To connect the different points of the network, the transmission and distribution of electric power used cables. Since few years, cables and especially their insulation part are evolving, going from paper insulation to a synthetic insulation. Nowadays, the insulation part of HVDC cables is in crosslinked polyethylene or XLPE.
This paper focuses on the set up and the validation of a numerical model for the analysis of the flow in reversible Francis pump-turbines in the S-Shape region. For such operating conditions the flow inside the pump-turbine is characterized by highly unsteady flow separations and complex rotor/stator interactions.
The paper presents a tool for technical and economic assessment of offshore wind power connecting architectures; they highly influence cost effectiveness of offshore wind generation, particularly when power electronic converter based transmission technologies and long distance transmission cables are employed.
High Voltage Direct Current (HVDC) converters are composed of hundreds of semiconductor switches connected in series to sustain the rated voltage of the converter (several hundred of kilovolts). Because of the large number of switches, it is highly probable that at least one of them will fail during the lifetime of the converter. Such failure should not cause the entire converter to shut down, despite the series connexion of the switches. As a consequence, each switch should be designed so that upon failure, it becomes a short circuit and keeps carrying the current (“fail-to-short” behaviour).
PhD Albert PEREIRA « Design methodology of a medium frequency transformer for high voltage and high power DC-DC converters »
The transmission and distribution of electric power is normally made by ac networks (50 Hz or 60 Hz), where one of the key elements of this infrastructure is the power transformer; used for more than a century, its design is very well understood, with a level of operating efficiency normally greater than 99%.