches about 110 dB, which is converted to an accuracy level of 2.8 ppm to improve the accuracy of the entire device. After being filtered by the analog-to-digital conversion sampling module 310, the frequency components with extremely small amplitudes can be ignored after passing through the filter.

[0102] The analog-to-digital conversion sampling module 310 integrates a development board with high-performance ADS1278 sigma-delta, and is built-in with a 24-bit, 8-channel synchronous sampling Δ-Σ analog-to-digital converter. Through the analog-to-digital conversion sampling module 310, Δ-Σ modulation technology can be realized, and combined with a low-noise front-end design, an extremely low noise level is achieved. The analog-to-digital conversion sampling module 310 combines high-precision industrial measurement with excellent DC and AC specifications, and provides an available signal bandwidth of up to 90% of the Nyquist rate.

[0103] In the square wave-based standard electronic transformer angular difference traceability device 100, a sampling system for analog-to-digital synchronization is constructed by utilizing the characteristic that the phase of the fundamental wave signal inherent in the square wave voltage signal is in-phase and the internal anti-aliasing filter of the sigma-delta based analog-to-digital conversion ADS1278, and the analog quantity and digital quantity are directly associated through the clock synchronization signal.

[0104] In one embodiment, the standard analog-to-digital conversion mutual inductance module 30 further includes a protocol conversion control module 320. The protocol conversion control module 320 is connected to the signal processing module 110 and the analog-to-digital conversion sampling module 310, and is used to control the analog-to-digital conversion sampling module 310 to perform analog-to-digital conversion sampling on the square-wave voltage signal according to the clock synchronization signal, perform protocol conversion on the digital sampling signal to obtain a digital voltage signal, and send it to the calibration angle difference determination module 40 in the form of message data.

[0105] In this embodiment, under the control of the clock synchronization signal, the protocol conversion control module 320 continuously controls the analog-to-digital conversion sampling module 310 to collect the square-wave voltage signal. Further, the protocol conversion control module 320 performs protocol conversion on the digital sampling signal, converts it into a digital voltage signal in the IEC61850-9-2 standard, and sends it to the calibration angle difference determination module 40 in the form of message data for analysis and processing.

[0106] In one embodiment, 1V of the digital sampling signal corresponds to 10kV of the IEC61850-9-2 standard, which can reduce quantization errors. Among them, the voltage conversion relationship can also be configured according to actual needs. The protocol conversion control module 320 sets the packet number corresponding to the message data to 0 according to the synchronization moment of the clock synchronization signal, as the starting position of the digital voltage signal of the digital quantity.

[0107] In one embodiment, the protocol conversion control module 320 and the analog-to-digital conversion sampling module 310 are connected through a Serial Peripheral Interface (SPI) for reading the sampling data of the analog-to-digital conversion to obtain a digital sampling signal.

[0108] In one embodiment, the protocol conversion control module 320 can be an ADSP-BF609_ezkit, which integrates peripherals such as Ethernet, SPI interface, timer, power supply, and reference.

[0109] Through the square-wave-based standard electronic transformer angle difference traceability device 100 provided by the present application, it is not necessary to rely on expensive equipment or high-precision foreign instruments such as 3458A, reducing the cost of angle difference traceability.

[0110] Please refer to Figure 7 , the present application provides a square-wave-based standard electronic transformer angle difference traceability method, which uses the square-wave-based standard electronic transformer angle difference traceability device 100. The square-wave-based standard electronic transformer angle difference traceability method includes:

[0111] Step S10, sending a square-wave voltage signal and a clock synchronization signal through the signal generation module 10;

[0112] Step S20: The delay phase determination module 20 receives the square wave voltage signal, and determines the fundamental wave delay phase corresponding to the square wave voltage signal according to the rising time or falling time of the square wave voltage signal.

[0113] Step S30: The standard analog-to-digital conversion mutual inductance module 30 receives the clock synchronization signal, and performs analog-to-digital conversion sampling on the square wave voltage signal according to the clock synchronization signal to obtain a digital voltage signal.

[0114] Step S40: Perform a discrete Fourier transform on the digital voltage signal to obtain the fundamental wave phase corresponding to the digital voltage signal, and perform angular difference traceability on the measured electronic current transformer according to the calibration angular difference calculated from the fundamental wave phase and the fundamental wave delay phase.

[0115] In this embodiment, the relevant descriptions of step S10 can refer to the relevant descriptions in the above embodiments. The relevant descriptions of step S20 can refer to the relevant descriptions in the above embodiments. The relevant descriptions of step S30 can refer to the relevant descriptions in the above embodiments. The relevant descriptions of step S40 can refer to the relevant descriptions in the above embodiments.

[0116] In one embodiment, the signal generation module 10 outputs a 50 Hz square wave voltage signal and a clock synchronization signal (such as a clock synchronization PPS signal). The rising edges of the square wave voltage signal and the clock synchronization signal are aligned. The clock synchronization signal is a signal output by the timer in the signal processing module 110 in the signal generation module 10, which can be accurate to 10 ns. Furthermore, the output moments of the square wave voltage signal and the clock synchronization signal output by the signal generation module 10 can be accurate to 10 ns.

[0117] If the delay phase determination module 20 measures the rising time or falling time td of the square wave voltage signal, then the delay time corresponding to the square wave voltage signal in the actual state from 0 to positive is td / 2, which can be converted into the corresponding fundamental wave delay phase. Among them, the value of td is 100 ns, and the delay of td / 2 is 50 ns, then the fundamental wave delay phase is:

[0118] .

[0119] The fundamental wave delay phase is -0.054 minutes. It can also be understood that the phase error of the delay caused by the slew rate of the analog switch module 130 and the first operational amplifier module 140 is -0.054 minutes.

[0120] Under the control of a clock synchronization signal (such as a clock synchronization PPS signal), the standard analog-to-digital conversion mutual inductance module 30 continuously performs filtering and analog-to-digital conversion sampling at a sampling rate of 4000 samples per second (4k Samples Per Second, 4kSPS), and converts the sampled digital sampling signal into data compliant with the IEC61850-9-2 protocol.

[0121] In one embodiment, the calibration angular difference determination module 40 can be IEC61850-9-2 protocol analysis software, which performs a discrete Fourier transform on the digital voltage signal and calculates the fundamental wave phase corresponding to the digital voltage signal. φ 2. In one embodiment, the IEC61850-9-2 protocol analysis software is a set of software running on a computer with an RJ45 Ethernet interface.

[0122] According to the fundamental wave phase φ 2 and the fundamental wave delay phase φ 1 are calculated to obtain the calibration angular difference of the standard analog-to-digital conversion mutual inductance module 30. φ It can be expressed as:

[0123] φ = φ 2 - φ 1.

[0124] The calibration angular difference is the phase delay converted from the analog quantity to the digital quantity of the standard analog-to-digital conversion mutual inductance module 30 and can be used as a calibration value.

[0125] Among them, in the formula of the calibration angular difference φ , the fundamental wave delay phase φ 1 is negative, which can be understood as the phase shift caused by the delay of the rising time (or the rising edge time) or the falling time (or the falling edge time) of the square wave voltage signal. The fundamental wave phase φ 2 corresponding to the digital voltage signal is negative, which can be understood as the phase shift formed by the delay of the sampling process (AD sampling) in the analog-to-digital conversion plus the delay of the rising time (or the falling time) of the square wave voltage signal.

[0126] By calculating the calibration angular difference of the standard analog-to-digital conversion mutual inductance module 30 φ , the calibration of the angular difference of the standard analog-to-digital conversion mutual inductance module 30 by the square wave voltage signal is completed. The calibration angular difference of the standard analog-to-digital conversion mutual inductance module 30, as a key reference for calibration, can be used as a calibration basis and an error correction foundation to realize the angular difference traceability process.

[0127] Thus, through the square-wave-based standard electronic current transformer angular difference traceability device 100 and the square-wave-based standard electronic current transformer angular difference traceability method provided by this application, by comparing the square-wave voltage signal with the clock synchronization signal using an oscilloscope, the value of the delay time td can be determined to be 100 ns, and it can be traced back to the national measurement standard or internationally recognized measurement standards. The delay time corresponding to the square-wave voltage signal in the actual state from 0 to positive is td / 2 = 50 ns, and the corresponding fundamental wave delay phase is -0.054 minutes. When converted to the national measurement standard, the accuracy level is 15 ppm, which is better than the domestic 0.01% electronic current transformer calibrator calibration device and the European 30 ppm Power Management Unit (PMU) calibration device. It can calibrate electronic current transformers with an accuracy level of 0.01 or below, and achieve an angular difference transfer accuracy better than 20 ppm for electronic current transformers.

[0128] Furthermore, through the square-wave-based standard electronic current transformer angular difference traceability device 100 and the square-wave-based standard electronic current transformer angular difference traceability method provided by this application, based on the comparison of the square-wave voltage signal with the clock synchronization signal, compensating and deducting the 50 ns delay of the square-wave voltage signal can achieve a delay of less than 10 ns. When converted to the corresponding fundamental wave delay phase, it is 0.0108 minutes. When converted to the national measurement standard, the accuracy level is 3 ppm. This can further reduce the delay of the square-wave voltage signal, and then reduce the fundamental wave delay phase corresponding to the square-wave voltage signal, enabling a higher accuracy level, and better exceeding the levels of domestic 0.01% electronic current transformer calibrator calibration devices and European 30 ppm PMU calibration devices. It can calibrate electronic current transformers with an accuracy level of 0.01 or below.

[0129] In one embodiment, the conversion of the accuracy levels in the above various embodiments can refer to the JJG 313 current transformer verification regulation.

[0130] In one embodiment, in step S40, the step of performing angular difference traceability on the electronic current transformer under test according to the calibrated angular difference calculated from the fundamental wave phase and the fundamental wave delay phase includes:

[0131] Step S410, obtaining the measured angular difference of the electronic current transformer under test for the input signal measurement;

[0132] Step S420, determining the actual angular difference of the electronic current transformer under test according to the measured angular difference and the calibrated angular difference to achieve angular difference traceability.

[0133] In this embodiment, when it is necessary to calibrate or test the electronic current transformer under test (such as the electronic current transformer calibrator under test, etc.), the input signal of the standard analog-to-digital conversion mutual inductance module 30 is transformed to be the same as the input signal of the electronic current transformer under test through a voltage converter or a current converter, so that the standard analog-to-digital conversion mutual inductance module 30 and the electronic current transformer under test have the same signal source input. The standard analog-to-digital conversion mutual inductance module 30 can be used as an electronic current transformer or an analog input merging unit and serve as the calibration reference for the electronic current transformer under test. Thus, the measured angular difference obtained by the electronic current transformer under test for the input signal minus the calibrated angular difference of the standard analog-to-digital conversion mutual inductance module 30 is the actual angular difference of the electronic current transformer under test, realizing the angular difference traceability of the electronic current transformer under test.

[0134] Therefore, through the square-wave-based standard electronic current transformer angular difference traceability device 100 and the square-wave-based standard electronic current transformer angular difference traceability method provided by this application, the angular difference of the electronic current transformer under test can be measured based on the calibrated angular difference of the standard analog-to-digital conversion mutual inductance module 30, and the measurement result can be compared with the calibrated angular difference of the standard analog-to-digital conversion mutual inductance module 30 with a higher level of accuracy to determine the accuracy and uncertainty of the electronic current transformer under test. The entire angular difference traceability process can be traced back to the national measurement standard.

[0135] It should be understood that the magnitudes of the sequence numbers of the steps in the above embodiments do not mean the order of execution. The order of execution of each process should be determined according to its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of this application.

[0136] Those skilled in the art can clearly understand that for the convenience and brevity of description, only the above-mentioned division of each functional unit and module is used as an example. In practical applications, the above functions can be allocated to different functional units and modules according to needs, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated into a processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above integrated unit can be implemented in the form of hardware or in the form of a software functional unit. In addition, the specific names of each functional unit and module are only for the convenience of mutual distinction and do not limit the protection scope of this application. The specific working processes of the units and modules in the above system can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated here.

[0137] In the above embodiments, the descriptions of each embodiment have their own emphases. For the parts not detailed or recorded in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0138] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. A professional technician can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this application.

[0139] In the embodiments provided in this application, it should be understood that the disclosed device / terminal device and method can be implemented in other ways. For example, the device / terminal device embodiments described above are merely illustrative. For example, the division of the modules or units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection to each other can be through some interfaces. The indirect coupling or communication connection of the device or unit can be in an electrical, mechanical or other form.

[0140] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0141] In addition, the functional units in each embodiment of this application can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0142] When the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, to implement all or part of the processes in the above-described embodiment methods of this application, it can also be completed by instructing relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps of the above-described various method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file, or some intermediate form, etc. The computer-readable medium can include: any entity or device that can carry the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disc, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the content included in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0143] The above-described embodiments are only used to illustrate the technical solutions of this application, rather than to limit them; although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A standard electronic transformer angle difference tracing device based on square wave, characterized in that: include: A signal processing module (110), configured to generate a switch control signal and a clock synchronization signal; wherein the switch control signal is synchronized with the clock synchronization signal; A voltage generating module (120), used for generating a positive voltage signal and a negative voltage signal; an analog switch module (130), connected to the signal processing module (110) and the voltage generating module (120) respectively, and configured to switch and output the positive voltage signal and the negative voltage signal according to the switch control signal, so as to form a square wave voltage signal; A first operational amplifier module (140), connected to the analog switch module (130), used for amplifying the positive voltage signal and the negative voltage signal, and outputting the amplified square wave voltage signal; A time delay phase determination module (20) connected to the first operational amplifier module (140) and used to determine a fundamental wave time delay phase of an analog quantity corresponding to the amplified square wave voltage signal according to a rise time or a fall time of the amplified square wave voltage signal; A standard analog-to-digital conversion mutual inductance module (30) connected to the signal processing module (110) and the first operational amplifier module (140), and configured to filter and perform analog-to-digital conversion sampling on the amplified square wave voltage signal according to the clock synchronization signal to obtain a digital voltage signal; A calibration angle difference determination module (40) is connected to the standard analog-to-digital conversion mutual inductance module (30) and the delay phase determination module (20), and is used to perform a discrete Fourier transform on the digital voltage signal to obtain a fundamental wave phase of a digital quantity corresponding to the digital voltage signal, and to perform angle difference tracing on the electronic mutual inductor under test based on a calibration angle difference calculated from the fundamental wave phase of the digital quantity and the fundamental wave delay phase of the analog quantity; wherein the calibration angle difference is used to establish a phase relationship between the fundamental wave phase of the digital quantity and the fundamental wave delay phase of the analog quantity.

2. The square wave-based standard electronic transformer angle difference tracing device according to claim 1, characterized in that: The standard analog-to-digital conversion mutual inductance module (30) comprises: The analog-to-digital conversion sampling module (310) is connected to the first operational amplifier module (140) and is used to filter and perform analog-to-digital conversion sampling on the amplified square wave voltage signal to obtain a digital sampling signal.

3. The square wave-based standard electronic transformer angle difference tracing device according to claim 2, characterized in that: The standard analog-to-digital conversion mutual inductance module (30) further includes: A protocol conversion control module (320) is connected to the signal processing module (110) and the analog-to-digital conversion sampling module (310), and is used to control the analog-to-digital conversion sampling module (310) to perform analog-to-digital conversion sampling on the amplified square wave voltage signal according to the clock synchronization signal, and to perform protocol conversion on the digital sampling signal to obtain the digital voltage signal, and to send the digital voltage signal to the calibration angle difference determination module (40) in the form of message data.

4. The square wave-based standard electronic transformer angle difference tracing device according to any one of claims 1 to 3, characterized in that: The voltage generation module (120) comprises: A positive voltage generating module (121), used for outputting the positive voltage signal; The positive voltage generating module (121) is connected to the analog switch module (130) and is used to send the positive voltage signal to the analog switch module (130).

5. The square wave-based standard electronic transformer angle difference tracing device according to claim 4, characterized in that: The voltage generation module (120) further includes: A first resistance module (122), one end of the first resistance module (122) being connected to the positive voltage generating module (121); a second operational amplifier module (123), wherein an inverting input terminal of the second operational amplifier module (123) is connected to the other end of the first resistance module (122), a non-inverting input terminal of the second operational amplifier module (123) is grounded, and an output terminal of the second operational amplifier module (123) is connected to the analog switch module (130) for sending the negative voltage signal to the analog switch module (130); A second resistance module (124), one end of the second resistance module (124) is connected to the other end of the first resistance module (122), and the other end of the second resistance module (124) is connected to the output end of the second operational amplifier module (123).

6. A square wave-based standard electronic transformer angle difference tracing method, characterized in that: include: Sending a switch control signal and a clock synchronization signal through a signal processing module (110); wherein the switch control signal is synchronized with the clock synchronization signal; Generating a positive voltage signal and a negative voltage signal through a voltage generation module (120); Receiving the switch control signal through an analog switch module (130), switching and outputting the positive voltage signal and the negative voltage signal to form a square wave voltage signal; amplifying the positive voltage signal and the negative voltage signal through a first operational amplifier module (140), and outputting the amplified square wave voltage signal; The amplified square wave voltage signal is received through a delay phase determination module (20), and a fundamental wave delay phase of an analog quantity corresponding to the amplified square wave voltage signal is determined according to a rise time or a fall time of the amplified square wave voltage signal; The clock synchronization signal is received through a standard analog-to-digital conversion mutual inductance module (30), and according to the clock synchronization signal, the amplified square wave voltage signal is filtered and analog-to-digital converted and sampled to obtain a digital voltage signal; Perform a discrete Fourier transform on the digital voltage signal to obtain the fundamental phase of the digital quantity corresponding to the digital voltage signal, and trace the angle difference of the electronic transformer under test based on the calibration angle difference calculated based on the fundamental phase of the digital quantity and the fundamental delay phase of the analog quantity; wherein the calibration angle difference is used to establish the phase relationship between the fundamental phase of the digital quantity and the fundamental delay phase of the analog quantity.

7. The square wave-based standard electronic transformer angle difference tracing method according to claim 6, characterized in that: The step of tracing the angle difference of the electronic transformer under test based on the calibration angle difference calculated based on the fundamental wave phase of the digital quantity and the fundamental wave delayed phase of the analog quantity comprises: Obtaining a measurement angle difference obtained by measuring an input signal by the electronic transformer under test; The actual angular difference of the electronic transformer under test is determined according to the measured angular difference and the calibrated angular difference.

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