AC and DC Networks Association. Setting Up and Utilisation

What is an AC power network? A set of lines or cables connecting a large number of generators, usually three-phase AC, to receivers (or loads) via transformers or converters, since transmission requires the use of high voltage.

The arrival of renewable energies (wind turbines, tidal turbines, photovoltaics, etc.) and power converters (with IGBT transistors) is encouraging installers to use direct current for electricity transmission. This new situation has prompted electricians to consider using high-voltage DC networks alongside AC networks. This approach is known as HVDC (High Voltage Direct Current).

We're interested in the particular transients that occur, for example, in the event of a sudden short-circuit on an AC cable, compared with those on the same DC cable, subject to the same voltage. This leads us to a study of the possibilities of power transfers between the two networks, to obtain an optimal combination.

It is then possible to consider the geographical location of direct current generators (wind turbines, photovoltaic panels, water turbines, batteries, etc.) to make this combination optimal. Examples of HVDC networks already in service or planned around the Mediterranean are presented.

At the end of the article, the subject of Brittany, which currently has an energy deficit, is addressed, with suggestions for the construction of a new direct current network exploiting renewable energies, which are particularly varied in this region: wind, sea, light...