Optimal Tuning of Controllers for Cascade Temperature Control of Superheater Using Nelder Mead Algorithm

A superheater is a vital part of the steam generation process in the boiler-turbine system. Reliable control of temperature in the superheated steam temperature system is important to ensure high efficiency and high load-following capability in the operation of modern power plant. The PI and PID controllers are widely applied in cascade control of secondary superheated steam temperature process and the tuning method of PI and PID controller parameters is still a hot research area. A Nelder mead based optimization tuning scheme is developed for cascade control of superheater steam temperature process. It is an efficient and fast tuning scheme compared to other conventional tuning techniques. The mathematical model of the superheater is derived by sets of nonlinear partial differential equations. From the dynamical model of the superheater, a FOPTD (First order plus dead time model) model is derived using frequency response method. Then optimum gains for PI and PID controllers in the cascade control loop are determined based on the value of ITAE (Integral Time absolute error).