//Phd

Phd Raphael CHASSAGNOUX “Dielectric study of liquid and boiling nitrogen – Application to a superconducting fault current limiter”

2019-11-15T15:23:07+01:00November 14th, 2019|High Voltage Substation Equipment, Phd|

The increasing number of interconnections in electrical networks and the massive integration of renewable energies nowadays comes with an increase of short circuit currents, and more constraints on high voltage circuit breaker during the current clearance. To solve this problem, a solution consists in inserting a fault current limiting device on electrical lines. Among the available technologies, the superconducting fault current limiter is ideal from the perspective of transmission system operator. However the design of this device is non-trivial, especially the electrical insulation, which is very specific to this apparatus: electrical insulation in a cryogenic environment (liquid nitrogen at - 196°C), superconducting tapes inducing electric field reinforcement, and strong transient heating generating numerous vapor bubbles.

Phd Alexis FOUINEAU “Medium Frequency Transformers design methodologies for high voltage grids and railway grids”

2019-11-15T15:20:17+01:00November 13th, 2019|High Voltage Substation Equipment, Phd|

Medium Frequency Transformers (MFT) are an innovative technology compared to low frequency transformers, with the promise of reduced volume and increased efficiency. This PhD thesis focuses in particular on their design for high voltage, high power applications, such as high voltage and medium voltage DC networks, as well as railway networks. In these applications, MFTs are used in converters that can generate specific constraints to be taken into account during their design: non-sinusoidal signals, polarization voltage, target inductance values.

Phd Guilherme DANTAS DE FREITAS “Development of a methodology for DC grid protection strategies comparison”

2019-10-22T18:15:05+01:00October 18th, 2019|Phd, Supergrid Architecture & Systems|

High Voltage Direct Current (HVDC) grids are considered a promising solution for problems faced by nowadays power system such as: lines congestion, integration of large amounts of renewable power and enhancement of AC system stability. Among the challenges in the deployment of a HVDC meshed grid, the protection of these grids is regarded as one of the most critical. The protection of HVDC grid is challenging not only because the swift transients and fault currents without zero-crossing, but also due to the impact a DC faults can have on the AC system. Several propositions for HVDC grids protection strategies can be found in literature...

Phd Priscillia DANIEL “Electrical properties study of cross-linked polyethylene insulated cables in presence of gaseous cavities aged under DC or DC with harmonic voltages”

2019-07-09T16:00:23+01:00July 5th, 2019|High Voltage Substation Equipment, HVDC Cable Systems, Phd|

This study aims to examine possible impact of these harmonics in presence of microcavities. Depending on their size and on the electrical field, partial discharges (PD) can occur in these microcavities. Two types of cables have been aged: a medium voltage AC (MVAC) cable with millimetric cavities induced artificially and a model cable with an HVDC XLPE grade.

PhD Loriane DESMARS “Study of electrical and thermal properties of epoxy-anhydride composite materials for high voltage insulation”

2019-04-04T11:12:50+01:00April 2nd, 2019|High Voltage Substation Equipment, HVDC Cable Systems, Phd|

The work presented in this manuscript has been motivated by the necessity to develop more efficient electrical insulating materials compared to commercially available ones. An epoxy-anhydride matrix filled with micron sized alumina, often used to produce GIS solid insulators, has been used as a reference for this study.

PhD Amjad MOUHAIDALI “Contribution to the modelling of HVDC cables for electromagnetic transient simulations”

2019-02-13T11:02:37+01:00February 13th, 2019|Phd, Supergrid Architecture & Systems|

The integration of new technologies in the electric grids made them more and more complex, and most likely future growth of power grids will be based more on underground cables than overhead lines. One problem here, is that the mathematical model for electromagnetic simulation of power cables still has some shortcomings regarding stability, accuracy and passivity. In this thesis, we evaluate the cable parameters using analytical and numerical methods.

PhD Juan-Carlos GONZALEZ “Transient stability of high voltage AC-DC electric transmission systems”

2019-01-29T17:24:27+01:00January 29th, 2019|Phd, Supergrid Architecture & Systems|

This thesis addresses the transient stability analysis of hybrid AC/DC electric transmission systems. More precisely two questions sought to be investigated: What is the impact of a DC contingency on AC transient stability? How can we take advantage of the DC transmission systems as control inputs in order to enhance AC transient stability?

PhD Quentin MOLIN “High Voltage SiC MOSFET Robustness study: threshold voltage shift and short-circuit behaviour”

2018-12-17T16:51:42+01:00December 17th, 2018|Phd, Power Electronics & Converters|

This manuscript is a contribution to reliability and robustness study of MOSFET components on silicon carbide “SiC”, wide band gap semiconductor with better characteristics compared to silicon “Si” material. Those new power switches can provide better switching frequencies or voltage withstanding for example in power converter. SiC MOSFET are the results of approximately 10 years of research and development and can provide increased performances and weight to some converter topology for high voltage direct current networks.

PhD Miguel ROMERO RODRIGUEZ “Supervisory control synthesis for MMC-based HVDC systems”

2018-11-09T13:52:00+01:00November 9th, 2018|Phd, Supergrid Architecture & Systems|

This work proposes a method for the full development, from conception to implementation, of the supervisory control of a multi-terminal HVDC (MT-HVDC) system.