Griese, M.; Pawlik, T.; Schulte, T.; Maas, J.: Scalable model of a CHP unit for HIL simulation of a smart combined grid system, II. International Energy Technologies Conference, ENTECH ‘14, S. 189-200, Türkei (Istanbul), 2014. Scalable model of a CHP unit for HIL simulation of a smart combined grid system Martin Griese, Thomas Pawlik, Thomas Schulte, Jürgen Maas Hochschule Ostwestfalen-Lippe University of Applied Sciences IES – Intelligent Energy Systems Liebigstraße 87, 32657 Lemgo, Germany ABSTRACT Due to the increasing energy demand and shortage of fossil fuels, the energy systems will be transformed from mainly centralized into more decentralized systems, also incorporating more renewable energy. However, optimizing the control and structure of these systems is rather complex. A method for analyzing and planning of such systems is an adapted variant of the so called Hardware-in-the-Loop simulation. This approach comprises virtual energy components as models combined with data from experimental components. As a virtual energy component, a simulation model describing the physical behavior of CHP units is proposed in this contribution. The modeling approach is based on a time domain approach using state variables of the multiple domains to describe the dynamic behavior. For instance, the first law of thermodynamics is applied to model the thermal quantities. Furthermore, the model is scalable regarding the modeling depth and the power ratings which allows an application for different simulation scenarios. Finally, the overall model is parameterized and validated with data of a medium sized CHP plant. I. INTRODUCTION The increasing shortage of fossil fuels as well as the climate change due to greenhouse gases leads to an increasing relevance of renewable energy. The current energy system will be transformed from a centralized generation by conventional power plants to a distributed energy system consisting mainly of renewable energy generators, (Alanne and Saari, 2006), (Garrity, 2009). While centralized energy systems are approved during the past decades, the control and structural expansion of a decentralized energy system is rather complex due to volatility of the renewable energy and the high number of geographically distributed energy sources. Therefore, beside developing and installing new distributed energy plants, also an energy management is required to operate the combined grid system under optimal conditions (Grimm, Neumann and Mahlknecht, 2013). In the same manner, efficient methods for buffering the volatile energy are required. Since the direct storage of electrical energy is rather inefficient or extremely expensive and limited, an efficient conversion into other forms of energy need to be considered. By using power-to-gas (P2G), widely established gas grids could be used which provide a very high capacitance. In this case an efficient reconversion is given by the well-established combined heat and power (CHP) technique which is further modeled in the scope of this