A Co-ordinated Control Methodology for Rapid Load-Following Operation of a Pressurized Water Reactor Based Small Modular Reactor

The Pressurized Water Reactor (PWR) based Small Modular Reactors (SMRs) are best suited to perform load-following operation because of their inherent self-stabilizing and self-regulating characteristics. Therefore, these PWR based SMRs can not only acts as standalone electricity generating units but also work alongside intermittent renewable energy sources in Hybrid Energy Systems (HES) configuration. In both the cases, the PWR based SMRs are expected to perform rapid load-following operation along with satisfaction of constraints imposed by overall power coefficients of reactivity. The conventional mode of PWR operation-namely, the Normal Mode and Alternate Mode could not guarantee very rapid power maneuvering alongside satisfaction of the reactivity constraints. This paper puts forward a novel control methodology, which combines the advantages of both the Normal Mode and Alternate Mode, to accomplish very rapid power maneuver without defying the reactivity constraints. The load-following controllers were designed using Incremental Nonlinear Dynamic Inversion (INDI) which guarantees efficient tracking and does not require additional state observer and knowledge of inherent system nonlinearities. However, the nonlinear tracking controllers whose reference signal changes very rapidly are victims of unwanted glitches/spikes in control output which may ultimately lead to actuator wear-out. This problem has been handled by the use of a Reference Shaper whose detailed design methodology has also been presented. The performance of the control methodology and the controllers are verified in real-time using real-time Hardware-in-Loop (HiL) simulations.