Disturbance rejection in thermal power plants

A typical thermal power plant is characterized by nonlinearity, changing parameters, unknown disturbances, large time-delays, large inertia and highly coupled dynamics among various control loops, making it one of the most challenging industrial control problems beyond scope of existing theories. Currently proportional-integral-derivative (PID) control, an eighty-year-old technology, is still the predominant tool of choice in power plant control. Given the potential economic payoff, better solutions to power plant control are highly desired. An alternative framework is proposed in this paper to study the control problem in thermal power plants in which disturbance rejection is the central theme. As a result, control problems are better understood as well as the means of solving them. This new formulation of existing problems is followed by a systematic review of disturbance rejection methods that ultimately leads us to the concept of Active Disturbance Rejection.