Power electronic traction transformers in 25 kV / 50 Hz systems: Optimisation of DC/DC Isolated Converters with 3.3 kV SiC MOSFETs

2019-05-09T09:36:48+00:00mai 9th, 2019|Electronique de puissance & convertisseurs, Publications|

In AC electric trains, power electronic traction transformers (PETT) are multilevel single phase AC/DC converters connected to the AC medium voltage overhead line. For indirect topologies, DC/DC isolated converters are key elements of PETTs. This paper shows a method to design such DC/DC converters, and several variants are considered. Finally, the comparison results, in the case of a 25 kV / 50 Hz power supply and 3.3 kV SiC MOSFETs, show that the variant with a resonant AC link, with only one controlled bridge and a switching frequency lower than the resonant frequency, offers the best efficiency at rated power for a given volume.

A New Energy Management Control of Modular Multilevel Converters for Coping with Voltage Stress on Sub-Modules

2019-04-24T08:58:03+00:00avril 24th, 2019|Architecture & systèmes du supergrid, Publications|

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.

Study of Turn-to-Turn Electrical Breakdown for Superconducting Fault Current Limiter Applications

2018-11-09T14:59:14+00:00novembre 2nd, 2018|Appareillage électrique haute tension, Publications|

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.

Arc appearance and cathode spot distribution in a long gap high-current vacuum arc controlled by an external axial magnetic field

2018-11-15T16:33:23+00:00octobre 31st, 2018|Appareillage électrique haute tension, Publications|

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.

Electrical properties of epoxy systems based on ionic liquids

2018-11-12T09:50:54+00:00octobre 12th, 2018|Appareillage électrique haute tension, Publications|

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...

Models of AC and DC cable systems for technical and economic evaluation of offshore wind farm connection

2019-01-10T10:06:54+00:00septembre 3rd, 2018|Appareillage électrique haute tension, Publications, Systèmes de câbles & jonctions HVDC|

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.

Space Charge Measurements for HVDC GIS Spacer using the Thermal Step Method

2018-11-12T09:51:09+00:00août 31st, 2018|Appareillage électrique haute tension, Publications|

High voltage direct current (HVDC) technologies are currently emerging to develop new energy transmission networks able to integrate renewable energy sources with remote locations from consumers. Gas Insulated Substations (GIS) have been widely used in alternating current (AC) transmission due to their low footprint and high reliability.

Discharging micro cavities and electric field enhancement due to cavities in HVDC XLPE cables

2018-11-12T09:54:29+00:00août 31st, 2018|Publications, Systèmes de câbles & jonctions HVDC|

This paper presents simulation and calculation results of electric field enhancement due to various cavity shapes carried out on polymeric high voltage direct current (HVDC) cables. Two aspects are considered: partial discharges (PD) in microcavities and field enhancement factor under DC.

A 100 kW 1.2 kV 20 kHz DC-DC converter prototype based on the Dual Active Bridge topology

2018-11-12T10:08:40+00:00août 24th, 2018|Electronique de puissance & convertisseurs, Publications|

This article presents the design, the fabrication, and the test of an isolated DC-DC converter for renewable energy applications. The converter is based on the Dual Active Bridge topology and uses silicon carbide power semiconductors and a medium frequency transformer. The design process covers hardware ranging from the semiconductor die to the complete power converter. For the control, a rapid prototyping approach was used. The experimental validation of the 100 kW prototype is presented.