Future wind power production variations in the Swedish power system

Abstract

The future for wind power in Sweden is a well covered issue by many reports bringing up different problems and trying their best to simulate the future system with different tools. Summarizing these reports and comparing their conclusions is a difficult task not only due to the many reports but also since they are based on different data and focus on different aspects of the potential problems. The only thing that can be said certain is that the current electric power system is not constructed for a large expansion of an intermittent power source which will have such a geographical spread as the potential wind power expansion. Geographical spread should not be mistaken to be an equal installation of wind power over the entire country of Sweden or an equal spread between the different areas of the electric power grid. Geographical spread means that wind power will be built on locations where wind potential is good. In this report the focus lies on magnitude of the future variations from wind power when the capacity is expanded. The base for the thesis is statistic data from the wind power production in 2009 from three different sources. The data has been used in an attempt to predict the future variations from wind power if the expansion is done in accordance with how the wind power has been expanded up to this point. The data has partly been divided into different times of the year, in this case following the seasons of the year, spring, summer, autumn and winter. And also into the geographic areas of Sweden which is normally used to describe the cross-sections in the transmission system. The results found indicates that for a system which is geographically large as Sweden the variations from wind power, between two hours, will only during a few times every year be more than ±10% of the installed wind power capacity. However there can be variations in the different transmission system areas which are larger and occur more often. There are also a few times every year that the variations might cause problems. The problems might occur due to the relation between the variation and the available reserves, especially when looking at future scenarios with quite large wind power penetration. This might cause problems the southern part of Sweden where the plan for expansion includes a large amount of wind power and there are little local balancing resources.