Abstract
Mitigation of corona discharge is fundamental problem that was formulated by Lord Kelvin in 1911 but has not yet received a proper technical solution.On HVAC transmission lines up to 30% of the total electric power losses accounted for corona discharge (CD).A peak of losses occurs during adverse (wet) weather conditions, such as rain and snow.Coating on the surface of aluminium wire using microarc oxidation (MAO), also known as electrolytic plasma oxidation (EPO) was implemented to reduce losses due to CD.Samples covered by the surface with porous high-temperature α-Al2O3 aluminium oxide, silicon oxide SiO2, silicon carbide SiC reinforced with graphene oxide and carbon nanotubes.Industrial high-voltage testing shows that the significant reduction of the power loss due to corona of 30-50% has been measured in the present work where wires were coated with strong, adhesive, and super-hydrophilic layer.The corona ignition threshold voltage increased up to 40% in the rain conditions, and up to 15% for dry conditions.Simulations using finite element method (FEM) have shown a significant dependence of a local electric field enhancement factor on the surface wettability (hydrophilicity).Highly porous and hygroscopic properties of newly engineered surfaces allow to control contact angle of a water droplet on the wire and reduce the field enhancement factor in comparison with a uncoated surface via the effect of dielectric shielding.