Fault positioning system and method based on fiber grating current sensor

Abstract

The invention discloses a fault positioning system and method based on a fiber bragg grating current sensor. The system comprises a fiber bragg grating sensor module, a signal acquisition module, a signal processing module, a fault positioning analysis module and an interaction terminal module. The fiber grating sensor module is used for measuring a magnetic field change signal generated by the current; the signal acquisition module is used for receiving the magnetic field change signal output by the fiber grating sensor module; the signal processing module is used for analyzing the magnetic field change signal to identify fault features; the fault positioning analysis module is used for determining a fault position according to the fault characteristics; and the interaction terminal module is used for displaying the fault position determined by the fault positioning analysis module. According to the method, the fault positioning and reclosing operation can be quickly and consistently executed when the fault occurs, the fault detection and positioning speed of the mixed frame line can be improved, and the result output time is shortened, so that the contradictory problem of the reclosing strategy is solved, and the reliability and the safety of a power system are improved.

Description

Technical Field

[0001] The invention relates to the technical field of power system engineering, and in particular to a fault location system and method based on a fiber grating current sensor. Background Art

[0002] In response to the problem of contradictory reclosing strategies after a mixed-frame line fault, current research generally monitors electrical signals and then wirelessly sends data back to the background for analysis and processing. However, this method leads to a long result output time. For this reason, the present invention proposes a fault location system and method based on a fiber grating current sensor, which can quickly identify and locate faults after data collection by developing an efficient real-time signal processing algorithm. Summary of the invention

[0003] In view of the deficiencies of the prior art, the present invention provides a fault location system and method based on a fiber grating current sensor, which solves the problem in the background technology that after monitoring electrical signals, the data is wirelessly sent back to the background for analysis and processing, resulting in a long time for outputting results.

[0004] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0005] A fault location system based on a fiber Bragg grating current sensor, comprising a fiber Bragg grating sensor module, a signal acquisition module, a signal processing module, a fault location analysis module and an interactive terminal module;

[0006] The fiber grating sensor module is used to measure the magnetic field change signal generated by the current;

[0007] The signal acquisition module is used to receive the magnetic field change signal output by the fiber grating sensor module;

[0008] The signal processing module is used to analyze the magnetic field change signal to identify fault characteristics;

[0009] The fault location analysis module is used to determine the fault location according to the fault characteristics;

[0010] The interactive terminal module is used to display the fault location determined by the fault location analysis module.

[0011] A fault location method based on a fiber grating current sensor comprises the following steps:

[0012] S1: Initialization; deploying and setting the fiber grating sensor module on the hybrid line, and configuring the parameters and system of the fiber grating sensor module to measure the magnetic field change signal generated by the current;

[0013] S2: signal acquisition; the signal acquisition module acquires magnetic field change signals from the fiber grating sensor module;

[0014] S3: signal processing; the signal processing module processes the magnetic field change signal collected by the signal acquisition module, including amplification, filtering and feature extraction, so as to identify the fault characteristics;

[0015] S4: Fault location analysis; the fault location analysis module performs fault analysis based on the fault features identified by the signal processing module to determine the fault location;

[0016] S5: Result output; displaying the fault information and fault location through the user interface of the interactive terminal module.

[0017] Furthermore, when the magnetic field change signal generated by the current in S1, the relationship between the magnetic field and the current is:

[0018]

[0019] in:

[0020] B is the magnetic field strength, μ0 is the vacuum permeability, I is the current, and r is the distance from the current source to the sensor.

[0021] Furthermore, the fiber grating sensor response calculation formula in S2 is: Where Δλ is the wavelength change, λ0 is the original wavelength, n is the refractive index, and Δn is the refractive index change; the wavelength change obtained by the fiber grating sensor is amplified by the signal acquisition module, and the calculation method is: V out =G·V in ; where V out is the output voltage, G is the gain, V in is the input voltage.

[0022] Furthermore, the fiber grating sensor response calculation formula in S2 is: Where Δλ is the wavelength change, λ0 is the original wavelength, n is the refractive index, and Δn is the refractive index change; the wavelength change obtained by the fiber grating sensor is amplified by the signal acquisition module, and the calculation method is: V out =G·V in ; where V out is the output voltage, G is the gain, V in is the input voltage.

[0023] Furthermore, the normalized wavelength value method is:

[0024] Measuring the Bragg wavelength λ of a fiber Bragg grating in a reference state without strain or temperature change Bragg ;

[0025] Within the expected use range of the sensor, the minimum wavelength λ is measured respectively min and maximum wavelength λ max ; Calculate the normalized wavelength value λ by the formula ref ;

[0026] Input to the system: Input the calculated normalized wavelength value into the configuration program of the fiber Bragg grating interrogator as the reference wavelength of the sensor; the calculated normalized wavelength value λ ref The calculation formula is:

[0027]

[0028] Among them, λ Bragg is the Bragg wavelength of the fiber Bragg grating, λ min is the wavelength value of the sensor at maximum strain or maximum temperature, λ max is the wavelength value of the sensor at the minimum strain or lowest temperature.

[0029] Furthermore, the feature extraction method in S3 is:

[0030] Extract time domain features, including signal amplitude, signal energy, and zero-crossing rate; use Fourier transform method to extract frequency domain features, including frequency and phase; use wavelet transform method to extract time-frequency features;

[0031] The signal amplitude formula is A=max(|x(t)|); the signal energy formula is The zero-crossing rate calculation formula is: Where sgn is the sign function, T is the sampling period, and N is the number of sampling points.

[0032] Furthermore, after the feature extraction, feature statistics are performed, and principal component analysis is performed, including covariance matrix and eigenvalue problems. The covariance matrix calculation formula is: The calculation formula for the eigenvalue problem is: Σv i =λ i v i ; where v i is the eigenvector, λ i is the corresponding eigenvalue.

[0033] Furthermore, in S4, the fault location is estimated by measuring the signal strength at different locations according to the attenuation characteristics of the signal, and the formula is: Where P l oss is the path loss, n is the path loss exponent, P r ef is the signal strength at the reference point, P meas is the signal strength at the measurement point.

[0034] The present invention provides a fault location system and method based on a fiber grating current sensor, which has the following beneficial effects: it can ensure that fault location and reclosing operations can be performed quickly and consistently when a fault occurs. This method can improve the speed of mixed-frame line fault detection and location, reduce the result output time, thereby resolving the contradiction problem of the reclosing strategy and improving the reliability and safety of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram of a module of a fault location system based on a fiber Bragg grating current sensor according to the present invention;

[0036] Figure 2 A schematic diagram of a fault location method based on fiber grating current sensor. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] See also Figure 1 ,The embodiment of the present invention provides a technical solution: a fault location system based on a fiber Bragg grating current sensor, comprising a fiber Bragg grating sensor module, a signal acquisition module, a signal processing module, a fault location analysis module and an interactive terminal module;

[0039] The fiber grating sensor module is used to measure the magnetic field change signal generated by the current;

[0040] The signal acquisition module is used to receive the magnetic field change signal output by the fiber grating sensor module;

[0041] The signal processing module is used to analyze the magnetic field change signal to identify fault characteristics;

[0042] The fault location analysis module is used to determine the fault location according to the fault characteristics;

[0043] The interactive terminal module is used to display the fault location determined by the fault location analysis module.

[0044] See also Figure 2 The embodiment of the present invention also provides a fault location method based on a fiber Bragg grating current sensor, comprising the following steps:

[0045] S1: Initialization; deploying and setting the fiber grating sensor module on the hybrid line, and configuring the parameters and system of the fiber grating sensor module to measure the magnetic field change signal generated by the current;

[0046] S2: signal acquisition; the signal acquisition module acquires magnetic field change signals from the fiber grating sensor module;

[0047] S3: signal processing; the signal processing module processes the magnetic field change signal collected by the signal acquisition module, including amplification, filtering and feature extraction, so as to identify the fault characteristics;

[0048] S4: Fault location analysis; the fault location analysis module performs fault analysis based on the fault features identified by the signal processing module to determine the fault location.

[0049] S5: Result output; displaying the fault information and fault location through the user interface of the interactive terminal module.

[0050] The relationship between the magnetic field and current in S1 is: Where B is the magnetic field strength, μ0

[0051] is the magnetic permeability of vacuum, I is the current, and r is the distance from the current source to the sensor.

[0052] The calculation formula of the fiber Bragg grating sensor response in S2 is: Where Δλ is the wavelength change, λ0 is the original wavelength, n is the refractive index, and Δn is the refractive index change; the wavelength change obtained by the fiber Bragg grating sensor is amplified by the signal acquisition module and the calculation method is: V out =G·V in ; where V out is the output voltage, G is the gain, V in is the input voltage.

[0053] The sensor parameters in S1 are configured by starting the JEMETech fiber Bragg grating demodulation configuration program, including spectrum setting, sensor type selection, and sensor parameter input. The sensor parameter input includes normalized wavelength value, minimum wavelength value, and maximum wavelength value, and the sensor calibration coefficient is set according to the calibration report; ensure that the number of peaks in each channel is consistent with the number of sensors under test, and adjust the optical power threshold to avoid invalid values ​​caused by wavelength value overlap.

[0054] The normalized wavelength value method is to measure the Bragg wavelength λ of the fiber Bragg grating under the reference state without strain or temperature change. Bragg ; Within the expected use range of the sensor, measure the minimum wavelength λ min and maximum wavelength λ max ; Calculate the normalized wavelength value λ by the formula ref; Input to the system: Input the calculated normalized wavelength value into the configuration program of the fiber Bragg grating demodulator as the reference wavelength of the sensor; where the calculated normalized wavelength value λ ref The calculation formula is:

[0055]

[0056] Among them, λ Bragg is the Bragg wavelength of the fiber Bragg grating, λ min is the wavelength value of the sensor at maximum strain or maximum temperature, λ max is the wavelength value of the sensor at the minimum strain or lowest temperature.

[0057] The parameters of the fiber Bragg grating temperature sensor in this embodiment are as follows:

[0058] λ Bragg =1550nm (wavelength at reference temperature); λ min =1545nm (wavelength at the highest temperature); λ max =1555nm (wavelength at the lowest temperature); then the normalized wavelength value λ ref The calculation is as follows: In the reference state, the wavelength value of the sensor is relative to 25% of its entire measuring range.

[0059] The feature extraction method in S3 is:

[0060] Extract time domain features, including signal amplitude, signal energy, and zero-crossing rate (number of times the waveform crosses zero); use Fourier transform and other methods to extract frequency domain features, including frequency and phase; use wavelet transform and other methods to extract time-frequency features to capture the characteristics of non-stationary signals; determine the features most relevant to the fault type and location, and use principal component analysis (PCA) to reduce feature dimensions and improve algorithm efficiency;

[0061] The signal amplitude formula is A=max(|x(t)|); the signal energy formula is The formula for calculating the zero-crossing rate is: Where sgn is the sign function, T is the sampling period, and N is the number of sampling points;

[0062] The Fourier transform formula is The wavelet transform formula is Where ψ is the wavelet function, s and t are the scale and time parameters of the wavelet transform respectively;

[0063] After feature extraction, statistical feature extraction is performed, and principal component analysis is performed, including covariance matrix and eigenvalue problems. The covariance matrix calculation formula is: The calculation formula for the eigenvalue problem is: Σv i=λ i v i where v i is the eigenvector, λ i is the corresponding eigenvalue.

[0064] In S4, the fault location is estimated by measuring the signal strength at different locations according to the attenuation characteristics of the signal. The formula is: Where P l oss is the path loss, n is the path loss exponent, P r ef is the signal strength at the reference point, P meas is the signal strength at the measurement point.

[0065] In this embodiment, the propagation time of the signal between the fault point and the monitoring point is known, and the signal propagation speed is the speed of light c≈3×10 8 m / s; if the detected arrival time difference of the fault signal at the two monitoring points is Δt=t2-t1, the distance d between the fault point and the reference monitoring point is calculated by the above delay estimation formula.

[0066] The above method can ensure that fault location and reclosing operations can be performed quickly and consistently when a fault occurs. This method can improve the speed of mixed-rack line fault detection and location, reduce the result output time, thereby solving the contradiction problem of reclosing strategy and improving the reliability and safety of the power system.

[0067] Table 1: Sensor parameter configuration table

[0068] Bragg wavelength (nm) Maximum wavelength (nm) Minimum wavelength (nm) Normalized wavelength value Calibration coefficient 1550 1545 1555 0.25 1.05 1550 1547 1553 0.30 1.07

[0069] The Bragg wavelength of all sensors was set at 1550nm, which indicates that the sensors are consistent in design. The normalized wavelength values ​​varied between 0.25 and 0.30, which may reflect differences in sensor response under different operating conditions. The calibration coefficients ranged from 1.05 to 1.07, which indicates that the sensors may need fine-tuning to ensure accuracy in actual applications.

[0070] Table 2: Signal acquisition data table

[0071] Sensor No. Signal Amplitude(V) Signal energy (J) Zero crossing rate (times / s) Sampling period(s) Number of sampling points 1 0.5 0.2 120 0.001 1000 2 0.6 0.25 130 0.001 1200

[0072] Table 3: Feature extraction results

[0073] Sensor No. Frequency (Hz) Phase (degrees) Time-frequency characteristics Principal component 1 Principal component 2 Principal component 3 1 50 30 - 0.7 0.2 0.1 2 55 35 - 0.65 0.25 0.1

[0074] The principal component analysis (PCA) results show that principal component 1 usually has the highest variance contribution.

[0075] Table 4: Fault location results table

[0076]

[0077] The measurement results of the fault position show that the fault can occur at different positions with high positioning accuracy, which proves the effectiveness of the present invention.

[0078] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0079] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A fault location system based on a fiber Bragg grating current sensor, characterized by: It includes fiber Bragg grating sensor module, signal acquisition module, signal processing module, fault location analysis module and interactive terminal module; The fiber grating sensor module is used to measure the magnetic field change signal generated by the current; The signal acquisition module is used to receive the magnetic field change signal output by the fiber grating sensor module; The signal processing module is used to analyze the magnetic field change signal to identify fault characteristics; The fault location analysis module is used to determine the fault location according to the fault characteristics; The interactive terminal module is used to display the fault location determined by the fault location analysis module.

2. A fault location method based on fiber Bragg grating current sensor, characterized in that: The steps include: S1: Initialization: Deploy and set up the fiber Bragg grating sensor module on the hybrid line, and configure the parameters and system of the fiber Bragg grating sensor module to measure the magnetic field change signal generated by the current; S2: Signal acquisition: The signal acquisition module collects magnetic field change signals from the fiber Bragg grating sensor module; S3: Signal processing: The signal processing module processes the magnetic field change signal collected by the signal acquisition module, including amplification, filtering and feature extraction, to identify fault characteristics; S4: Fault location analysis; the fault location analysis module performs fault analysis based on the fault features identified by the signal processing module to determine the fault location; S5: Result output; the fault information and fault location are displayed through the user interface of the interactive terminal module.

3. The fault location method based on fiber Bragg grating current sensor according to claim 2, characterized in that: When the magnetic field change signal is generated by the current in S1, the relationship between the magnetic field and the current is: in: B is the magnetic field strength, μ0 is the vacuum permeability, I is the current, and r is the distance from the current source to the sensor.

4. The fault location method based on a fiber Bragg grating current sensor according to claim 2, characterized in that: The calculation formula of the fiber Bragg grating sensor response in S2 is: Where Δλ is the wavelength change, λ0 is the original wavelength, n is the refractive index, and Δn is the refractive index change; the wavelength change obtained by the fiber Bragg grating sensor is amplified by the signal acquisition module and the calculation method is: V out =G·V in ; where V out is the output voltage, G is the amplification factor, V in is the input voltage.

5. The fault location method based on fiber Bragg grating current sensor according to claim 2, characterized in that: The parameters of the fiber Bragg grating sensor module in S1 are configured by starting the JEMETech fiber Bragg grating demodulation configuration program, including spectrum setting, sensor type selection, and sensor parameter input, wherein the sensor parameter input includes normalized wavelength value, minimum wavelength value, and maximum wavelength value.

6. The fault location method based on fiber Bragg grating current sensor according to claim 5, characterized in that: The normalized wavelength value method is: Measuring the Bragg wavelength λ of a fiber Bragg grating in a reference state without strain or temperature change Bragg ; Within the expected use range of the sensor, the minimum wavelength λ is measured respectively min and maximum wavelength λ max ; Calculate the normalized wavelength value λ by the formula ref ; Input to the system: Input the calculated normalized wavelength value into the configuration program of the fiber Bragg grating interrogator as the reference wavelength of the sensor; The normalized wavelength value λ is calculated ref The calculation formula is: Among them, λ Bragg is the Bragg wavelength of the fiber Bragg grating, λ min is the wavelength of the sensor at maximum strain or maximum temperature, λ max is the wavelength value of the sensor at the minimum strain or lowest temperature.

7. The fault location method based on fiber Bragg grating current sensor according to claim 5, characterized in that: The feature extraction method in S3 is: Extract time domain features, including signal amplitude, signal energy, and zero-crossing rate; use Fourier transform method to extract frequency domain features, including frequency and phase; use wavelet transform method to extract time-frequency features; The signal amplitude formula is A=max(|x(t)|); the signal energy formula is The zero-crossing rate calculation formula is: Where sgn is the sign function, T is the sampling period, and N is the number of sampling points.

8. The fault location method based on fiber Bragg grating current sensor according to claim 7, characterized in that: After the feature extraction, feature statistics are performed and principal component analysis is performed, including covariance matrix and eigenvalue problems. The covariance matrix calculation formula is: The calculation formula for the eigenvalue problem is: Σv i =λ i v i ; where v i is the eigenvector, λ i is the corresponding eigenvalue.

9. The fault location method based on fiber Bragg grating current sensor according to claim 2, characterized in that: In S4, the fault location is estimated by measuring the signal strength at different locations based on the attenuation characteristics of the signal. The formula is: Among them, P l oss is the path loss, n is the path loss exponent, P r ef is the signal strength at the reference point, P meas is the signal strength at the measurement point.

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