Model-Free Coordinated Control for MHTGR-Based Nuclear Steam Supply Systems

Abstract

Abstract:The modular high temperature gas-cooled reactor (MHTGR) is a typical small modular reactor (SMR) that offers simpler, standardized and safer modular design by being factory built, requiring smaller initial capital investment, and having a shorter construction period. Thanks to its small size, the MHTGRs could be beneficial in providing electric power to remote areas that are deficient in transmission or distribution and in generating local power for large population centers. Based on the multi-modular operation scheme, the inherent safety feature of the MHTGRs can be applicable to large nuclear plants of any desired power rating. The MHTGR-based nuclear steam supplying system (NSSS) is constituted by an MHTGR, a side-by-side arranged helical-coil once-through steam generator (OTSG) and some connecting pipes. Due to the side-by-side arrangement, there is a tight coupling effect between the MHTGR and OTSG. Moreover, there always exists the parameter perturbation of the NSSSs. Thus, it is meaningful to study the model-free coordinated control of MHTGR-based NSSSs for safe, stable, robust and efficient operation. In this paper, a new model-free coordinated control strategy that regulates the nuclear power, MHTGR outlet helium temperature and OTSG outlet overheated steam temperature by properly adjusting the control rod position, helium flowrate and feed-water flowrate is established for the MHTGR-based NSSSs. Sufficient conditions for the globally asymptotic closed-loop stability is given. Finally, numerical simulation results in the cases of large range power decrease and increase illustrate the satisfactory performance of this newly-developed model-free coordinated NSSS control law.

Dynamic Modeling and Control Characteristics of the Two-Modular HTR-PM Nuclear Plant

“…There have been many process control system design approaches such as the relative gain analysis-(RGA-) based method. In this paper, both the feedback loops and control laws of HTR-PM control system are designed by the use of the physicsbased NSSS control method proposed in [30][31][32][33][34][35][36] and module coordination control method proposed in [28,29], which provide the globally asymptotic closed-loop stability through guaranteeing the convergence of Lyapunov functions determined by the shifted-ectropies of neutron kinetics and thermodynamics as well as the kinetic energy stored in secondary-loop FFN.…”

“…The physics-based control (PBC) method is an effective way to design nonlinear reactor control laws by retaining or strengthening stable subdynamics and by cancelling or suppressing unstable subdynamics, which has been applied to the load-following control design for the PWR [30,31], MHTGR [32][33][34], and OTSG [35]. Very recently, based upon the PBC method, a novel model-free MHTGR-based NSSS module control strategy was proposed in [36], which provides globally asymptotic stability (GAS) for the NSSS module if the feedwater temperature is constant and both the helium and feedwater flowrate are well regulated. This NSSS module control strategy can be realized by feedback loops given in Section 3.2.1 and simple control laws given in Section 3.3.1.…”

“…The module control laws include the feedback regulation algorithms of the nuclear power, primary helium flowrate, feedwater flowrate, MHTGR outlet helium temperature, and OTSG outlet steam temperature, which are designed based on the physics-based NSSS control method proposed in [30][31][32][33][34][35][36].…”

Passivity-Based Power-Level Control of Nuclear Reactors

“…By considering the nonlinearity from dead zone and saturation as well as the coupled primary pressure dynamics, the simple control given in [26] can be further enhanced [28,29]. Moreover, based on the basic idea of PBC, the coordinated control for a single mHTGR-based nuclear steam supply system (NSSS) module [30,31] and that for several NSSS modules coupled by a common steam turbine [32] are also proposed for the control of the entire plant. The current PBC design for the power control of nuclear reactors are mainly based on the classic CbI method.…”