CONTEXTThe European Transmission Network (ETN) has been developed and operated up to around the year 2000 under the so-called UCPTE (now ENTSO-E) rules. At that time, utilities were usually national monopolies vertically integrated from generation down to the retail distribution. Each utility had the responsibility of balancing the power delivered to their clients by means of their own generation fleet. The interconnection of the national networks basically had the sole role of sharing generation reserve in case of tripping of a generating unit somewhere in the ETN. The savings in generation capacity and the possibility to install larger, more efficient units in the smaller utilities paid for the investment of the interconnection lines. The consequences of the UCPTE rules at the level of the operation of the ETN were such:
- The flows on the interconnectors were normally low or zero.
- In case of major disturbances, the interconnections were intentionally tripped in order to avoid the extension of a possible blackout.
- The N-1 network security was managed at national level.
- Very few data exchange between countries was needed.
Today the paradigm of the ETN has changed:
- The liberalization of the electricity market and the implementation of the IEM (Internal Electricity Market) make use of the total available cross border transfer capacity and call for reinforcement of the transmission network. But new investments are late.
- The integration of a large amount of intermittent renewables, either dispersed in the distribution system or remotely located far away from the load centers call for network reinforcement (possibly a supergrid), cross border load balancing, much more sophisticated grid operation and operation planning, and smarter distribution grids.
- New technologies in the domains of ICT and power electronics are available to help the ETN to become smarter. This calls for new models for generating units, wind farms, FACTS and electrical interface of load with the system and is a major difficulty managed in this project.
- For political and security of supply reasons, further extensions of the ETN are planned (Turkey) or contemplated (Russia, Mediterranean ring) leading to the most extended interconnected system in the world.