Coordinated Control Scheme Design of a Nuclear Heating Reactor Cogeneration Plant for Balancing Renewables

To balance the intermittent renewable energy (IRE), it is necessary for nuclear power plants (NPPs) to operate flexibly. The flexibility can be given by cogeneration, where the main steam flow are used to drive several thermal loads such as the turbine and seawater desalination process. The electric power of a nuclear cogeneration plant (NCP) can be regulated through adjusting the excess steam flow to the cogeneration processes. Due to the fluctuation of IRE generation, the distribution of main steam to different thermal loads in a NCP varies with net demand frequently, which in turn results in a floating feedwater temperature, and further forms a disturbance to the operation of nuclear reactor. To mitigate the fluctuation of process variables caused by balancing IRE generation, it is necessary to study the coordinated control of flexible nuclear cogeneration plants. In this paper, the scheme of a NCP form by a 200MWth nuclear heating reactor NHR-200II based nuclear steam supply system (NSSS) driving a turbine and a seawater desalination process is first introduced. To balance the IRE generation, a plant coordinated control strategy is newly proposed. The feasibility of this control is verified through numerical simulation, which shows that this NCP can be adopted for balancing IRE.

Proportional-Integral Disturbance Observer of Nuclear Reactors

A proportional-integral disturbance observer (PI-DO) for monitoring nuclear reactors is newly proposed, which is driven by the measurements of neutron flux and coolant temperature at reactor inlet as well as their integrations. This PI-DO provides a globally asymptotic estimation with a bounded steady-state error for the reactor key process variables as well as the total disturbances in channels of the neutron kinetics and primary coolant thermal-hydraulics. Moreover, the PI-DO is applied to reconstruct the unmeasurable state variables and total disturbances of a nuclear heating reactor (NHR). Numerical simulation results not only verify the theoretic analysis but also show both the satisfactory performance and the influence of observer parameters.

Automatic Generation Control of Nuclear Heating Reactor Power Plants

A nuclear heating reactor (NHR) is a typical integral pressurized water reactor (iPWR) with advanced design features such as an integral primary circuit, self-pressurization, full-power-range natural circulation, and hydraulic control rods. Through adjusting its electric power output according to the variation of demand, NHR power plants can be adopted to stablize the fluctuation of grid frequency caused by the intermittent nature of renewable generation, which is useful for deepening the penetration of renewables. The flexibility of an NHR power plant relies on the automatic generation control (AGC) function of the plant coordination control system, whose central is the AGC law. In this paper, the plant control system with AGC function is designed for NHR plants, where the AGC is realized based on the stabilizers of grid frequency and main steam pressure. Then, the AGC problem is transferred to the disturbance attenuation problem of a second-order dynamic system, and an active disturbance attenuation control (ADRC), which is just the addition of a feedback control given by a proportional‒integral (PI) law and a feedforward control driven by a disturbance observer (DO), is then proposed. Finally, this ADRC is applied to realize the AGC function for NHR-200II reactor power plant, and numerical simulation results show the implementation feasibility and satisfactory performance.