The increasing participation of intermittent renewable energy sources (RES) in modern power systems makes expansion and operational planning an even more complex task, especially in hydro-based systems. To properly assess the impact that intermittent generation may have on generation expansion planning (GEP) decisions, higher temporal resolution methodologies for GEP are required that take into consideration the system operation as well. This paper proposes a soft-linking methodology for the GEP problem of large hydrothermal power systems with increasing expansion of RES. The proposed methodology coordinates power system models ranging from expansion planning to hourly hydrothermal scheduling. It has been applied to a ten-year expansion planning of the Brazilian power system: the importance of considering the short-term wind generation intermittency is demonstrated by the necessity of changing the original expansion plan both in terms of installed generation and interconnection capacity.