Analysis of Meteorological Factors of Wind Power Ramps in Hokkaido and Tohoku Area

Abstract

This study examines meteorological conditions associated with ramp events of wind farms in the Hokkaido and Tohoku area in the eastern Japan using phenomenological and statistical analysis. The result of the analysis for the area-integrated wind power generation shows clear seasonal and diurnal variations of the occurrence rate of the wind ramps. The ramp events mainly occur in cold season. The occurrence rate of ramp-up (down) increases in the daytime (night) as the diurnal variation. It could be conceivable that the diurnal variation is mainly related to development/decay of atmospheric boundary layer. As a common result of phenomenological and statistical analysis focusing on the sea level pressure pattern around the areas, we identify that there are dominant surface pressure patterns. The major weather patterns of the ramp-up events are corresponding with the strengthening of (or transition to) the winter monsoon and approaching of an extratropical cyclone to the area. On the other hand, the major patterns for the ramp-down are weakening of the winter monsoon and that the area is covered by the high-pressure system.