40.8% of the overall electricity demand was supplied on real time basis by wind power some days ago in the Spanish electricity system. This record constitutes a real challenge for transmission system operators (TSOs).
In more general terms, renewable energy penetration strongly depends on the ability of TSO to evolve towards a new way of operating the system: dedicated predictability for renewable generation, voltage dip management and managing the power balance.
The big issue for the coming years (especially taking into account the targets set by the EU Directive on the use of energy from renewable sources) is balancing the transmission system in the presence of high renewable power penetration. This not only requires to redesign grid codes, but also a deep revision of power reserve policy. Along with renewable sources growth, a market for upgraded reserves is becoming necessary.
This paper shows some good practices from the Spanish TSO, REE, leading to better integration of renewable generation: commissioning a dedicated centre for renewable energy management, grid code evolution, development of specific applications to maximize renewable generation and provide production limits to each renewable energy plant, voltage control and congestion management.Hans De Keulenaer