400 kV Almaraz-Guillena Axis
This electricity infrastructure, which was allocated an investment of approximately 270 million euros, represents a significant improvement in the guarantee and quality of the electricity supply in the regions of Extremadura and Andalusia.

The 400 kV axis, links the central and southern areas of the Spanish peninsula, linking the substations of Almaraz, San Serván, Brovales and Guillena by means of 327 km of electricity lines. Similarly, the axis includes another 48 km of 220 kV lines to Mérida and Balboa.

Objectives of the axis

  • Strengthen transmission grid meshing in an area with insufficient power generating stations.
  • Further the interconnection with Portugal, via the Guillena-Puebla de Guzman-Portuguese border axis.
  • Provide support for the electricity distribution network in the area.
  • Facilitate the evacuation of new renewable generation.


San Serván Substation

 Parque de 220 kV - Banco de transformadores - Parque de 400 kV.

It is one of the substations that make up the electricity axis. It is comprised of 2 switchyards: one 400 kV in a one and a half switch configuration, and one 220 kV in a double busbar configuration. The connection between these two switchyards is performed through a 600 MVA autotransformer bank.

Main environmental measures applied in the axis:

  • Comprehensive field survey of areas in which work is to be performed, as well as continuous environmental monitoring of work.
  • Increasing the height of towers in order to save wooded areas.
  • Signage and marking off of access routes and work areas close to populations of endangered or catalogued flora.
  • 62% of towers assembled using a boom crane (method that minimizes the need to open access roads and work sites).
  • Pilot cable hung by hand (142 km) to prevent damage arising from use of vehicles.
  • Conducting birdlife census in winter, pre-reproductive and reproductive periods.
  • Comprehensive monitoring of birds in the migratory, pre-migration and wintering seasons.
  • Biological stoppages of works in 78 towers during different periods.
  • Marking of sections of line with bird flight diverters.
  • Recovery and restoration of all areas affected by the works.