The impact of large renewable deployment on electricity high voltage systems

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Conference Papers
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G. Celli
S. Mocci
F. Pilo
S. Tedde
G. Fulli
A. Purvins
E. Tzimas

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In the last decades an increasing integration of renewable energy sources (RES) in the extra high voltage (EHV) and high voltage (HV) networks, boosted by technical reasons and political decisions has been noticed. RES introduce significant environmental benefits, but also considerable difficulties to power system planning and operation. In fact, if RES are correctly allocated, they allow deferring network upgrade investments and decreasing Joule losses.

On the other hand, the uncertainty of RES production may cause dispatching problems, malfunctioning of protection and voltage regulation systems, etc. Many European Union (EU) research projects concluded that RES might be useful to accomplish economic, environmental and reliability targets removing the existing barriers to innovation and liberalized market.

The paper is part of a Research Project financed by the European Commission  to study the influence of a large penetration of RES on the EHV and HV electrical grids.  The case study proposed in the paper refers to a portion of the Italian grid, the Sardinian power system, interconnected to the Italian mainland by means of the existing 200 kV and 500 kV high voltage direct current (HVDC) submarine cables (SA.CO.I. and SA.PE.I). Sardinia is one of the most favorable Italian regions for the exploitation of wind and solar energy and it has been experiencing a great increment of wind power production, which will be doubled in the next ten years.

In the paper, the models to predict at 2020 and 2030 the generation park, demand profiles, as well as the development of the electricity infrastructures in Sardinia are briefly described. The steady-state analysis of the Sardinian grid with AC Power Flow studies applied to the foreseen load and generation scenarios in 2020 and 2030 allowed identifying critical conditions of the grid caused by RES production, load profile, and the lack of homotheticity between generation and load.