  We devise the Unit Commitment Nearest Neighbor (UCNN) algorithm to be used as
a proxy for quickly approximating outcomes of short-term decisions, to make
tractable hierarchical long-term assessment and planning for large power
systems. Experimental results on updated versions of IEEE-RTS79 and IEEE-RTS96
show high accuracy measured on operational cost, achieved in runtimes that are
lower in several orders of magnitude than the traditional approach.
