Greenlink will use high voltage direct current voltage source converter (HVDC VSC) technology to link the two power systems. HVDC has been selected over an AC connection, because AC is technically difficult over this distance. VSC technology has the main benefit that it reduces the size of the converters (when compared to similar technologies).
The Greenlink Interconnector converter station
The indicative converter station site footprint would be circa. 1.85 hectares (185m x 100m). A converter station consists of various components. These include a converter hall, converter transformers, AC switchgear and busbars, harmonics filters, lightning towers, ancillary plant such as cooling bank and diesel generators, and a control building. Typically the tallest components are the lightning towers at circa 26 metres high and the converter hall, which could be up to 21 metres high at its apex. The converter hall and main building are usually one continuous building with height difference. The layout of the converter station and final dimensions will depend on the local terrain, physical constraints, the results of environmental surveys, consultations and the supplier’s technical requirements.
A typical converter station layout
A tail station is a substation built adjacent to infrastructure such as a converter station and remote generation plant. Following consultation, EirGrid has confirmed that a tail station will need to be developed alongside the converter station in Ireland. We will now incorporate a tail station within the design to be assessed within the final planning application in Ireland.
We are using a 60m x 70m footprint for the potential tail station. However consultations are taking place with EirGrid to reduce the footprint of the tail station to minimise environmental and landscape impacts.
Substations are used within distribution and transmission networks to provide a connection point for lines as well as a location for voltage levels to be changed for transmission or distribution.
Greenlink will be connecting into existing transmission substations that are part of the wider national transmission networks. At these substations Greenlink's electricity will flow to or from the wider transmission and distribution networks, providing power to customers where it is needed.