Extremum-seeking control of a supercritical carbon-dioxide closed Brayton cycle in a direct-heated solar thermal power plant

Abstract

One promising avenue for the development of next generation CST (Concentrating Solar Thermal) technology focuses on the use of a direct-heated sCO2 (supercritical-CO2) CBC (closed Brayton cycle) as the generator power cycle. Initial investigations into such a CST plant, while promising, have found its power output and efficiency to be sensitive to fluctuations in solar heat input and ambient temperature over a day and between seasons. Given the difficulty in developing complete models across all operating conditions due to non-linearities in CO2 properties, an extremum-seeking controller is proposed to maximise the power output of the CBC as the solar heat input and cooling-air temperatures ..