Development of S-CO2 system control methodology using modern control theory

Abstract

As greenhouse gas emission is becoming a problem in maritime trade, an alternative fuel system is required to rely less on fossil fuel. A small modular reactor is attracting attention as an alternative marine propulsion system, and KAIST-MMR, which uses the supercritical CO2 system as a power conversion system, is one of them. However, the power maneuvering required in the marine propulsion changes the operating conditions of the system, and correcting this is necessary for safe and efficient operation. Therefore, it is necessary to control the pre-cooler to cool the supercritical carbon dioxide to the design point of a compressor, but research and experimental verification of the controller have not been sufficient. In this thesis, a system analysis is performed using the MARS code verified with experimental results. Based on the analyzed transfer function and the state space, a controller based on modern control theory is designed. The designed controller is verified experimentally with Autonomous Brayton Cycle (ABC) test loop constructed at KAIST. Based on the verification results, a precooler controller to be used in KAIST-MMR is presented.