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Corona performance of transmission lines in foul weather conditions, icing particularly, have attracted widely attentions recently. In this research, the influence of freezing water conductivity on positive corona performance of soft rime ice-covered conductor is studied in corona cage via energized artificial icing method. The most important finding of this research is that the maximum deviation of the corona inception voltage obtained by the compared three corona inception method could reach 14.7% in soft rime icing condition, and the quadratic law method is recommended. The formed soft rime is composed of the divergent dendritic layer and the ice layer. Based on the ultraviolet photon videos and the corona current pulses waveform, the corona development process of soft rime ice-covered conductor is divided into four stages: feeble discharge mode, positive onset streamer mode, positive glow mode, and positive pre-breakdown streamer mode. Moreover, with higher freezing water conductivity, the obtained icing weight and icing thickness are bigger, consequently, the corresponding corona loss and audible noise are also larger.

Corona performance of transmission lines in foul weather conditions, icing particularly, have attracted widely attentions. In this research, the influence of voltage polarity on corona performance of two icing categories, glaze and soft rime icing, is studied in corona cage via artificial icing method. The most important finding of this research is that a linear relationship is found between audible noise (AN) and the corona loss (CL) in dB above 1 W/m for the first time, the slopes of the line are voltage polarity-dependent. A 10.4 dBA and 13.7 dBA variation in the AN value for a 10 dB increase in the CL for negative and positive voltage respectively, with little influence icing categories. Moreover, the negative polarity conductors are attending to accumulate much more glaze ice than positive polarity conductors. Taylor cones and hemispheres are observed on the tip of glaze icicles when subjected to DC and AC electric field, respectively. For both icing categories, the CL of negative polarity conductors are bigger than that of positive polarity conductors, the contrary is the case of AN. When the voltage gradient is greater than 18.0 kV/cm, contrary to popular perception, the generated CL and AN of glaze ice-covered conductor are bigger than that of rain condition and fair weather, respectively.

Wind turbines often suffer from blade icing issues in cold regions, which causes the degradation of the blade aerodynamic performance and the loss of power production. In the paper, a 3D numerical simulation model of the wind turbine rotor is put forward by using a commercial computational fluid dynamics (CFD) solver ANSYS Fluent to estimate the blade aerodynamic performance after icing. The multiple reference frame (MRF) model, Reynold Averaged Navier Stokes (RANS) and k-ω SST turbulence model are used in the simulation. Results show that CFD computational results are in accordance with the experimental results for clean and rime-iced rotors within rated wind speed, and overrated for glaze-iced rotors at high wind speed. As the wind speed increases, the rotor speed and output power of wind turbines decrease more dramatically under icing conditions. Besides, ice shapes mainly affect pressure distribution at the leading edge of airfoils, and thus reduce the normal force and tangential force significantly at approximate 62%–89% radial position. Influenced by ice shapes, blades are more likely to work in stall region at the same wind speed. In addition, flow separation around the iced blade is more serious at larger wind speed, which will produce more momentum and frictional loss, especially for glaze ice. The results provide a valuable reference for the wind farms operation and generator system evaluation in cold regions.