Continuous Order Identification of PHWR Models Under Step-back for the Design of Hyper-damped Power Tracking Controller with Enhanced Reactor Safety

摘要

In this paper, discrete time higher integer order linear transfer functionmodels have been identified first for a 500 MWe Pressurized Heavy Water Reactor(PHWR) which has highly nonlinear dynamical nature. Linear discrete time modelsof the nonlinear nuclear reactor have been identified around eight differentoperating points (power reduction or step-back conditions) with least squareestimator (LSE) and its four variants. From the synthetic frequency domain dataof these identified discrete time models, fractional order (FO) models withsampled continuous order distribution are identified for the nuclear reactor.This enables design of continuous order Proportional-Integral-Derivative (PID)like compensators in the complex w-plane for global power tracking at a widerange of operating conditions. Modeling of the PHWR is attempted with variouslevels of discrete commensurate-orders and the achievable accuracies are alsoelucidated along with the hidden issues, regarding modeling and controllerdesign. Credible simulation studies are presented to show the effectiveness ofthe proposed reactor modeling and power level controller design. The controllerpushes the reactor poles in higher Riemann sheets and thus makes the closedloop system hyper-damped which ensures safer reactor operation at varyingdc-gain while making the power tracking temporal response slightly sluggish;but ensuring greater safety margin.