Modeling of combined heat and power generation unit for dynamic analysis of integrated thermal-electric grids*

Abstract

Despite the availability of extensive literature on the benefits and optimization of integrated thermal-electric grids, the dynamics aspects of their operation are not often investigated and well understood. Combined Heat and Power (CHP) units that simultaneously generate electricity and useful heat are one of the main coupling elements between thermal and electric systems with complex dynamic behavior. This paper describes the effort to develop a dynamic model of a CHP unit that will be adequate for use in studies of integrated thermal-electric grids. The proposed model consists of the combustion engine, heat exchanger, exhaust heat exchanger and an induction generator. The developed model is calibrated using parameters of a CHP unit with the goal to validate the behavior of the model against the hardware testbed with the same CHP unit in the laboratory at the Research Center for Combined Smart Energy Systems (CoSES) of the Technical University of Munich (TUM). The individual components, internal combustion engine, heat exchanger, exhaust heat exchanger and induction generator, are modeled separately in from Modelica library. The water heat exchanger and the exhaust heat exchanger are modelled considering the condensing effect of water.