The digital substation, an accelerator of the ecological transition

The ecological transition is advancing at an unstoppable pace and the scenario it outlines - characterised by the massive integration of renewable energy, new electricity demand and generation segments, new energy storage mechanisms and a more active role for the consumer - poses challenges that can only be met successfully if we have a more efficient and sustainable electricity system, and in this context, power transmission grids play an essential role.

There is no longer any doubt that without grid there will be no ecological transition. This new scenario will not only require more kilometres of grid, but it also demands that greater intelligence and digitalisation be incorporated into the grids to further strengthen their flexibility and resilience.

Red Eléctrica has already been working along this path for some time through its commitment to technological innovation and has been progressively incorporating digital solutions into its infrastructure. Among the courses of action taken, noteworthy are those focused on electricity substations, as they are the nerve centres of the grid and essential assets in order to successfully achieve this energy transition.

Specifically, Red Eléctrica is working on the development of the so-called 'digital substation', a new concept of substation whose cornerstone is the implementation of new automation and fibre optic communication systems. This digital shift translates into an increase in productivity, functionality and reliability, as well as improving the safety of the professionals working within the facilities. It also leads to greater technical and economic efficiency and a reduced carbon footprint as a result of eliminating extensive copper cabling, reducing the size of equipment and optimising maintenance, civil works and the use of materials.

Chronology of milestones

Red Eléctrica has been working on the digitalisation of the transmission grid since 2005 and one of its first steps was the implementation of the IEC 61850 standard in a project developed in the Gatica substation (Vizcaya) in 2007, where an exchange of coded signals between companies was carried out regarding a distribution transformer.

In 2011, the Company achieved an important milestone, this time in Latin America. For the first time, it installed the so-called ‘Station Bus’ with the IEC 61850 standard in the TESUR project in Peru. This solution provides communication between protection and switch control equipment via a bus; a fibre-optic Ethernet network that replaces the electrical wiring. Years later, this new system was implemented in the following projects in Peru and Chile: Chilota, TESUR2, TESUR3, TESUR4, Redenor and Redenor 2.   

The next step forward was to work on the ‘Process Bus’ and this was done at the Rocamora substation (Alicante), adapting all the signals exchanged between the switchgear and the protection equipment to the IEC 61850 standard.

Thanks to the experience acquired, the Company continued along this path with two new pilot projects, one at the 400 kV Cañaveral substation (Cáceres) and the other in the Cariñena substation (Zaragoza), where, for the first time, it implemented a ‘Process Bus’ and a ‘Station Bus’, making a great leap forward in data interoperability and in the reliability and availability of the system. This new communication exchange system was brought into service at the Cañaveral substation in 2020. The Cariñena substation will also start to use this new system throughout 2021.

So, what are the next steps? 

There are only two steps left to complete the design of a fully digital substation: to digitise and transfer numerical samples of current and voltage signals of transformers and to have an intelligent electronic device integrated into the switchgear that eliminates the actual intermediate connection with the ‘Process Bus’ by means of electrical wiring.

Red Eléctrica is almost there. Soon, the digital substation will be a reality, increasing the intelligence of our transmission grid, and with it, the energy transition will be less about the future and more about the present.

In detail

The main focus of the digital substation is the digitalisation of communications, the management of information through fibre optic data networks and the implementation of detail engineering and substation remote terminal units and control systems. All this under a new communication standard, the substation automation system using IEC 61850, which guarantees interoperability between the different electrical equipment and the management and control systems, hence increasing efficiency of the system as a whole.

This new protocol - the International Electrotechnical Commission (IEC) 61850 standard - establishes the implementation of solutions that ensure this interoperability, i.e., the ability to exchange information between equipment from different manufacturers by defining not only a common language but also a standardised data model and communication services that make it possible to create an automatic protection, diagnosis, monitoring and remote-control system.