Modeling Combined Heat and Power Systems for Microgrid Applications

This paper presents the modeling of combined heat and power (CHP) systems for microgrid applications. When generating electricity, a CHP unit can recycle waste heat to supply building thermal loads to improve the overall efficiency of a traditional generation system. The ramping capability of a CHP unit makes it an ideal resource for load following and frequency regulation in microgrid operation. In this paper, a CHP model built in Simulink is developed. The CHP model includes three key components: generator, turbine, and absorption chiller. A new isochronous governor control strategy is proposed to provide zero-steady-state-error frequency regulation. The supply of building thermal loads is modeled to facilitate the calculation of the overall CHP system efficiency. The impact of ambient temperature on the maximum electrical output is considered. The developed model is implemented on OPAL-RT for testing the microgrid controller performance in a microgrid system.