6. Conductor self-damping and dampers

The influence of external and internal damping mechanisms was considered in the conductor vibration model. The factors considered included the following [1, 32]:


The high voltage transmission line damped model is expressed in Eq. (48) as:

$$EI\frac{\partial^4 y(\mathbf{x},t)}{\partial \mathbf{x}^4} - S\frac{\partial^2 y(\mathbf{x},t)}{\partial \mathbf{x}^2} + \beta I \frac{\partial^5 y(\mathbf{x},t)}{\partial \mathbf{x}^4 \partial t} + \mathbb{C} \frac{\partial y(\mathbf{x},t)}{\partial t} + \rho A \frac{\partial^2 y(\mathbf{x},t)}{\partial t^2} = f(\mathbf{x},t) \tag{48}$$

Where C and β represent damping constants. In the presence of axial load, viscous air damping, strain rate damping or Kelvin-Voigt damping, high voltage transmission line integrity can be managed.

There are various types of dampers that can be used to reduce vibration. The dampers are excited by the vibration of the power conductor and the vibration of their masses connected by the massager cable help to damp out energy. Stockbridge dampers are commonly installed on high voltage transmission lines to reduce aeolian vibrations. Stockbridge dampers can be symmetrical or asymmetrical in their design. An example of dampers installed on high voltage transmission lines is shown in Figure 1. The design of Stockbridge dampers follows the principle of cantilever beams with mass at the free ends. The contribution of dampers to power conductor vibration mitigation is to lower the severity of the vibration to a level that might prevent failure to the line.

Figure 1. Asymmetrical damper.
