Nos publications scientifiques
Models of AC and DC cable systems for technical and economic evaluation of offshore wind farm connection
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.
Virtual capacitor for DC grid stability enhancement
With a growing number of commercial installations around the world, HVDC technology increased its presence and importance in the power systems. Among various converter topologies, the Modular Multilevel Converters (MMCs) are considered as the most suitable one for HVDC application today. Besides its recognised advantages over conventional converters, the MMC has an interesting extra degree of freedom, which is the energy stored in the distributed cell capacitors. Although the amount of this energy is relatively small, it can provide a significant contribution to the DC system stability when properly used. This paper presents experiment results that demonstrate the effectiveness of virtual capacitor control. This control, previously proposed by the authors, makes use of the above additional degree of freedom to attenuate fluctuations of the DC voltage, which tend to be inherently volatile against power disturbances compared to the frequency of conventional AC systems. Under the virtual capacitor control, the MMC behaves as if there were a capacitor on the DC side of the converter whose size is easily adjusted by the control variable and can be even bigger than the physical capacitor actually embedded in the converter. In practice, the emulation of the capacitor dynamics is realised by the auxiliary control which adjusts the exchange of the energy between the stacked cell capacitors and the DC grid during the transient. Thus, no adverse effect is imposed on the AC grid. Furthermore, the system operator can optionally adjust the equivalent capacitance of the system to achieve desired mitigation level of DC voltage fluctuation during the operation. Therefore, this additional degree of freedom can largely extend the operability of the DC systems. The feasibility and effectiveness of the virtual capacitor control is demonstrated by experimental results obtained by using a small-scale MMC prototype.
Space Charge Measurements for HVDC GIS Spacer using the Thermal Step Method
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.
Breakdown Characteristics and Pre-Breakdown Phenomena in Liquid and Boiling Nitrogen with Tape Electrode for r-SCFCL Applications
The rational insulation design of a resistive superconducting fault current limiter (r-SCFCL) requires data gathered from experimental setups relevant for the final apparatus.
Discharging micro cavities and electric field enhancement due to cavities in HVDC XLPE cables
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.
Discharging micro cavities and electric field enhancement due to cavities in HVDC XLPE cables
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
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.
Optimal sizing of a power electronic traction transformer for railway applications
This paper presents a methodology to optimize the sizing of such power converters in order to compare different topologies for a given application. The proposed procedure maximises the efficiency of the converter under a limited volume.
Uncertainty Quantification for the Eulerian-Lagrangian simulation of evaporating sprays
Evaporating sprays can be almost routinely simulated using an Eulerian-Lagrangian approach which relies on a RANS modeling of the continuous phase and a Lagrangian description of the discrete phase, including a turbulent dispersion model to express the effect of turbulent fluctuations within the carrier phase on the spray particles and an evaporation model for the spray droplets.
Semi-Analytical Methods for Calculation of Leakage Inductance and Frequency-Dependent Resistance of Windings in Transformers
This paper focuses on analytical or semi-analytical calculation techniques to be integrated into a medium frequency transformer optimization process.