Economic Load Dispatch (ELD) is an important topic in the operation of power plants which can help to build up
effecting generating management plans. The ELD problem has no smooth cost function with equality and inequality
constraints which make it difficult to be effectively solved. The paper presents an application of Cuckoo Search
Algorithm (CSA) to solve Economic Load Dispatch (ELD) problems with smooth and non-smooth fuel cost objective
functions. Main objective of ELD is to determine the most economic generating dispatch required to satisfy the
predicted load demands including line losses over a certain period of time while relaxing various equality and
inequality constraints. The unit Min/Max operational constraints, effects of valve-point loading ripples and line losses
are considered for the practical applications. This paper describes the implementation of smooth and non smooth fuel
cost function by CSA Method and its comparison with BAT method. We have used 6 and 12 bus system for calculating
their total fuel cost.