Commonly Used Anti-Swing Devices for Overhead Transmission Lines and Their Characteristics

1. Overview of the swing

Overhead transmission line conductors occur after eccentric icing, in the wind excitation generated under a low frequency, large amplitude self-excited vibration phenomenon. In layman’s terms when the wind blows to the non-circular cross-section of the wire due to icing, a certain aerodynamic force is generated. This will induce the wire to produce a low frequency (about 0.1 ~ 3 Hz), the large amplitude of self-excited oscillation, due to its form up and down, shaped like a dragon pendulum, called swing.

2. Commonly used anti-swing device

Each type of anti-swing device has its own special design and application conditions, and the cost of different anti-swing devices also varies greatly. The following table lists the current overhead transmission lines commonly used anti-swing devices and their main performance.

3. anti-swing device application characteristics

3.1 Line clip rotary spacer bar

Line clip rotary spacer bar (for splitting the wire) is a new anti-swing device developed in recent years in China. Its characteristics are spacer bar part of the line clip can be free (or in a certain angle range) rotary, part of the line clip and ordinary chuck the same, can not be free to turn. The movable chuck part can change the shape of the ice-covered wire, thus changing the aerodynamic coefficient of the ice-covered wire. Because of this anti-swing device both spacer bar and anti-dancer dual role, and will not additionally increase the concentrated load on the transmission line, the line running stress basically no effect. Its arrangement mainly considers the influence of sub-file distance oscillation, flip self-recovery, etc. A clamp rotary spacer bar is slightly more expensive than an ordinary spacer bar. The spacer bar has been widely used in the anti-swing work of overhead transmission lines in China.

3.2 Inter-phase spacer bar

Inter-phase spacer bar (single conductor, split conductor are available) is a spacer bar with insulation performance and mechanical strength used between phases or circuits. It connects each conductor mechanically so that the movement of each conductor is mutually restrained to suppress the purpose of dancing. The inter-phase spacer bar is a synthetic insulating structure consisting of an FRP core bar and a silicone rubber sheath. It has high tensile strength, is lightweight, and has a certain flexibility. Good impact resistance, not broken. It has the characteristics of high foul flash voltage resistance.

The interphase spacer bar can not only suppress swinging, but also prevent jumping office, and prevent wind deflection to a certain extent, and its anti-swinging function is the best among all kinds of existing anti-swinging devices. The inter-phase spacer bar has been widely used in the anti-dance work of transmission lines of 220 kV and below, and the inter-phase spacer bar has been increasingly used for the anti-swing of compact transmission lines of 220 kV and above. The interphase spacer bar is most suitable for the anti-swinging of multi-tower lines with vertically aligned phase conductors. Of course, the inter-phase spacer bar degradation, bending stiffness, and other problems, its service life to be tested, the inter-phase spacer bar dance prevention cost is higher.

3.3 double pendulum anti-swing device

A double pendulum anti-swing device is a kind of anti-swing device with a good anti-swing performance developed based on the stability mechanism. In order to improve the power stability of the wiring system, but also both the function of pressure weight anti-swing. At present, the double pendulum anti-swing device has been applied to many split conductor lines in China and has achieved a better anti-swing effect. At the same time accumulated a wealth of experience, is the most widely used overhead transmission line in China to prevent swing devices. A double pendulum anti-dance device is a rigid anti-swing device, from the application of experience, if the design is reasonable, it can effectively swing dance, if the design is not reasonable (the actual ice and wind conditions exceed the set-up range), the line may still occur dance. But from the overall situation, the double pendulum anti-swing device can basically prevent or to some extent inhibit the swing. A double pendulum anti-swing device also has a lower cost, is easy to install, and has other characteristics. A double pendulum anti-swing device has a complete set of design calculations and must be a specific analysis of specific issues. If not after the design calculation and blindly apply or copied, it will greatly reduce its anti-swing effect, and even the safe operation of the line has a negative impact.

3.4 Disturbance anti-swing device

A disturbance anti-swing device (for a single conductor) is the use of plastic made of prefabricated interference wire, wrapped around the wire. This makes the individual cross-sectional shapes of the conductor and the scrambled wire composite different from each other, even after icing. This anti-swing device is light in mass, easy to install, and has a minimal negative impact on the conductor. The anti-dancing effect is better when the ice cover is thin (≤10 mm). At the same time, the constant change of the cross-section along with the pitch also disturbs the vortex vibration, which is beneficial for vibration prevention. While in the thick ice cover (> 10 mm), due to the thick ice cover makes the ice cover after the wire cross-section tends to be the same, the effect of the disturbance is reduced, it is better to use another anti-swing device. In addition, because the spoiler anti-swing device is generally made of polyvinyl chloride, it is different from the wire’s coefficient of linear expansion, which in the summer will produce slack, which may cause the position of the slip. In addition, because it is a polymer material, there are problems such as aging and deterioration.

3.5 Concentrated anti-vibration hammer

Concentrated anti-vibration hammer (for single conductor) is the principle of anti-dance pressure weight anti-oscillation, pressure weight anti-oscillation is to limit the amplitude of the pressure point, the formation of nodes, so as to inhibit the amplitude of the wire and vibration type, in order to control the purpose of the wire dance.

The advantage of the centralized anti-vibration hammer dance is easy to take the material, and easy to install. However, the installation location and quantity should be designed and calculated. In addition, one should pay attention to the relatively fixed anti-vibration hammer position, to prevent the operation of the anti-vibration hammer position slip, one should also pay attention to the anti-vibration hammer itself quality stability. In short, in a single conductor transmission line take a concentrated anti-vibration hammer to prevent the pendulum to be careful.

3.6 Integral eccentric hammer

This anti-dance device with improved power stability, provide torsional feedback control, disrupt the airflow distribution along with the file, and other comprehensive anti-dance function. And the cost is relatively low, is a cost-effective anti-swing device.

Integral eccentric heavy hammer has been applied to the anti-dancing practice of transmission lines in China. Anti-dance design should pay attention to the design of the quality of the heavy hammer to avoid excessive mass, resulting in line breeze vibration exceeding the standard.






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