Charge accumulation on solid insulator in Gas Insulated Substation (GIS) is one of the major issues under Direct Current (DC). A specific device has been developed in order to assess the origin of such charges within SF6, in a coaxial geometry.
The recent interest in renewable energies has encouraged the research on a new concept of electrical grid - the Supergrid based on HVDC meshed grids. To be implemented, this new system requires the development of new technologies. One key-enabling technology is the high power DC-DC converter, a topic that is increasingly gaining more attention from both academia and industry.
The silicon carbide (SiC) power semiconductor and the medium frequency transformer (MFT) are two enabling technologies that are allowing the efficiencies and power densities of power electronic converters to be pushed beyond the limits of those that have previously been possible...
This paper is aimed at the experimental study of creeping discharges and flashover of cylindrical epoxy solid insulators with and without barrier.
HVDC (High Voltage Direct Current) technology is particularly suitable for the transmission of high-power energy over long distances. However, some technical/technological problems have to be addressed/managed when passing from HVAC to HVDC due among others to the fact that the electric field distribution in gas insulated systems (GIS) operating under DC stress is very different from AC conditions.
This paper is aimed at the propagation of discharges over a surface of insulator and the development of an analytical flashover model in air at atmospheric pressure. The experimental results show that the critical conditions of flashover are over the half of creeping distance.
Dimensionning of DC isulation is relatively complexe and need to take into account must more effects and parameters than in AC. This paper presents simulation methodology to applied for DC GIS and GIL.
In the future, Medium Frequency Transformers (MFT with a frequency range 5 kHz to 100 kHz) will be major components in DC-DC converter applications, for both Medium Voltage Direct Current (MVDC) and High Voltage Direct Current (HVDC) networks. Importantly, the corresponding power losses should be accurately calculated in order to reach performance targets (very high efficiency).
The paper focuses on the role of disconnectors for load transfer duties in the operation of MTDC meshed grids. As there are no topology existing today and no standard, some switching duties are presented for which disconnectors could act instead of using circuit breaker. Based on an empirical model relying on tests performed in air, severity of the different switching duties are presented and first conclusions are proposed.
In view of the increasing global market for high voltage (HV) vacuum circuit breakers in the voltage rating ≥ 72.5 kV, it is necessary to focus our attention on developing the vacuum interrupters (VIs) for these ratings. VCBs have already penetrated the 72.5 kV market and trials are progressing with introducing up to 145 kV VIs into the power networks. Prototype of the 252 kV VI has already been demonstrated.
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