Line windage yaw monitoring method using single circuit ac transmission line ground wire induced harmonic current

Abstract

A line wind deviation monitoring method and system using single return AC transmission line ground wire induction harmonic current. The method comprises the following steps: constructing a three-dimensional rectangular coordinate system of the ground wire, and establishing a three-dimensional space model of the ground wire under the wind deviation working condition; dividing the line parameters of the ground wire into static and dynamic parameters, combining the three-phase conductor harmonic current source, calculating the frequency-varying parameter matrix for each harmonic frequency point, forward solving the ground wire induction harmonic current at each frequency point, and constructing a multi-frequency point observation data set; introducing multi-frequency point harmonic measurement information to convert the observation equation into an over-determined equation set, taking the wind deviation angles of multiple ground wires as decision variables, constructing an objective function containing the measured ground wire induction harmonic current and the solved ground wire induction harmonic current, and using a heuristic algorithm for global optimization and iterative operation combined with the physical boundary constraint of the wind deviation angle. The present application realizes high-voltage operation-free, weather-influenced ground wire induction harmonic current monitoring wind deviation online monitoring.

Description

Technical Field

[0001] This invention belongs to the field of line wind deflection monitoring, and specifically relates to a method and system for line wind deflection monitoring using the induced harmonic current of the ground wire of a single-circuit AC transmission line. Background Technology

[0002] Overhead transmission lines are the lifeblood of the power system and also the weakest link in the safe operation of the power grid, accounting for more than 40% of all grid faults. Traditional manual line inspections are extremely difficult and lack timeliness. Although a large number of drones and helicopters have been deployed and a large amount of image monitoring equipment has been installed, these methods are difficult to apply in weather conditions most prone to accidents, such as strong winds, rain, snow, and heavy fog. Moreover, the time and location of many abnormal conditions are highly random. Therefore, there is an urgent need to develop all-weather real-time online monitoring technology for transmission lines.

[0003] Various solutions have been developed both domestically and internationally to address the diverse condition monitoring needs of overhead transmission lines. Statistics on fault causes show that, compared to tower failures (tower collapse, loose bolts, etc.) and transmission channel intrusion (tree obstructions, external damage, etc.), abnormal conditions related to conductors and ground wires (lightning strikes, wind deflection, icing, galloping, etc.) are the primary causes of line faults. When transmission lines experience wind deflection due to wind, flashover faults can easily occur due to insufficient distance between phase conductors or between phase conductors and ground wires, threatening the normal operation of the transmission line. Wind deflection can also easily cause conductor galloping, leading to subsequent accidents. Therefore, monitoring wind deflection of transmission line conductors and ground wires can improve the operational stability of transmission lines, and developing remote online monitoring technology can reduce the operation and maintenance costs of transmission lines.

[0004] The main monitoring schemes for conductor and ground wire wind deflection information are summarized below, including their technologies and existing problems: (1) Tilt / Acceleration Monitoring: Tilt and acceleration sensors can be installed along the span of the line to obtain information such as conductor / ground wire displacement and galloping. However, multiple sets of these sensors need to be installed on the same conductor within one span, which requires power outage or live work, making installation and maintenance inconvenient. The high potential and strong electric field of the conductor will further accelerate the aging and failure of the electronic equipment inside the sensor, resulting in a low equipment survival rate.

[0005] (2) Position monitoring based on BeiDou / GPS: BeiDou / GPS can directly obtain the spatial position information of the sensor location, but multiple sensors often need to be installed within a range to achieve accurate monitoring of conditions such as sag. This type of method requires the sensors to be installed in a distributed manner within the range, thus having the same problem as tilt / accelerometer sensors.

[0006] (3) Image recognition monitoring: The camera is used to take pictures of the conductor and ground wire, and the wind deflection of the conductor and ground wire is monitored by image recognition technology. The main problems of this method are: in the weather conditions where the line is most likely to be in danger, such as ice, snow or fog, the camera is easily blocked by ice, snow and fog, the line of sight is greatly shortened, the image is blurry and the monitoring effect is worse; image data transmission requires a lot of communication resources and has high power consumption.

[0007] (4) Spatial Electric / Magnetic Field Monitoring: Existing technologies at home and abroad obtain the spatial position of conductors by deploying electric or magnetic field sensor arrays on the ground. However, current monitoring methods cannot obtain the location information of the ground wire. In actual operation, due to the low temperature of the ground wire, it is affected by icing far more than the conductor, making it a key part of line monitoring. In addition, the electromagnetic field on the tower is severely affected by the surrounding structure, making actual on-site implementation very difficult. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a method and system for monitoring line wind deflection using induced harmonic current in the ground wire of a single-circuit AC transmission line. This solves the technical problems of existing overhead transmission line conductor and ground wire sag wind deflection technology being greatly affected by severe weather, having high installation difficulty of monitoring devices, and being unable to comprehensively monitor conductor and ground wire wind deflection information.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0010] This invention first discloses a method for monitoring line wind deflection using induced harmonic current in the ground wire of a single-circuit AC transmission line. The method includes the following steps: Step 1: Based on the physical rigidity of the conductor and ground wire of a single-circuit AC transmission line, construct a three-dimensional rectangular coordinate system for the conductor and ground wire, determine the correspondence between the wind deflection angle and the spatial position of the conductor and ground wire, and establish a three-dimensional spatial model of any point on the conductor and ground wire under wind deflection conditions. Step 2: Divide the line parameters of the conductor into non-time-varying static parameters and dynamic parameters that vary with wind deflection. Combined with the harmonic current source of the three-phase conductor, calculate the frequency-varying parameter matrix including self-impedance and mutual impedance for each harmonic frequency point. Use this matrix to solve the induced harmonic current of the ground wire at each frequency point in the forward direction and construct a multi-frequency observation dataset. Step 3: Introduce multi-frequency harmonic measurement information to transform the observation equation into an overdetermined set of equations. Using the wind deflection angle of multiple conductors as decision variables, construct an objective function that includes the measured ground wire induced harmonic current and the solved ground wire induced harmonic current. Use a heuristic algorithm for global optimization and combine iterative calculation with the physical boundary constraints of the wind deflection angle to output the inversion result of the conductor and ground wire wind deflection angle.

[0011] The present invention further includes the following preferred embodiments: The construction of the three-dimensional rectangular coordinate system for the conductor ground wire further includes: For a line with two suspension points at equal heights, a three-dimensional rectangular coordinate system is established: the horizontal direction along the line is the x-direction, the vertical direction is the y-direction, and the horizontal direction perpendicular to the line's orientation is the z-direction; under the initial state of no wind deflection, its geometric curve is:

[0012] in y 0 represents the initial height of the conductor suspension point; for the conductor, the vertical length of its insulator is... d The line span is l The maximum sag when there is no wind is f m ； For the ground wire, the insulator string length d = 0.

[0013] The establishment of a three-dimensional spatial model of any point on the conductor under wind deflection conditions further includes: When the conductor is deflected by lateral wind, its spatial position shifts in three dimensions. The vertical coordinate y of any point on the line is calculated as follows:

[0014] Meanwhile, its horizontal offset coordinate z is:

[0015] in z 0 represents the initial horizontal coordinate of the conductor suspension point. For the conductor, the vertical length of its insulator is... d The line span is l The maximum sag when there is no wind is f m Wind deflection angle is i .

[0016] The static parameters include conductor radius, resistance per unit length, conductor hanging point coordinates, and tower structural parameters; the dynamic parameters include conductor sag, conductor wind deflection angle, tower grounding resistance, and soil resistivity.

[0017] The forward calculation of the induced harmonic current of the ground wire at each frequency point further includes: For any number of lines i Second harmonic frequency f i The input current matrix on the conductor side is denoted as: The three terms correspond to the three-phase input currents A, B, and C, respectively. The theoretical induced harmonic current of the ground wire at this frequency point is derived through forward derivation. :

[0019] The construction of the objective function, which includes the measured ground wire induced harmonic current and the solved ground wire induced harmonic current, further includes: The objective function is to minimize the norm of the error between the actual measured ground wire induced harmonic current and the ground wire induced harmonic current calculated by the model.

[0020] in Indicates the sensor number i The complex phasor of the ground current was obtained by actual measurement at each harmonic frequency point and extracted by Fast Fourier Transform (FFT). This indicates that, based on the electromagnetic coupling model of the conductor and ground wire, the wind deflection angle of the conductor and ground wire is taken as... The estimated value of the ground wire current obtained by calculation.

[0021] The wind deflection angle i This is the set of wind deflection angles for all conductors and ground wires in a single-circuit line. ;in, i A , i B , i C These represent the wind deflection angles of the three phase conductors A, B, and C, respectively. i g1 , i g2 These represent the wind deflection angles of the two ground wires, respectively.

[0022] This invention also discloses a line wind deflection monitoring system utilizing the aforementioned method for monitoring line wind deflection using the induced harmonic current of a single-circuit AC transmission line ground wire, comprising: The conductor-ground wire spatial location model construction module is used to construct a three-dimensional rectangular coordinate system of the conductor-ground wire based on the physical rigidity of the conductor-ground wire of a single-circuit AC transmission line, determine the correspondence between the wind deflection angle and the spatial location of the conductor-ground wire, and establish a three-dimensional spatial model of any point of the conductor-ground wire under wind deflection conditions. The electromagnetic coupling model construction module is used to divide the line parameters of the conductor and ground wire into non-time-varying static parameters and dynamic parameters that vary with wind deflection. Combined with the harmonic current source of the three-phase conductor, it calculates the frequency-varying parameter matrix including self-impedance and mutual impedance for each harmonic frequency point. The matrix is ​​used to solve the induced harmonic current of the ground wire at each frequency point in the forward direction and construct a multi-frequency observation dataset. The conductor-ground wire wind deflection monitoring module is used to introduce multi-frequency harmonic measurement information to transform the observation equation into an overdetermined set of equations. Using the wind deflection angle of multiple conductors-ground wires as decision variables, it constructs an objective function that includes the measured ground wire induced harmonic current and the solved ground wire induced harmonic current. It uses a heuristic algorithm for global optimization and combines iterative calculation with the physical boundary constraints of the wind deflection angle to output the conductor-ground wire wind deflection angle inversion result.

[0023] Accordingly, this application also discloses a terminal, including a processor and a storage medium; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the steps of the aforementioned method for monitoring line wind deflection using induced harmonic current in the ground wire of a single-circuit AC transmission line.

[0024] Accordingly, this application also discloses a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the aforementioned method for monitoring line wind deflection using the induced harmonic current of a single-circuit AC transmission line ground wire.

[0025] The beneficial effects of this invention are as follows: Compared with the prior art, this invention provides a method and system for monitoring line wind deflection using harmonic current induced by the ground wire of a single-circuit AC transmission line. The conductor-to-ground wire wind deflection inverse algorithm does not rely on complex and easily damaged tilt sensors or GPS / BeiDou positioning modules; the current sensing terminals used in the system only need to be installed on the ground wire side of the transmission line or on the tower body. This measurement method, which does not require contact with high-voltage phase conductors, completely eliminates the high cost and safety risks of live-line work, is easy to install, and has low maintenance costs; it overcomes the fatal defect of image recognition monitoring being easily "blinded" in low-visibility weather conditions such as ice, snow, and heavy fog. This method is based on the physical coupling law of low-frequency electromagnetic fields, is not affected by optical line of sight, and the external data on which the algorithm depends is easy to acquire, truly realizing all-weather real-time online monitoring; it eliminates the large communication bandwidth required for image and video backhaul, only requiring the transmission of current phasor data at specific harmonic frequencies, greatly reducing data transmission pressure and the power consumption of front-end equipment. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the shape of a single conductor before and after wind deflection in this invention.

[0027] Figure 2 This is a schematic diagram of the ground wire induced harmonic current calculation method in this invention.

[0028] Figure 3 This is a schematic diagram of the tower structure used in the simulation of this invention.

[0029] Figure 4 This is a schematic diagram of the equivalent inductance model in this invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0031] The embodiments described in this application are merely some, not all, embodiments of the present invention. Based on the spirit of the present invention, other embodiments obtained by those skilled in the art without inventive effort are all within the protection scope of the present invention.

[0032] To address the shortcomings of existing technologies, this invention proposes a method and system for monitoring line wind deflection using induced harmonic current in the ground wire of a single-circuit AC transmission line. This transforms the traditional underdetermined power frequency problem into an overdetermined problem by introducing multi-frequency harmonic information. The complete process of this method consists of three key stages. First, multi-frequency harmonic information of the line is extracted and a spatial electromagnetic coupling basic model is established by combining it with time-varying static parameters. Second, the spatial displacement of the conductor and ground wire under wind deflection conditions is quantified by combining spatial geometric equations. Finally, a nonlinear optimization objective function is constructed, and the wind deflection angle of the ground wire is derived through a heuristic algorithm.

[0033] The method for monitoring line wind deflection using induced harmonic current in the ground wire of a single-circuit AC transmission line disclosed in this invention includes the following steps: Step 1: Based on the physical rigidity of the conductor and ground wire of a single-circuit AC transmission line, construct a three-dimensional rectangular coordinate system for the conductor and ground wire, determine the correspondence between the wind deflection angle and the spatial position of the conductor and ground wire, and establish a three-dimensional spatial model of any point on the conductor and ground wire under wind deflection conditions.

[0034] When inferring wind deflection information, to ensure both computational accuracy and model efficiency, this invention assumes that the overall physical shape of the conductor / ground wire remains unchanged when it deflects, retaining its catenary (or parabolic approximation) form. That is, it assumes that when a single conductor / ground wire deflects under wind load, its entirety remains within the same inclined plane, and the insulator string is considered a rigid straight rod. For example... Figure 1 As shown, for a conductor, let the vertical length of its insulator be denoted as . d The line span is l The maximum sag when there is no wind is f m Wind deflection angle is i .

[0035] For a track with two suspension points at equal heights, a three-dimensional rectangular coordinate system is established: the horizontal direction along the track is defined as the x-direction, the vertical direction as the y-direction, and the horizontal direction perpendicular to the track's orientation as the z-direction. Under the initial condition of no wind deflection, its geometric curve is:

[0036] in y 0 represents the initial height of the conductor suspension point. For the ground wire, since it is usually directly connected to the tower and there is no insulator string, it can be considered as the length of the insulator string. d = 0.

[0037] When the conductor is deflected by lateral wind, its spatial position shifts in three dimensions. At this time, the coordinates of any point on the line in the vertical direction (y-axis) are updated as follows:

[0038] Meanwhile, its horizontal offset coordinate in the horizontal direction (z-axis) is:

[0039] in z 0 represents the initial lateral coordinate of the conductor suspension point. Through the above spatial geometric description, a rigorous mathematical mapping relationship was established between the wind deflection angle and the three-dimensional spatial coordinates of any point on the line, laying the foundation for subsequent calculations of mutual inductance parameters between lines.

[0040] Step 2: Divide the line parameters of the conductor into non-time-varying static parameters and dynamic parameters that vary with wind deflection. Combined with the harmonic current source of the three-phase conductor, calculate the frequency-varying parameter matrix including self-impedance and mutual impedance for each harmonic frequency point. Use this matrix to solve the induced harmonic current of the ground wire at each frequency point in the forward direction and construct a multi-frequency observation dataset.

[0041] Wind deflection alters the relative spatial distance between conductors and ground wires, leading to drastic changes in electromagnetic coupling parameters. For example... Figure 2 As shown, this invention divides the parameters affecting the induced current of the ground wire into two categories and constructs a multi-frequency calculation architecture: Time-invariant parameters (static parameters): These include conductor / ground wire radius, resistance per unit length, conductor / ground wire anchorage coordinates, and tower structural parameters. These parameters can be obtained in advance through design drawings or through a one-time on-site measurement.

[0042] Time-varying parameters (dynamic parameters): These include conductor sag and conductor wind deflection angle, which are difficult to measure directly in real time. The grounding resistance of the poles and towers, as well as the soil resistivity, etc.

[0043] Given the above parameters and information on the harmonic current sources of the phase conductors, for any _____ existing in the line i Second harmonic frequency f i The input current matrix on the conductor side is denoted as: (The three terms correspond to the three-phase input currents A, B, and C, respectively). Using static and time-varying parameters, the frequency-varying parameter matrix at this specific frequency point is calculated. .

[0044] See Figure 4 The calculation of induced harmonic current in the ground wire needs to consider the tower impedance. This invention adopts the equivalent inductance model according to the DL / T620-1997 standard. At frequency... Next, record Impedance matrix within one range:

[0045] in These represent the block matrices in the impedance matrix that represent the interactions between conductors and the interactions between ground wires, respectively. This represents the block matrix in the impedance matrix that represents the interaction between the conductor and the ground wire;

[0046] This represents the potential difference between the two ground wires at the beginning and end of the tower in a given range. These represent the two ground wires in... Voltage at frequency:

[0047] and This indicates the ground current of an internal conductor, where Indicates the ground current at frequency The following amount, Indicates the current in the conductor at frequency The following components are:

[0048] At the first tower, there are:

[0049]

[0050]

[0051] in Indicates the potential at the tower head, in the subscript. Indicates the first tower. Let represent the impedance from the suspension point of ground wire 1 to the tower head, the impedance from the suspension point of ground wire 2 to the tower head, and the impedance from the tower head to the grounding point of the tower, respectively. Simplifying, we get:

[0052] Notation:

[0053] Similarly, at the end tower, we have:

[0054] From the above formula, we can obtain:

[0055] By splitting the matrix and rearranging the terms, we can obtain:

[0056] remember Then the above formula can be simplified to:

[0057] The above analysis and calculations are for a single frequency point. f i Using static and time-varying parameters, the frequency-varying parameter matrix at a specific frequency point is calculated. This matrix includes self-impedance and mutual impedance considering earth backflow effects (such as Carson's formula). From this, the theoretical induced harmonic current of the ground wire at this frequency can be derived in a forward manner. :

[0058] The process is carried out in parallel at all extractable harmonic frequencies (such as the 3rd, 5th, and 7th harmonics) to form a multi-dimensional observation dataset.

[0059] Step 3: Introduce multi-frequency harmonic measurement information to transform the observation equation into an overdetermined set of equations. Using the wind deflection angle of multiple conductors as decision variables, construct an objective function that includes the measured ground wire induced harmonic current and the solved ground wire induced harmonic current. Use a heuristic algorithm for global optimization and combine iterative calculation with the physical boundary constraints of the wind deflection angle to output the inversion result of the conductor and ground wire wind deflection angle.

[0060] Because single-circuit AC transmission lines are typically equipped with two ground wires and three phase conductors, traditional power frequency monitoring can only provide a limited set of observation equations. When the number of unknowns (wind deflection angles of the five conductors and ground wires) exceeds the number of equations, it becomes an underdetermined problem, and a unique solution cannot be obtained. When only power frequency electromagnetic signals are used, four equations can be derived based on the amplitude and phase angle of the induced signals on the two ground wires, which is less than the five unknowns (wind deflection angles of the conductors and ground wires). Therefore, the equation set is underdetermined, and it is impossible to effectively invert the wind deflection information of the conductors and ground wires. In operating AC transmission lines, odd-order harmonic currents (3rd, 5th, 7th, etc.) often appear on the phase conductors. These harmonic currents also induce harmonic currents on the ground wires. Using harmonic information, the number of equations can be increased, with four equations for each harmonic. Furthermore, because the parameters in the electromagnetic coupling model of the transmission line change with frequency, the equations are independent of each other. Using this approach, the equations for inverse calculation of wind deflection of transmission line conductors and ground wires can be transformed into an overdetermined equation system. The wind deflection information of the conductors and ground wires can then be retrieved by solving an optimization problem. This invention introduces measurement information from multiple odd-order harmonic frequencies, and with each frequency... i As the number of observation equations increases, the problem is transformed into solving an overdetermined system of equations.

[0061] Using the aforementioned forward electromagnetic coupling model, a least-squares optimization problem is constructed to inversely solve for the wind deflection angle of the conductor and ground wire. The decision variable of the optimization problem is defined as the set of wind deflection angles of all conductors and ground wires in a single circuit. i :

[0062] in, i A , i B , i C These represent the wind deflection angles of the three phase conductors A, B, and C, respectively. i g1 , i g2 These represent the wind deflection angles of the two ground wires, respectively.

[0063] The objective function of the optimization problem is to minimize the norm of the error between the measured ground wire induced harmonic current and the ground wire induced harmonic current calculated by the model.

[0064] in Indicates the sensor number i The complex phasor of the ground current obtained by actual measurement at each harmonic frequency point and extraction through Fast Fourier Transform (FFT) This indicates that, based on the electromagnetic coupling model of the conductor and ground wire (theoretical induced harmonic current), the wind deflection angle of the conductor and ground wire is taken as... The estimated value of the ground wire current obtained by calculation.

[0065] Due to the matrix It involves complex spatial distance calculations and nonlinear electromagnetic coupling characteristics; the objective function... It is a highly nonlinear, multi-peak function. Conventional gradient descent methods are prone to getting trapped in local optima. Therefore, this scheme employs a heuristic intelligent optimization algorithm (Particle Swarm Optimization, PSO) to perform global optimization in the multidimensional solution space. The heuristic algorithm does not rely on a rigorous mathematical expression or gradient information of the objective function, but rather iterates and accumulates experience in a multidimensional unknown space by simulating biological evolution or swarm intelligence behavior. The specific computational steps for the wind drift inversion model of this invention include: Multidimensional space initialization: The set of wind deflection angles of all conductors and ground wires in a single-circuit line is mapped to a particle swarm (PSO) in the algorithm space. An initial set of candidate solutions is randomly generated within the boundary constraints that combine the actual physical limits of the transmission line.

[0066] Fitness evaluation based on error norm: Each generated candidate wind deflection angle combination is substituted into the multi-frequency variable electromagnetic coupling matrix to calculate the estimated ground wire current at each harmonic frequency. The objective function is to minimize the norm of the error between the actual measured ground wire current and the estimated value. ( ) Conduct fitness assessment.

[0067] Gradient-free global iteration: Utilizing the unique "Personal Experience and Group Information Sharing" (PSO) mechanism of heuristic algorithms, the solution set is guided to evolve towards a better direction in multi-dimensional space, effectively escaping the local minima trap caused by complex electromagnetic coupling characteristics.

[0068] Convergence Criteria and Precise Output: When the objective function converges to the set tolerance threshold after continuous iteration, the algorithm stops operating. The optimal wind deflection combination locked at this point is the precise inversion value of the wind deflection angle of the current line conductor and ground wire.

[0069] Meanwhile, boundary constraints are incorporated into the optimization solution process, taking into account the actual physical limits of the transmission lines. (For example, limiting the wind deflection angle to between -30° and 30°) to accelerate algorithm convergence and eliminate unreasonable mathematical pseudo-solutions. When the objective function When the iteration converges to the set tolerance threshold, at this point... The combination is the accurate inversion value of the wind deflection angle of the current line conductor and ground wire.

[0070] By deeply integrating heuristic intelligent optimization algorithms into the conductor-ground wire wind deflection inversion model, compared with traditional mathematical analysis, it breaks through the local optimum trap and achieves high-precision global optimization; avoids high-dimensional complex differentiation and reduces the risk of computational collapse; is compatible with physical boundary constraints and eliminates mathematical pseudo-solutions; and exhibits good solution robustness in the face of complex working conditions.

[0071] The beneficial effects of this invention are as follows: Compared with the prior art, this invention provides a method and system for monitoring line wind deflection using harmonic current induced by the ground wire of a single-circuit AC transmission line. The conductor-to-ground wire wind deflection inverse algorithm does not rely on complex and easily damaged tilt sensors or GPS / BeiDou positioning modules; the current sensing terminals used in the system only need to be installed on the ground wire side of the transmission line or on the tower body. This measurement method, which does not require contact with high-voltage phase conductors, completely eliminates the high cost and safety risks of live-line work, is easy to install, and has low maintenance costs; it overcomes the fatal defect of image recognition monitoring being easily "blinded" in low-visibility weather conditions such as ice, snow, and heavy fog. This method is based on the physical coupling law of low-frequency electromagnetic fields, is not affected by optical line of sight, and the external data on which the algorithm depends is easy to acquire, truly realizing all-weather real-time online monitoring; it eliminates the large communication bandwidth required for image and video backhaul, only requiring the transmission of current phasor data at specific harmonic frequencies, greatly reducing data transmission pressure and the power consumption of front-end equipment.

[0072] The beneficial effects and algorithm accuracy of this invention have been fully verified through actual line structure data combined with numerical simulation. Compared with existing contact or visual wind deflection monitoring methods, this invention demonstrates significant advantages in measurement accuracy, equipment reliability, installation and maintenance costs, and all-weather adaptability.

[0073] (1) Construction and operating condition settings of the simulation verification platform This invention is verified by combining actual line data with simulation. The line structure selected for the simulation is based on an actual 500kV single-circuit AC line, such as... Figure 3 As shown. Considering that in actual engineering operation, the middle phase (B phase) conductor of this type of 500kV line is usually suspended by V-shaped insulator strings, its lateral displacement is limited by the mechanical structure, and wind deflection generally does not occur or is minimal. Therefore, in the simulation settings, the complex scenario of the side phases (A phase and C phase) and the two ground wires producing different wind deflection angles under different meteorological conditions is mainly examined to maximize the reproduction of the real operating conditions.

[0074] (2) Data analysis and verification of inversion accuracy Table 1. Actual and inverse values ​​of wind deflection angle in simulation.

[0075] The nonlinear inversion algorithm based on harmonic induced current proposed in this invention was used to solve various set wind deflection conditions. The comparison results between the actual set values ​​and the inverted values ​​are shown in Table 1. In-depth analysis of the data in the table reveals that: Ground wire stationary, conductor wind deflection condition: When the two ground wires (g1, g2) do not experience wind deflection (wind deflection angle is 0°), even if the three-phase conductors experience severe and asymmetrical wind deflection (for example, condition 2 in Table 1: phase A 15°, phase B 13°, phase C 15°), the algorithm of this invention can still accurately isolate and invert the state of each phase, with inverted values ​​of 14.3°, 12.5°, and 15.7° respectively.

[0076] Combined asynchronous wind deflection of conductor and ground wire: In strong wind conditions, the ground wire and conductor often deflect simultaneously with varying amplitudes. In the latter half of the conditions in Table 1 (e.g., ground wire deflection of 4° and 5°, conductor deflection of 13°, 5°, and 12°), the inversion algorithm exhibits extremely strong robustness in dealing with this highly complex spatial nonlinear coupling state. The inverted results (5.5°, 9.9°, 12.0°, 6.3°, and 11.8°) closely match the actual situation. This fully demonstrates that the algorithm proposed in this invention possesses high-precision inversion capabilities under various complex conductor and ground wire wind deflection conditions.

[0077] This invention can be a system, method, and / or computer program product. This invention also discloses a line wind deflection monitoring system based on the aforementioned method for monitoring line wind deflection using induced harmonic current in the ground wire of a single-circuit AC transmission line, comprising: The conductor-ground wire spatial location model construction module is used to construct a three-dimensional rectangular coordinate system of the conductor-ground wire based on the physical rigidity of the conductor-ground wire of a single-circuit AC transmission line, determine the correspondence between the wind deflection angle and the spatial location of the conductor-ground wire, and establish a three-dimensional spatial model of any point of the conductor-ground wire under wind deflection conditions. The electromagnetic coupling model construction module is used to divide the line parameters of the conductor and ground wire into non-time-varying static parameters and dynamic parameters that vary with wind deflection. Combined with the harmonic current source of the three-phase conductor, it calculates the frequency-varying parameter matrix including self-impedance and mutual impedance for each harmonic frequency point. The matrix is ​​used to solve the induced harmonic current of the ground wire at each frequency point in the forward direction and construct a multi-frequency observation dataset. The conductor-ground wire wind deflection monitoring module is used to introduce multi-frequency harmonic measurement information to transform the observation equation into an overdetermined set of equations. Using the wind deflection angle of multiple conductors-ground wires as decision variables, it constructs an objective function that includes the measured ground wire induced harmonic current and the solved ground wire induced harmonic current. It uses a heuristic algorithm for global optimization and combines iterative calculation with the physical boundary constraints of the wind deflection angle to output the conductor-ground wire wind deflection angle inversion result.

[0078] Based on the spirit of this invention, those skilled in the art will readily conceive of a computer program product that can be obtained based on the aforementioned method for monitoring line wind deflection using the induced harmonic current of a single-circuit AC transmission line ground wire. The computer program product may include a computer-readable storage medium on which computer-readable program instructions are loaded to enable a processor to implement various aspects of this disclosure. That is, this application also includes a terminal comprising a processor and a storage medium; the storage medium is used to store instructions; the processor is used to operate according to the instructions to execute the steps of the aforementioned method for monitoring line wind deflection using the induced harmonic current of a single-circuit AC transmission line ground wire.

[0079] Computer-readable storage media can be tangible devices capable of holding and storing instructions for use by an instruction execution device. Computer-readable storage media can be, for example, but not limited to, electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination of the foregoing. The computer-readable storage media used herein are not to be construed as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

[0080] The computer-readable program instructions described herein can be downloaded from computer-readable storage media to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to the computer-readable storage media in the respective computing / processing device.

[0081] Computer program instructions used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing the status information of the computer-readable program instructions to implement various aspects of this disclosure.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for monitoring line wind deflection using induced harmonic current in the ground wire of a single-circuit AC transmission line, characterized in that, Includes the following steps: Step 1: Based on the physical rigidity of the conductor and ground wire of a single-circuit AC transmission line, construct a three-dimensional rectangular coordinate system for the conductor and ground wire, determine the correspondence between the wind deflection angle and the spatial position of the conductor and ground wire, and establish a three-dimensional spatial model of any point on the conductor and ground wire under wind deflection conditions. Step 2: Divide the line parameters of the conductor into non-time-varying static parameters and dynamic parameters that vary with wind deflection. Combined with the harmonic current source of the three-phase conductor, calculate the frequency-varying parameter matrix including self-impedance and mutual impedance for each harmonic frequency point. Use this matrix to solve the induced harmonic current of the ground wire at each frequency point in the forward direction and construct a multi-frequency observation dataset. Step 3: Introduce multi-frequency harmonic measurement information to transform the observation equation into an overdetermined set of equations. Using the wind deflection angle of multiple conductors as decision variables, construct an objective function that includes the measured ground wire induced harmonic current and the solved ground wire induced harmonic current. Use a heuristic algorithm for global optimization and combine iterative calculation with the physical boundary constraints of the wind deflection angle to output the inversion result of the conductor and ground wire wind deflection angle.

2. The method for monitoring line wind deflection using induced harmonic current in the ground wire of a single-circuit AC transmission line according to claim 1, characterized in that, The construction of the three-dimensional rectangular coordinate system for the conductor ground wire further includes: For a line with two suspension points at equal heights, a three-dimensional rectangular coordinate system is established: the horizontal direction along the line is the x-direction, the vertical direction is the y-direction, and the horizontal direction perpendicular to the line's orientation is the z-direction; under the initial state of no wind deflection, its geometric curve is: in y 0 represents the initial height of the conductor suspension point; for the conductor, the vertical length of its insulator is... d The line span is l The maximum sag when there is no wind is f m ； For the ground wire, the insulator string length d = 0.

3. The method for monitoring line wind deflection using induced harmonic current in the ground wire of a single-circuit AC transmission line according to claim 2, characterized in that, The establishment of a three-dimensional spatial model of any point on the conductor under wind deflection conditions further includes: When the conductor is deflected by lateral wind, its spatial position shifts in three dimensions. The vertical coordinate y of any point on the line is calculated as follows: Meanwhile, its horizontal offset coordinate z is: in z 0 represents the initial horizontal coordinate of the conductor suspension point. For the conductor, the vertical length of its insulator is... d The line span is l The maximum sag when there is no wind is f m Wind deflection angle is θ .

4. The method for monitoring line wind deflection using induced harmonic current in the ground wire of a single-circuit AC transmission line according to claim 3, characterized in that, The static parameters include conductor radius, resistance per unit length, conductor hanging point coordinates, and tower structural parameters; the dynamic parameters include conductor sag, conductor wind deflection angle, tower grounding resistance, and soil resistivity.

5. The method for monitoring line wind deflection using induced harmonic current in the ground wire of a single-circuit AC transmission line according to claim 4, characterized in that, The forward calculation of the induced harmonic current of the ground wire at each frequency point further includes: For any number of lines i Second harmonic frequency f i The input current matrix on the conductor side is denoted as: The three terms correspond to the three-phase input currents A, B, and C, respectively. Using static and time-varying parameters, the frequency-varying parameter matrix at a specific frequency point is calculated. ; The theoretical induced harmonic current of the ground wire at this frequency point is derived through forward derivation. : 。 6. The method for monitoring line wind deflection using induced harmonic current in the ground wire of a single-circuit AC transmission line according to claim 5, characterized in that, The construction of the objective function, which includes the measured ground wire induced harmonic current and the solved ground wire induced harmonic current, further includes: The objective function is to minimize the norm of the error between the actual measured ground wire induced harmonic current and the ground wire induced harmonic current calculated by the model. in Indicates the sensor number i The complex phasor of the ground current was obtained by actual measurement at each harmonic frequency point and extracted by Fast Fourier Transform (FFT). This indicates that, based on the electromagnetic coupling model of the conductor and ground wire, the wind deflection angle of the conductor and ground wire is taken as... The estimated value of the ground wire current obtained by calculation.

7. The method for monitoring line wind deflection using induced harmonic current in the ground wire of a single-circuit AC transmission line according to claim 6, characterized in that, The wind deflection angle θ This is the set of wind deflection angles for all conductors and ground wires in a single-circuit line. ； in, θ A , θ B , θ C These represent the wind deflection angles of the three phase conductors A, B, and C, respectively. θ g1 , θ g2 These represent the wind deflection angles of the two ground wires, respectively.

8. A line wind deflection monitoring system utilizing the induced harmonic current in the ground wire of a single-circuit AC transmission line, characterized in that, include: The conductor-ground wire spatial location model construction module is used to construct a three-dimensional rectangular coordinate system of the conductor-ground wire based on the physical rigidity of the conductor-ground wire of a single-circuit AC transmission line, determine the correspondence between the wind deflection angle and the spatial location of the conductor-ground wire, and establish a three-dimensional spatial model of any point of the conductor-ground wire under wind deflection conditions. The electromagnetic coupling model construction module is used to divide the line parameters of the conductor and ground wire into non-time-varying static parameters and dynamic parameters that vary with wind deflection. Combined with the harmonic current source of the three-phase conductor, it calculates the frequency-varying parameter matrix including self-impedance and mutual impedance for each harmonic frequency point. The matrix is ​​used to solve the induced harmonic current of the ground wire at each frequency point in the forward direction and construct a multi-frequency observation dataset. The conductor-ground wire wind deflection monitoring module is used to introduce multi-frequency harmonic measurement information to transform the observation equation into an overdetermined set of equations. Using the wind deflection angle of multiple conductors-ground wires as decision variables, it constructs an objective function that includes the measured ground wire induced harmonic current and the solved ground wire induced harmonic current. It uses a heuristic algorithm for global optimization and combines iterative calculation with the physical boundary constraints of the wind deflection angle to output the conductor-ground wire wind deflection angle inversion result.

9. A terminal, comprising a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the steps of the line wind deflection monitoring method according to any one of claims 1-7 using the induced harmonic current of the ground wire of a single-circuit AC transmission line.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by the processor, the program implements the steps of the line wind deflection monitoring method using the induced harmonic current of the ground wire of a single-circuit AC transmission line as described in any one of claims 1-7.

Images