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).
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).
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%.
FastGrid is a project funding for an amount of 7.2 M€ by the European Union’s Horizon 2020. It started in January 2017 for a period of 42 months. Together 9 academic and 3 industrial partners participate to the development of a superconductive fault current limiter associated with a DC breaker will fulfil the requirement of one the protection strategies of the future HVDC networks. The project is divided in 4 technical main packages.
When a voltage is applied to a cable, electric charges are established in its electrodes, inducing an electric field in the dielectric. This electric field implies that the cable is submitted to an electrical stress which, under certain circumstances induces an accelerated ageing of its dielectric which may be followed by its breakdown.
Globally, the energy landscape is shifting; the generation of electricity is moving towards greener energies, to incorporate more and more renewable power. Transmitted over continents and oceans, transmission lines are spanning over longer distances when connecting power generation areas to consumers. How can we help making this international electrical network of the near-future into a reality?
Globally, the energy landscape is shifting; the generation of electricity is moving towards greener energies, to incorporate more and more renewable power. Transmitted over continents and oceans, transmission lines are spanning over longer distances when connecting power generation areas to consumers. How can we help making this international electrical network of the near-future into a reality?
Numerous High Voltage Direct Current (HVDC) submarine cables have been installed in Europe and more are yet to come. Such transmission allows the trading of energy or the supply of isolated areas with almost no limitations on distance (typically 100-1000km). Interconnections such as NorNed and soon Nord Link and North Sea Link will provide a safe path for the large integration of renewable energies in northern Europe (Figure 1).
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