Thermodynamic modeling and control of hybrid solar-fossil fuel power generation and storage system

Hybrid solar-fossil fuel power generation and storage (HSFF-PGS) is an innovative technology characterized by renewable and conventional hybrid energy utilization and thermochemical energy storage. The HSFF-PGS system has prominent advantages in improving the solar energy grade and storing thermal energy with a high energy density. However, investigations on its dynamic characteristics and real-time control are inadequate, which hinders the development of the system's automation level to some degree. To deal with this issue, first, in this paper a dynamic model that includes the thermal inertia and reaction kinetics is constructed. Simulations under the nominal conditions show that the net solar utilization efficiency and energy savings ratio can reach 48.28% and 34.5%. Second, the design/off-design working condition properties are presented and the dynamic characteristics, such as nonlinearity and coupling, are explored to identify the control difficulties. The calculation results show that the relative gain array value ranges from 1 to 5 and the Vinnicombe gap is greater than 0.4 under most working conditions. Based on the dynamic analysis results, distributed active disturbance rejection control (ADRC) strategies for power generation and exhaust temperature regulation are developed. Then, the control performances of the proposed distributed ADRC and the conventional proportional integral derivative (PID) control are compared under nominal working conditions and typical-day scenarios. The control performance indexes are improved by 66.7% on average. Thus, the distributed ADRC is confirmed to be a better control method and has a good potential for dynamic operation of the HFSS-PGS system.