Comparing Thermal Library Modeling Suites for Integrated Modeling of Nuclear Power Plant and Power Grids

Decarbonization efforts in the United States has resulted in the increasing interest in flexible operation of nuclear power plants or thermal storage-based hybrid energy systems integrated with the power grid. Consequently, the need for rapid and effective modeling and simulation of such integrated systems is becoming critical. This requires modeling a approach that offers capabilities for multi-domain simulation that allows to model coupled phenomena accurately. This work focused on developing a proof of concept of such multi-domain models by designing a nominal model of a nuclear power plant balance of plant (BOP) system using the Modelica libraries. To model the thermofluidic domain, three libraries are evaluated, namely, ORNL's TRANSFORM, Modelon's ThermalPower, and Casella's ThermoPower. Next, the thermofluidic model is coupled with an electrical grid model built using the OpenIPSL. To understand the tradeoffs of each library, the response of each different model to power transients in the nuclear power plant was analyzed. Simulation results and modeling methods were compared. The BOP model in TRANSFORM was found to be stiff and may require more detailed component models, e.g. condenser and feed water heater, to model the BOP more realistically and rapidly.