Miss Anusuya Ananthasingam received the University research grant with the submission of a successful research grant application. This research work is started from September 2014. Today’s era on adding large renewable energy parks, the cost of the generation mix will be changing. This research will add another dimension to the electricity cost analysis, where renewable power plants’ output can be maximized by operating with the coordination of large hydro power plants. Outcome of this research will be very helpful to minimize the electricity cost thus the tariff or electricity bills for consumers while benefiting to the power system operators without losing the reliability of the system.