Hydro-Québec

About: Hydro-Québec is a government organization based out in Montreal, Quebec, Canada. It is known for research contribution in the topics: Electric power system & Dielectric. The organization has 2596 authors who have published 4433 publications receiving 100878 citations.

Energy storage in metal cobaltite electrodes: Opportunities & challenges in magnesium cobalt oxide

Abstract: Ternary metal cobaltites (TMCs) offering high charge storability, multiple oxidation states, and improved electrical conductivity are widely explored as electrodes for energy storage devices. Among them, magnesium cobalt oxide or magnesium cobaltite (MgCo2O4) could be a cheaper analogue due to the abundance of magnesium; however, limited by materials stability in certain electrolytic conditions, formation of insulating layers hindering the charge response under charge/discharge conditions. While certain morphologies of MgCo2O4 delivered capacities higher than the theoretical capacity in lithium ion storage mode, it delivered only a quarter of the theoretical value in a supercapattery storage mode. This review critically analyzes the progress in MgCo2O4 as a charge storing electrode for lithium-ion battery, supercapattery (battery-type electrode), and magnesium rechargeable battery cathodes. A detailed account of the research undertaken is presented herewith and identifies opportunities and research gaps, which are expected to serve as a guide for future research in ternary metal cobaltites.

Corona Loss Characteristics of Practical HVDC Transmission Lines, Part I: Unipolar Lines

Abstract: The method of calculating corona losses, developed for unipolar operation mode, is used in the paper to study corona loss characteristics of several practical HVDC transmission lines. Detailed results on the influence of various line parameters upon corona loss characteristics of monopolar lines with single as well as bundle conductors, of homopolar lines, and of monopolar lines with overhead ground wires are given.

Influence of internal mechanical stress and strain on electrical performance of polyethylene electrical treeing resistance

Abstract: Crosslinked polyethylene (XLPE) and low-density polyethylene (LDPE) insulations used in HV cables are not only subjected to electrical and thermal stresses, but also exposed to mechanical stresses, whether residual internal stresses created during the cooling process of the fabrication, external forces when cables are bent during installation or thermomechanical stresses caused by differential thermal expansion between the conductor and the polymeric material. In order to investigate the possible influence of mechanical stresses on dielectric properties of polyethylene, measurements were conducted on pin-plane XLPE and LDPE samples with various magnitudes of residual mechanical stresses around the embedded electrode. The time to inception, the growing rate and the shape of the electrical trees under different voltages are reported in this paper. Specimens with the highest values of residual stresses were found to have the shortest inception times and the longest trees after one hour of aging under different voltages. When the mechanical stress was allowed to relax, the treeing resistance was measured to be significantly improved.