Our scientific publications
Comparaison de mesures de conductivité obtenues par spectroscopie diélectrique et mesure de courant sous tension continue sur une résine époxy
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.
SuperGrid Institute’s participation in PROMOTioN’s Work Package 9
SuperGrid Institute is proud to have been an active participant in the PROMOTioN project since 2016. This project is part of the European Union’s Horizon 2020 program and is made up of several work packages (WP) that share a common aim: developing meshed HVDC offshore grids that are both cost effective and reliable, through technological innovation. SuperGrid Institute is an active member of several Work Packages, including WP9 whose objective is to develop fault clearing strategies using Hardware-in-the-Loop (HIL) real-time simulation (RTS).
Structural Analysis and Modular Control Law for Modular Multilevel Converter (MMC)
This paper proposes an in-depth analysis from the control point of view of dynamic models of a Modular Multilevel Converter (MMC) for high-voltage direct current (HVDC) application.
New challenges for High voltage transmission
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.
A New Energy Management Control of Modular Multilevel Converters for Coping with Voltage Stress on Sub-Modules
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.
Packaging Solution for SiC Power Modules with a Fail-to-Short Capability
Fail-to-short packages, which can still carry current after the failure of their semiconductor devices, are required for HVDC applications. However, all existing solutions are dedicated to silicon components. Here, a fail-to-short package is proposed for SiC devices. Its manufacturing process is described. 4 modules are built and submitted to intense short circuit currents (up to 2000 A). It is found that they offer a stable short-circuit failure mode, providing that the modules are mechanically clamped to prevent separation during the surge current test.
FMEA of a non-selective fault-clearing strategy for HVDC grids
The Failure Mode Effect Analysis (FMEA) is a technique used to investigate failures in a process or component and to identify the resultant effects of these failures on system operations. In this paper it is explained how the FMEA can be used to define and assess the impact of the failure modes (FM) of a protection strategy for High Voltage Direct Current (HVDC) grids.
Study of the impact of DC-DC converters on the protection strategy of HVDC grids
This paper studies the role of DC-DC converters in the protection of HVDC grids acting as firewalls to stop the propagation of faults. The effects of blocking the converter or actively controlling its operation during faults are presented.The results demonstrate the capabilities of DC-DC converters beyond DC voltage transformation.
Dielectric properties of ceramic substrates and current developments for medium voltage applications
Why are ceramic materials (when compared to organic materials) necessary for the purpose of electric isolation in power modules, especially for medium voltage applications...
Packaging of 10 kV SiC MOSFETs: Trade-Off Between Electrical and Thermal Performances
SiC transistors can achieve blocking voltages of 10kV and more. This makes them especially attractive for energy transmission and distribution. Although SiC devices can in theory operate at high temperature (more than 200°C), the on-state resistance of SiC MOSFETs exhibits a strong dependency on the junction temperature. As a consequence, it is shown that these transistors must actually operate at a relatively low junction temperature (less than 100°C) to increase conversion efficiency and prevent thermal runaway. This requirement for high-performance cooling systems has consequences on the packaging technology: the corresponding power modules must both offer a high voltage insulation and a low thermal resistance. In particular, there is a trade-off in the thickness of the ceramic substrate located between the SiC devices and the cooling system. We propose a new substrate structure, with raised features, which improves the voltage strength of a substrate without increasing its thickness. This structure is demonstrated experimentally.
