Smoothing out the wind power production patterns by connecting different countries within Europe

Abstract

The increase in wind power production changes variability in the power system on a large scale. The smoothing out effect is the extent to which this variability can be changed. Wind output fluctuation is of a great importance for evaluating and assessing the impacts in a power system with a large number of wind turbines interconnected. In this thesis two methods are used in order to investigate the extent to which wind power production patterns can be smoothed out by connecting different countries within Europe. The first one is a step change analysis based on time series of wind power production. The second one is based on the comparison of relative wind power production. Furthermore, the wind power variability is studied on all time scales in the period 2011-2013 for five European countries (Denmark, Germany, Ireland, France and Spain). Two indicators are used for the quantification of smoothing effect, the standard deviation of paired countries and of countries individually and the correlation coefficient of paired countries. Also, the distance, the size of area and the wind power capacity are important factors that affect the behavior of that effect. In this study, logarithmic relations are identified between the factors taken into account and the two indicators. It can be noticed that the standard deviation of the change in power production per time step decreases asymptotically with the increase of the area and the wind power. For example, at hourly basis it drops by 15% and 18% from 600,000 km^2 to 800,000 km^2 area and from 30 TWh to 50 TWh wind energy, respectively. In a similar way, the distance seems to have an asymptotic effect on the correlation coefficient of paired countries. For instance, at hourly basis the indicator decreases by 56% from 500 km to 1000 km distance. In overall, the relative variability of wind power decreases when considering a large inter-connected system composed of the five European countries. In this system, the aggregated hourly wind power variations are most of the time within ±2% of installed capacity. Finally, it is recommended that the smoothing effect of wind power should be investigated combined with the load variability of each country.