Optimization of the Power Conversion System for a Pulsed Fusion Power Plant with Multiple Heat Sources using a Dynamic Process Model

The optimization of the power conversion system, responsible for thermal-to-electrical energy conversion, for a pulsed fusion power plant is presented. A spherical tokamak is modelled as three heat sources, all pulsed, with different stream temperatures and available amounts of heat. A thermal energy storage system is considered in the design to compensate for the lack of thermal power during a dwell. Thermal storage enables continued power generation during a dwell and can avoid thermal transients in sensitive components like turbomachines. Multiple lower grade heat sources are integrated into the process through parallel preheating trains. The evaluation of a dynamic model of the power conversion system is used to define an objective function with multiple criteria. A bi-objective optimization problem is defined to investigate the trade-off between the size of the thermal energy storage system and the variability in turbine power output during a dwell. The set of non-dominated designs demonstrates the trade-off, with designs covering the range from steady state turbine power output to a design that reduces the turbine power output by 46.3% during a dwell. The dynamics of three non-dominated designs demonstrate the power conversion system can maintain relatively stable conditions at the turbine inlet under different operating conditions, but molten salt temperature control is an issue.