Journal of Applied Sciences1812-56541812-5662Asian Network for Scientific Information10.3923/jas.2011.3791.3796RabiiA.MobaieenS.MohamadyB.SuroodyA.1220111123Valve-points effects and prohibited operation zones (POZ) make the generating units’ cost functions non-linear and non-smooth. Hence, the Economic Dispatch (ED) problem is a highly non-convex optimization problem. The consideration of the transmission losses makes the ED problem even more complicated. This study presents a novel and heuristic algorithm for solving ED problems, by employing a new heuristic method, called Imperialist Competition Algorithm (ICA). The effectiveness of the proposed method is examined and validated by carrying out extensive tests on two different test systems. The valve-point effects, POZs, ramp-rate constraints and transmission losses are considered in the analysis. The numerical results show that the ICA method has good convergence property. Furthermore, the generation costs of the ICA approach are lower than other optimization algorithms reported in recent literature.]]>Wood, A.J. and B.F. Wollenberg,1996Chiang, C.L.,2007Walters, D.C. and G.B. Sheble,1993Chiang, C.L.,2005Ling, S.H. and F.H.F. Leung,2007Kim, J.O., D.J. Shin, J.N. Park and C. Singh,2002Subbaraj, P., R. Rengaraj and S. Salivahanan,2009Amjady, N. and H. Nasiri-Rad,2010Niknam, T., H.D. Mojarrad and H.Z. Meymand,2011Kumar, R., D. Sharma and A. Sadu,2011Subbaraj, P., R. Rengaraj, S. Salivahanan and T.R. Senthilkumar,2010Sun, J., W. Fang, D. Wang and W. Xu,2009Niknam, T.,2010Selvakumar, A.I. and K. Thanushkodi,2008Nomana, N. and H. Iba,2010Amjady, N. and H. Sharifzadeh,2010Wang, S.K., J.P. Chiou and C.W. Liu,2007Selvakumar, A.I. and K. Thanushkodi,2007Pothiya, S., I. Ngamroo and W. Kongprawechnon,2008Panigrahi, B.K. and V.R. Pandi,2008Niknam, T., H.D. Mojarrad and H.Z. Meymand,2011Sinha, N., R. Chakrabarti and P.K. Chattopadhyay,2003Bhattacharya, A. and P.K. Chattopadhyay,2010Bhattacharya, A. and P.K. Chattopadhyay,2010Meng, K., H.G. Wang, Z.Y. Dong and K.P. Wong,2010He, D., F. Wang and Z. Mao,2008Atashpaz-Gargari, E. and C. Lucas,2007Jalilvand, A., S. Behzadpoor and M. Hashemi,2010Niknam, T., E.T. Fard, N. Pourjafarian and A. Rousta,2011