A digital demodulation method for even-order harmonics of magnetic modulator based on full phase analysis

Abstract

The invention discloses a digital demodulation method for all even harmonics of a magnetic modulator based on full phase analysis, and relates to the field of electrical technology. The digital demodulation method for all even harmonics of a magnetic modulator based on full phase analysis obtains the standard voltage timing data output by the magnetic modulator when a DC calibration current of a set value is passed into the magnetic modulator during calibration of the magnetic modulator, establishes an output voltage sequence of full phase Fourier analysis based on the standard voltage timing data, and performs preprocessing, performs comprehensive analysis on the preprocessed output voltage sequence of the full phase Fourier analysis, and obtains each standard even harmonic signal and current conversion coefficient. The invention uses the full phase Fourier analysis technology to perform comprehensive preprocessing and comprehensive analysis on the output voltage signal of the magnetic modulator, significantly reducing the spectrum leakage and phase disorder problems, thereby ensuring that the data sampled at different time points can be fully utilized, making the signal processing more accurate.

Description

Technical Field

[0001] The invention relates to the field of electrical technology, in particular to a full-phase analysis-based full-even harmonic digital demodulation method for a magnetic modulator. Background Art

[0002] As voltage levels continue to increase, faults caused by insulation defects in high-voltage DC equipment are becoming increasingly prominent, seriously restricting the safe and stable operation of DC transmission systems. However, the progress of online monitoring technology for the insulation status of high-voltage DC equipment is relatively slow. The main reason is that the leakage current of high-voltage DC equipment is relatively extreme. The most critical DC leakage current amplitude is extremely small. Under normal insulation conditions, it is only 10μA. The existing non-contact current sensing technology cannot meet the demand.

[0003] At present, non-contact DC sensing technologies mainly include Hall current sensors, magnetoresistive current sensors and magnetic modulation current sensors. Among them, magnetic modulators have the advantages of high resolution, high sensitivity, high precision, small temperature drift, stable working characteristics, etc., which are more in line with the application requirements of 10μA DC current measurement.

[0004] However, existing magnetic modulators usually only achieve non-contact measurement of DC currents at the hundreds of μA level. In terms of demodulation, the main reasons that limit the further improvement of its measurement accuracy are: even if the magnetic modulator adopts a dual-core differential sensing structure, due to the inconsistency of the magnetic properties of the two cores, there is still a problem that the odd harmonic components of the output voltage are much larger than the even harmonics, and the spectrum leakage problem of the odd harmonic components will affect the monitoring accuracy of the even harmonics; secondly, due to the asymmetry of the hysteresis loop of the core material itself, the magnetic modulator generally has μA-level zero-point bias noise, which will inevitably seriously affect the measurement accuracy of 10μA-level DC signals. Therefore, a high-precision digital demodulation method for magnetic modulators is urgently needed to reduce the influence of odd harmonic spectrum leakage and zero-point bias noise of magnetic modulators, laying a foundation for further improving measurement accuracy. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a full even-order harmonic digital demodulation method for a magnetic modulator based on full-phase analysis, which solves the problem that even if the magnetic modulator adopts a dual-core differential sensing structure, due to the inconsistency of the magnetic properties of the two cores, the odd-order harmonic components of the output voltage are still much larger than the even-order harmonics, and the spectrum leakage problem of the odd-order harmonic components will affect the monitoring accuracy of the even harmonics; secondly, due to the asymmetry of the hysteresis loop of the core material itself, the magnetic modulator generally has μA-level zero-point bias noise, which will inevitably seriously affect the measurement accuracy of the 10μA-level DC signal.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: a method for digital demodulation of full even harmonics of a magnetic modulator based on full phase analysis, comprising the following steps: obtaining standard voltage timing data output by the magnetic modulator when a DC calibration current of a set value is passed into the magnetic modulator during calibration of the magnetic modulator, wherein the standard voltage timing data includes standard output voltage signal values ​​at several time points, specifically, converting the output voltage analog signal of the magnetic modulator into a digital signal by using a digital acquisition device; establishing an output voltage sequence of full phase Fourier analysis based on the standard voltage timing data, and performing preprocessing; synthesizing the output voltage sequence of the preprocessed full phase Fourier analysis The method comprises the following steps: performing comprehensive analysis to obtain each standard even harmonic signal and current conversion coefficient; obtaining the time series data of the weak voltage to be measured output by the magnetic modulator when the weak DC signal current to be measured is passed into the magnetic modulator after the magnetic modulator is calibrated, and performing comprehensive analysis to obtain each weak even harmonic signal to be measured, wherein the weak voltage time series data to be measured includes the values ​​of the weak output voltage signal to be measured at several time points, specifically, using a digital acquisition device to convert the output voltage analog signal of the magnetic modulator into a digital signal; performing comprehensive analysis on each weak even harmonic signal to be measured and the current conversion coefficient to obtain a full even harmonic detection signal; and analyzing the measured value of the weak DC signal current to be measured based on the full even harmonic detection signal.

[0007] Furthermore, the specific steps of establishing the output voltage sequence of the full-phase Fourier analysis are as follows: 2N are selected from the standard output voltage data of the magnetic modulator after preprocessing. a The standard output voltage signal value at -1 time point establishes the output voltage sequence of the full-phase Fourier analysis; wherein, the expression of the output voltage sequence of the full-phase Fourier analysis is as follows:

[0008] U d =[u d (0),u d (1),…,u d (2N a -1)] T Among them, U d The input of the full phase Fourier analysis

[0009] Output voltage sequence, u d (0) is the standard output voltage signal value at the first time point of the output voltage sequence analyzed by full-phase Fourier analysis, u d (1) is the standard output voltage signal value at the second time point of the output voltage sequence of the full-phase Fourier analysis, u d (2N a -1) is the standard output voltage signal value at the last time point of the output voltage sequence of the full-phase Fourier analysis.

[0010] Furthermore, the specific steps for preprocessing the output voltage sequence of the full-phase Fourier analysis are as follows: establishing a Hamming window function sequence and performing convolution analysis to obtain a convolution window sequence; performing a comprehensive analysis on the output voltage sequence of the full-phase Fourier analysis and the convolution window sequence to obtain a sequence after full-phase preprocessing.

[0011] Furthermore, the specific steps to obtain the convolution window sequence are as follows: establish a length of N a The Hamming window function sequence is convolved with itself to obtain 2N a -1D convolution window sequence, the specific formula is as follows:

[0012] Furthermore, the specific steps of obtaining the sequence after full phase preprocessing are as follows: multiply the output voltage sequence and the convolution window sequence item by item to obtain a new data sequence, and add the kth item of the new data sequence to the Nth item. s +k items are added in sequence to obtain the sequence after full phase preprocessing;

[0014] Furthermore, the specific steps of obtaining each standard even harmonic signal are as follows: Fourier analysis is performed on the sequence after full phase preprocessing to obtain the full harmonic characteristics of the standard output voltage signal, and the full harmonic characteristics of the standard even harmonic signal are analyzed based on this; wherein, the full harmonic characteristics of the standard output voltage signal are as follows:

[0015] Furthermore, the phasor expressions of the even harmonic signals are as follows:

[0016] Furthermore, the current conversion coefficient is obtained by analyzing each standard even harmonic signal and the DC calibration current, and its specific formula is as follows:

[0017] Furthermore, the expression of the full even harmonic detection signal is as follows:

[0018] Furthermore, the specific formula for analyzing the measured value of the weak DC signal current to be measured is as follows:

[0019] The present invention has the following beneficial effects:

[0020] (1) The full-phase analysis-based magnetic modulator full even-order harmonic digital demodulation method uses full-phase Fourier analysis technology to perform comprehensive preprocessing and comprehensive analysis on the output voltage signal of the magnetic modulator, significantly reducing the spectrum leakage and phase disorder problems, thereby ensuring that the data sampled at different time points can be fully utilized, making signal processing more accurate, especially by using the Hamming window function and the convolution window sequence for preprocessing, so that the sudden changes in the signal boundary are effectively smoothed, greatly reducing the influence of the edge effect on the spectrum analysis, thereby improving the accuracy and reliability of the measurement results.

[0021] (2) The digital demodulation method of the magnetic modulator full even harmonics based on full phase analysis utilizes the uniformity of the phase of the actual even harmonics caused by the DC calibration current and the dispersion of the zero-point bias noise phase of each even harmonic. By calculating the current conversion coefficient and converting the detection signal of each even harmonic, the influence of the zero-point bias noise is effectively suppressed. In this way, the measurement sensitivity and accuracy can be significantly improved, especially in weak signal detection, such as 10μA level DC signal measurement. This improvement is of great significance for high-precision measurement equipment, especially for application in high-voltage DC transmission systems.

[0022] (3) The full-phase analysis-based digital demodulation method for the magnetic modulator full-even harmonics can effectively extract the useful components in the weak signal by comprehensively analyzing the full-even harmonic detection signal and utilizing the accurate calculation of the current conversion coefficient, thereby avoiding the measurement error caused by insufficient sensitivity of the equipment. In particular, by analyzing the full-phase harmonic characteristics of the weak DC signal current to be measured, the change of the weak signal can be accurately captured in a high noise environment. This high-sensitivity measurement capability plays an important role in accurately monitoring and evaluating the operating status of equipment in modern power systems, and can timely discover and warn of potential faults.

[0023] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a flow chart of a method for digital demodulation of all even-order harmonics of a magnetic modulator based on full phase analysis.

[0025] Figure 2 The present invention is a flow chart of an embodiment of a method for digital demodulation of all even-order harmonics of a magnetic modulator based on full phase analysis. DETAILED DESCRIPTION

[0026] The embodiment of the present application solves the problem that even if the magnetic modulator adopts a dual-core differential sensing structure, due to the inconsistency of the magnetic properties of the two cores, the odd-order harmonic components of the output voltage are still much larger than the even-order harmonics, and the spectrum leakage problem of the odd-order harmonic components will affect the monitoring accuracy of the even harmonics; secondly, due to the asymmetry of the hysteresis loop of the core material itself, the magnetic modulator generally has μA-level zero-point bias noise, which will inevitably seriously affect the measurement accuracy of 10μA-level DC signals.

[0027] The overall idea of ​​the problem in the embodiment of this application is as follows:

[0028] A DC calibration current of a set value is passed through the magnetic modulator to obtain the standard voltage timing data output by the magnetic modulator. The output voltage analog signal is converted into a digital signal using a digital acquisition device to obtain the standard output voltage signal value. The establishment and preprocessing of the full-phase Fourier analysis: Based on the standard voltage timing data, the output voltage sequence of the full-phase Fourier analysis is established, and the output voltage sequence is preprocessed, including establishing a Hamming window function sequence and performing convolution analysis to obtain a convolution window sequence. The output voltage sequence and the convolution window sequence are comprehensively analyzed to obtain a sequence after full-phase preprocessing. Fourier analysis and current conversion coefficient calculation: After full-phase preprocessing The sequence is subjected to Fourier analysis to obtain each standard even-order harmonic signal, and the current conversion coefficient between each standard even-order harmonic signal and the DC calibration current is calculated. The acquisition and analysis of the signal to be measured: the weak DC signal current to be measured is passed into the magnetic modulator to obtain the timing data of the weak voltage to be measured, and the output voltage analog signal is converted into a digital signal using a digital acquisition device to obtain the value of the weak output voltage signal to be measured. The full even-order harmonic detection signal and the current to be measured are calculated: the weak even-order harmonic signal to be measured and the current conversion coefficient are comprehensively analyzed to obtain the full even-order harmonic detection signal, and the measurement value of the weak DC signal current to be measured is calculated based on the full even-order harmonic detection signal.

[0029] See also Figure 1 The embodiment of the present invention provides a technical solution: a method for digital demodulation of all even harmonics of a magnetic modulator based on full-phase analysis, comprising the following steps: obtaining standard voltage timing data output by the magnetic modulator when a DC calibration current of a set value is passed into the magnetic modulator during calibration of the magnetic modulator, wherein the standard voltage timing data includes standard output voltage signal values ​​at several time points, specifically, converting the output voltage analog signal of the magnetic modulator into a digital signal by using a digital acquisition device; establishing an output voltage sequence of full-phase Fourier analysis based on the standard voltage timing data, and performing preprocessing; performing comprehensive analysis on the output voltage sequence of the preprocessed full-phase Fourier analysis to obtain standard even harmonic signals and current conversion coefficients of each order; obtaining the standard voltage timing data after calibration of the magnetic modulator; and obtaining the standard voltage timing data after calibration of the magnetic modulator. When a weak DC signal current to be measured is passed into the magnetic modulator, the weak voltage time series data to be measured output by the magnetic modulator is obtained and comprehensively analyzed, including: an establishment step of an output voltage sequence of full-phase Fourier analysis, a preprocessing step, and a comprehensive analysis step of the output voltage sequence of the preprocessed full-phase Fourier analysis; each weak even-order harmonic signal to be measured is obtained, and the weak voltage time series data to be measured includes the weak output voltage signal values ​​to be measured at several time points, specifically, the output voltage analog signal of the magnetic modulator is converted into a digital signal by using a digital acquisition device; each weak even-order harmonic signal to be measured and the current conversion coefficient are comprehensively analyzed to obtain a full even-order harmonic detection signal; and the measured value of the weak DC signal current to be measured is analyzed based on the full even-order harmonic detection signal.

[0030] Specifically, the specific steps for establishing the output voltage sequence of the full-phase Fourier analysis are as follows: select 2N from the standard output voltage data of the magnetic modulator after preprocessing a The output voltage sequence of the full-phase Fourier analysis is established by using the standard output voltage signal value at -1 time point; wherein the expression of the output voltage sequence of the full-phase Fourier analysis is as follows: d =[u d (0),u d (1),…,u d (2N a -1)] T Among them, U d is the output voltage sequence of the full-phase Fourier analysis, u d (0) is the standard output voltage signal value at the first time point of the output voltage sequence analyzed by full-phase Fourier analysis, u d (1) is the standard output voltage signal value at the second time point of the output voltage sequence of the full-phase Fourier analysis, u d (2N a -1) is the standard output voltage signal value at the last time point of the output voltage sequence of the full-phase Fourier analysis.

[0031] In this implementation, establishing an output voltage sequence of full-phase Fourier analysis can greatly improve the accuracy of spectrum analysis. By selecting preprocessed voltage signal data and performing full-phase Fourier analysis on it, spectrum leakage caused by signal edge effects can be reduced. Specifically, full-phase processing of the standard output voltage signal value ensures that the signal at each time point is fully utilized, thereby making the Fourier transform result more accurate, which is crucial for high-precision signal analysis and detection, especially when detecting weak signals, it can significantly improve the sensitivity and reliability of detection. By establishing an output voltage sequence of full-phase Fourier analysis, the robustness of signal processing can be enhanced. The full-phase Fourier analysis method takes into account the phase information of the signal at different time points, thereby making the entire signal processing process more resistant to noise and interference. This method has stronger resistance to interference. It can better capture the essential characteristics of the signal, especially in the presence of zero-point bias noise. Through comprehensive analysis and preprocessing, it can effectively suppress the influence of noise on signal measurement and improve the overall stability and reliability of the signal processing system. This method lays a solid foundation for subsequent harmonic analysis and current measurement. By establishing the output voltage sequence of full-phase Fourier analysis, it can more accurately extract each harmonic component, especially the even harmonic component. In the subsequent steps, through Fourier analysis and calculation of current conversion coefficients, the current value of the weak DC signal to be measured can be measured more accurately. The optimized signal processing process not only improves the measurement accuracy, but also simplifies the measurement steps, making the entire measurement process more efficient and reliable, and suitable for high-precision current detection applications.

[0032] Specifically, the specific steps for preprocessing the output voltage sequence of the full-phase Fourier analysis are as follows: establish a Hamming window function sequence and perform convolution analysis to obtain a convolution window sequence; perform a comprehensive analysis on the output voltage sequence of the full-phase Fourier analysis and the convolution window sequence to obtain a sequence after full-phase preprocessing.

[0033] In this implementation scheme, by establishing a Hamming window function and performing convolution analysis, the spectrum leakage problem in signal processing can be effectively reduced. The application of the Hamming window function can smooth the signal edges and reduce the spectrum leakage effect caused by window truncation. The convolution window sequence further enhances this effect, making the spectrum analysis result of the Fourier transform more accurate. This preprocessing method can ensure that the representation of the signal in the frequency domain is closer to the actual situation and reduce the error introduced by the boundary effect. Especially in high-precision measurement and analysis, this improvement significantly improves the reliability of the results. The preprocessing steps of the full-phase Fourier analysis, including the convolution analysis with the Hamming window, can enhance the robustness of the signal processing. The Hamming window function helps to reduce the high-frequency noise and boundary effects in the signal, making the processed signal smoother and easier to analyze. The sequence after full-phase preprocessing The key features of the signal are retained while suppressing noise and interference, making the subsequent Fourier analysis and harmonic extraction more accurate. This method is particularly suitable for precise signal measurement in a high-noise environment, which helps to improve the stability and reliability of the overall system. After preprocessing and convolution analysis of the Hamming window function, the output voltage sequence of the full-phase Fourier analysis is smoothed to eliminate many interference factors. Such preprocessing helps to optimize subsequent harmonic analysis and current measurement. The preprocessed signal is clearer and the harmonic components are easier to identify and analyze, so that the current conversion coefficient can be calculated more accurately and the even harmonic signals can be extracted. This not only improves the measurement accuracy, but also simplifies the signal processing process, making the entire measurement process more efficient and reliable, and is particularly suitable for high-precision current detection applications, such as the precise measurement of weak DC signals.

[0034] Specifically, the specific steps to obtain the convolution window sequence are as follows: establish a length of N a The Hamming window function sequence is convolved with itself to obtain 2N a -1D convolution window sequence, the specific formula is as follows:

[0035] In this implementation, the Hamming window function sequence can effectively reduce the spectrum leakage problem in Fourier transform through its special weighting method. The convolution window sequence further smoothes the signal, which greatly reduces the impact of edge effects on the spectrum. This smoothing process ensures that the signal representation in the frequency domain is more realistic and accurate, and reduces the false frequency phenomenon caused by signal truncation, which is very critical for application scenarios that require high-precision spectrum analysis, such as precision current measurement and signal processing. The convolution window sequence further improves the robustness of signal processing through convolution operation with the Hamming window function sequence. This processing method can suppress high-frequency noise and edge effects in the signal, making the processed signal smoother and more stable. Full-phase Fourier analysis combined with convolution The convolution window sequence can more effectively capture the essential characteristics of the signal, especially in an environment with noise and interference, improve the anti-interference ability of signal processing, and thus improve the overall stability and reliability of the system. By preprocessing the output voltage sequence of the full-phase Fourier analysis and using the convolution window sequence, the harmonic components in the signal can be more accurately extracted. The application of the convolution window sequence makes the harmonic characteristics of the signal clearer and easier to analyze, so that the current conversion coefficient can be calculated more accurately and the even harmonic signals can be extracted. This optimization processing not only improves the measurement accuracy, but also simplifies the signal processing process, making the entire measurement process more efficient and reliable. It is particularly suitable for accurate measurement of weak DC signals and high-precision current detection.

[0036] Specifically, the specific steps of obtaining the sequence after full phase preprocessing are as follows: multiply the output voltage sequence and the convolution window sequence item by item to obtain a new data sequence, and add the kth item of the new data sequence to the Nth item. s +k items are added in sequence to obtain the sequence after full phase preprocessing;

[0037] In this implementation, by multiplying the output voltage sequence with the convolution window sequence item by item, the frequency and time domain characteristics of the signal can be effectively fused, and the spectrum leakage caused by the edge effect can be reduced. This processing method ensures the accuracy of the Fourier transform result, because each data point in the signal has been smoothed, reducing the influence of high-frequency noise and other interference, thereby improving the accuracy and reliability of signal processing, which is crucial for high-precision current measurement and signal analysis, especially in application scenarios requiring high accuracy. The robustness of the signal can be effectively improved through the sequence after full-phase preprocessing. The item-by-item multiplication and addition processing method can ensure that each part of the signal is fully considered, making the processed signal smoother and more stable, which can better capture the essential characteristics of the signal and reduce noise and interference. The influence of the noise on the signal measurement can be significantly suppressed, especially in the presence of zero-point bias noise, thereby improving the overall stability and anti-interference ability of the system. The preprocessing steps of multiplying and adding the output voltage sequence and the convolution window sequence item by item can significantly optimize the subsequent harmonic analysis and current measurement. The sequence after full-phase preprocessing more clearly reflects the harmonic characteristics of the signal, so that the Fourier transform can more accurately extract the harmonic components of each order. This optimization processing not only improves the accuracy of harmonic analysis, but also simplifies the signal processing process, making the entire measurement process more efficient and reliable. It is particularly suitable for accurate measurement of weak DC signals and high-precision current detection. Through this preprocessing method, the current conversion coefficient can be calculated more accurately, thereby improving the sensitivity and accuracy of current measurement.

[0038] Specifically, the specific steps of obtaining each standard even harmonic signal are as follows: perform Fourier analysis on the sequence after full phase preprocessing to obtain the full harmonic characteristics of the standard output voltage signal, and use this to analyze each standard even harmonic signal; wherein, the full harmonic characteristics of the standard output voltage signal are as follows:

[0039] In this implementation, by performing Fourier analysis on the sequence after full-phase preprocessing, the frequency components of the signal, including the amplitude and phase of each harmonic, can be accurately extracted. This extraction method ensures that the subtle features of the signal at different frequencies can be captured, especially in complex signals with multiple harmonic components. Through this analysis method, each even harmonic signal can be accurately identified and separated, which helps to more deeply understand the frequency characteristics and dynamic changes of the signal, and improves the accuracy and reliability of spectrum analysis. The full-phase Fourier analysis method can significantly enhance the sensitivity of harmonic analysis. The signal sequence after full-phase preprocessing retains the complete phase information of the signal and reduces the influence of edge effects, so that Fourier analysis can more sensitively detect weak harmonics. This highly sensitive analysis is very important for detecting and analyzing harmonic features in weak DC signals, and helps to improve the accuracy of signal measurement, especially in the applications of low current measurement and high-precision signal analysis. By extracting the amplitude and phase of each standard even harmonic signal, the full harmonic characteristics of the signal can be more accurately described. This method can effectively suppress the influence of noise and interference on signal measurement, and ensure the stability and reliability of the measurement results. The full-phase Fourier analysis combined with the Hamming window preprocessing fully processes the edge effect of the signal, reduces spectrum leakage and phase disorder, and improves the accuracy of signal measurement. This processing method is particularly suitable for high-precision current detection and weak signal analysis, and can significantly improve the overall performance and reliability of the measurement system.

[0040] Specifically, the phasor expressions of the even harmonic signals are as follows:

[0041] In this implementation, by decomposing each even-order harmonic signal into a true even-order harmonic component and a zero-point bias noise component, the useful information and noise in the signal can be separated more accurately. The true even-order harmonic component represents the effective signal caused by the DC current, while the zero-point bias noise component represents the noise interference in the signal. Through this separation method, the influence of noise can be effectively suppressed in signal processing, thereby improving the accuracy and reliability of measurement, which is particularly important in weak signal detection and high-precision measurement. By analyzing the phasor of each even-order harmonic signal, the robustness and stability of signal processing can be enhanced. The phasor expression provides the amplitude and phase information of the signal, so that the signal can still be accurately captured in an environment with noise and interference. The true characteristics of the even harmonic components, the amplitude and phase uniformity of the true even harmonic components, and the phase dispersion of the zero-point bias noise can be more clearly reflected through the phasor expression, thereby effectively suppressing the interference of noise on signal processing and ensuring the stability and consistency of the signal processing process. The phasor expression of each even harmonic signal makes harmonic analysis and current measurement more accurate. By decomposing the true harmonic components and noise components in the signal, the harmonic characteristics can be more accurately extracted and analyzed, thereby calculating a more accurate current conversion coefficient. This method not only improves the accuracy of harmonic analysis, but also optimizes the current measurement process, so that in high-precision current detection applications, weak DC signals can be measured more accurately, improving the overall performance and reliability of the measurement system.

[0042] Specifically, the current conversion coefficient is obtained by analyzing each standard even harmonic signal and the DC calibration current, and its specific formula is as follows:

[0043] In this embodiment, the voltage signal of each harmonic can be converted into a corresponding current signal by calculating the current conversion coefficient. This conversion method ensures the accuracy of signal measurement, because the current conversion coefficient is calculated by the known calibration current and the measured harmonic signal. The calibration process eliminates the influence of equipment errors and environmental factors on the measurement results, thereby improving the accuracy of current measurement. This is particularly important in weak signal detection, because small errors may significantly affect the measurement results. By introducing the current conversion coefficient, the analysis process of complex signals can be simplified. After the current conversion, the harmonic signals can be more intuitively compared and analyzed, especially when multiple harmonic components coexist. The conversion coefficient is used to convert different frequency components. Signal normalization helps to more accurately identify and separate different harmonic components, simplifies the steps of signal processing and analysis, and improves the efficiency of signal processing. The calculation of the current conversion coefficient is based on the standard even harmonic signal and the DC calibration current, which ensures the robustness and stability of the measurement system. Through the calibration process, the nonlinearity and drift in the system can be compensated, making the measurement results more stable and reliable. The introduction of the current conversion coefficient can also provide a consistent conversion standard under different measurement conditions, reducing the impact of environmental changes on the measurement results, thereby improving the overall performance of the system. This is especially critical for high-precision current detection and long-term monitoring applications, because it ensures that the measurement system maintains high consistency and high reliability under various operating conditions.

[0044] Specifically, the expression of the full even harmonic detection signal is as follows:

[0046] In this implementation scheme, the contribution of even-order harmonic signals of different orders to the total signal can be comprehensively considered through the calculation method of the full even-order harmonic detection signal. Each even-order harmonic signal is normalized according to its current conversion coefficient, and then accumulated to obtain the full even-order harmonic detection signal. This can eliminate the amplitude difference between different frequency components and improve the accuracy and stability of signal detection. Especially in complex signal environments, it can more accurately identify and extract target signals and improve the sensitivity and reliability of measurement. Through the calculation of the full even-order harmonic detection signal, the influence of zero-point bias noise on signal detection can be significantly reduced. Zero-point bias noise usually affects the accuracy of measurement, especially in weak signal detection. By normalizing each even-order harmonic signal, the signal can be effectively detected. The processing and weighted accumulation can effectively suppress the interference of noise on the detection signal, thereby improving the robustness and anti-interference ability of the measurement system. This method ensures that even in a high noise environment, weak signals can be accurately detected. The calculation method of the full even harmonic detection signal can optimize the signal processing process and improve the measurement efficiency. The normalization and weighted accumulation of each even harmonic signal not only simplifies the signal processing steps, but also improves the speed and efficiency of data processing. The calculation results of the full even harmonic detection signal can be directly used for subsequent current measurement and signal analysis, reducing the complexity of the intermediate links. This optimization processing method not only improves the response speed of the system, but also ensures the rapid acquisition of high-precision measurement results. It is suitable for real-time monitoring and efficient measurement applications.

[0047] Specifically, the specific formula for analyzing the measured value of the weak DC signal current to be measured is as follows:

[0048] In this implementation scheme, by using the formula to calculate the measured value of the weak DC signal current to be measured, the accuracy and sensitivity of the weak signal measurement can be significantly improved. The absolute value of the full even harmonic detection signal reflects the intensity of the effective harmonic component in the signal. By normalizing and weighting it, the effective current component of the weak signal can be accurately extracted. This method is particularly suitable for detecting and measuring weak DC signals, and can ensure the accuracy of the measurement results in high-precision measurement applications. The formula can simplify the measurement process and improve the measurement efficiency by calculating the full even harmonic detection signal with the set current conversion coefficients of the highest even harmonic and the second even harmonic. The formula directly provides the conversion from the full even harmonic detection signal to the actual current measurement value. The simplified processing method avoids tedious intermediate steps and complex calculation processes. It can improve the response speed and measurement efficiency of the system and is suitable for real-time monitoring and efficient measurement scenarios. By normalizing the full even-order harmonic detection signal, the influence of noise and interference on the measurement results can be effectively suppressed, and the stability and reliability of the measurement system can be improved. Especially in a high-noise environment, the measurement value calculated by this formula can maintain high accuracy and consistency. The full even-order harmonic detection signal integrates the information of multiple harmonic components. The application of the normalized current conversion coefficient and the highest even-order harmonic can further improve the robustness and anti-interference ability of the measurement system and ensure the reliability of the measurement results under various conditions.

[0049] See also Figure 2 , a specific example of the full even harmonic digital demodulation method of the magnetic modulator based on full phase analysis is as follows:

[0050] Step 1: When measuring for the first time, pass a 10mA DC calibration current I into the magnetic modulator. ca ;

[0051] Step 2: Use digital acquisition equipment to convert the output voltage analog signal into a digital signal to obtain the time series data of the output voltage signal, and use 19999 time series data to construct the output voltage sequence U of the full-phase Fourier analysis. d ;

[0052] Step 3: Construct a Hamming window function sequence HW with a length of 10000, and calculate the convolution window sequence GW, and then convert the output voltage sequence U d and the convolution window sequence GW, and multiply the kth term by the Nth term. s +k items are added in sequence to obtain the sequence U after full phase preprocessing ap ;

[0053] Step 4: Sequence U ap Perform Fourier analysis to obtain the full harmonic characteristics of the output voltage signal, and calculate the even harmonic signals accordingly

[0055] Step 5: It is not difficult to see from the above formula that the zero-point bias noise of the magnetic modulator is about 100 μA level. ca It can be basically ignored, so the current conversion coefficient K of each even harmonic can be calculated at this time i :

[0057] Step 6: After calibration, a 0.1 mA weak DC signal current I is passed into the magnetic modulator. p , at this time, the detection signal of each even harmonic

[0059] At this point, it is not difficult to see from the above formula that the zero-point bias noise of the magnetic modulator will seriously affect the measurement accuracy of the 0.1mA weak DC signal.

[0060] Step 7: Based on the current conversion coefficient K i Convert even harmonic detection signals

[0062] Step 8: Detecting signals using the full even harmonics

[0064] The all-even harmonic digital demodulation method of the present invention can significantly weaken the influence of zero-point bias noise and further improve the measurement sensitivity and accuracy of the magnetic modulator.

[0065] In summary, this application has at least the following effects:

[0066] By using the full-phase Fourier analysis technology, the output voltage signal of the magnetic modulator is comprehensively preprocessed and comprehensively analyzed, which significantly reduces the spectrum leakage and phase disorder problems, thereby ensuring that the data sampled at different time points can be fully utilized, making the signal processing more accurate. In particular, by using the Hamming window function and the convolution window sequence for preprocessing, the sudden changes in the signal boundary are effectively smoothed, which greatly reduces the influence of the edge effect on the spectrum analysis, thereby improving the accuracy and reliability of the measurement results.

[0067] By utilizing the uniformity of the phase of the actual even-order harmonics caused by the DC calibration current and the dispersion of the zero-point bias noise phase of each even-order harmonic, the influence of the zero-point bias noise is effectively suppressed by calculating the current conversion coefficient and converting the detection signal of each even-order harmonic. In this way, especially in weak signal detection, such as 10μA-level DC signal measurement, the measurement sensitivity and accuracy can be significantly improved. This improvement is of great significance for high-precision measurement equipment, especially for its application in high-voltage DC transmission systems.

[0068] By comprehensively analyzing the full-even harmonic detection signals and using the accurate calculation of the current conversion coefficient, the useful components in the weak signal can be effectively extracted, avoiding the measurement error caused by insufficient equipment sensitivity. In particular, by analyzing the full-phase harmonic characteristics of the weak DC signal current to be measured, the changes in weak signals can still be accurately captured in a high-noise environment. This high-sensitivity measurement capability plays an important role in accurately monitoring and evaluating the operating status of equipment in modern power systems, and can promptly detect and warn of potential faults.

[0069] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0070] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for digital demodulation of all even harmonics of a magnetic modulator based on full phase analysis, characterized in that: The following steps are involved: Acquire standard voltage timing data output by the magnetic modulator when a DC calibration current of a set value is passed into the magnetic modulator during calibration of the magnetic modulator, wherein the standard voltage timing data includes standard output voltage signal values ​​at a plurality of time points; Based on the standard voltage timing data, the output voltage sequence of full-phase Fourier analysis is established and preprocessed; Comprehensively analyze the output voltage sequence of the pre-processed full-phase Fourier analysis to obtain the standard even harmonic signals and current conversion coefficients; Obtaining the time series data of the weak voltage to be measured output by the magnetic modulator when the weak DC signal current to be measured is passed into the magnetic modulator after the magnetic modulator is calibrated, and performing comprehensive analysis to obtain each weak even harmonic signal to be measured, wherein the time series data of the weak voltage to be measured includes the values ​​of the weak output voltage signal to be measured at several time points; Comprehensively analyze each weak even-order harmonic signal to be tested and the current conversion coefficient to obtain a full even-order harmonic detection signal; Analyze the measured value of the weak DC signal current to be measured based on the full even harmonic detection signal; The specific steps for preprocessing the output voltage sequence of full-phase Fourier analysis are as follows: Establish a Hamming window function sequence and perform convolution analysis to obtain a convolution window sequence; The output voltage sequence of the full-phase Fourier analysis is comprehensively analyzed with the convolution window sequence to obtain the full-phase preprocessed sequence.

2. The method for digital demodulation of magnetic modulator full even harmonics based on full phase analysis according to claim 1 is characterized in that: The specific steps to establish the output voltage sequence for full-phase Fourier analysis are as follows: Select from the standard output voltage data of the magnetic modulator after preprocessing The standard output voltage signal value at each time point establishes the output voltage sequence of full-phase Fourier analysis; Among them, the expression of the output voltage sequence of full-phase Fourier analysis is as follows: ; in, is the output voltage sequence of the full-phase Fourier analysis, is the standard output voltage signal value at the first time point of the output voltage sequence of the full-phase Fourier analysis, is the standard output voltage signal value at the second time point of the output voltage sequence of the full-phase Fourier analysis, It is the standard output voltage signal value at the last time point of the output voltage sequence of the full phase Fourier analysis.

3. The method for digital demodulation of magnetic modulator full even harmonics based on full phase analysis according to claim 1 is characterized in that: The specific steps to obtain the convolution window sequence are as follows: Create a length of The Hamming window function sequence is convolved with itself to obtain dimensional convolution window sequence, the specific formula is as follows: ; in, is the Hamming window function at index The value on is a natural constant, is the sample index within the Hamming window, and is the length of the Hamming window, is the convolution window sequence, is the Hamming window function sequence.

4. The method for digital demodulation of magnetic modulator full even harmonics based on full phase analysis according to claim 3 is characterized in that: The specific steps to obtain the sequence after all-phase preprocessing are as follows: Multiply the output voltage sequence and the convolution window sequence item by item to obtain a new data sequence, and convert the first Item and The items are added in sequence to obtain the sequence after full phase preprocessing; ; Among them, y is the new data sequence, is the output voltage sequence, is the convolution window sequence, is the sequence after full phase preprocessing, is the corresponding element in the new data sequence, where is the length of the Hamming window.

5. The method for digital demodulation of magnetic modulator full even harmonics based on full phase analysis according to claim 1 is characterized in that: The specific steps to obtain each standard even harmonic signal are as follows: Perform Fourier analysis on the sequence after full phase preprocessing to obtain the full harmonic characteristics of the standard output voltage signal, and use this to analyze the standard even harmonic signals of each order; Among them, the full harmonic characteristics of the standard output voltage signal are as follows: ; in, Respectively The amplitude and phase of the subharmonics, is the fundamental angular frequency of the square wave excitation source, is the total number of harmonics.

6. The method for digital demodulation of magnetic modulator full even harmonics based on full phase analysis according to claim 5, characterized in that: The phasor expressions of the even harmonic signals are as follows: ; in, are even harmonic signals, Respectively The amplitude and phase of the subharmonics, is the amplitude and phase of the real even harmonics caused by the DC current, is the zero-point bias noise of each even-order harmonic, is the total number of harmonics.

7. The method for digital demodulation of magnetic modulator full even harmonics based on full phase analysis according to claim 6 is characterized in that: The current conversion coefficient is obtained by analyzing each standard even harmonic signal and the DC calibration current. The specific formula is as follows: ; in, For the The current conversion factor of subharmonics, For the Even harmonic signals of subharmonics, is the DC calibration current, is the total number of harmonics.

8. The method for digital demodulation of magnetic modulator full even harmonics based on full phase analysis according to claim 7, characterized in that: The expression of the full even harmonic detection signal is as follows: ; in, is the full even harmonic detection signal, The highest even harmonic set in all even harmonic demodulation. It is the current conversion coefficient of the highest even harmonic set in full even harmonic demodulation. It is the weak even harmonic signal to be measured when it is the highest even harmonic set in full even harmonic demodulation.

9. The method for digital demodulation of magnetic modulator full even harmonics based on full phase analysis according to claim 8, characterized in that: The specific formula for analyzing the measured value of the weak DC signal current to be measured is as follows: ; in, is the measured value of the weak DC signal current to be measured, is the full even harmonic detection signal, This is the highest even harmonic set in all even harmonic demodulation.

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