Dynamical modeling and coordinated control design of a multimodular nuclear power-hydrogen cogeneration plant

Based on the idea of interconnecting the modular high temperature gas-cooled reactor (mHTGR), steam Rankine cycle, Cu-Cl cycle and high temperature electrolysis (HTE), the schematic design of a multimodular nuclear power-hydrogen cogeneration is proposed. This cogeneration plant can be utilized to balance the net load by redistributing the motive steam between power generation and hydrogen production. The operational flexibility provided by steam redistribution relies heavily on plant-wide coordinated control. Since dynamic modeling is a crucial basis of control design, a lumped-parameter dynamic model of this nuclear cogeneration plant (NCP) is developed and implemented as a numerical simulation program. The steady-state modeling results show that the rated thermal power of this NCP is about 1523 MW, and the maximal values of hydrogen production rate and output electric power are 11.76 metric tons per hour and 647.3 MW, respectively. The open-loop transient analysis shows that the model's dynamic behavior is in good accordance with physical mechanisms. Further, a hierarchical coordinated control scheme is designed for this NCP, providing a load-following control function based upon steam redistribution, and the corresponding validations are also given. For the load decreasing with ramp rate at 8 MW/min and amplitude of 540 MW, the control system guarantees the grid frequency deviation is smaller than 0.2 Hz while the reactor thermal power, as well as the temperatures and pressures of hydrogen production reactions, are maintained around their expected values. The results in this paper show that the mHTGR-based power-hydrogen cogeneration plant is not only a clean source of electricity and hydrogen but also a flexible source for grid frequency stabilization.