Multi-fluxgate joint demodulation method based on time domain time-sharing orthogonality

Abstract

The invention discloses a multi-fluxgate joint demodulation method based on time-domain time-sharing orthogonality, and the method comprises the steps: dividing 2N fluxgate sensors into two groups according to odd and even numbers, and enabling the square wave excitation sources of the fluxgate sensors to have a quarter period phase difference; the excitation sources are triggered in pairs in sequence according to the time-sharing starting matrix; acquiring a multi-sensor mixed output voltage signal by using one path of acquisition equipment, and acquiring a reference square wave excitation signal by using the other path of acquisition equipment; and performing windowing FFT (Fast Fourier Transform) on the reference signal to construct a standard waveform, and performing time-sharing cross-correlation operation with the mixed signal by virtue of the waveform and the 90-degree phase shift plate thereof so as to demodulate direct-current measurement values of each fluxgate in the odd-numbered group and the even-numbered group. According to the invention, joint demodulation of a plurality of fluxgate sensors is realized, the number of high-precision analog-to-digital conversion equipment is significantly reduced, the system cost can be effectively reduced, the problem that the engineering application is restricted due to too high equipment cost in multi-channel DC leakage current monitoring is solved, and powerful support is provided for popularization of a high-voltage DC equipment insulation state on-line monitoring technology.

Description

Technical Field

[0001] This invention belongs to the field of electrical technology, and more specifically, relates to a multi-fluxgate joint demodulation method based on time-domain time-division orthogonality. Background Technology

[0002] With the continuous increase in voltage levels, faults caused by insulation defects in high-voltage direct current (HVDC) equipment are becoming increasingly prominent, seriously affecting the safe and stable operation of HVDC transmission systems. Currently, the development of online monitoring technology for the insulation status of HVDC equipment is still relatively slow, with the main bottleneck being the extremely weak leakage current signal—under normal insulation conditions, the DC leakage current is only at the 10 μA level, placing extremely high demands on the sensitivity and accuracy of measuring instruments.

[0003] Among existing non-contact DC sensors, fluxgate sensors, with their high resolution, high sensitivity, and stable operation, demonstrate excellent applicability for measuring weak DC currents in the 10 μA range, and accurate measurement of this level of current has been achieved in a laboratory environment. This type of high-performance fluxgate measurement method typically relies on high-precision analog-to-digital converters to convert analog output signals into digital signals, and then combines this with advanced signal processing techniques such as Fourier analysis to improve the detection accuracy of weak DC signals.

[0004] However, high-precision analog-to-digital converters (ADCs) are expensive, while in actual DC transmission projects, there are numerous high-voltage DC devices to be monitored, and leakage current branches are widely distributed. If each magnetic modulator is equipped with a separate high-precision ADC, the overall monitoring system cost will increase dramatically, resulting in poor economic efficiency. This severely restricts the large-scale application of magnetic modulators in engineering projects and hinders the promotion of online monitoring technology for the insulation status of high-voltage DC equipment.

[0005] Therefore, there is an urgent need to develop a multi-fluxgate joint demodulation method that can significantly reduce the number of analog-to-digital converters used by sharing signal acquisition and processing resources, thereby reducing the overall system cost and providing strong support for promoting the practical engineering application of online monitoring technology for the insulation status of high-voltage equipment. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a multi-fluxgate joint demodulation method based on time-domain time-division orthogonality, which aims to achieve efficient and coordinated acquisition and demodulation of output signals from multiple fluxgate sensors, significantly reduce the number of high-precision analog-to-digital converters required, and effectively solve the problems of high system cost and difficulty in engineering promotion caused by excessive configuration of analog-to-digital converter units.

[0007] To achieve the above objectives, the present invention provides a multi-fluxgate joint demodulation method based on time-domain time-division orthogonality, characterized by comprising the following steps: S1. Number the 2N fluxgate sensors sequentially as 1, 2, ..., 2N, and divide the 2N fluxgate sensors into odd-numbered groups and even-numbered groups according to the parity of the numbers; S2. The amplitude and fundamental frequency of the square wave excitation source of the odd-array and even-array fluxgates are both set to U. A with f std However, the square wave excitation source u of the even array fluxgates sq2 (t) Lag or lead the odd number u sq1 (t) is one-quarter of the excitation source cycle; S3. Set the square wave excitation sources of the 2N fluxgate sensors according to the time-division starting matrix T=[t1, t1+T] d , …, t1+(N-1) T d They are started in pairs sequentially, with each square wave excitation source lasting for a duration of T0. In the formula, T is the time-sharing startup matrix, t1 is the initial startup time, and T d This refers to the startup interval. S4. Acquire the mixed output voltage signal u of the 2N fluxgate sensors in real time using only one acquisition device. m (t), and use another acquisition device to acquire the square wave excitation source data u of fluxgate No. 1. sq (t); S5. The square wave excitation source data u sq (t) Perform windowed FFT analysis to obtain the fundamental frequency f std Amplitude U at the location sq.A With phase This is used to construct a standard cosine waveform u std (t); S6. Using the aforementioned standard cosine waveform u std (t) for the mixed output voltage signal u m (t) Perform time-division cross-correlation to obtain the measured values ​​I of all fluxgate gates in the odd array. No ; S7. The standard cosine waveform u std (t) After a 90° phase shift, it is then combined with the mixed output voltage signal u m (t) Perform time-division cross-correlation to obtain the measured values ​​I of all fluxgate gates in the even array. Ne .

[0008] Optionally, according to the method of claim 1, the square wave excitation source u in step S2 is characterized in that... sq2 (t) and u sq1 The lag or lead relationship of (t) is: In the formula, For even-array fluxgates, a square wave excitation source is used. As a square wave excitation source for odd-array fluxgate magnetometers, For time, This is the fundamental frequency.

[0009] Optionally, according to the method of claim 1, in step S3, one odd-numbered and one even-numbered fluxgate are started sequentially according to the time-sharing start matrix; the duration T0 is less than the start interval T. d .

[0010] Optionally, according to the method of claim 1, the mixed output voltage signal u in step S4 is characterized in that... m (t) represents the time-domain superposition of the output waveforms of 2N fluxgate sensors.

[0011] Optionally, according to the method of claim 1, the standard cosine waveform u in step S5 is characterized in that... std The expression for (t) is: In the formula, For standard cosine waveforms, For amplitude, For phase.

[0012] Optionally, according to the method of claim 1, the odd-numbered fluxgate measurement value I in step S6 is... No The calculation expression is: In the formula, For odd-numbered fluxgate magnetometer measurements, The coefficient for the first sampling period. for The standard cosine waveform below, for The mixed output voltage signal, the scaling factor It depends on the sensor calibration value.

[0013] Optionally, according to the method of claim 1, the even-array fluxgate measurement value I in step S7 is... Ne The calculation expression is: In the formula, For even-numbered fluxgate magnetometer measurements, The coefficient for the first sampling period. for Standard cosine waveform scaling factor It depends on the sensor calibration value.

[0014] Compared with the prior art, the above-described technical solutions conceived in this invention can achieve the following beneficial effects: 1. The present invention provides a multi-fluxgate joint demodulation method based on time-domain time-division orthogonality, which can realize the mixed acquisition and separate demodulation of the output signals of 2N fluxgate sensors with only two acquisition devices, greatly reducing the number of high-precision analog-to-digital conversion devices used, significantly reducing system costs, and promoting the large-scale application of multi-channel DC leakage current monitoring technology in practical engineering.

[0015] 2. The present invention provides a multi-fluxgate joint demodulation method based on time-domain time-division orthogonality. Through the design of odd-even grouping, time-division start and orthogonal reference signal demodulation, it effectively avoids mutual interference between multiple signals. While realizing single-channel mixed acquisition of multiple sensor signals, it ensures the accuracy and independence of the measurement results of each channel. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating a multi-fluxgate joint demodulation method based on time-domain time-division orthogonality provided in an embodiment of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention 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 merely illustrative and not intended to limit the invention.

[0018] This invention provides a multi-fluxgate joint demodulation method based on time-domain time-division orthogonality, which aims to achieve efficient and coordinated acquisition and demodulation of output signals from multiple fluxgate sensors, significantly reducing the number of high-precision analog-to-digital converters used, and effectively solving the problems of high system cost and difficulty in engineering promotion caused by too many analog-to-digital converter units.

[0019] To achieve the above objectives, the following steps are included: S1. Number the 2N fluxgate sensors sequentially as 1, 2, ..., 2N, and divide the 2N fluxgate sensors into odd and even groups according to the parity of the numbers; S2. The amplitude and fundamental frequency of the square wave excitation source for both the odd-array and even-array fluxgates are set to U. A with f std However, the square wave excitation source u of the even array fluxgates sq2 (t) Lagging or leading odd number u sq1 (t) is one-quarter of the excitation source cycle; S3. Set the square wave excitation sources of 2N fluxgate sensors according to the time-division starting matrix T=[t1, t1+T] d , …, t1+(N-1) T d They are started in pairs sequentially, with each square wave excitation source lasting for a duration of T0. S4. Use a single acquisition device to acquire the mixed output voltage signal u of 2N fluxgate sensors in real time. m (t), and use another acquisition device to acquire the square wave excitation source data u of fluxgate No. 1. sq (t); S5. Square wave excitation source data u sq (t) Perform windowed FFT analysis to obtain the fundamental frequency f std Amplitude U at the location sq.A With phase This is used to construct a standard cosine waveform u std (t); S6. Using the standard cosine waveform u std (t) for the mixed output voltage signal u m (t) Perform time-division cross-correlation to obtain the measured values ​​I of all fluxgate gates in the odd array. No ; S7. Convert the standard cosine waveform u std (t) After a 90° phase shift, it is then mixed with the output voltage signal u. m (t) Perform time-division cross-correlation to obtain the measured values ​​I of all fluxgate gates in the even array. Ne .

[0020] Optionally, the square wave excitation source u in step S2 sq2 (t) and u sq1 The lag or lead relationship of (t) is: Optionally, in step S3, according to the time-sharing start matrix, one odd-array and one even-array fluxgate are started sequentially each time; the duration T0 is less than the start interval T. d .

[0021] Optionally, the mixed output voltage signal u in step S4 m (t) represents the time-domain superposition of the output waveforms of 2N fluxgate sensors.

[0022] Optionally, the standard cosine waveform u described in step S5 std The expression for (t) is: Optionally, the odd-array fluxgate measurement value I in step S6 No The calculation expression is: In the formula, the proportionality coefficient It depends on the sensor calibration value.

[0023] Optionally, the even-array fluxgate measurement value I in step S7 Ne The calculation expression is: In the formula, the proportionality coefficient It depends on the sensor calibration value.

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, such as... Figure 1 As shown, the specific steps for demodulating to obtain multiple current measurement values ​​are as follows: Step 1: Number the 10 fluxgate sensors sequentially as 1, 2, ..., 10, and divide the 10 fluxgate sensors into odd and even groups according to the parity of the numbers; Step 2: The amplitude and fundamental frequency of the square wave excitation source for both odd-array and even-array fluxgates are set to 10V and 100Hz, respectively, but the square wave excitation source u of the even-array fluxgates is... sq2 (t) Lag odd number u sq1 A quarter of the excitation source cycle of (t), that is: Step 3: Set all 10 fluxgate sensors to start in pairs according to the time-division start matrix T=[0, 2s, ..., 18s], and the duration of each square wave excitation source is 1s; Step 4: Use a single acquisition device to acquire the mixed output voltage signal u from 10 fluxgate sensors in real time. m (t), and use another acquisition device to acquire the square wave excitation source data u of fluxgate No. 1. sq (t); Step 5: Obtain square wave excitation source data u sq (t) Perform windowed FFT analysis to obtain the amplitude U at the fundamental frequency of 100Hz. sq.A With phase This is used to construct a standard cosine waveform u std (t); Step 6: Use the standard cosine waveform u std (t) for the mixed output voltage signal u m (t) Perform time-division cross-correlation to obtain the measured values ​​I of all fluxgate gates in the odd array. No ; In the formula, the proportionality coefficient It depends on the sensor calibration value.

[0025] S7. Convert the standard cosine waveform u std (t) After a 90° phase shift, it is then mixed with the output voltage signal u. m (t) Perform time-division cross-correlation to obtain the measured values ​​I of all fluxgate gates in the even array. Ne .

[0026] This invention provides a multi-fluxgate joint demodulation method based on time-domain time-division orthogonality, which aims to achieve efficient and coordinated acquisition and demodulation of output signals from multiple fluxgate sensors, significantly reducing the number of high-precision analog-to-digital converters used, and effectively solving the problems of high system cost and difficulty in engineering promotion caused by too many analog-to-digital converter units.

[0027] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A time-domain time-sharing orthogonal-based multi-fluxgate joint demodulation method, characterized in that, The method comprises the following steps: S1. numbering 2N fluxgate sensors as 1, 2, …, 2N in sequence, and dividing the 2N fluxgate sensors into an odd-numbered group and an even-numbered group according to the odd and even nature of the numbers; S2. The odd set and the even set of fluxgate square wave excitation source amplitude, fundamental frequency are set to U A and f std , but the even set of fluxgate square wave excitation source u sq2 (t) is a quarter of the excitation source period of the odd set u sq1 (t) lag or lead; S3. Set the square wave excitation source of the 2N fluxgate sensors to start in turn according to the time-sharing start matrix T=[t1, t1+T d , …, t1+(N-1)T d ] two by two, and the duration of each square wave excitation source is T0; where T is the time-sharing start matrix, t1 is the initial start time, T is the start interval time d ; S4. Real-time acquisition of the mixed output voltage signal u of the 2N fluxgate sensors with only one acquisition device m (t), acquisition of the square wave excitation source data u of the first fluxgate with another acquisition device sq (t); S5. Windowed FFT analysis of the square wave excitation source data u sq (t) to obtain the amplitude U std and phase sq.A at the fundamental frequency f , thus constructing the standard cosine waveform u std (t). S6. Utilizing the standard cosine waveform u std (t) to perform a time-division cross-correlation operation on the mixed output voltage signal u m (t) to obtain the measurement value I No of all the magnetic flux gates of the odd-numbered group; S7. The standard cosine waveform u std (t) is shifted by 90° and then time-division cross-correlated with the mixed output voltage signal u m (t) to obtain the measurement value I Ne of all the even-numbered fluxgates.

2. The method of claim 1, wherein, The square wave excitation source u in the step S2 sq2 (t) and u sq1 The lag or lead relationship of (t) and u wherein is an even square wave excitation source for a fluxgate, is an odd square wave excitation source for a fluxgate, is time, is the fundamental frequency.

3. The method of claim 1, wherein, The step S3 starts one odd group and one even group respectively according to the time-sharing starting matrix; the duration T0 is less than the starting interval time T d .

4. The method of claim 1, wherein, The mixed output voltage signal u in the step S4 m (t) is the time domain superposition value of the output waveforms of the 2N fluxgate sensors.

5. The method of claim 1, wherein, The standard cosine waveform u in the step S5 std (t) is given by the expression: wherein is a standard cosine waveform, is an amplitude, is a phase.

6. The method of claim 1, wherein, The step S6 said odd number of magnetic fluxgate measurement value I No The calculation expression is: wherein is the odd array fluxgate measurement, is the first sampling period coefficient, is the standard cosine waveform under is the mixed output voltage signal under the proportional coefficient depends on the sensor calibration value.

7. The method of claim 1, wherein, The step S7 said even number of fluxgate measurement value I Ne The calculation expression is: wherein is the even magnetic flux gate measurement value, is the first sampling period coefficient, is the is the standard cosine waveform under the ratio coefficient depends on the sensor calibration value.

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