TABLE OF CONTENTS G. Prasad
In today's privatised power industry, a thermal power plant capable of making faster adjustments in power output in response to the system demand has significant com petitive advantages. Such a plant may often be required to operate in a load-cycling or two-shifting manner resulting in non-linear changes in plant variables. A thermal power plant is a highly coupled large-scale multivariable dynamic system. It is normally controlled by multiloop PI/PID controllers. The control performance of these loops is adversely affected by inter-loop interactions. In addition, normal working of a power plant is severely affected by the occurrence of a range of system disturbances. Some common disturbances are changes in active burner configuration, heat-exchanger tube fouling, and variations in condenser vacuum. Being a highly coupled system, the disturbances in one part of the plant can have a significant effect on the rest of the plant as well.
In order to minimise the influence of both plant-wide interactions and disturbances so as to ensure a higher rate of load change without violating thermal constraints, a coordinated control strategy is required. This control strategy should coordinate the activities of various subsystems of a thermal power plant to achieve optimal performance during large load changes and system disturbances by minimising the adverse effects of plant-wide interactions. Such a control strategy can very effectively be implemented by making effective use of the tremendous...
