A method and device for online energy extraction from magnetic field on towers around AC transmission lines

Abstract

The present invention provides a method and device for online energy harvesting from the magnetic field on towers surrounding AC transmission lines. The method comprises establishing a finite element model of a three-phase transmission conductor and a steel structure model of a target transmission tower's tower window. A simulated magnetic core rod is established within the tower window steel structure model and at a distance from the steel structure rods. The simulated magnetic core rod is short-circuited in parallel with a closed or open tower window steel structure model. The magnetic flux density of the simulated magnetic core rod and the magnetic flux density of the steel structure rod connected in parallel are calculated by simulation. The magnetic core rod for practical application in online energy harvesting and power supply is then fabricated and fixed to the steel structure rod in the tower window of the target transmission tower. A coil is wound around the magnetic core rod, and a series compensation circuit is connected to the coil's output end. A conversion circuit is then used to stabilize the coil's output voltage at the rated DC voltage required by online transmission line monitoring equipment. The present invention enables self-sufficiency and stable power supply for online transmission line monitoring equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of online energy harvesting from the magnetic field of a transmission tower, and in particular to a method and device for online energy harvesting from the magnetic field on a tower surrounding an AC transmission line. Background Art

[0002] my country's power transmission lines cover a vast area. To ensure the safe and stable operation of the power grid system, online monitoring of transmission line operating conditions is often required. Because transmission line towers and wire systems often operate in complex outdoor environments, current online monitoring technologies primarily rely on traditional methods such as solar energy, wind energy, and batteries, or on powering online monitoring equipment through CT wires. However, these traditional power supply methods are subject to instability due to severe weather, while the CT wires require direct connection to the transmission lines, posing significant safety risks such as electric shock and leakage, as well as limited power supply. Ensuring a continuous and stable power supply for online monitoring equipment remains a pressing issue. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method and device for online energy extraction from the magnetic field on the towers around the AC transmission line, which is not easily affected by weather and has stable power supply. The magnetic field energy around the transmission line does not require additional consumption of other energy sources, and can achieve self-sufficiency in electrical energy for online monitoring equipment of the transmission line.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A method for online energy extraction from magnetic fields on towers around AC transmission lines, comprising the following steps:

[0006] Step 1: Based on the actual operating parameters of the AC transmission line on the target transmission tower, establish finite element models of the A-phase, B-phase, and C-phase transmission conductors. The B-phase and C-phase transmission conductors are located on both sides of the A-phase transmission conductor, and set the current excitation magnitude and relative magnetic permeability of the three-phase transmission conductors.

[0007] Step 2: Obtain the tower window structural parameters of the target transmission tower, determine whether the tower window is closed, and establish a closed or non-closed tower window steel structure model around the A-phase transmission conductor based on the determination result;

[0008] Step 3: Short-circuit a simulated magnetic core rod in parallel within the closed or open tower window steel structure model and at a certain distance from the steel structure rod, set the relative magnetic permeability corresponding to the closed or open tower window steel structure model and the simulated magnetic core rod, and simulate and calculate the magnetic flux density result of the simulated magnetic core rod;

[0009] Step 4: Make a magnetic core rod with a coil wound around it for practical applications in online energy supply. Short-circuit it in parallel with the steel structure in the tower window of the target transmission tower. Connect a series compensation circuit to the output end of the coil. Calculate the output voltage of the coil based on the magnetic flux density of the simulated magnetic core rod. Then, use a conversion circuit to stabilize the output voltage of the coil at the rated DC voltage required by the online monitoring equipment of the transmission line.

[0010] Furthermore, in step 1, for the case of multiple split conductors in the transmission line, when establishing a three-phase transmission conductor model, it is necessary to equate the multiple split conductors of each phase to one conductor, wherein the calculation method of the equivalent conductor radius Req is:

[0011]

[0012] Where m is the number of split conductors of each phase; r is the radius of each sub-conductor of the split conductor; d 1k It is the distance between the first and kth sub-conductors in each phase split conductor.

[0013] Furthermore, in step 2, if the tower window of the target transmission tower is closed, a closed tower window steel structure model is established around the A-phase transmission conductor to form a closed external magnetic circuit, and the closed tower window steel structure model includes multiple steel rods connected end to end to form a loop. If the tower window of the target transmission tower is not closed, a non-closed tower window steel structure model is established around the A-phase transmission conductor to form a non-closed external magnetic circuit, and the non-closed tower window steel structure model includes multiple steel rods, one of which is disconnected from another.

[0014] Furthermore, in step 3, the cross-sectional shape of the simulated magnetic core rod includes but is not limited to a rectangle, a square, a circle or an ellipse; and

[0015] When the cross-sectional shape of the simulated magnetic core rod is a rectangle, the cross-sectional parameters and height of the simulated magnetic core rod are adjusted, and the solution with the maximum magnetic flux density of the simulated magnetic core rod is taken as the cross-sectional parameters and height of the magnetic core rod for actual application.

[0016] Furthermore, the length of the simulated magnetic core rod is 28-42 cm and the width is 5-30 mm.

[0017] Furthermore, in step 4, the material of the magnetic core rod actually used includes but is not limited to silicon steel, permalloy, and ferrite.

[0018] Furthermore, the coil wire has 8000 turns and is made of enameled wire with a wire diameter of 0.8 mm. The coil is wound in layers, with 800 turns in each layer, and a total of 10 layers.

[0019] Furthermore, the magnetic core rod used in actual application is clamped and fixed to the steel structure rod by a U-shaped clamp, and the selected steel structure rod position can be any steel structure rod in the tower window structure of the transmission tower.

[0020] Furthermore, the material of the magnetic core rod was adjusted, and the energy extraction effect of the magnetic core rods in actual application under different materials was compared and analyzed. Finally, the material with the largest output voltage at both ends of the coil was selected as the optimal solution.

[0021] An online energy harvesting device for magnetic field on a tower around an AC transmission line, comprising:

[0022] The magnetic core rod is short-circuited in parallel with the steel structure rod in the tower window of the target transmission tower;

[0023] The coil is wound on the magnetic core rod;

[0024] Among them, a series compensation circuit is connected to the output end of the coil to compensate and eliminate the reactive power generated by the internal resistance and self-inductance of the coil to achieve maximum power transmission for online energy supply, and then the output voltage of the coil is stabilized at the rated DC voltage required by the online monitoring equipment of the transmission line through the conversion circuit.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0026] (1) The method and device for online energy extraction from the magnetic field on the towers around the AC transmission lines described in the present invention can effectively utilize the magnetic flux energy of the steel rods in the tower window structure of the transmission towers around the AC transmission lines to obtain energy and supply power online. This method can not only improve the power of online energy extraction of the transmission lines, but also provide continuous and stable power supply for online monitoring equipment of the transmission lines.

[0027] (2) The present invention discloses a method and device for online energy harvesting from the magnetic field on the towers around AC transmission lines. The method of the present invention is applied to the field of online energy harvesting and power supply technology for AC transmission lines. This method can achieve the goal of being unaffected by and restricted by the time and space environment, while also reducing the installation and maintenance costs under traditional power supply methods and improving economic benefits.

[0028] (3) The method and device for online energy harvesting from the magnetic field on the tower around an AC transmission line described in the present invention are applicable to AC transmission lines of various voltage levels and have broad application prospects in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0030] Figure 1 Detailed flow chart of the method of the present invention.

[0031] Figure 2 This is a finite element model of a three-phase transmission line established in an embodiment of the present invention.

[0032] Figure 3 The model established in the embodiment of the present invention includes tower window steel structure members and measurement magnetic core rods of a transmission tower.

[0033] Figure 4 This is a simulation result curve when the magnetic core rod exists alone in the embodiment of the present invention.

[0034] Figure 5 This is a model established in an embodiment of the present invention in which a measuring magnetic core rod is short-circuited in parallel with a steel structure member of a tower window structure.

[0035] Figure 6 This is a simulation result curve after the magnetic core rod and the steel structure member are connected in parallel in an embodiment of the present invention.

[0036] Among them, 1. A-phase transmission wire; 2. B-phase transmission wire; 3. C-phase transmission wire; 4. Tower window steel structure model; 5. Steel structure rod; 6. Simulated magnetic core rod. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0038] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0039] In the related art, the online monitoring technology for transmission lines mainly uses traditional methods such as solar energy, wind energy, batteries, or the method of obtaining energy through conductor CT to power the online monitoring equipment. However, the traditional power supply method of the former is limited by the influence of bad weather, resulting in an unstable power supply system. The latter conductor CT energy obtaining method requires direct connection to the transmission line, which has major safety hazards such as electric shock and leakage and low power supply. The embodiment of the present invention solves the problems of unstable online energy supply of transmission lines, certain safety hazards and low power supply in the prior art by providing a method and device for online energy collection from the magnetic field on the towers around the AC transmission lines. It does not require additional consumption of other energy sources and can achieve self-sufficiency and stability in the power supply of the online monitoring equipment of the transmission lines.

[0040] The following will be combined with the appended Figure 1 Taking the actual operating parameters of a 500kV AC transmission line on a target transmission tower as an example, the technical solution in the embodiment of the present invention is clearly and completely described.

[0041] The present invention provides a method for online energy extraction from magnetic field on towers around AC transmission lines, such as Figure 1 As shown, the following steps are included:

[0042] Step 1: According to the actual operating parameters of the target transmission tower AC transmission line, establish Figure 2 The finite element model of the three-phase transmission conductors shown is A-phase transmission conductor 1, B-phase transmission conductor 2, and C-phase transmission conductor 3, wherein A-phase transmission conductor 1 is in the middle, and B-phase and C-phase transmission conductors 3 are respectively on the left and right sides of A-phase transmission conductor 1. The current excitation magnitude and relative magnetic permeability of the three-phase transmission conductors are set, and the magnetic flux density results of the three-phase conductors are obtained by simulation calculation.

[0043] In the present invention, the current excitation size of the three-phase transmission conductor is set according to the actual operating parameters of a 500kV AC transmission line on a target transmission tower. The current excitations of the A-phase transmission conductor 1, the B-phase transmission conductor 2, and the C-phase transmission conductor 3 are set to 500A, -250A, and -250A, respectively. The relative permeability of the three-phase transmission conductor is set to 1. The simulation calculation results of the magnetic flux density of the A-phase transmission conductor 1, the B-phase transmission conductor 2, and the C-phase transmission conductor 3 are 1.02mT, 0.50mT, and 0.50mT, respectively.

[0044] Step 2: Obtain the tower window structural parameters of the target transmission tower, determine whether the tower window is closed, and establish a closed or non-closed tower window steel structure model 4 around the A-phase transmission conductor 1 based on the determination result;

[0045] Step 3: Short-circuit the simulated magnetic core rod 6 in parallel in the closed or non-closed tower window steel structure model 4 and at a certain distance from the steel structure rod 5, set the relative magnetic permeability corresponding to the closed or non-closed tower window steel structure model 5 and the simulated magnetic core rod 6, and simulate and calculate the magnetic flux density result B of the simulated magnetic core rod 6. m ;

[0046] Step 4: Make a coiled magnetic core rod for online energy supply based on the simulated magnetic core rod 6, short-circuit it in parallel with the steel rod in the tower window of the target transmission tower, connect the series compensation circuit at the output end of the coil, and calculate the magnetic flux density B of the simulated magnetic core rod 6. m The output voltage of the coil is obtained, and then the output voltage of the coil is stabilized at the rated DC voltage required by the transmission line online monitoring equipment through the conversion circuit.

[0047] The coil will be rotated according to the magnetic flux density B in the core rod. m A certain AC output voltage U is induced, and the specific calculation formula is:

[0048] U=2πf×B m ×S×N

[0049] Where f is the operating frequency of the AC transmission line, S is the cross-sectional area of ​​the magnetic core bar, and N is the number of turns of wire in the coil wound around the magnetic core bar.

[0050] Parallel short circuit means that both ends of the magnetic core rod are fixed to the steel structure rod.

[0051] In the present invention, the closed tower window steel structure model 4 includes multiple steel rods 5 connected end to end in sequence to form a loop. If the tower window of the target transmission tower is not closed, a non-closed tower window steel structure model 4 is established around the A-phase transmission conductor 1 to form a non-closed external magnetic circuit. The non-closed tower window steel structure model 4 includes multiple steel rods 5, one of which is disconnected from another steel rod 5.

[0052] In one embodiment of the present invention, Figure 3 As shown, a closed tower window steel structure model 4 of the target transmission tower is established around the A-phase transmission conductor 1 to form a closed external magnetic circuit. At the same time, a finite element model of a high-permeability simulated magnetic core rod 6 is established at a position 0.1m away from the left steel structure. The length of the simulated magnetic core rod 6 is set to 0.5 meters, and the cross-sectional shape of the simulated magnetic core rod 6 is a rectangular cross-sectional size of 30mm×5mm. At the same time, according to the Q235 steel structure material of the transmission tower, its relative permeability is set to 300, and the relative permeability of the simulated magnetic core rod 6 is set to 10000. Then, a finite element magnetic field simulation calculation is performed to obtain the following: Figure 4The result curve shows that the magnetic flux density of the left steel structure member is 7.25mT, and the magnetic flux density of the simulated magnetic core rod 6 is 0.2mT. It can be seen that when the magnetic core rod exists independently, the magnetic resistance is large, and its magnetic flux density is much smaller than the magnetic flux density in the nearby steel structure.

[0053] like Figure 5 As shown, the simulated magnetic core rod 6 is short-circuited in parallel in the closed external steel structure member, and the result curve obtained by simulation calculation is as follows Figure 6 As shown, at this time, the magnetic flux density of the simulated magnetic core rod 6 is 15.2mT, and the magnetic flux density of the steel structure rod short-circuited in parallel with it is 0.8mT. By comparison, it can be seen that when the simulated magnetic core rod 6 is connected to the steel structure rod, the magnetic flux density of the simulated magnetic core rod 6 is greatly improved.

[0054] In another embodiment of the present invention, a steel structure rod at the upper part of the closed tower window steel structure model 4 is removed to put the external magnetic circuit in a non-closed state, forming a non-closed tower window steel structure model 4, and the simulated magnetic core rod 6 and the steel structure rod 5 are kept short-circuited in parallel. Simulation calculation shows that the magnetic flux density of the simulated magnetic core rod 6 at this time is 15mT. By comparison, it is found that the magnetic circuit defect state has little effect on the magnetic flux density result in the simulated magnetic core rod 6.

[0055] Therefore, according to the simulation results, when the simulated magnetic core rod 6 is short-circuited in parallel on the steel rods in the tower structure around the transmission line, the magnetic flux density in the simulated magnetic core rod 6 can be greatly improved regardless of whether the external steel magnetic circuit is closed. This shows that it is possible to connect high magnetic permeability magnetic core rods in parallel to the steel rods in the transmission tower structure to obtain magnetic field energy.

[0056] In the embodiment of the present invention, a coil for online energy supply is manufactured. First, the cross-sectional shape of the magnetic core rod is set to a rectangular cross-section in the simulation model. The magnetic flux density in the magnetic core rod under eight different conditions, namely, cross-sectional areas of 40*30mm, 40*20mm, 40*10mm, 40*5mm, 30*30mm, 30*20mm, 30*10mm, and 30*5mm, is compared. The specific results are as follows:

[0057]

[0058] Therefore, the cross-sectional area corresponding to the maximum magnetic flux density result, namely 30*5mm, is selected as the best reference standard for the actual production of the magnetic core rod. The length of the magnetic core rod in the coil is determined to be l=0.5m according to the actual installation situation.

[0059] Then, based on the optimal reference standard of 30*5mm for the cross-sectional area of ​​the magnetic core rod, different types of high magnetic permeability materials such as silicon steel, permalloy, and ferrite were made into thin sheets with a thickness h of 0.5mm and a width w of 30mm. Ten thin sheets were stacked and assembled into a magnetic core rod with a total thickness of 5mm. That is, the cross-sectional dimensions of the magnetic core rod were 30*5mm and the length was 0.5m. The number of turns of the external coil wire of the magnetic core rod was selected to be 8000 turns, and the wire diameter was 0.8mm. The coil was wound in layers, with 800 turns per layer, for a total of 10 layers. Then, the actual energy extraction effect of the magnetic core rod under the three different material groups was compared and analyzed. The specific results are as follows:

[0060] Material Type Silicon steel Permalloy Ferrite Output voltage across the coil 12.8V 8.3V 7.6V

[0061] Therefore, silicon steel was chosen as the optimal material for the coil core rod. The prepared energy-harvesting power supply coil was mounted on the steel structure of the transmission tower window using a U-shaped fixture. A series compensation circuit was then connected to the coil's output to eliminate the reactive power generated by the coil's internal resistance and self-inductance, thereby achieving maximum power transmission for the online energy supply. AC / DC and DC / DC conversion circuits were then used to stabilize the coil's output voltage at the rated DC voltage required by the transmission line online monitoring equipment, thereby providing continuous, efficient, and stable power to the equipment.

[0062] The present invention provides an online energy harvesting method for the magnetic field on the towers around the AC transmission lines, which can effectively utilize the magnetic flux energy of the steel rods in the tower window structure of the transmission towers around the AC transmission lines for online energy harvesting and power supply. This method can not only improve the power of online energy harvesting of the transmission lines, but also provide continuous and stable power supply for the online monitoring equipment of the transmission lines.

[0063] The present invention provides a method for online energy extraction from the magnetic field on the tower around the AC transmission line. The method of the present invention is applied to the field of online energy extraction and power supply technology for AC transmission lines. It can be unaffected by and restricted by the time and space environment, and at the same time can reduce the installation and maintenance costs under the traditional power supply mode and improve economic benefits.

[0064] The method for online energy extraction from the magnetic field on a tower around an AC transmission line of the present invention is applicable to AC transmission lines of various voltage levels and has broad application prospects in the future.

[0065] In the present invention, in step 1, for the case of multiple split conductors in the transmission line, when establishing a three-phase transmission conductor model, it is necessary to equate the multiple split conductors of each phase to one conductor, wherein the calculation method of the equivalent conductor radius Req is:

[0066]

[0067] Where m is the number of split conductors of each phase; r is the radius of each sub-conductor of the split conductor; d 1k It is the distance between the first and kth sub-conductors in each phase split conductor.

[0068] In the present invention, in step 3, the cross-sectional shape of the simulated magnetic core rod 6 is adjusted to perform simulation, and the solution with the maximum magnetic flux density of the simulated magnetic core rod 6 is taken as the cross-sectional shape of the magnetic core rod for actual application.

[0069] The cross-sectional shape of the simulated magnetic core rod 4 includes but is not limited to a rectangle, a square, a circle or an ellipse.

[0070] In the embodiment of the present invention, the cross-sectional shape of the simulated magnetic core rod 6 is assumed to be rectangular for simulation.

[0071] In the present invention, in step 3, when the cross-sectional shape of the simulated magnetic core rod 6 is a rectangle, the cross-sectional parameters and height of the simulated magnetic core rod 6 are adjusted, and the scheme with the largest change in the magnetic flux density of the simulated magnetic core rod 6 is taken as the preferred scheme, and the cross-sectional parameters and height of the magnetic core rod used in actual application are used.

[0072] In the present invention, the length of the simulated magnetic core rod 6 is 28-42 cm and the width is 5-30 mm.

[0073] In the present invention, in step 3, simulation is performed by adjusting the distance between the simulated magnetic core rod 6 and the closed tower window steel structure, and the solution with the largest change in magnetic flux density of the simulated magnetic core rod 6 is taken as the distance between the simulated magnetic core rod 6 and the closed tower window steel structure for actual application. Usually, the distance between the simulated magnetic core rod 6 and the closed tower window steel structure is 0.1-0.2m.

[0074] After testing, the cross-sectional width w of the magnetic core rod is preferably 40mm and 30mm. The specific cross-sectional area of ​​the magnetic core rod is determined according to simulation analysis. The cross-sectional area of ​​the magnetic core rod in the simulation model mainly considers eight different situations, namely 40*30mm, 40*20mm, 40*10mm, 40*5mm, 30*30mm, 30*20mm, 30*10mm, and 30*5mm. That is, the magnetic flux density in the magnetic core rods under different cross-sectional areas in the simulation model is compared, and the cross-sectional area corresponding to the maximum magnetic flux density result is selected as the best reference standard for the actual production of the magnetic core rod. The specific value of the length l of the magnetic core rod in the coil is determined according to the actual installation situation.

[0075] In step 4, the material of the magnetic core rod actually used includes but is not limited to silicon steel, permalloy, and ferrite.

[0076] In the present invention, according to the obtained optimal reference standard for the cross-sectional area of ​​the magnetic core rod, different types of high magnetic permeability materials are made into thin sheets with a thickness h of 0.4-0.6 mm. The width w of the thin sheet is based on the optimal cross-sectional parameters determined by finite element simulation. According to the different numbers of thin sheets, magnetic core rods with different cross-sectional areas can be assembled, and the assembled magnetic core rods are automatically tightened and fixed by winding a coil on the outside.

[0077] For example, when the cross-sectional shapes of the simulated magnetic core rod 6 and the measured magnetic core rod are rectangular, the width and length of the simulated magnetic core rod 6 are adjusted, and the scheme with the largest change in the magnetic flux density of the simulated magnetic core rod 6 is taken as the preferred scheme, and the width and length of the simulated magnetic core rod 6 are used for the thin film.

[0078] The coil wire has 8000 turns and is made of enameled wire with a diameter of 0.8 mm. The coil is wound in layers, with 800 turns per layer, for a total of 10 layers.

[0079] In the present invention, the magnetic core rod used in actual application is clamped and fixed to the steel structure rod by a U-shaped clamp, and the selected steel structure rod position can be any steel structure rod in the tower window structure of the transmission tower.

[0080] In the present invention, by adjusting the material of the magnetic core rod and comparing and analyzing the energy extraction effects of the magnetic core rods in actual application under different materials, the material with the largest output voltage at both ends of the coil is finally selected as the preferred solution.

[0081] The present invention also provides an online energy harvesting device for a magnetic field on a tower around an AC transmission line, comprising:

[0082] The magnetic core rod is short-circuited in parallel with the steel structure rod in the tower window of the target transmission tower;

[0083] The coil is wound on the magnetic core rod;

[0084] Among them, a series compensation circuit is connected to the output end of the coil to compensate and eliminate the reactive power generated by the internal resistance and self-inductance of the coil to achieve maximum power transmission for online energy supply, and then the output voltage of the coil is stabilized at the rated DC voltage required by the online monitoring equipment of the transmission line through an AC / DC or DC / DC conversion circuit.

[0085] In summary, during the safe and stable operation of AC transmission lines, there is an alternating magnetic field in the air around the transmission lines and on the towers, and the magnetic field energy contained therein is relatively stable. The present invention uses this magnetic field energy for online energy extraction, which is not only not affected and restricted by external factors such as weather, but also can reduce the installation and maintenance costs under traditional power supply methods. In addition, the magnetic field energy around the transmission lines does not require additional consumption of other energy sources, and can achieve self-sufficiency in the electrical energy of the online monitoring equipment of the transmission lines, and has broad application prospects in the future.

[0086] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for online energy extraction from magnetic fields on towers around AC transmission lines, characterized in that: The following steps are involved: Step 1: Based on the actual operating parameters of the AC transmission line on the target transmission tower, establish finite element models of the A-phase, B-phase, and C-phase transmission conductors. The B-phase and C-phase transmission conductors are located on both sides of the A-phase transmission conductor, and set the current excitation magnitude and relative magnetic permeability of the three-phase transmission conductors. Step 2: Obtain the tower window structural parameters of the target transmission tower, determine whether the tower window is closed, and establish a closed or non-closed tower window steel structure model around the A-phase transmission conductor based on the determination result; Step 3: Short-circuit a simulated magnetic core rod in parallel within the closed or open tower window steel structure model and at a certain distance from the steel structure rod, set the relative magnetic permeability corresponding to the closed or open tower window steel structure model and the simulated magnetic core rod, and simulate and calculate the magnetic flux density result of the simulated magnetic core rod; Step 4: Fabricate a magnetic core rod with a coil wound around it for practical online energy supply applications. Short-circuit the rod in parallel with the steel structure in the tower window of the target transmission tower. Connect a series compensation circuit to the output end of the coil. Calculate the coil output voltage based on the magnetic flux density of the simulated core rod. Then, use a conversion circuit to stabilize the coil output voltage at the rated DC voltage required by the transmission line online monitoring equipment. In step 2, if the tower window of the target transmission tower is closed, a closed tower window steel structure model is established around the A-phase transmission conductor to form a closed external magnetic circuit. The closed tower window steel structure model includes multiple steel rods connected end to end to form a loop. If the tower window of the target transmission tower is not closed, a non-closed tower window steel structure model is established around the A-phase transmission conductor to form a non-closed external magnetic circuit. The non-closed tower window steel structure model includes multiple steel rods, one of which is disconnected from another.

2. The method for online energy extraction from magnetic fields on towers around AC transmission lines according to claim 1, characterized in that: In step 1, for the case of multiple split conductors in the transmission line, when establishing a three-phase transmission conductor model, it is necessary to equate the multiple split conductors of each phase to a single conductor, where the calculation method of the equivalent conductor radius Req is: in, is the number of splits of each phase conductor; is the radius of each sub-conductor of the split conductor; It is the distance between the first and kth sub-conductors in each phase split conductor.

3. The method for online energy harvesting from magnetic fields on towers surrounding AC transmission lines according to claim 1, characterized in that: In step 3, the cross-sectional shape of the simulated magnetic core rod includes but is not limited to a rectangle, a square, a circle or an ellipse; and When the cross-sectional shape of the simulated magnetic core rod is a rectangle, the cross-sectional parameters and height of the simulated magnetic core rod are adjusted, and the solution with the maximum magnetic flux density of the simulated magnetic core rod is taken as the cross-sectional parameters and height of the magnetic core rod for actual application.

4. The method for online energy extraction from magnetic fields on towers around AC transmission lines according to claim 3, characterized in that: The length of the simulated magnetic core rod is 28-42 cm, and the width is 5-30 mm.

5. The method for online energy extraction from magnetic fields on towers around AC transmission lines according to claim 1, characterized in that: In step 4, the material of the magnetic core rod actually used includes but is not limited to silicon steel, permalloy, and ferrite.

6. The method for online energy extraction from magnetic fields on towers around AC transmission lines according to claim 5, characterized in that: The coil wire has 8000 turns and is made of enameled wire with a diameter of 0.8 mm. The coil is wound in layers, with 800 turns per layer, for a total of 10 layers.

7. The method for online energy extraction from magnetic fields on towers around AC transmission lines according to claim 6, characterized in that: The magnetic core rod used in actual application is clamped and fixed to the steel structure rod by a U-shaped clamp, and the selected steel structure rod position can be any steel structure rod in the tower window structure of the transmission tower.

8. The method for online energy extraction from magnetic fields on towers around AC transmission lines according to claim 6, characterized in that: Adjust the material of the magnetic core rod, compare and analyze the energy extraction effect of the magnetic core rods in actual application under different materials, and finally select the material with the largest output voltage at both ends of the coil.

9. An online energy harvesting device for magnetic field on a tower around an AC transmission line, characterized in that: According to any one of claims 1 to 8, the device comprises: The magnetic core rod is short-circuited in parallel with the steel structure rod in the tower window of the target transmission tower; The coil is wound on the magnetic core rod; Among them, a series compensation circuit is connected to the output end of the coil to compensate and eliminate the reactive power generated by the internal resistance and self-inductance of the coil to achieve maximum power transmission for online energy supply, and then the output voltage of the coil is stabilized at the rated DC voltage required by the online monitoring equipment of the transmission line through the conversion circuit.

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