CN-121983898-A - Insulation blocking cable for controlling wind deflection displacement of extra-high voltage line and design method

CN121983898ACN 121983898 ACN121983898 ACN 121983898ACN-121983898-A

Abstract

The invention relates to the field of wind deflection control of extra-high voltage transmission lines, and discloses an insulation barrier cable for controlling wind deflection displacement of the extra-high voltage transmission lines and a design method. The blocking cable consists of an upper section, a middle section and a lower section of composite insulator and a protection hardware fitting, wherein the middle section adopts a thickened core rod and is provided with an lengthened sheath to cover the impact area of the split conductor, and the passive regulation and limit control of the non-electric variable of the wind deflection angle of the blocking cable to the conductor are realized by optimizing geometric arrangement and sectionally hinging. The wind deflection angles and blocking forces of the upper section and the lower section under different wind speeds are determined through geometric shape finding and sectional mechanical analysis, an overrun control threshold value is set by utilizing a load limiting structure formed by a load limiting bolt and a Z-shaped hanging plate, and the safe release of a stress path is realized through bolt fracture under an overload working condition, so that the iron tower is prevented from being damaged. The invention can realize the offset control under the normal state, the safety blocking under the design wind speed and the controllable falling under the extreme wind speed, and effectively improve the running stability and the reliability of the extra-high voltage circuit.

Inventors

LI PENG
ZHAO BIN
HAN JINGSHAN
LIU DINGGUO
WANG FENG
XIAO JUN
LIU CHANG
Xi Chongyu
SHI YUZHI
HUANG GUO
HAN XUEFENG
TU DEJUN
ZHU KUANJUN
LI JUNHUI
PENG BO
WANG XIULONG
JI KUNPENG

Assignees

国网电力工程研究院有限公司
国网湖南省电力有限公司超高压输电公司

Dates

Publication Date: 20260505
Application Date: 20260106

Claims (13)

1. The insulation blocking cable for controlling the wind deflection displacement of the extra-high voltage line is characterized by comprising a composite insulator and a protection hardware fitting, wherein two ends of the insulation blocking cable are respectively connected with a pole tower and a pole tower main body in an oblique bridging mode; the composite insulator comprises an upper section composite insulator, a lower section composite insulator and a middle section composite insulator rod which is positioned between the upper section composite insulator and the lower section composite insulator and has no umbrella skirt; The protection fitting comprises a load limiting bolt and a Z-shaped hanging plate which are combined to form a load limiting structure, so that rated breaking force of the protection fitting is smaller than tensile strength of the barrier rope and smaller than stress limit of hanging points of the iron tower, and the load limiting bolt breaks and enables the barrier rope to naturally sag integrally under an overload working condition, thereby avoiding secondary discharge and tower material damage.
2. The insulated barrier wire of claim 1, wherein the middle composite insulation rod is provided with an elongated sheath in the impact area to cover the impact range of the large split conductor.
3. The insulated wire for controlling windage yaw displacement of an extra-high voltage line of claim 1, wherein the load limiting structure has an upper target breaking force limit set to 40 kN.
4. The insulation barrier cable for controlling windage yaw displacement of extra-high voltage line according to claim 1, wherein the upper section composite insulator, the lower section composite insulator and the middle section composite insulator are connected by adopting a hinge.
5. The insulated barrier wire for controlling windage yaw displacement of an extra-high voltage line according to claim 1, wherein the barrier wire selects a construction hole of a tower as an upper hanging point.
6. The insulated barrier cable for controlling the windage yaw displacement of the extra-high voltage line according to claim 1, wherein the middle section composite insulating rod is thickened in diameter to adapt to a scene that the impact force of a wire is obviously increased under the condition of extra-high voltage and large span, and is matched with an lengthened sheath to realize the synergistic effect of impact resistance and insulation matching.
7. The insulated barrier wire for controlling windage yaw displacement of an extra-high voltage line of claim 2, wherein the elongated sheath has an effective length that covers an impact area of the associated split conductor such that impact energy is dissipated within the sheath and deterioration of insulation fit due to local electric field distortion is avoided.
8. A method for designing an insulation barrier cable for controlling windage yaw displacement of an extra-high voltage line, which is applicable to the insulation barrier cable for controlling windage yaw displacement of an extra-high voltage line according to any one of claims 1 to 7, and is characterized in that the method comprises the following steps: The contact process of the suspension string and the barrier rope is regarded as quasi-static balance; Respectively constructing two auxiliary circles by taking the length of the upper section composite insulator and the total length of the lower section composite insulator and the protection hardware fitting as radiuses; the stable position and the included angle of the middle section composite insulating rod are determined by translating the middle section composite insulating rod to enable two end points of the middle section composite insulating rod to be intersected with the two auxiliary circles respectively; determining the wind deflection angle of the upper section composite insulator and the lower section composite insulator according to the stable position and the included angle; calculating a blocking acting force according to the wind deflection angle; And establishing a stress equation according to a static force balance relation, and calculating to obtain the upper end tension and the lower end tension of the barrier rope and the load limiting parameters of the protection fitting according to the blocking acting force.
9. The method of claim 8, wherein determining the wind deflection angles of the upper section composite insulator and the lower section composite insulator according to the stable position and the included angle comprises calculating the wind load of the suspension string and the wind load of the wire according to the wind deflection angles obtained by geometric shape finding by adopting a standard formula, and reversely solving the blocking acting force of the blocking cable on the suspension string to be used as a boundary condition for solving the stress of the middle section of the blocking cable and the upper section and the lower section.
10. The method for designing a protective armour clamp according to claim 8, wherein the step of establishing a stress equation according to a static equilibrium relation and calculating the upper end tension, the lower end tension and the protective armour clamp load limiting parameters of the barrier cable according to the blocking acting force comprises the step of calculating the gravity, wind load, suspension string counter force and upper and lower section tension of a middle section according to the static equilibrium relation so as to obtain an analytical expression of the upper and lower section end tensions, wherein the analytical expression is used for checking the stress limits of a tower hanging point and a construction hole and determining the fracture threshold of the protective armour clamp.
11. The method of claim 8, wherein the breaking criteria of the protection hardware is set to be not lower than the safety shut-off requirement at normal operating wind speeds and lower than the tower hanging point limit.
12. The design method of claim 8, wherein the end pull calculation and the critical wind speed check are respectively carried out for the upper phase, the middle phase and the lower phase of the ultra-high voltage same-tower double-circuit line, and the load limiting sensitivity of the protection hardware is improved or the middle section geometric position is adjusted when the end pull of the upper phase and the end pull of the lower phase exceed the limit of a construction hole.
13. The method of claim 12, wherein the upper and lower end tensions do not exceed the stress limit of the tower construction hole at the designed wind speed.

Description

Insulation blocking cable for controlling wind deflection displacement of extra-high voltage line and design method Technical Field The invention belongs to the field of wind deflection control of extra-high voltage transmission lines, and particularly relates to an insulation barrier cable for controlling wind deflection displacement of an extra-high voltage transmission line and a design method. Background In the large-scale construction and operation process of the ultra-high voltage alternating current transmission line, the safety and stability of the line are always key problems of reliable power supply of a power grid. The extra-high voltage circuit has high voltage level, large span, large wire weight and obvious wind load effect, and when the extra-high voltage circuit encounters extreme weather conditions such as typhoons, strong convection and the like, the circuit insulator string and the wire are extremely easy to deviate due to the action of transverse wind force, and the phenomenon is commonly called 'windage' in the industry. When windage yaw occurs, the wire and the insulator string can deviate to the direction of the tower body at a certain angle, and if the air gap between the wire and the tower body is insufficient to bear line voltage at the moment, air breakdown is very easy to occur, and further an arc discharge phenomenon is caused. The discharge can leave electric burn marks on towers and wires, and also can cause equipment damage and line tripping accidents, thereby bringing serious threat to the safe operation of a large power grid. In the operation experience of the existing transmission line, the faults caused by wind deflection are not occasional events, but gradually show a high-frequency trend along with the increase of extreme weather frequency. In recent years, the occurrence frequency of strong typhoons, extreme thunderstorms and strong convection weather is increased due to climate change, and wind deflection discharge accidents occur when a power transmission line runs in coastal and partial high-wind areas. Once the accident happens, the influence range is wide, the recovery difficulty is high, and even large-area power failure can be caused, so that adverse effects are brought to social economy and power grid safety. In order to solve the problem of wind deflection, various measures have been proposed in the industry. The wind deflection process and the discharge mechanism are predicted by methods such as simulation, numerical calculation and the like, so that the safety margin is increased in the design stage. However, such methods can only provide theoretical evaluation, and are difficult to play a direct protective role in actual operation. The other is a device protection measure aiming at the line structure, wherein a blocking device is additionally arranged on the outer side of the insulator string so as to limit the deflection of the wire under the action of wind power. The existing insulation blocking cable scheme for controlling the windage yaw displacement of the extra-high voltage line is designed aiming at a conventional voltage class line, and the structural size and the mechanical property of the insulation blocking cable scheme are usually determined according to the operation working condition of 220 kV or 500 kV alternating current line. However, for extra-high voltage alternating current lines, because the voltage class is 1000 kV and above, the line span is larger, the quality and the windward area of the lead are obviously increased, the impact force of the lead is far greater than the level of the line with the conventional voltage class, the strength of the existing blocking device is insufficient, and the existing blocking device is extremely easy to break or fail under the action of strong wind. In addition, existing partial barrier wire designs, while capable of limiting wire deflection to some extent, may be subject to excessive tension at their connection points with the pylon under over-design wind speed conditions. If the reasonable load limiting and protecting measures are lacking, excessive tensile force can directly act on the construction hole or the main structure of the iron tower, so that components are deformed or even damaged, the problem of windage yaw cannot be solved, and the risk of damage to the tower body is increased. Therefore, in the actual operation of the extra-high voltage line, the conventional device is difficult to meet the double requirements of wire windage limit and iron tower safety protection. The problem is that the prior device is mainly focused on a 'blocking wire contact tower', but lacks a controllable limiting mechanism for the wind deflection displacement of the wire and the adjusting capability for a stress path. When wind deflection forces exceed conventional levels, the blocking structure may be subjected to excessive transient tensile forces, thereby transmitting forces directly to the pylon attachmen