“…where Ng expresses the generators' number, T symbols the overall scheduling hours, P i (t) is the ith unit power generated at instant t, I i (t) represents the switching status (ON/OFF) of ith unit at instant t, F i (P i (t)) is the ith unit fuel cost which is given in Equation ( 27), S i (t) is the ith unit start-up cost, which is presented as S i (t) = Sh i i f T i,o f f (t) ≤ T i,Down + T i,cold Sc i i f T i,o f f (t) > T i,Down + T i,cold (28) where Sh i and Sc i are the hot and cold start-up costs, T i,off (t) is the duration of ith unit's continuous inactivity, T i,Down is the minimum downtime of ith unit, and T i,cold is the cold start-up time of the ith unit.…”