Identifying causes of electrical discharge in high-voltage transmission lines

Increased urbanization, electrification, and population growth mean communities increasingly rely on electricity generated by large power plants and transported long distances via high-voltage direct current (HVDC) transmission lines. While these transmission lines can carry more electricity further distances, they are also uniquely susceptible to damage and degradation from severe weather conditions.

Deng et al. employed particle simulations to observe streamer discharges from HVDC transmission lines due to the presence of raindrops. These discharges can lead to energy loss and equipment failure in HVDC systems and produce audible noise for nearby residents.

To capture the kinetic and non-local effects of charged particles inside these discharges, the authors turned to particle-in-cell simulations with Monte Carlo collisions.

They developed a trio of models and used them to investigate the effects of single and multiple raindrops, surface-attached and free-falling raindrops, as well as both horizontal and vertical raindrop spacing.

“The results indicate that reduced raindrop spacing and increased raindrop number lead to earlier discharge initiation, stronger electric fields, and higher electron density,” said author Weili Fan.

The researchers also observed discharge bifurcation and revealed the non-equilibrium nature of streamer discharges, displaying a bi-Maxwellian distribution with two distinct electron temperatures, after analyzing the electron energy probability functions.

“These findings provide practical insights for enhancing the protection of HVDC transmission systems,” said Fan. “For instance, system operators could improve transmission line design by exploring hydrophobic coatings to reduce raindrop adhesion or by implementing effective electromagnetic shielding to reduce the interactions between raindrops and conductors.”

The authors plan to continue to develop their simulations and use them to develop improved HVDC transmission designs.

Source: “Particle simulation of streamer discharges on DC transmission conductors with presence of multiple raindrops,” by Tengkun Deng, Jinzhu Wang, Sen Yu, Xinchun Zhang, Fucheng Liu, Shuo Wang, and Weili Fan, Journal of Applied Physics (2025). The article can be accessed at https://doi.org/10.1063/5.0281421 .