Nowadays, economic load dispatch between generation units with least cost involved is one of the most important issues in utilizing power systems. In this paper, a new method i.e. Water Cycle Algorithm (WCA) which is similar to other intelligent algorithm and is based on swarm, is employed in order to solve the economic load dispatch problem between power plants. WCA is used to solve complicated problems including non-linear cost functions such as the constraint for input steam valve, constraint for loss, ramp rate of generators and prohibited operating zones of generators’ production. This algorithm is employed on a system with 3 units and load demand of 850 MW and on a system with 15 units and load demand of 2630 MW with and without considering the constraints. The results of the paper comparing to the results of the other valid papers show that the proposed algorithm can be used to solve in any kind of economic dispatch problems with proper results. تفاصيل المقالة