| The characteristics of optimal load-follow control of PWR plant are investigated in this study. A simple system model which describes main features of physical processes in the system was developed. The system model includes core neutronics with all the spatial dependent feedback effects, Xe-I dynamics, core thermal balances, primary loop thermal balances, and steam generator dynamic responses to turbine load changes. An optimal control problem which describes power level control and power distribution control problem together and considers all the important system operation limits as hard inequality constraints was formulated. The full-length control rod bank positions, part-length control rod positions, and boron concentration changes were modeled as control variables and turbine load variations were used as the forcing variable. Because modern PWR operating policy is to leave the part-length rods uninserted, the part-length rods were not used as a control variable in the optimal control calculations. The optimal control problem was converted to unconstrained nonlinear optimization problem by using the discretization approximation and the penalty function technique. The converted problem was solved by the non-linear Gauss-Newton method which showed superior performance over all of the other tested optimization methods.;The differences in calculated optimal control strategies were investigated for the cases of steady state T... |
