Complex sentence: On September 22,2012, Nizhny Novgorod Metro was completely closed for the first time in order to complete the work of switching power to the new control system of the station under construction.
Split into simpler sentences: On September 22,2012 for the first time Nizhny Novgorod Metro was completely closed. This was due to the work of switching power to the new control system of the station under construction.