The problem of ED can be easily solved when transmission line losses are neglected. As the losses are neglected, the system model can be understood as shown in Fig. 1.7, where n number of generating units are connected to a common bus bar, collectively meeting the total power demand PD. It should be understood that share of power demand by the units does not involve losses.
Since transmission losses are neglected, total demand PD is the sum of all generations of n-number of units. For each unit, a cost functions Ci is assumed and the sum of all costs computed from these cost functions gives the total cost of production CT.
Fig 1.7 System with n-generators
where the cost ...