A synergetic effect between hBN and alumina has been observed regarding thermal and electrical properties. A 500% increase in the thermal conductivity could be achieved with a limited impact on viscosity increase.
One of the possible SF6 alternatives that emerged in recent times is a fluoronitrile (FN), NovecTM 4710, based mixture.
Using Gibbs free energy method, a theoretical study has been conducted on SF6 replacement candidates listed above.
This article presents the measurements of the equivalent B(H) and the equivalent magnetic permeability of two three-phase MFT prototypes.
This paper points out the challenges to overcome when applying a protection strategy based on a non-selective fault clearing philosophy without DC reactors to an overhead line based multi-terminal DC grid.
We propose a parametric single-ended fault identification algorithm to be used in full selective protection strategy.
This paper aims at the detection and characterization of partial discharges (PD) in GIS under HVDC constraints in the presence of a protrusion/metallic particle on the high voltage conductor.
Recent studies have demonstrated that fluoronitrile (FN) NovecTM 4710 and fluoroketone (FK) NovecTM 5110 show higher dielectric strength than SF6. These gases can be mixed with a buffer gas such as CO2 and technical air to have suitable dielectric properties for high voltage insulation applications.
This paper gives an overview of electrical DC phenomena in GIL/GIS, the influence of insulating properties of SF6 and filled epoxy resin, and design of new support insulator for 320kV HVDC GIL/GIS. The busbar system including the insulator was designed not only to satisfy all standard requirements such as mechanical, temperature rise, heating cycle performance but also particular requirements for HVDC applications such as superimposed impulse tests. Finally and for the first time at actual scale, type test according to CIGRE JWG D1/B3.57 was conducted in EDF R&D Les Renardières laboratory to verify the design and insulating performance of the 320kV HVDC GIL/GIS system. The satisfactory results allow to confirm the high technology readiness level of HVDC GIL/GIS.
Power electronic traction transformers (PETT) are multilevel AC/DC on-board converters, studied for railway applications to replace traditional solution with low frequency transformers. This paper focuses on the insulated DC/DC converter in a PETT. Three variants of resonant single active bridges (R-SAB) with 3-level NPC primaries are optimised to maximise the efficiency, under mass and dimension constraints. They are sized and compared for a 2 MW PETT on a 15 kV/16.7 Hz railway infrastructure, using 3.3 kV SiC MOSFETs and nanocrystalline C-core transformers with cast resin insulation and forced air cooling. The highest efficiency at nominal power, 99.17 %, is reached for a configuration with a 3-level full bridge NPC primary, a 2-level full bridge secondary, and a 32.1 L/49.1 kg transformer operating at 6 kHz.
