A modular method of modeling a power plant includes selecting a major component module model from a library of component module models for each major component of the power plant, with each major component module representing a power plant major component of a unique configuration. The method also includes inputting initial model information into a database for the selected modules, with the initial model information including at least convergence criteria and a maximum number of passes. The method further includes running the modular model by running each selected module and enabling data exchange between the selected modules.