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Effective Permeability of Multi Air Gap Ferrite Core 3-Phase Medium Frequency Transformer in Isolated DC-DC Converters

2020-04-08T09:56:22+02:00mars 14th, 2020|Electronique de puissance & convertisseurs, Publications|

This article presents the measurements of the equivalent B(H) and the equivalent magnetic permeability of two three-phase MFT prototypes.

Partial Discharge Behavior of Protrusion on High Voltage Conductor in GIS/GIL under High Voltage Direct Current: Comparison of SF6 and SF6 Alternative Gases

2020-04-02T15:15:10+02:00février 28th, 2020|Appareillage électrique haute tension, Publications|

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.

Design and validation tests of 320kV HVDC GIL/GIS

2019-11-21T10:37:01+01:00novembre 21st, 2019|Appareillage électrique haute tension, Publications|

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.

NPC assessment in insulated DC/DC converter topologies using SiC MOSFETs for Power Electronic Traction Transformer

2019-10-22T11:33:28+02:00octobre 24th, 2019|Electronique de puissance & convertisseurs, Publications|

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.

Electric field computation for HVDC GIS/GIL spacer under superimposed impulse conditions

2019-10-21T17:08:39+02:00octobre 21st, 2019|Appareillage électrique haute tension, Publications|

This paper evidences the influence of different parameters on the electric field on DC spacers in GIS/GIL and thus their dielectric withstand under S/IMP tests. A notable difference in term of electric field can be observed in function of impulse polarity, load condition (with/without heating current) and insulating material’s properties. For example, an overstress of 0.3pu was obtained on spacer’s surface in case of superimposed impulse test with opposite impulse polarity, high load condition and high leakage current in gas. Contrary to AC system where the simple LI tests were enough, S/IMP tests with both impulse polarity, ZL and HL conditions are mandatory to verify the insulating performance of HVDC GIS/GIL spacer. This paper gives a better understanding of the electric field distribution in HVDC GIS/GIL and helps for the design and tests