[IEEE 2013 IREP Symposium - Bulk Power System Dynamics and Control - IX Optimization, Security and Control of the Emerging Power Grid (IREP) - Rethymno, Greece (2013.08.25-2013.08.30)] 2013 IREP Symposium Bulk Power System Dynamics and Control - IX Optimization, Security and Control of the Emerging Power Grid - Impact assessment of large scale RES penetration for the Hellenic power system; A market simulation model analysis