An experimental study of breakdown and pre-breakdown phenomena in liquid nitrogen (LN2) is performed in this paper, in order to provide useful knowledge for the design of high voltage superconducting systems.
De par sa facilité d’utilisation et sa capacité à isoler la permittivité complexe représentant les pertes dans un matériau tout en faisant un balayage fréquentiel, la spectroscopie diélectrique semble être une méthode de choix pour obtenir la valeur de conductivité ohmique d’un matériau. Cette méthode pourrait permettre de s’affranchir des temps conséquents de stabilisation généralement associés aux mesures de conductivité issues de courbes courant-tension effectuées suivant la norme IEC 62631-3. Par l’intermédiaire d’une comparaison entre ces 2 méthodes, les auteurs vont revenir sur les limites de chacune d’entre elle.
The national congress of dielectric spectroscopy (SDM2) took place at LyonTech on the 6th and 7th of June at the La Doua academic campus. A number of our materials experts attended to present some of the innovative studies that are under way at SuperGrid Institute.
In able to fully integrate renewable energies and to stop to use fossil energy and nuclear power, there is a need to evolve the current electric grid in a new one called the supergrid. This new grid will be based on a mix of High Voltage AlternativeCurent (HVAC) and High voltage Direct Current (HVDC) junctions highly meshed with Gas Insulation Substation (GIS) as nodes. While HVAC GIS technologies are well mastered, HVDC ones are still at the beginning. One weakness of the equipment being dielectric insulators, industries may have to conceive new dielectric formulations or improved ones. This paper presents a list of properties and values to target for future dielectrics formulation. At the end, it highlights as well, the importance of health and environnement and how their consideration have to be at the same level of attention than the final properties of the dielectrics.
This paper investigates the impact of the operating condition on the SM voltage ripples. In particular, it is revealed that under the classical control scheme where the Modular Multilevel Converter internal energy varies naturally with the DC grid voltage, the traditional sizing approach based on the analytical expression of instantaneous SM voltage may fail to respect the SM voltage constraint. To tackle this problem, this paper presents a solution by incorporating the advantages of the explicit energy management and the developed analytical expressions of the SM voltage ripple, which achieves a better utilization of the converter asset.
The rational insulation design of a resistive superconducting fault current limiter (r-SCFCL) requires data gathered from experimental setups representative of the final apparatus. Therefore, an experimental study was performed to characterize the electrical breakdown (BD) of liquid nitrogen (LN2) in the peculiar conditions of a quenching superconducting device.
An experimental study of a high-current vacuum arc (VA) generated between two static CuCr25 contacts spaced 20 or 30 mm apart was conducted to characterize the arc appearance and the cathode spot (CS) distribution.
In accordance with their interesting properties, ionic liquids (ILs) have attracted in the recent years a great interest in the material field. Recently, few authors have demonstrated the reactivity of ionic liquids towards epoxy in order to form new epoxy-based networks...
This thesis aimed to characterize partial discharges in DC gas-insulated substations, and to develop an automatic defect identification tool. The first step of this work was the development of a partial discharge measuring bench. The complete study has been performed in a GIS section, so that the results can be directly applied to industrial equipment.
Accurate cable modeling is a recurrent issue for electric architecture evaluation and design, especially in specific contexts, like offshore wind farms. This paper proposes optimal analytical cable models for the technical and economic assessment of offshore wind generation systems.
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