Mutual inductor broadband detection method and system

Abstract

The invention discloses a broadband detection system for a mutual inductor. The broadband detection system comprises a signal generator, broadband detection equipment and an industrial personal computer, the signal generator is used for generating an original signal and transmitting the original signal to the broadband detection equipment; the broadband detection equipment is used for placing a to-be-detected mutual inductor and is also used for amplifying an original signal so that the original signal meets the primary side input requirement of the mutual inductor; the industrial personal computer is provided with an acquisition card and is used for acquiring detection data of the broadband detection equipment; the industrial personal computer is connected with the signal generator and is used for realizing output control of the signal generator; the industrial personal computer is further provided with broadband detection software which is used for completing the broadband detection of the mutual inductor to be detected. On the other hand, the invention provides a mutual inductor broadband detection method which adopts the mutual inductor broadband detection system.

Description

Technical Field

[0001] The present invention relates to the technical field of test and calibration of electrical measurement devices, and in particular to a wide-frequency detection system and compensation method for transformers. Background Art

[0002] With the high-proportion grid connection of new energy and the large-scale application of power electronic devices, the dynamic characteristics of the power system present broadband (0 - 10 MHz) and multi-modal characteristics. Limited by the low-frequency response range (power frequency to several thousand Hz), traditional transformers are difficult to accurately measure broadband signals such as sub / supersynchronous harmonics and high-frequency oscillations, resulting in misjudgment of equipment status and failure of protection systems.

[0003] In the scenario of new energy grid connection, problems such as broadband oscillations, harmonic distortions, and high-frequency electromagnetic interference caused by the interaction between power electronic devices and the power grid occur frequently. There is an urgent need for a broadband transformer to capture fast-changing signals in real time to provide data support for system stability analysis and fault location. In addition, the broadband impedance characteristic is a key indicator for evaluating potential faults such as equipment insulation deterioration and partial discharge. Traditional detection methods cannot meet the early warning requirements due to frequency band limitations. The broadband detection system can improve the comprehensiveness and reliability of equipment status assessment through the integration of broadband impedance spectrum analysis and intelligent algorithms, ensuring the safe and economic operation of the power grid. Summary of the Invention

[0004] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] A wide-frequency detection system for transformers includes a signal generator, a wide-frequency detection device, and an industrial control computer;

[0006] The signal generator is used to generate an original signal and transmit it to the wide-frequency detection device;

[0007] The wide-frequency detection device is used to place the transformer under test and also to amplify the original signal to meet the input requirements of the primary side of the transformer;

[0008] The industrial control computer is configured with a data acquisition card for collecting the detection data of the wide-frequency detection device;

[0009] The industrial control computer is connected to the signal generator for realizing the output control of the signal generator;

[0010] The industrial control computer is also configured with wide-frequency detection software for completing the wide-screen detection of the transformer under test.

[0011] Further, the wide-frequency detection device supports the simultaneous access of two transformers under test for testing;

[0012] The data acquisition card configured by the industrial control computer is a 4-channel PCI-E data acquisition card with a sampling rate of 40 MHz.

[0013] On the other hand, the present invention provides a method for wide - band detection of transformers. Using the aforementioned wide - band detection system for transformers, it includes the following steps:

[0014] S1. Configure the transformer to be measured on the wide - band detection device, and the user sets the frequency - sweeping test parameters on the industrial control computer;

[0015] S2. Based on the wide - band detection software configured on the industrial control computer, automatically generate a signal frequency sequence according to the frequency - sweeping test parameters set by the user;

[0016] S3. The wide - band detection software automatically calculates the division number and the number of sampling points for each signal frequency according to the highest sampling rate of the acquisition card of the industrial control computer;

[0017] S4. After the user confirms that the signal frequency sequence is set correctly, start the frequency - sweeping test, traverse all signal frequency sequences, and conduct single - signal - frequency tests one by one;

[0018] S5. Complete the single - signal - frequency test;

[0019] S6. For the sampled data that meets the requirements, the wide - band detection software calls the wide - band characteristic evaluation algorithm for transformers, obtains the calculation results of the wide - band characteristic evaluation algorithm for transformers, and saves the sampled data file;

[0020] S7. The wide - band detection software plots the calculation results on the relevant result curves;

[0021] S8. If all signal frequency sequences have been executed, the wide - band detection software outputs and saves the test report and test data, and ends the frequency - sweeping test. Otherwise, after returning to step S4, according to the signal frequency sequence, jump to the next signal frequency to continue the test.

[0022] Further, in step S5, it specifically includes the following steps:

[0023] S5a. For any signal frequency, when conducting a single - signal - frequency test, first determine whether the acquisition card parameter settings are successful. If successful, enter step S5b. Otherwise, after returning to step S4, according to the signal frequency sequence, jump to the next signal frequency to continue the test. If there is no next signal frequency, end the frequency - sweeping test;

[0024] S5b. The wide - band detection software starts the acquisition of the acquisition card through a control command;

[0025] S5c. Determine whether the signal generator is set successfully. If successful, enter step S5d. Otherwise, after returning to step S4, according to the signal frequency sequence, jump to the next signal frequency to continue the test. If there is no next signal frequency, end the frequency - sweeping test;

[0026] S5d. The start signal generator issues the original signal of the current frequency;

[0027] S5e. Determine whether enough sampling points have been collected for the current signal frequency. If so, complete the single-signal frequency test of the current signal frequency and enter step S6; otherwise, return to step S5b and continue the acquisition.

[0028] Furthermore, in step S6, the evaluation algorithm for the wide-frequency characteristics of the mutual inductor specifically includes the following steps:

[0029] S6a. The wide-frequency detection software reads the amplified waveform of the collected original signal and the waveform data of the output of the mutual inductor to be measured;

[0030] S6b. The wide-frequency detection software automatically trims the waveform in the memory and performs FFT calculation;

[0031] S6c. Calculate the effective value and phase angle of each channel at the current signal frequency;

[0032] S6d. Calculate the amplitude-frequency response value according to the amplitude-frequency response formula and compare it with the -3dB value;

[0033] S6e. Calculate the phase-frequency response value according to the phase-frequency response formula;

[0034] S6f. Calculate the amplitude deviation according to the amplitude deviation formula;

[0035] S6g. When the algorithm calculation ends, the amplitude-frequency response value, phase-frequency response value, and amplitude deviation in the calculation results are respectively used to draw the amplitude-frequency characteristic, phase-frequency characteristic, and amplitude error curves in step S7.

[0036] Furthermore, in step S6b, when the wide-frequency detection software automatically trims the waveform in the memory, 10 cycles are taken for each channel, with 200 points per cycle, and then FFT calculation is performed.

[0037] Furthermore, in step S6d, the amplitude-frequency response formula is:

[0038] Amplitude-frequency response value = 20 * log10 (effective value of the mutual inductor channel / effective value of the amplified output of the original signal).

[0039] Furthermore, in step S6e, the phase-frequency response formula is:

[0040] Phase-frequency response value = current phase angle of the mutual inductor channel - phase angle of the amplified output of the original signal;

[0041] And the phase-frequency response value is controlled between -180 and 180 degrees.

[0042] Furthermore, in step S6f, the amplitude deviation formula is:

[0043] Amplitude deviation = (rms value of the current transformer channel - rms value of the amplified output of the original signal) / rms value of the amplified output of the original signal.

[0044] Compared with the prior art, the current transformer broadband detection method and system provided by the present invention generate a signal through a signal generator. The signal is input into a self-designed broadband detection device. After signal amplification and the signal passing through the current transformer under test, both are output to an industrial control computer equipped with a high-precision acquisition card. The dedicated broadband detection software on the industrial control computer compares the amplitude-frequency characteristics, phase-frequency characteristics, amplitude error, etc. of the amplified original signal and the data sensed by the current transformer, plots characteristic curves, and gives a conclusion of the detection report, thereby achieving the detection purpose of evaluating the broadband characteristics of the current transformer. By detecting the sensing characteristics of the current transformer in a broadband environment, it is then possible to determine whether there are distortions or other abnormal conditions that will affect the normal operation of the power grid. Description of the Drawings

[0045] Figure 1 It is a schematic flowchart of the current transformer broadband detection method provided by the present invention;

[0046] Figure 2 It is a schematic flowchart of the current transformer broadband characteristic evaluation algorithm. Detailed Embodiments

[0047] To make the technical means, creative features, achieved purposes, and functions of the present invention easy to understand, the following further elaborates how the present invention is implemented in combination with specific embodiments.

[0048] In a specific embodiment, the present invention provides a current transformer broadband detection system, including a signal generator, a broadband detection device, and an industrial control computer.

[0049] The signal generator is used to generate an original signal and transmit it to the broadband detection device. Specifically, a commercially available signal generator that is relatively mature in the current market can be used, and an arbitrary waveform small signal output can be constructed through a function.

[0050] The broadband detection device is used to place the current transformer under test and also to amplify the original signal to meet the input requirements of the primary side of the current transformer. In this embodiment, the broadband detection device supports the simultaneous access of two groups of current transformers under test for testing.

[0051] The industrial control computer is configured with an acquisition card for collecting the detection data of the broadband detection device; the industrial control computer is connected to the signal generator for realizing the output control of the signal generator; the industrial control computer is also configured with broadband detection software for completing the broadband detection of the current transformer under test.

[0052] In this embodiment, a mature embedded industrial computer is adopted. The configured acquisition card is a 4-channel PCI-E data acquisition card with a sampling rate of 40 MHz. It supports simultaneous acquisition of 4 channels of inputs at a sampling rate of 40 MHz and is integrated on the industrial computer through a PCI-E interface to provide high-precision data acquisition capabilities. On this basis, a broadband detection system software is developed to achieve network communication with the signal generator and control of small-signal output, as well as control of synchronous data acquisition of the acquisition card. The broadband detection system software can perform TCP / IP communication with the signal generator through the VISA interface and directly operate the data acquisition card through the function API interface for data acquisition. In addition, the industrial computer is equipped with devices such as a keyboard, mouse, and display to achieve human-computer interaction and test control. At the same time, the broadband detection system software can also perform various functions such as parameter configuration, test control, calculation of broadband characteristic evaluation algorithms, and report output based on the data collected by the acquisition card.

[0053] Furthermore, referring to Figure 1 as shown, on the other hand, the present invention provides a method for broadband detection of a mutual inductor, which adopts the aforementioned mutual inductor broadband detection system and includes the following steps:

[0054] S1. Configure the mutual inductor to be measured on the broadband detection device, and the user sets the sweep frequency test parameters on the industrial computer. The sweep frequency test parameters include, for example: frequency range, signal generator IP and port, acquisition card logical device address, primary-secondary transformation ratio of the mutual inductor to be measured, etc.

[0055] S2. Based on the broadband detection software configured on the industrial computer, automatically generate a signal frequency sequence according to the sweep frequency test parameters set by the user.

[0056] S3. The broadband detection software automatically calculates the division number and sampling points of each signal frequency according to the highest sampling rate (such as 40 MHz) of the acquisition card of the industrial computer.

[0057] S4. After the user confirms that the signal frequency sequence is set correctly, start the sweep frequency test, traverse all signal frequency sequences, and perform single-signal frequency tests one by one.

[0058] S5. Complete the single-signal frequency test.

[0059] S6. For the sampled data that meets the requirements, the broadband detection software calls the mutual inductor broadband characteristic evaluation algorithm, obtains the calculation results of the mutual inductor broadband characteristic evaluation algorithm, and saves the collected data file.

[0060] S7. The broadband detection software plots the calculation results on the relevant result curves.

[0061] S8. If the execution of the signal frequency sequence is completed, the broadband detection software outputs and saves the test report and test data, and ends the frequency sweep test. Otherwise, after returning to step S4, according to the signal frequency sequence, jump to the next signal frequency to continue the test.

[0062] Further, in step S5, it specifically includes the following steps:

[0063] S5a. For any signal frequency, when performing a single signal frequency test, first determine whether the acquisition card parameter settings are successful. If successful, enter step S5b; otherwise, after returning to step S4, according to the signal frequency sequence, jump to the next signal frequency to continue the test. If there is no next signal frequency, end the frequency sweep test.

[0064] S5b. The broadband detection software starts the acquisition card to start acquisition through a control command.

[0065] S5c. Determine whether the signal generator is set successfully. If successful, enter step S5d; otherwise, after returning to step S4, according to the signal frequency sequence, jump to the next signal frequency to continue the test. If there is no next signal frequency, end the frequency sweep test.

[0066] S5d. Start the signal generator to emit the original signal of the current frequency.

[0067] S5e. Determine whether enough sampling points have been collected for the current signal frequency. If so, complete the single signal frequency test for the current signal frequency and enter step S6; otherwise, return to step S5b to continue the acquisition.

[0068] Further, in step S6, the mutual inductor broadband characteristic evaluation algorithm specifically includes the following steps:

[0069] S6a. The broadband detection software reads the amplified waveform of the collected original signal and the waveform data output by the mutual inductor to be measured.

[0070] S6b. The broadband detection software automatically trims the waveform in the memory and performs FFT calculation. Specifically, when the broadband detection software automatically trims the waveform in the memory, 10 cycles are taken for each channel, with 200 points per cycle, and then FFT calculation is performed.

[0071] S6c. Calculate the effective value and phase angle of each channel at the current signal frequency.

[0072] S6d. Calculate the amplitude-frequency response value according to the amplitude-frequency response formula and compare it with the -3dB value. The amplitude-frequency response formula is:

[0073] Amplitude-frequency response value = 20 * log10 (mutual inductor channel effective value / original signal amplified output effective value).

[0074] S6e. Calculate the phase-frequency response value according to the phase-frequency response formula. The phase-frequency response formula is:

[0075] Phase-frequency response value = current phase angle of the transformer channel - phase angle of the amplified output of the original signal.

[0076] And control the phase-frequency response value between -180 and 180 degrees.

[0077] S6f. Calculate the amplitude deviation according to the amplitude deviation formula. The amplitude deviation formula is:

[0078] Amplitude deviation = (rms value of the transformer channel - rms value of the amplified output of the original signal) / rms value of the amplified output of the original signal.

[0079] S6g. When the algorithm calculation is completed, the amplitude-frequency response value, phase-frequency response value, and amplitude deviation in the calculation results are respectively used to plot the amplitude-frequency characteristic, phase-frequency characteristic, and amplitude error curve in step S7.

[0080] In this embodiment, during the single-signal frequency test, by controlling the signal generator to output a single-frequency signal (such as 10 kHz), and simultaneously triggering the data acquisition card for acquisition, check the signal restoration degree of the transformer at the single frequency, and calculate the amplitude-frequency response, phase-frequency response, and amplitude error through spectrum analysis. The single-frequency test is the basis of the sweep-frequency test, and the sweep-frequency test is composed of a combination of single-frequency tests with multiple different signal frequencies.

[0081] The sweep-frequency test is achieved through a combination of a set (not less than 20) of single frequencies, covering the detected frequency range. For example, the 1 Hz - 500 KHz sweep is composed of 33 single frequencies: 1 hz, 2 hz, 4 hz, 5 hz, 8 hz, 10 hz, 20 hz, 40 hz, 50 hz, 80 hz, 100 hz, 200 hz, 400 hz, 500 hz, 800 hz, 1 khz, 1.25 khz, 1.6 khz, 2 khz, 2.5 khz, 4 khz, 5 khz, 8 khz, 10 khz, 12.5 khz, 20 khz, 25 khz, 40 khz, 50 khz, 100 khz, 200 khz, 400 khz, 500 khz. Then in step S2, generate the signal frequency sequence composed of the above 33 single-signal frequency discrete points.

[0082] By calculating the amplitude-frequency response, phase-frequency response, and amplitude error for each single frequency, the calculation results are plotted into three curves: amplitude-frequency characteristic, phase-frequency characteristic, and amplitude error, and finally the conclusion of the sweep-frequency test is given, so as to quantitatively evaluate the broadband characteristics of the transformer in the 1 Hz - 500 KHz frequency range.

[0083] The test report can be automatically generated after the test, and all historical data can be retrieved within the software; it supports multiple methods such as manual testing, automatic testing, and scheduled testing, which can improve the testing efficiency of testers.

[0084] In summary, compared with the prior art, for the wide-band frequency detection method and system provided by the present invention, a signal is generated by a signal generator, and the signal is input into a self-designed wide-band frequency detection device. After the signal is amplified and the signal of the current transformer to be measured, both are output to an industrial control computer with a high-precision acquisition card. The dedicated wide-band frequency detection software on the industrial control computer compares the amplitude-frequency characteristics, phase-frequency characteristics, amplitude error, etc. of the amplified original signal and the data after being sensed by the current transformer, draws characteristic curves, and gives the conclusion of the detection report, so as to achieve the detection purpose of evaluating the wide-band frequency characteristics of the current transformer; by detecting the sensing characteristics of the current transformer in a wide-band frequency environment, it is further possible to determine whether there are distortions or other abnormal conditions that will affect the normal operation of the power grid.

[0085] Facing the requirements of smart grid and digital upgrade, the wide-band frequency detection system is a necessary technical foundation for building a highly resilient power grid and realizing coordinated control of power sources, grids, loads, and energy storage. Its application will promote the leapfrog development of measurement technology from power frequency steady state to full frequency domain dynamic perception.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A wide-band detection system for mutual inductors, characterized in that, It includes a signal generator, a broadband detection device and an industrial control computer; The signal generator is used to generate an original signal and transmit it to the broadband detection device; The broadband detection device is used to place the mutual inductor to be tested, and is also used to amplify the original signal to meet the primary side input requirements of the mutual inductor; The industrial control computer is configured with a data acquisition card for acquiring the detection data of the broadband detection device; The industrial control computer is connected to the signal generator for realizing the output control of the signal generator; The industrial control computer is also configured with broadband detection software for completing the broadband detection of the mutual inductor to be tested.

2. The wide-band detection system for mutual inductors according to claim 1, wherein The broadband detection device supports the simultaneous access of two groups of mutual inductors to be tested for experiments; The data acquisition card configured by the industrial control computer is a 4-channel PCI-E data acquisition card with a sampling rate of 40 MHz.

3. A wide-band detection method for a mutual inductor, characterized in that, Adopt the mutual inductor broadband detection system described in claim 1 or 2, and include the following steps: S1. Configure the mutual inductor to be tested on the broadband detection device, and the user sets the sweep frequency test parameters on the industrial control computer; S2. Based on the broadband detection software configured on the industrial control computer, automatically generate a signal frequency sequence according to the sweep frequency test parameters set by the user; S3. The broadband detection software automatically calculates the division number and the number of sampling points of each signal frequency according to the highest sampling rate of the data acquisition card of the industrial control computer; S4. After the user confirms that the signal frequency sequence is set correctly, start the sweep frequency test, traverse all signal frequency sequences, and perform single-signal frequency tests one by one; S5. Complete the single-signal frequency test; S6. For the acquired sampling data that meets the requirements, the broadband detection software calls the mutual inductor broadband characteristic evaluation algorithm, obtains the calculation result of the mutual inductor broadband characteristic evaluation algorithm, and saves the acquired data file; S7. The broadband detection software plots the calculation result on the relevant result curve; S8. If all the signal frequency sequences are executed, the broadband detection software outputs and saves the test report and test data, ends the sweep frequency test, otherwise returns to step S4, and jumps to the next signal frequency to continue the test according to the signal frequency sequence.

4. The wide-band detection method of the mutual inductor according to claim 3, characterized in that In step S5, it specifically includes the following steps: S5a. For any signal frequency, when performing a single-signal frequency test, first judge whether the data acquisition card parameter setting is successful. If successful, enter step S5b, otherwise return to step S4, and jump to the next signal frequency to continue the test according to the signal frequency sequence. If there is no next signal frequency, end the sweep frequency test; S5b. The broadband detection software starts the data acquisition card to start acquisition through a control command; S5c. Judge whether the signal generator is set successfully. If successful, enter step S5d, otherwise return to step S4, and jump to the next signal frequency to continue the test according to the signal frequency sequence. If there is no next signal frequency, end the sweep frequency test; S5d. Start the signal generator to emit the original signal of the current frequency; S5e. Judge whether enough sampling points are acquired for the current signal frequency. If so, complete the single-signal frequency test of the current signal frequency and enter step S6. Otherwise, return to step S5b to continue the acquisition.

5. The wide-band detection method of the mutual inductor according to claim 3, wherein In step S6, the mutual inductor broadband characteristic evaluation algorithm specifically includes the following steps: S6a. The broadband detection software reads the amplified waveform of the collected original signal and the waveform data output by the current transformer under test. S6b. The broadband detection software automatically clips the waveform in memory and performs FFT calculation. S6c. Calculate the effective value and phase angle of each channel at the current signal frequency. S6d. Calculate the amplitude-frequency response value according to the amplitude-frequency response formula and compare it with the -3dB value. S6e. Calculate the phase-frequency response value according to the phase-frequency response formula. S6f. Calculate the amplitude deviation according to the amplitude deviation formula. S6g. When the algorithm calculation is completed, the amplitude-frequency response value, phase-frequency response value and amplitude deviation in the calculation results are respectively used to plot the amplitude-frequency characteristic, phase-frequency characteristic and amplitude error curve in step S7.

6. The wide-band detection method of the mutual inductor according to claim 5, characterized in that In step S6b, when the broadband detection software automatically clips the waveform in memory, 10 cycles are taken for each channel, with 200 points per cycle, and then FFT calculation is performed.

7. The wide-band detection method of the mutual inductor according to claim 5, characterized in that In step S6d, the amplitude-frequency response formula is: Amplitude-frequency response value = 20 * log10 (effective value of the current transformer channel / effective value of the amplified output of the original signal).

8. The method for wide-band detection of an instrument transformer according to claim 5, characterized in that, In step S6e, the phase-frequency response formula is: Phase-frequency response value = current phase angle of the current transformer channel - phase angle of the amplified output of the original signal; And the phase-frequency response value is controlled between -180 and 180 degrees.

9. The wide-band detection method of the mutual inductor according to claim 5, characterized in that In step S6f, the amplitude deviation formula is: Amplitude deviation = (effective value of the current transformer channel - effective value of the amplified output of the original signal) / effective value of the amplified output of the original signal.

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