The purpose of generation economic dispatch is to procure a generation schedule for each generating unit for a specific time period. The procured generation schedule should be economically optimized, which means that the total generation cost for all units based on this schedule is the minimum compared to any other generation schedules. The fundamental requirement of generation economic dispatch is that the total generation from all units should satisfy the system load of the time period, and the generation of each unit is within its operation upper and lower limits. The objective and requirement of economic generation dispatch can be expressed using an optimization model,