This paper presents a biogeography-based optimization (BBO) algorithm to solve the economic loadDispatch (ELD) problem with generator constraints in thermal plants. The applied method can solvethe ELD problem with constraints like transmission losses, ramp rate limits, and prohibited operatingzones. Biogeography is the science of the geographical distribution of biological species. The modelsof biogeography explain how a organisms arises, immigrate from an environment to another and getseliminated. The BBO has some characteristics that are shared with other population basedoptimization procedures, similar to genetic algorithms (GAs) and particle swarm optimization (PSO).The BBO algorithm mainly based on two steps: migration and mutation. The BBO has some goodfeatures in reaching to the global minimum in comparison to other evolutionary algorithms. Thisalgorithm applied on two practical test systems that have six and fifteen thermal units, results of thispaper are used to see the comparison between performances of the BBO algorithm with other existingalgorithms. The result of this investigation proves the efficiency and good performance of applyingBBO algorithm on ELD problem and show that this method can be a good substitute for otheralgorithms. تفاصيل المقالة