Multi-stage Observer Designs for Three-Time-Scale System with Application to AHWR

The chapter focuses on the ninetieth-order system of the Advanced Heavy Water Reactor (AHWR), characterized by a complex three-time-scale structure. The system comprises 38 slow, 35 fast, and 17 very fast state variables, necessitating an effective controller for spatial power regulation. The study proposes full and reduced-order observers using a novel method for this intricate three-time-scale system. The key innovation lies in multi-stage observer designs, streamlining complexity and computational time while maintaining the flexibility to independently design observer gains for the subsystems. These observers are then applied to estimate the AHWR state, facilitating spatial stabilization through feedback control. Performance evaluations, conducted on the nonlinear AHWR model amidst transients, compare these observers with a controller (without an observer) and a fast output sampling-based controller.