Novel dc flashover model for predicting flashover voltage of the iced insulators

In order to improve the stability and reliability of high voltage direct current (HVDC) transmission lines in cold regions, this article investigated the corona discharges and the icicle growth characteristics on outdoor insulators under DC voltages. The experiments were conducted at CIGELE laboratory at University of Quebec. The simulation model of corona discharges and the theoretical model of icicle growth were established. The dynamic process and interactive characteristics between the icicle growth and corona discharges under different HVDC voltages were obtained. The results showed that the discharge activity was strong and the cooling effect of ionic air was weak under negative DC voltage, resulting in a large number of bubbles inside the icicle. More negative ions were produced under negative DC voltage, which enhanced the polarisation of water droplets, leading to a greater density of ice beads outside the icicles. In addition, the longest icicles of each insulator under high humidity could bridge the shed gap. The accumulated charge and leakage current were higher under negative DC voltage, as well as the corona discharge at the top of the icicles lasted longer. Therefore, the negative DC corona discharge more significantly inhibited the growth of the icicle, resulting in a slower growth rate of the icicles.

Section: Introductionmentioning

confidence: 99%

Dynamic interactive characteristics between icicle growth and corona discharge on HVDC outdoor insulators during icing accretion

Liu

Yin

et al. 2023

“…Serious accidents are easily caused by the icing of 10 kV transmission lines, which brings considerable challenges to the safe operation of the power grid [1][2][3][4]. In 2008, normal activities in southern China were severely disrupted due to largescale line failures caused by continuous ice and snow [5,6].…”

Section: Introductionmentioning

confidence: 99%

Experimental study on ice monitoring method for 10 kV transmission line with tangent tower in alpine landform

Yang,

Chen,

Hao

et al. 2023

Ice monitoring methods were applied for 110 kV and above transmission lines with tangent towers. However, the change in the vertical span is not considered, and a significant difference lies in the tower‐conductor structure of 10 kV transmission lines. For this reason, a proposal is made about the ice monitoring method for the 10 kV transmission line with tangent tower in alpine landform, which includes the ice monitoring system based on pressure measurement and corresponding equivalent ice thickness calculating methods. Different methods calculate the vertical span under different height difference coefficients. A finite element simulation model and a simulated ice load experiment system are established based on real conductors and insulators. Experiments and simulations under four simulated terrains are conducted within 2.5–20 mm ice thickness range. The comparison is made between this method and the method without considering the change in vertical span. The results show that the two methods are consistent and the relative errors are lower than ±4% in simulation and ±10% in experiment when the height difference coefficient is 0. When it is not 0, the relative errors of this method fall between +0.38% and +6.78% in simulation and −6.40% to +6.60% in experiment, while the relative errors of the method without considering the change in vertical span ranges between −11.13% and −20.23% in simulation and −11.65% to −23.20% in experiment.

“…Ice accretion on transmission lines not only aggravates ice and wind loads, but also leads to the flashover of ice-coated insulators [6,7]. A considerable number of insulators icing tests have been carried out at home and abroad, and the growth and flashover models of ice-covered insulators have been established [8][9][10]. In Refs [11,12], the effect of AC electric field on glaze icing on 220 kV composite insulators was studied in the laboratory.…”

Section: Introductionmentioning

confidence: 99%

Influence of positive DC electric field on rime icing on the insulator and its experimental verification in the natural environment

Liu

Jiang

et al. 2022

Self Cite

The electric field imposes a significant effect on ice accretion on the insulator. The impact of an AC electric field on insulator icing in an artificial climate chamber has been addressed. Compared with AC, DC electric field exerts an attraction on supercooled water droplets, which is more detrimental to the power system. Moreover, the icing on energised insulators is rarely studied in the natural environment. In the present research, an electrical, fluid coupled‐field simulation was carried out on the insulator. The force characteristics and motion deviation features of water droplets at different positive DC electric field strengths were studied. On this basis, rime icing on the insulator energised with different positive DC voltages was investigated in the field. Results show that the charged droplet shifts along the electric field line under a positive DC voltage. The deviation degree of the droplet increases with the increment of the voltage and droplet size and decreases with an increase in wind speed. As the voltage rises, the surface roughness, icing amount and icing length of rime ice‐covered insulator increase. Consequently, compared with that without energisation, the local collision coefficient, icing amount and icing length increase by 17.6%, 46.4% and 63.9%, respectively, under a 40 kV DC voltage.