Strategies for the integration of wind energy into the grid: An application to the Portuguese power system

The integration of wind energy into the grid is responsible for some constraints in the operation of the power system such as power unbalances between generation and demand due to the fact that higher wind power availability occurs in periods of lower demand. To address this issue three different strategies are studied in to the present paper : the curtailment of the excess of wind energy, exporting the excess of wind to neighbor systems and the use of energy storage systems to absorb the power unbalances. The application of the strategies to the Portuguese case study show that the curtailment of the excess of wind energy is the worst case, resulting in a waste of 10.4 % of the annual wind generation. In opposition, the use of the pumping-hydro installed capacity combined with the installation of an additional energy storage system enables the total integration of the wind energy into the grid.