Nonlinear Traits of Leakage Current and Dynamic Actions of Surface Discharges on Ice-Covered Insulators Under DC Voltages

In order to improve the technology for predicting flashover risks of ice-covered insulators, this article delves into the nonlinear characteristics of leakage current (LC) and the phase changes of arcing discharges. The dynamic relationship between them is analyzed quantitatively. The dc ice flashover experiment is conducted in the CIGELE artificial climate room. The dynamic characteristics of arcs during the dc ice flashover process were studied. The chaos of the LC time series is examined by estimating the maximum Lyapunov exponent (
${L}_{\text {max}}$
) using embedded space theory and the phase space reconstruction method. An analysis of the dynamic behavior of LC is conducted using recurrent plot (RP) technology, leading to the development of an index to quantify the regularity of the LC. A quantitative analysis of the cooperative relationship between the LC and arc length, as extracted through image processing, is performed, confirming the regular patterns of LC variation. The findings indicate that variations in the LC and arc length are effective in distinguishing between the three stages of ice flashover.
${L}_{\text {max}}$
exceeds zero at all stages, indicating the chaotic nature of the LC, which is most pronounced during the early phase of the second stage. RP technology provides a clear, dynamic visualization of icing insulator discharge behavior through graphic texture transformation. The nonlinear indexes, RR and DET, of LC, demonstrate an increase alongside the development of arc discharge, indicating a growth of the regular and deterministic components of the discharge. Additionally, there is a synchronous increase in the LC and arc length, with a clear correlation exhibited during the four arc extension periods (T1–T4). As the flashover approaches, the degree of fitting between them increases significantly.