Icing galloping identification method and device for overhead transmission line

Abstract

The invention discloses an icing galloping identification method and device for an overhead transmission line, and belongs to the technical field of overhead transmission line non-contact measurement, and the method comprises the steps: obtaining the magnetic induction intensity of a magnetic field sensor right above a target cable in a direction perpendicular to the cable, and recognizing the icing galloping of a transmission line based on the frequency spectrum of the obtained magnetic induction intensity; and establishing an association relationship between the icing galloping of the power transmission conductor and a space magnetic field generated by the icing galloping on the basis of the Biot-Saval law, and performing fast Fourier decomposition on the obtained magnetic induction intensity to obtain a frequency spectrum of the magnetic induction intensity so as to identify the icing galloping of the power transmission conductor. According to the icing galloping identification method and device for the overhead transmission line, the tunneling magnetoresistance effect sensor placed at a specific position is used for obtaining the magnetic induction intensity and identifying conductor icing galloping according to the magnetic induction intensity, non-contact rapid identification of conductor icing galloping is achieved, and the method and device have the advantages of being timely in identification, high in accuracy and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of non-contact measurement of overhead transmission lines, and in particular to a method and device for identifying icing galloping of overhead transmission lines. Background Art

[0002] Traditional icing galloping of conductors mainly uses force sensors installed on the line. When icing galloping occurs, under the action of wind force, the tension on the line will change with the galloping, and this change can be captured by the mechanical sensor to achieve galloping identification. Since the force sensor needs to be directly connected to the target cable, there are certain drawbacks in installation and maintenance. In recent years, the method for predicting icing galloping of transmission lines represented by deep learning can achieve early warning before galloping occurs by analyzing multiple factors (including environmental factors and line factors), but this method requires a large amount of data to train the model, with high costs and poor adaptability.

[0003] The non-contact measurement technology of the spatial state of overhead transmission lines based on magnetic sensors overcomes the drawbacks of the above measurement methods, and has the advantages of flexible installation, easy maintenance, low cost, high reliability, etc., and is widely used in the field of wide-area measurement of power systems. Summary of the Invention

[0004] The purpose of the present invention is to provide a method and device for identifying icing galloping of overhead transmission lines, which uses tunneling magnetoresistance effect sensors placed at specific positions to obtain the magnetic induction intensity and thereby identify the icing galloping of conductors, achieving non-contact and rapid identification of conductor icing galloping, and having the advantages of timely and accurate identification.

[0005] To achieve the above purpose, the present invention provides a method for identifying icing galloping of overhead transmission lines, including the following steps:

[0006] S1. Obtain the magnetic induction intensity of the magnetic field sensor directly above the target cable in the direction perpendicular to the cable;

[0007] S2. Identify the occurrence of icing galloping of the transmission conductor based on the spectrum of the obtained magnetic induction intensity.

[0008] Preferably, in S1, the correlation relationship between conductor icing galloping and spatial magnetic field is established as:

[0009]

[0010] where B Xs (a p L , a p L , f p L , f pR , t) represents the magnetic induction intensity at the s-th sensor at a certain moment t, where s = 1, 2, 3, a p L , a p R , f p L , f p R respectively represent the amplitudes a of ice-covered galloping of the left half span L and the right half span R of the p-th phase conductor p L / R and the vibration frequency f p L / R , L / R represents the left half span L or the right half span R; r ps represents the distance from the p-th phase conductor to the s-th sensor, A Xps L / R (a P L / R , f P L / R , t) represents the magnetic induction intensity coefficient at the s-th sensor of the left half span L and the right half span R of the p-th phase conductor, θ ps represents the angle between the connection line of the p-th phase conductor and the s-th sensor and the vertical direction, p = 1, 2, 3, μ0 represents the magnetic permeability of vacuum, I p (t) represents the phase current of the p-th phase conductor.

[0011] Preferably, A Xps L / R (a p L / R , f p L / R , t) is calculated as follows:

[0012]

[0013] where, (x s , y s , z s ) represents the position coordinates of the sensor in the space coordinate system, (x p , y p , z p ) represents the infinitesimal element of the cable in the space coordinate system, that is, the space position coordinates of the cable during ice-covered galloping.

[0014] Preferably, the space position coordinates (x p , y p , z p ) of the cable during ice-covered galloping are calculated as follows:

[0015]

[0016] where p = 1, 2, 3, l p represents the distance of the wire from the origin of the coordinate system in the x-axis direction, a p L / R represents the amplitude of ice-covered galloping, f p L / R represents the vibration frequency; y p L / R is the y of the p-phase wire under the left half span L or the right half span R, y p , y t represents the distance from the line to the ground.

[0017] Preferably, by curve fitting, A Xps L / R (a P L / R , f P L / R , t) is simplified to:

[0018] A Xps L / R (a P L / R , f P L / R , t) = k p L / R a P L / R sin(2πft P L / R );

[0019] where k p L / R represents the galloping amplitude proportionality coefficient rate.

[0020] Preferably, in S2, the correlation between the ice-covered galloping of the wire and the magnetic induction intensity around it is simplified to:

[0021]

[0022] where s = 1, 2..., p = s, is the starting vibration phase difference between the wires in the left and right spans, I k (t) represents the current of the k-th phase and k ≠ s, k p L represents the galloping amplitude proportionality coefficient rate of the left span, k p R represents the galloping amplitude proportionality coefficient rate of the left span, r ks represents the distance from the k-th phase wire to the s sensor, θ ks represents the angle between the line connecting the k-th phase wire to the s sensor and the vertical direction.

[0023] Preferably, the effective value of the magnetic induction intensity interval at a specific position within a fixed period in the time window T is obtained as follows:

[0024]

[0025] where represents the effective value of the magnetic induction intensity within the time interval ΔT, t0 is the initial time, and n is

[0026] Preferably, the identification of conductor galloping due to ice coating using the magnetic induction intensity at a specific position is as follows:

[0027]

[0028] If B(f main ) ≥ threshold and f main ∈(0.1Hz, 3Hz) holds, then galloping occurs;

[0029] where FFT represents the fast Fourier transform, B(f1, f2,..., f n ) represents the magnetic induction intensity spectrum after the fast Fourier transform, B(f main ) represents the main frequency component of the magnetic induction intensity, threshold represents the preset value, and when the main frequency component exceeds the preset value threshold and the main frequency is within the galloping frequency range, it is considered that galloping occurs.

[0030] The present invention provides an ice - coating galloping identification device for an overhead transmission line, including a sensor and a signal processing unit; the sensor is a uniaxial tunneling magnetoresistive effect sensor, and the sensitive direction of the sensor is parallel to the sensor direction; the signal processing unit is used to obtain the magnetic field sensor directly above the target conductor and identify the ice - coating galloping of the conductor.

[0031] Preferably, the signal processing unit includes an operational amplifier, an analog - to - digital converter, and a data processor; the operational amplifier is used to filter and amplify the differential voltage signal output by the sensor, the analog - to - digital converter is used to perform analog - to - digital conversion on the signal output by the operational amplifier, and the data processor is used to obtain the spectrum of the magnetic induction intensity directly above the conductor and identify the occurrence of galloping.

[0032] Therefore, the present invention adopts the above - mentioned ice - coating galloping identification method and device for an overhead transmission line, and has the following advantages:

[0033] (1) The present invention uses three magnetic field sensors placed at the tower and directly above the transmission line to sense the change in the spatial magnetic induction intensity perpendicular to the cable direction generated by the cable to be measured to identify the galloping of the ice - coated conductor.

[0034] (2) The present invention has the advantages of small size, low power consumption, flexible installation, easy maintenance, high reliability, etc. It can realize the rapid and accurate identification of conductor galloping caused by icing, has good adaptability, and can meet the requirements of real-time monitoring of the power system.

[0035] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0036] Figure 1 It is a diagram of the tower model and the placement positions of sensors in an embodiment of a method and device for identifying galloping of an overhead transmission line caused by icing according to the present invention;

[0037] Figure 2 It is a diagram of the spatial position change of a certain phase conductor during galloping caused by icing in an embodiment of a method and device for identifying galloping of an overhead transmission line caused by icing according to the present invention;

[0038] Figure 3 It is an approximation of A using curve fitting in an embodiment of a method and device for identifying galloping of an overhead transmission line caused by icing according to the present invention Xps L / R (a p L / R , f p L / R , t) diagram;

[0039] Figure 4 It is a flowchart of an algorithm for detecting galloping of a conductor caused by icing in an embodiment of a method and device for identifying galloping of an overhead transmission line caused by icing according to the present invention;

[0040] Figure 5 It is a diagram of the hardware circuit composition in an embodiment of a method and device for identifying galloping of an overhead transmission line caused by icing according to the present invention. Detailed Embodiments

[0041] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0042] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the ordinary meanings as understood by those of ordinary skill in the field to which the present invention pertains. The "first", "second" and similar terms used in the present invention do not denote any order, quantity or importance, but are only used to distinguish different components. Words such as "comprising" or "including" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. Words such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Upper", "lower", "left", "right", etc. are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0043] Embodiment 1

[0044] The present invention provides a method for identifying icing galloping of an overhead transmission line, comprising the following steps:

[0045] S1. Obtain the output differential voltage signal in the direction perpendicular to the cable at the position directly above the target cable through a magnetic sensor, and perform signal processing on the differential signal to obtain the magnetic induction intensity directly above the target cable;

[0046] Establish the correlation between conductor icing galloping and the spatial magnetic field as:

[0047]

[0048] where B Xs (a p L , a p L , f p L , f p R , t) represents the magnetic induction intensity at the s-th sensor at a certain moment t, where s = 1, 2, 3, a p L , a p R , f p L , f p R respectively represent the amplitude a p L / R and vibration frequency f p L / R of the icing galloping of the left half span L and the right half span R of the p-th phase conductor, L / R represents the left half span L or the right half span R; r psRepresents the distance from the p - phase conductor to the s - th sensor, A Xps L / R (a P L / R ,f P L / R ,t) represents the magnetic induction intensity coefficient of the left - hand span L and the right - hand span R of the p - phase conductor at the sensor s, θ ps Represents the angle between the line connecting the p - phase wire and the s - th sensor and the vertical direction, p = 1, 2, 3, μ0 represents the magnetic permeability of vacuum, I p (t) represents the phase current of the p - phase wire.

[0049] A Xps L / R (a p L / R ,f p L / R ,t) The calculation formula is:

[0050]

[0051] Among them, (x s ,y s ,z s ) represents the position coordinates of the sensor in the space coordinate system, (x p ,y p ,z p ) represents the infinitesimal element of the cable in the space coordinate system, that is, the space position coordinates of the cable during ice - coated galloping.

[0052] As Figure 1 shown, Figure 1 shows the tower model and the placement position of the sensors in the specific embodiment of the present invention. Taking the ground directly below the connection between the B - phase and the tower as the origin, the direction perpendicular to the cable as the x - axis, the direction parallel to the tower as the y - axis, and the direction parallel to the cable as the z - axis, a space coordinate system is established. The three magnetic sensors are respectively located directly above the three cables, and the space coordinates are (x s ,y s ,z s ).

[0053] As Figure 2 shown, Figure 2 shows the spatial position change of a certain phase conductor during ice - coated galloping in the specific embodiment of the present invention. When galloping occurs, the conductor shows large - amplitude vibration in the vertical direction, and the entire line forms one or more standing waves. In historical data, one standing wave accounts for more than 80% of galloping. Therefore, the specific embodiment of the present invention uses the formation of one standing wave during ice - coated galloping of the wire to analyze. Under the space coordinate system defined in Figure 1 , the spatial position coordinates of the cable during ice - coated galloping (x p ,yp , z p ) The calculation formula is as follows:

[0054]

[0055] Where p = 1, 2, 3, l p represents the distance of the wire from the origin of the coordinate system in the x-axis direction, a p L / R represents the amplitude of ice-covered galloping, f p L / R represents the vibration frequency; y p L / R is the y of the pth-phase wire under the left half-span L or the right half-span R, p , y t represents the distance from the line to the ground.

[0056] The present invention obtains the correlation between ice-covered galloping of a conductor and a spatial magnetic field based on the Biot-Savart law, and its theoretical basis is as follows:

[0057] Taking a wire with a length of l, based on the Biot-Savart law, the magnetic field generated at point P is:

[0058]

[0059] Where μ0 is the vacuum magnetic permeability, is the wire element, is the distance vector from the wire element to point P. According to relation (3), the expression of the target cable element can be deduced:

[0060]

[0061] Where is the direction vector of the x-axis, is the direction vector of the y-axis, is the direction vector of the z-axis; in the space coordinate system, the distance vector from the cable element to the sensor is expressed as:

[0062]

[0063] Substituting relations (5) and (6) into relation (4) gives the x-axis component of the magnetic field at the jth sensor of the ith-phase cable:

[0064]

[0065] Where B Xps represents the magnetic induction intensity generated by the pth-phase cable at the sth sensor, a p L / R represents the amplitude of ice-covered galloping, f pL / R represents the vibration frequency, I p is the phase current of the p-th phase conductor, (x s , y s , z s ), represents the three-dimensional spatial position coordinates of the sensor, (x p , y p , z p ), represents the three-dimensional spatial position coordinates of the wire element. The magnetic fields generated by the three-phase cables are coupled at the sensor and manifested as linear superposition. Therefore, the magnetic induction intensity at the sensor s is:

[0066]

[0067] where, A Xis L / R (a pi L / R , f pi L / R , t) represents the product part except for the current in Equation (7). When the sensor is located at the position shown in Figure 1 , the icing galloping of the conductor directly below a certain sensor has a greater numerical impact on this sensor, while the movement of other conductors has almost negligible impact on this sensor, and a long straight wire is used for equivalence. Therefore, Equation (8) can be simplified, specifically as:

[0068]

[0069] where, s = 1, 2..., p = s. Since A Xps L / R (a p L / R , f p L / R , t) has complex integral terms and its specific functional expression cannot be obtained. Therefore, the curve fitting method is used for approximation. Note that A Xps L / R (a p L / R , f p L / R , t) is a function of time and amplitude. Therefore, using the numerical values of the embodiments of the present invention, the fitting function of A Xps L / R (a p L / R , f p L / R , t) with respect to time and amplitude is as shown in Figure 3 . By performing a fast Fourier transform, it can be found that this function is a sine function. Therefore, this equation can be simplified using the sine function, specifically as:

[0070] AXps L / R (a P L / R ,f P L / R ,t)=k p L / R a P L / R sin(2πf P L / R t) (10);

[0071] Among them, k p L / R represents the amplitude ratio coefficient of galloping.

[0072] S2. Based on the spectrum of the acquired magnetic induction intensity, identify the occurrence of ice-covered conductor galloping. Further simplify Equation (9) according to Equation (10), and simplify the correlation between ice-covered conductor galloping and the surrounding magnetic induction intensity to:

[0073]

[0074] where s = 1, 2..., p = s, is the starting vibration phase difference between the conductors in the left and right spans, I k (t) represents the current of the k-th phase and k ≠ s, k p L represents the amplitude ratio coefficient of galloping in the left span, k p R represents the amplitude ratio coefficient of galloping in the left span, r ks represents the distance from the k-th phase conductor to the s sensor, θ ks represents the angle between the connection line from the k-th phase conductor to the s sensor and the vertical direction.

[0075] The transmission current frequency of transmission lines in China is 50 Hz, that is, the time of one current cycle is 0.02 s. The frequency of ice-covered conductor galloping is 0.1 - 3 Hz, which is much lower than the power frequency of the current. Therefore, it can be approximately considered that the spatial state of the conductor remains unchanged within the time of one current cycle. Furthermore, obtain the effective value of the magnetic induction intensity every other current cycle within a period of time (nΔT):

[0076]

[0077] Among them, represents the effective value of the magnetic induction intensity within the time of ΔT, t0 is the initial time, and n is

[0078] As can be seen from Equation (11), ice - covered galloping will cause the magnetic induction intensity to have frequency components related to the conductor galloping frequency. Therefore, perform a fast Fourier transform on the effective value of the magnetic induction intensity obtained over a period of time to obtain its frequency composition:

[0079]

[0080] According to this frequency spectrum, the criterion for galloping determination can be obtained: If B(f main )≥threshold and f main ∈(0.1Hz, 3Hz) holds, then galloping occurs;

[0081] where, FFT represents the fast Fourier transform, B(f1, f2,..., f n ) represents the magnetic induction intensity frequency spectrum after the fast Fourier transform, B(f main ) represents the main frequency component of the magnetic induction intensity, and threshold represents the preset value. Therefore, the determination criterion is: If the main frequency component exceeds the preset value threshold and the main frequency is within the galloping frequency range, then it is considered that galloping occurs.

[0082] As Figure 4 shown, Figure 4 is the algorithm flow of a specific embodiment of the present invention. First, obtain the effective value of the magnetic induction intensity within one current cycle; obtain the effective values of the magnetic induction intensity multiple times within a period of time (nΔT) and perform a fast Fourier transform on these data to obtain its frequency distribution. Find its main frequency component and compare it with the pre - set threshold. If it is greater than the threshold and the main frequency is within the set galloping frequency range, then it is considered that galloping occurs, and the galloping frequency can be obtained according to the frequency spectrum; if the main frequency component is less than the threshold or not within the set galloping frequency range, then start over.

[0083] The present invention provides an icing galloping identification device for an overhead transmission line, including a sensor and a signal processing unit; wherein, the sensor is a uniaxial tunneling magnetoresistance effect sensor (TMR sensor), and its sensitive direction is parallel to the sensor direction. The signal processing unit is used to obtain the magnetic field sensor directly above the target conductor and identify the icing galloping of the conductor; the signal processing unit includes an operational amplifier, an analog-to-digital converter, and a data processor. The operational amplifier uses a dual-channel operational amplifier chip to filter and amplify the differential voltage signal output by the sensor; the output signal of the amplifier is an analog signal. For subsequent data processing, the analog signal output by the operational amplifier is converted into a digital signal by using an analog-to-digital converter, and the function of the analog-to-digital converter can be directly realized by the MCU; the obtained digital signal is processed by the MCU, including two FFTs (one is used to obtain the effective value of the magnetic induction intensity of each current cycle, and the other is used to perform FFT on these effective values to obtain the magnetic induction intensity spectrum) and the identification of icing galloping.

[0084] As Figure 5 shown, Figure 5 Figure 1 is the hardware circuit block diagram in a specific embodiment of the present invention. Among them, the hardware design of each sensor device is composed of a TMR sensor chip, an operational amplifier, an analog-to-digital converter, and an MCU data processor.

[0085] Therefore, the present invention adopts the above-mentioned icing galloping identification method and device for an overhead transmission line, uses the tunneling magnetoresistance effect sensor placed at a specific position to obtain the magnetic induction intensity and thereby identifies the icing galloping of the conductor, realizes the non-contact and rapid identification of the icing galloping of the conductor, and has the advantages of timely and accurate identification, etc.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An ice galloping recognition method for overhead transmission lines, characterized in that: Including the following steps: S1. Obtain the magnetic induction intensity of the magnetic field sensor directly above the target cable in the direction perpendicular to the cable; S2. Identify the occurrence of galloping of transmission conductors based on the spectrum of the obtained magnetic induction intensity.

2. The ice galloping identification method for an overhead transmission line according to claim 1, wherein: In S1, the correlation relationship between conductor galloping and spatial magnetic field is established as: Among them, B Xs (a p L , a p L , f p L , f p R , t) represents the magnetic induction intensity at the s-th sensor at a certain moment t, where s = 1, 2, 3, a p L , a p R , f p L , f p R respectively represent the amplitudes a of ice-covered galloping of the left half-span L and the right half-span R of the p-th phase conductor p L / R and the vibration frequencies f p L / R , L / R represents the left half-span L or the right half-span R; r ps represents the distance from the p-th phase conductor to the s-th sensor, A Xps L / R (a P L / R , f P L / R , t) represents the magnetic induction intensity coefficient at the s-th sensor of the left half-span L and the right half-span R of the p-th phase conductor, θ ps represents the angle between the connection line of the p-th phase conductor and the s-th sensor and the vertical direction, p = 1, 2, 3, μ0 represents the magnetic permeability of vacuum, I p (t) represents the phase current of the p-th phase conductor.

3. The icing galloping recognition method for an overhead transmission line according to claim 2, characterized in that: A Xps L / R (a p L / R ,f p L / R ,t) is calculated by the formula: Among them, (x s , y s , z s ) represents the position coordinates of the sensor in the space coordinate system, and (x p , y p , z p ) represents the infinitesimal element of the cable in the space coordinate system, that is, the spatial position coordinates of the cable during ice - covered galloping.

4. The ice galloping identification method for an overhead transmission line according to claim 3, characterized in that: Spatial position coordinates (x p , y p , z p ) of the cable during ice galloping are calculated as follows: where p = 1, 2, 3, l p represents the distance of the wire from the origin of the coordinate system in the x-axis direction, a p L / R represents the amplitude of ice-covered galloping, f p L / R represents the vibration frequency; y p L / R is the y of the p-th phase wire under the left half span L or the right half span R, p y t represents the distance from the line to the ground.

5. A method for identifying ice galloping of an overhead transmission line according to claim 4, characterized in that: Reduce A by curve fitting Xps L / R (a P L / R ,f P L / R ,t) to: A Xps L / R (a P L / R ,f P L / R ,t)=k p L / R a P L / R sin(2πf P L / R t); Among them, k p L / R represents the flutter amplitude proportional coefficient rate.

6. The ice - induced galloping identification method for an overhead transmission line according to claim 5, wherein: In S2, the correlation relationship between conductor galloping and the magnetic induction intensity around it is simplified as: where s = 1, 2..., p = s, is the starting vibration phase difference between the left and right span conductors, I k (t) represents the current of the k-th phase and k ≠ s, k p L represents the left span galloping amplitude proportionality coefficient rate, k p R represents the left span galloping amplitude proportionality coefficient rate, r ks represents the distance from the k-th phase conductor to the connection line of the s sensor, θ ks represents the angle between the connection line from the k-th phase conductor to the s sensor and the vertical direction.

7. A method for identifying ice galloping of an overhead transmission line according to claim 6, characterized in that: The effective value of the magnetic induction intensity at a specific position at fixed intervals within the time window T is: Among them, represents the effective value of the magnetic induction intensity within ΔT time, t0 is the initial time, and n is 8. A method for identifying ice-induced galloping of an overhead transmission line according to claim 7, characterized in that: Using the magnetic induction intensity at a specific position to identify conductor galloping is: If B(f main ) ≥ threshold and f main ∈ (0.1 Hz, 3 Hz) holds, then galloping occurs; Among them, FFT represents the fast Fourier transform, and B(f1, f2,..., f n ) represents the magnetic induction intensity spectrum after the fast Fourier transform, and B(f main ) represents the main frequency component of the magnetic induction intensity. Threshold represents a preset value. When the main frequency component exceeds the preset value threshold and the main frequency is within the galloping frequency range, galloping is considered to occur.

9. An ice galloping identification device for an overhead transmission line used in the ice galloping identification method for an overhead transmission line according to any one of claims 1-8, characterized in that: Including a sensor and a signal processing unit; the sensor is a uniaxial tunneling magnetoresistance effect sensor, and the sensitive direction of the sensor is parallel to the sensor direction; the signal processing unit is used to obtain the magnetic field sensor directly above the target conductor and identify the galloping of the conductor.

10. An ice galloping recognition device for an overhead transmission line according to claim 9, characterized in that: The signal processing unit includes an operational amplifier, an analog-to-digital converter, and a data processor; the operational amplifier is used to filter and amplify the differential voltage signal output by the sensor, the analog-to-digital converter is used to perform analog-to-digital conversion on the signal output by the operational amplifier, and the data processor is used to obtain the spectrum of the magnetic induction intensity directly above the conductor and identify the occurrence of galloping.

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