A simulated model for a once-through boiler by parameter adjustment based on genetic algorithms Ali Chaibakhsh * , Ali Ghaffari, S. Ali A. Moosavian Department of Mechanical Engineering, K.N. Toosi University of Technology, P.O. Box 19395-1999, Tehran, Iran Received 25 November 2006; received in revised form 7 May 2007; accepted 13 June 2007 Available online 17 August 2007 Abstract In this paper based on the physical rules, thermodynamics principles and energy mass balance, the simulation models are developed and applied to electrical power generating plants in order to characterize the essential dynamic behavior of the boiler subsystems and to use the corresponding models for the power plant processes. These models are developed for a sub-critical once through Benson type boiler based on the experimental data obtained from a complete set of field exper- iments. An optimization approach based on genetic algorithm (GA) is executed to estimate the model parameters and fit the models response on the real system dynamics. Comparison between the responses of the corresponding models with the response of the real plants validates the accuracy and performance of modeling approach. A similar comparison between the responses of these models with linear parametric models shows the effectiveness and feasibility of the developed model in term of more accurate and less deviation between the responses of the models and the corresponding subsystems. Ó 2007 Elsevier B.V. All rights reserved. Keywords: Power plant; Once-through boiler; Mathematical model; Genetic algorithm 1. Introduction Facing enormous demand for electricity and growing need for more and safer power generating has moti- vated investigation into dynamic analysis of power plants to design more reliable control systems. Better sys- tem performance means increase in power generation efficiency and also decrease in the maintenance costs. To design suitable controllers, adequate information about the system dynamics is required. The boiler–turbine modeling has a wide application in power plant control and process study. The dynam- ics of most power plants are highly nonlinear with numerous uncertainties. Thus, no mathematical model can exactly describe such a complicated physical process, and there will always be modeling errors due to un-mod- eled dynamics and parametric uncertainties. Besides, detailed modeling of plants dynamics is often not effi- cient for control synthesis. The plant model should describe the plant dynamics with sufficient accuracy and not describe the microscopic details occurring within individual plant components [1]. 1569-190X/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.simpat.2007.06.004 * Corresponding author. Tel.: +98 21 886 748 41; fax: +98 21 886 747 48. E-mail address: chaibakhsh@dena.kntu.ac.ir (A. Chaibakhsh). Simulation Modelling Practice and Theory 15 (2007) 1029–1051 www.elsevier.com/locate/simpat