Design of booster shed parameters for improving the electrical performance of post insulators under icing conditions /

Abstract

The optimized design of outdoor insulators that consider heavy icing and pollution conditions is a significant concern for the reliability of power networks. Based on field observations, the probability of flashover of EHV post insulators is higher than line insulators under the same heavy icing conditions. The flashover along the insulators is caused mainly by the presence of a water film on the ice surfaces (melting period) and partial arcs in ice-free zones (air gaps).One of the mitigation options is the use of booster sheds (BSs) to create air gaps along the iced insulator. A booster shed (BS) is a flexible c-shape device made of highquality insulating materials. Since BSs are easy to use, they seem to be simpler alternatives to upgrading insulators to those designed for cold climate regions. Despite the promising results of BS applications, still an important work must be achieved to propose optimized design of BS configurations.This project aims to provide a generic design approach to the use of BSs by optimizing their main parameters (number, diameter, inclination angle, position, and permittivity) on post insulators under heavy icing conditions. This approach is based on analyzing previous BS tests in CEGELE, an improved hypothesis of BS effects, numerical analysis using commercial software (e.g. Comsol Multiphysics™, Matlab, and Minitab), geometric modeling of ice-covered post insulator with BSs, and finally experimental validation tests. IllThe improved hypothesis states that the major effect of BSs is the creation of air gaps and their minor effect is the increase in dry arcing distance. Moreover, among total length of the air gaps, dry arcing distance, and total ice-free leakage distance (IFLD to t), the IFLD to t is a good indicator to quantify the BS effects on standard post insulators. Simulation analyses of BS configurations during the melting period demonstrate that the optimized relative permittivity of BS is an arbitrary value in its feasible variation range (2-15). The

Design of booster shed parameters for post insulators under heavy icing conditions using geometric modelling and the Taguchi method

“…ΔV tot = 99%), independently of the number, length, position, inclination angle, or diameter of the BSs. Moreover, ΔV tot is independent of the inclination angle of the icicles [18,19,22]. (2) In the previous BS tests, among DAD, the total length of the air gaps (L AG-tot ) and IFLD tot , the best indicator to quantify their electric performance is IFLD tot .…”

“…Therefore a 22.1% increase in IFLD tot (the average value of 21.3% and 23.0%) can be considered as a 15-kV increase in V WS for the BS configurations. Hence (see (1)) Equation (1) can be also expressed as (see (2)) Moreover, parametric simulations for the BS configurations during melting period shows that the variations in BS parameters have no significant effect on electric field distributions along the AGs [18,19,22]. Thus, IFLD tot will be used in this paper for the quantification of the BS effects for different configurations under heavy icing conditions.…”

“…Another way to solve the problems of the electrical performance of post insulators under heavy ice conditions is to substitute them with new types of insulators. However, new insulators and their handling and installation are much more expensive compared with the corresponding costs for BSs [22,[33][34][35]. In fact, a more economical approach would be to add optimum BSs to the existing power network insulators.…”