A power transmission conductor negative stiffness damper

Abstract

The present application provides a kind of transmission conductor negative stiffness damper, provides damping by another connection damper, negative stiffness device increases damping ratio, realizes conductor model damping effect;Main components are arranged side by side by fixed magnet and movable magnet, the interaction force between its magnets is basically linear increase, that is, it can guarantee constant negative stiffness value, damping effect is obvious and model loss is small, and durability is strong;Light weight, convenient transportation, easy to install and maintain;Transmission conductor negative stiffness damper is rigidly connected with insulator string as a whole, and can effectively transmit the vibration of conductor galloping;The present application is novel and unique in design, has wide range of application, and has good popularization and application value and economic benefits.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power systems, and relates to a negative stiffness damper for a power transmission conductor. BACKGROUND

[0002] With the increasing expansion of the power grid construction scale in China, the large-amplitude galloping of conductors is prone to cause mixed line short circuit, flashover trip, suspension insulator clamp slip, line hardware wear, spacer rod fracture and separation of current-carrying lines and jumper lines, which seriously affects the daily operation of the power grid and even causes major economic losses. In this realistic background, it is of great significance to carry out in-depth and effective research on the galloping prevention and control of power transmission lines.

[0003] At present, the devices, components and dampers in engineering practical applications are basically of positive stiffness, and negative stiffness is relatively rare, and usually requires certain reasonable structures to achieve. When the ratio of load increment to deformation increment is positive, the component is of positive stiffness, and when the directions of load increment and deformation increment are opposite, the ratio is negative, that is, the component is of negative stiffness. Figure 1 As shown in the load-displacement relationship of a special component, in the ab section of the curve, the ratio of load increment to displacement increment is positive, and the component is of positive stiffness; in the bc section of the curve, with the increase of displacement, the load decreases instead, the ratio of load increment to displacement increment is negative, and the stiffness of the component is negative at this time; in the cd section of the curve, with the increase of displacement, the load hardly changes, the ratio of load increment to displacement increment is 0, and the stiffness of the component is zero at this time; and in the de section of the curve, the ratio of load increment to deformation increment is positive again, and the component becomes a positive stiffness component again.

[0004] The direct cause of the galloping of the power transmission line is that the total damping ratio of the conductor is less than zero, that is, the absolute value of the aerodynamic negative damping ratio is greater than the structural damping ratio, so it is targeted to solve the conductor galloping problem by improving the structural damping ratio of the conductor line. According to the research, the negative stiffness damper (NSD) can play a better vibration reduction and energy dissipation effect than the traditional viscous damper and viscoelastic damper, can greatly improve the equivalent damping ratio of the system, and the negative stiffness damper (NSD) is less affected by the installation position of the damper, so the advantages of the negative stiffness damper (NSD) are very obvious. The damping vibration reduction technology has a good anti-galloping prospect for applying damping to the iced conductor, and the negative stiffness damper (NSD) is arranged near the tension tower to provide additional damping for the line system, so as to improve the structural modal damping ratio of the whole system and achieve the effect of inhibiting the galloping of the conductor. SUMMARY

[0005] The application aims at the problems in the background art, and provides a negative stiffness damper for a power transmission conductor.

[0006] To this end, the above object of the present application is achieved by the following technical solutions:

[0007] A power transmission conductor negative stiffness damper, characterized in that the power transmission conductor negative stiffness damper comprises a negative stiffness device and another damper;

[0008] The negative stiffness device comprises a fixed slot, the fixed slot comprises two oppositely arranged side plates and a plurality of limiting bolts connecting the two side plates, a plurality of fixed magnets are arranged on the inner side walls of the side plates of the fixed slot; a middle mechanism with a movable magnet is arranged between the plurality of fixed magnets; the upper end of the middle mechanism is hung on the insulator string of the power transmission conductor through a rigid connecting piece; the middle mechanism moves up and down in the space between the fixed magnets and always does not slide out of the fixed slot; the negative stiffness device increases the structural damping ratio by using the negative stiffness principle to achieve the effect of suppressing conductor galloping.

[0009] At least three fixed magnets are arranged on the single side plate of the fixed slot from top to bottom, the magnetic poles of the fixed magnet at the middle height position are opposite to those of the fixed magnets at the upper and lower sides, the magnetic poles of the fixed magnets on the other side plate of the fixed slot are opposite to those of the corresponding fixed magnets, and the magnetic poles of the movable magnet are the same as those of the fixed magnet at the middle height position;

[0010] The other damper is connected in parallel or in series with the rigid connecting piece on the negative stiffness device to provide damping.

[0011] While the above technical solutions are adopted, the present application can also adopt or combine the following technical solutions:

[0012] As a preferred technical solution of the present application: the middle mechanism comprises an upper baffle, a lower baffle, a movable magnet between the upper baffle and the lower baffle, and a vertical force transmission rod connected to the top of the upper baffle; the vertical force transmission rod is connected in parallel with the other damper or directly connected in series with the other damper through a horizontal force transmission rod;

[0013] A connecting plate connecting the upper baffle and the lower baffle is arranged between the upper baffle and the lower baffle, and the movable magnet is fixed on the connecting plate.

[0014] As a preferred technical solution of the present application: at least one slide rod is further arranged in the fixed slot of the power transmission conductor negative stiffness damper, both ends of the slide rod are sleeved on the limiting bolts through fixing members, and the upper baffle and the lower baffle are arranged on the slide rod so that the movable magnet moves up and down in the fixed slot.

[0015] As a preferred technical solution of the present application:

[0016] When the slide rod is one, the movable magnet is arranged on both sides of the slide rod;

[0017] When the slide bar is two, the movable magnet is arranged between the two slide bars.

[0018] When the slide bar is more than two, the movable magnet is arranged in a spaced form with the slide bar.

[0019] As a preferred technical scheme of the present application, the fixed member has horizontal bolt holes and vertical bolt holes, the fixed member is connected with the slide bar through the vertical bolt holes, and a limiting bolt is passed through the horizontal bolt holes of the fixed member.

[0020] As a preferred technical scheme of the present application, the length and width of the side of the movable magnet facing the side plate are respectively less than the length and width of the corresponding surface of the fixed magnet.

[0021] As a preferred technical scheme of the present application, the fixed magnet is a permanent magnet or an electromagnetic body.

[0022] The movable magnet is a permanent magnet or an electromagnetic body.

[0023] As a preferred technical scheme of the present application, the movable magnet comprises at least one magnet; when the movable magnet is multiple, the magnetic poles of the contact surfaces of the adjacent two movable magnets are different, and the end surfaces of all the movable magnets facing the fixed magnet are in the same plane.

[0024] As a preferred technical scheme of the present application, the horizontal distance between the end surface of the movable magnet facing the fixed magnet and the two side fixed magnets is the same, so that the movable magnet is in the central position of the two side fixed magnets.

[0025] As a preferred technical scheme of the present application, the other damping device is an eddy current damper or an oil damper.

[0026] The present application provides a power transmission conductor negative stiffness damper, which provides damping through another damping device, and a negative stiffness device increases the damping ratio to achieve the damping effect of the conductor model. The main components are arranged side by side through the fixed magnet and the movable magnet, the interaction force between the magnets is basically linearly increased, that is, the constant negative stiffness value can be guaranteed, the damping effect is obvious, the model loss is small, and the durability is strong. The power transmission conductor negative stiffness damper is light in weight, convenient to transport, and easy to install and maintain. The overall power transmission conductor negative stiffness damper is rigidly connected with the insulator string, and can effectively transmit the galloping vibration of the conductor. The present application has novel and unique design, wide application range, good popularization and application value, and good economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is the load-displacement curve of the positive, negative and zero stiffness components.

[0028] Figure 2 It is the front view of the power transmission conductor negative stiffness damper provided by the present application.

[0029] Figure 3 is a perspective view of a power transmission conductor stiffness damper.

[0030] Figures 4a-4c is a diagram of a negative stiffness device; wherein: Figure 4a is a front view of a negative stiffness device, Figure 4b is a side view of a negative stiffness device, Figure 4c is a perspective view of a negative stiffness device.

[0031] Figure 5 is an exploded view of a fixing groove without a limiting bolt.

[0032] Figure 6a , Figure 6b are respectively a front view and a perspective view of a middle mechanism.

[0033] Figure 7 is a schematic diagram of an arrangement of a fixed magnet and a movable magnet.

[0034] Figures 8a-8c are respectively a diagram of a sliding rod, a limiting bolt and a fixing member; wherein: Figure 8a is a connection relationship of a sliding rod, a limiting bolt and a fixing member, Figure 8b is a perspective view of a sliding rod, Figure 8c is a perspective view of a fixing member.

[0035] Figures 9a-9c is a diagram of a rigid connecting piece; wherein: Figure 9a is a perspective view of a vertical force transmission rod, Figure 9b is a perspective view of a horizontal force transmission rod, Figure 9c is a perspective view of a right-angle connecting piece.

[0036] Figure 10 is a variation law of a dynamic characteristic of a conductor-damper system with different line sag parameters of a negative stiffness damper (NSD) (K<0) and a traditional viscous damper (K=0), a viscoelastic damper (K>0) with a variation of an inner stiffness of the damper; wherein: Figures 10a-10c respectively show a variation of a maximum first-order damping ratio, an optimal damping coefficient and a first-order natural frequency of a system with a variation of an inner stiffness of the damper when the damper is symmetrically installed at positions of xdl=xd2=L / 10 from both ends of the conductor. DETAILED DESCRIPTION

[0037] The application is described in further detail with reference to the drawings and specific embodiments.

[0038] A power transmission conductor negative stiffness damper comprises a fixing groove 1, a middle mechanism 2, a sliding rod 3, a fixing member 4, another connecting damper 5, a rigid connecting piece 6 and a tension sensor 7.

[0039] The negative stiffness device comprises a fixed groove 1, a middle mechanism 2, a sliding rod 3, and a fixed component 4.

[0040] The fixed groove 1 comprises left and right side plates 101, and a limiting bolt 102 forms an internal space. Limiting holes 103 are arranged on the four corners of the left and right side plates 101, respectively. A limiting hole 104 is arranged in a central position area for fixing a fixed magnet 105 in the central position. In this embodiment, three pairs of fixed magnets are arranged. Limiting holes 106 / 107 are arranged in the symmetric position area for fixing the remaining two pairs of fixed magnets 108 / 109.

[0041] The middle mechanism 2 is composed of upper and lower baffles 201 / 202 and a connecting plate 203. A movable magnet 204 is fixed on the middle plate through a bolt 205. The upper and lower baffles 201 / 202 are provided with holes 206. The upper baffle 201 is connected to another damper 5 through a rigid connecting piece 6.

[0042] The sliding rod 3 is provided with threads 301 / 302 at the upper and lower ends.

[0043] The fixed component 4 is provided with vertical screw holes 401 and horizontal threads 402. The vertical screw holes are used to connect the sliding rod, and the horizontal threads 402 are used to connect the limiting bolt.

[0044] The rigid connecting piece 6 comprises a vertical force transmission rod 601, a horizontal force transmission rod 602, a right-angle connecting piece 603, and a middle connecting head 604. The vertical force transmission rod is provided with bolt holes 605 at the upper and lower end areas, and is connected to the horizontal force transmission rod through the right-angle connecting piece 603 and a bolt 606. The horizontal force transmission rod is provided with bolt holes 607 at both ends, and is connected to the vertical force transmission rod through the right-angle connecting piece and the bolt. A bolt hole 608 is arranged in the middle, and is connected to a tension sensor 7 and the middle connecting head 604. Wire vibration is transmitted to the horizontal force transmission rod through the middle connecting head, and then is transmitted to the vertical force transmission rod, so that the negative stiffness device and another damper 5 start to work.

[0045] In this embodiment, the left and right side plates 101 of the fixed groove are adjusted by the limiting bolt 102 to adjust the plate spacing between the two side plates. Of course, in other embodiments, a sliding rail or the like can be arranged to adjust the plate spacing.

[0046] In this embodiment, as shown in FIG. 2, three pairs of fixed magnets and one movable magnet are arranged side by side. Of course, in other embodiments, the number of magnets can be changed or the magnets can be arranged axially to achieve different negative stiffness values, so as to meet different requirements. In other embodiments, for example, more than three pairs of magnets are arranged. The magnetic poles of the fixed magnet in the middle position are opposite to the magnetic poles of the fixed magnets above and below the fixed magnet. Figure 7

[0047] ​In this embodiment, an independently developed eddy current damper was selected as the additional damper, which is connected in parallel with two negative stiffness devices via a horizontal force transmission rod. Of course, in other embodiments, the type, number, and connection method of the additional damper can be changed, such as by embedding two oil dampers within the negative stiffness device, to adapt to different requirements.

[0048] The following specific experiments verify the effect of the negative stiffness damper for transmission lines described in this invention. Figure 10 shows the dynamic characteristics of the conductor-damper system with different line sag parameters for the negative stiffness damper (NSD) (K<0), the traditional viscous damper (K=0), and the viscoelastic damper (K>0) as the damper internal stiffness changes. Figures 10a-10c The figures show the variations in the system's maximum first-order damping ratio, optimal damping coefficient, and first-order natural frequency with respect to the damper's internal stiffness when the dampers are symmetrically installed at distances of xd1 = xd2 = L / 10 from both ends of the conductor. In the figures, λ is a dimensionless line sag parameter reflecting the sag and tensile properties of the stay cable, calculated using the following formula:

[0049] λ=(mgL / T) 2 ·(EAL / TL e )

[0050] L e =L[1+8(f / L)] 2 ]

[0051] like Figure 10a As shown, when the damper stiffness is greater than 0, the first-order maximum damping ratio of the conductor-damper system decreases, indicating that the viscous damper (K=0) has a better effect on improving the first-order damping ratio than the viscoelastic damper (K>0). When the damper stiffness is negative, i.e., K<0, the damper's effect on improving the first-order equivalent damping ratio of the system is significantly increased compared to the viscous damper, and there exists an optimal negative stiffness Kopt that allows the first-order damping ratio of the system to reach its maximum. The negative stiffness damper can increase the first-order damping ratio to approximately 100 times that of the original line structure, while the traditional rotating spacer only increases the damping ratio to approximately 25 times that of the original structure. Figure 10b It can be seen that at the optimal negative stiffness Kopt, the optimal damping coefficient of the damper is also the smallest when the damper reaches its first-order maximum damping ratio. And... Figure 10c The results show that when a negative stiffness damper (NSD) is used to reduce the vibration of the conductor (i.e., K<0), the first natural frequency of the system will be significantly lower than that of a viscous damper. A lower natural frequency means less damage to the conductor and can minimize the possibility of conductor breakage due to galloping.

[0052] The above detailed description is merely exemplary in nature and is not intended to limit the application as described herein. Any modification or equivalent arrangement within the spirit or scope of the application should be considered to fall within the scope of the application.

Claims

1. A negative stiffness damper for power transmission lines, characterized in that: The negative stiffness damper for the transmission line includes a negative stiffness device and an additional damper. The negative stiffness device includes a fixing groove, which comprises two oppositely arranged side plates and multiple limiting bolts connecting the two side plates. Multiple oppositely arranged fixed magnets are respectively provided on the inner sidewalls of the side plates of the fixing groove. A central mechanism with movable magnets passes through the multiple oppositely arranged fixed magnets. The upper end of the central mechanism is hung on the insulator string of the transmission line via a rigid connector. The central mechanism moves up and down within the space between the fixed magnets and never slides out of the fixing groove. At least three fixed magnets are arranged sequentially from top to bottom on one side plate of the fixed groove. The magnetic poles of the fixed magnet at the middle height position are opposite to the magnetic poles of the fixed magnets on the upper and lower sides. The magnetic poles of the fixed magnets on the other side plate of the fixed groove are opposite to the magnetic poles of the corresponding fixed magnets. At the same time, the magnetic poles of the movable magnets are the same as the magnetic poles of the fixed magnets at the middle height position. The additional damper is connected in parallel or in series with the rigid connector on the negative stiffness device to provide damping; The central mechanism includes an upper baffle, a lower baffle, a movable magnet located between the upper and lower baffles, and a vertical force transmission rod connected to the top of the upper baffle; the vertical force transmission rod is connected in parallel with another damper via a horizontal force transmission rod or directly in series with another damper; A connecting plate is provided between the upper baffle and the lower baffle to connect the upper baffle and the lower baffle, and a movable magnet is fixed on the connecting plate; The fixed groove of the negative stiffness damper of the transmission line is also provided with at least one sliding rod. The two ends of the sliding rod are sleeved onto the limiting bolt through the fixing component. The upper baffle and the lower baffle are inserted into the sliding rod so that the movable magnet can move up and down in the fixed groove. The length and width of the side of the movable magnet facing the side plate are smaller than the length and width of the corresponding side of the fixed magnet, respectively.

2. The negative stiffness damper for transmission lines according to claim 1, characterized in that: When there is only one slide bar, the movable magnets are arranged on both sides of the slide bar; When there are two sliding rods, the movable magnet is arranged between the two sliding rods; When there are two or more sliding rods, the movable magnets are arranged in an alternating pattern with the sliding rods.

3. The negative stiffness damper for transmission lines according to claim 1, characterized in that: The fixing member has horizontal bolt holes and vertical bolt holes. The fixing member is connected to the slide rod through the vertical bolt holes, and the limiting bolt passes through the horizontal bolt holes of the fixing member.

4. The negative stiffness damper for transmission lines according to claim 1, characterized in that: The fixed magnet is a permanent magnet or an electromagnet; The movable magnet is a permanent magnet or an electromagnet.

5. The negative stiffness damper for transmission lines according to claim 1, characterized in that: The movable magnet includes at least one magnet; when there are multiple movable magnets, the magnetic poles of the contact surfaces of two adjacent movable magnets are opposite, and the end faces of all movable magnets facing the fixed magnet are on the same plane.

6. The negative stiffness damper for transmission lines according to claim 1, characterized in that: The end face of the movable magnet facing the fixed magnet is equidistant from the horizontal distance between the two fixed magnets on both sides, so that the movable magnet is positioned in the center of the two fixed magnets.

7. The negative stiffness damper for transmission lines according to claim 1, characterized in that: The additional damper is either an eddy current damper or an oil damper.

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