Magnetic negative stiffness energy trap device for vibration reduction of power transmission line

Abstract

The utility model discloses a magnetic force negative stiffness energy trap device for vibration reduction of a power transmission line, which comprises a power transmission line, a vibration reduction inhaul cable and power transmission towers, and the power transmission line is suspended between the power transmission towers; the upper end of the vibration reduction inhaul cable is connected with the power transmission line, the vibration reduction inhaul cable bypasses a fixed pulley fixed on the power transmission tower, and the lower end is connected with the negative stiffness energy trap device; the negative stiffness energy trap device comprises a positive stiffness line spring II, a steel bar, an inner magnetic ring, an outer magnetic ring, a positive stiffness line spring I and a pre-tightening device; the lower end of the vibration reduction inhaul cable is connected with the upper end of a steel bar through a positive stiffness line spring II, the steel bar is provided with a plurality of circular permanent magnets and an inner magnetic ring, and copper sleeves are arranged on the outer sides of the permanent magnets. The outer magnetic ring is arranged outside the inner magnetic ring; the lower end of the steel bar is connected with the pre-tightening device through the positive stiffness linear spring I; the device is simple in structure and low in cost, the inherent space of the bottom of the power transmission tower is fully utilized, external space resources are not occupied, and the functions of low-frequency vibration absorption and energy consumption vibration reduction can be achieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of overhead power transmission lines, and in particular relates to a magnetic negative stiffness energy sink device used for vibration reduction of power transmission lines. Background Art

[0002] Overhead transmission lines are large-span flexible structures. Under extreme environmental loads such as strong winds, earthquakes and deicing, the lines will produce large low-frequency dancing, which can cause phase-to-phase flashover tripping, hardware damage, and even serious accidents such as line breakage and tower collapse. Traditional anti-dancing and vibration reduction measures such as anti-vibration hammers and detuned pendulums are all developed for a specific excitation mechanism, and their anti-dancing and vibration reduction effects have great limitations. Aiming at the low-frequency dancing characteristics of transmission lines, the utility model proposes a new magnetic negative stiffness energy sink device with low-frequency energy dissipation and vibration reduction function. The device not only realizes the built-in installation of damping on the transmission line, but also has the dual anti-dancing functions of low-frequency energy dissipation and flexible cable constraint. Summary of the invention

[0003] In order to solve the above technical problems, the utility model provides a magnetic negative stiffness energy sink device for transmission line vibration reduction, which has a simple structure, low cost and low-frequency energy consumption and vibration reduction function.

[0004] The technical solution adopted by the utility model is: a magnetic negative stiffness energy sink device for transmission line vibration reduction, comprising a transmission line, a vibration reduction cable and a transmission tower, wherein the transmission line is suspended between the transmission towers; the characteristic is that the upper end of the vibration reduction cable is connected to the transmission line, the vibration reduction cable passes around a fixed pulley fixed on the transmission tower, and the lower end is connected to the negative stiffness energy sink device; the negative stiffness energy sink device comprises a positive stiffness wire spring II, a steel rod, a permanent magnet, a copper sleeve, an inner magnetic ring, an outer magnetic ring, a positive stiffness wire spring I and a preload device; the lower end of the vibration reduction cable is connected to the transmission line by the positive stiffness wire spring Ⅱ connects the upper end of the steel rod, on which a plurality of circular permanent magnets are arranged, a gap is left between two adjacent permanent magnets, and the two adjacent permanent magnets are arranged with the same poles facing each other; a copper sleeve is provided on the outer side of the permanent magnet; the copper sleeve is fixed on the steel section of the transmission tower; an inner magnetic ring is fixedly installed on the steel rod, the inner magnetic ring is located below the permanent magnet, and the outer magnetic ring is arranged on the outer side of the inner magnetic ring, the inner magnetic ring is coaxial with the outer magnetic ring, and a gap is left between the inner magnetic ring and the outer magnetic ring; the lower end of the steel rod is connected to the preload device through a positive stiffness wire spring I; the preload device, the outer magnetic ring, and the copper sleeve are fixed on the steel section of the transmission tower.

[0005] Furthermore, the permanent magnet is coaxial with the copper sleeve.

[0006] Furthermore, a plastic nut is provided between two adjacent permanent magnets on the steel rod.

[0007] Furthermore, the connection between the vibration-damping cable and the transmission line is treated with a metal insulator.

[0008] The working principle of the utility model is as follows: when the transmission line vibrates, the vibration reduction cable connected thereto will drive the steel rod in the vibration reduction device to vibrate up and down, so the permanent magnet fixed on the steel rod moves up and down in the copper sleeve. When the permanent magnet and the copper sleeve move relative to each other, the copper sleeve, as a conductor tube, cuts the radial magnetic induction line of the permanent magnet to generate an induced current, i.e., an eddy current. Since the conductor tube has resistance, the electric energy is eventually converted into heat energy and consumed. The eddy current damper can achieve the effect of energy consumption and vibration reduction; at the same time, as the mass rod vibrates up and down, the inner magnetic ring will leave the equilibrium position (its vibration amplitude does not exceed the height of the outer magnetic ring), and the outer magnetic ring generates a repulsive force on the inner magnetic ring to form a negative stiffness. The magnetic negative stiffness spring is connected in parallel with the positive stiffness line spring I and the positive stiffness line spring II, and its synthetic stiffness can take any small value, so the oscillator frequency of the vibration reduction device can be as low as to match the dancing frequency of the transmission line, meeting its functional requirements of low-frequency vibration absorption and energy consumption and vibration reduction.

[0009] Compared with the prior art, the utility model has the following beneficial effects:

[0010] (1) The utility model has a simple structure and low cost. It fully utilizes the inherent space at the bottom of the transmission tower and does not occupy external space resources.

[0011] (2) The utility model transmits the vibration energy of the transmission line through the vibration-damping cable, effectively solving the problem of damping energy dissipation and vibration reduction of the large-span flexible structure.

[0012] (3) The negative stiffness and positive stiffness of the utility model are connected in parallel, and the combined stiffness can take an arbitrarily small value. Therefore, the frequency of the steel rod can be as low as to match the dancing frequency of the transmission line, meeting its functional requirements of low-frequency vibration absorption and energy-consuming vibration reduction.

[0013] (4) The utility model has the typical characteristics of low dynamic stiffness and high static stiffness, avoiding the problems of excessive deformation and insufficient stability caused by using high-flexibility springs.

[0014] (5) In the present invention, as the amplitude increases, the negative stiffness of the magnetic spring gradually decreases, while the positive stiffness of the wire spring remains unchanged. The total synthetic stiffness increases nonlinearly with the increase of the amplitude. Therefore, the vibration reduction device has instantaneous resonance capture and targeted energy transfer mechanisms. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural diagram of the utility model.

[0016] Figure 2 It is a structural diagram of the negative stiffness energy sink device of the utility model. DETAILED DESCRIPTION

[0017] The utility model is further described below in conjunction with the accompanying drawings.

[0018] like Figure 1-2 As shown, the utility model includes a transmission tower 1, a vibration-damping cable 3 and a transmission line 2, and the transmission line 2 is suspended between the transmission towers 1. The upper end of the vibration-damping cable 3 is connected to the transmission line 2, and the connection is insulated and meets electrical requirements. The vibration-damping cable 3 passes around a fixed pulley 4 fixed on the transmission tower 1; the lower end of the vibration-damping cable 3 is connected to a negative stiffness energy sink device 5 at the bottom of the transmission tower 1.

[0019] like Figure 2 As shown, the magnetic negative stiffness energy sink device 5 includes a steel section 501 of a transmission tower, a positive stiffness wire spring II 502, a steel rod 503, a copper sleeve 504, an inner magnetic ring 509, an outer magnetic ring 508, a positive stiffness wire spring I 511 and a pre-tightening device 512. The copper sleeve 504 is fixed to the steel section 501 of the transmission tower through two clamps I 507, and the outer magnetic ring 508 is fixed to the steel section 501 of the transmission tower through a clamp II 510; the pre-tightening device 512 is fixed to the steel section 501 of the transmission tower through a clamp III 513. The outer magnetic ring 508 is located below the copper sleeve 504, and the pre-tightening device 512 is located below the outer magnetic ring 508.

[0020] The lower end of the vibration-damping cable 3 is connected to the upper end of the steel rod 503 through a positive stiffness wire spring II 502. The steel rod 503 is provided with a plurality of circular permanent magnets 505 and an inner magnetic ring 509. A plastic nut 506 is provided between two adjacent permanent magnets 505, and the two adjacent permanent magnets 505 are arranged with the same poles facing each other, so that there is a repulsive force between the two adjacent permanent magnets 505. A copper sleeve 504 is provided on the outer side of the permanent magnet 505, and the permanent magnet 505 is coaxial with the copper sleeve 504. The inner magnetic ring 509 is located below the permanent magnet 505, and the outer magnetic ring 508 is arranged on the outer side of the inner magnetic ring 509. The inner magnetic ring 509 is coaxial with the outer magnetic ring 508, and a gap is left between the inner magnetic ring 509 and the outer magnetic ring 508. The lower end of the steel rod 503 is connected to the preload device 512 through a positive stiffness wire spring I 511.

Claims

1. A magnetic negative stiffness energy sink device for transmission line vibration reduction, comprising a transmission line, a vibration reduction cable and a transmission tower, wherein the transmission line is suspended between the transmission towers; characterized in that: The upper end of the vibration-damping cable is connected to the transmission line, the vibration-damping cable is passed around the fixed pulley fixed on the transmission tower, and the lower end is connected to the negative stiffness energy sink device; the negative stiffness energy sink device includes a positive stiffness wire spring II, a steel rod, a permanent magnet, a copper sleeve, an inner magnetic ring, an outer magnetic ring, a positive stiffness wire spring I and a preload device; the lower end of the vibration-damping cable is connected to the upper end of the steel rod through the positive stiffness wire spring II, and the steel rod is provided with a plurality of circular permanent magnets, and there is a gap between two adjacent permanent magnets. A gap is left, and two adjacent permanent magnets are arranged opposite to each other with the same poles; a copper sleeve is provided on the outer side of the permanent magnet; the copper sleeve is fixed on the steel section of the transmission tower; an inner magnetic ring is fixedly installed on the steel rod, the inner magnetic ring is located below the permanent magnet, and the outer magnetic ring is arranged on the outer side of the inner magnetic ring, the inner magnetic ring is coaxial with the outer magnetic ring, and a gap is left between the inner magnetic ring and the outer magnetic ring; the lower end of the steel rod is connected to the preload device through a positive stiffness wire spring I; the preload device, the outer magnetic ring, and the copper sleeve are fixed on the steel section of the transmission tower.

2. The magnetic negative stiffness energy sink device for transmission line vibration reduction according to claim 1, characterized in that: The permanent magnet is coaxial with the copper sleeve.

3. The magnetic negative stiffness energy sink device for transmission line vibration reduction according to claim 1, characterized in that: A plastic nut is arranged between two adjacent permanent magnets on the steel rod.

4. The magnetic negative stiffness energy sink device for transmission line vibration reduction according to claim 1, characterized in that: The connection between the vibration-damping cable and the transmission line is processed with a metal insulator.

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