Modelling of cogeneration systems. Part 1: Historical perspective

Abstract

This paper presents a brief review of cogeneration plant models that have been developed to fulfil different modelling requirements. Three types of models are readily available in the literature, namely the static, part-load and optimization models. The static models are simple design-point models which have found wide application for quickly predicting plant performance and providing data for preliminary economic analysis. However, these models are unable to predict performance of the plant at off-design conditions. To predict the performance of the cogeneration plant away from design conditions, part-load models have been developed. These models use fundamental engineering equations to predict plant performance at part-load conditions but these complex packages are expensive. The optimization models use operations research techniques to optimize the operation of utility plants to minimize operating cost or to maximize revenue. Many of these models are developed using a regression analysis of measured data and use linear functions to simulate components. The models use simplifying assumptions to analyse the thermodynamic performance of the plant but these are usually sufficient for the optimization studies conducted. The method used is dependent on the objective of the modelling process and each type is suited to different applications.