The Influence of a Steam Turbine Control System on the Dynamic Characteristics of Boiler Steam Pressure as a Controlled Object

In view of the presence of destabilizing factors in boiler steam pressure caused by the power-frequency control of current large-sized mono-block thermal power plant units the authors have performed an analysis of the digital electric-hydraulic (DEH) control modes. It is noted that there exists a substantial difference in the influence on the dynamic characteristics of a boiler object when various DEH control modes are put into use. In case the DEH control assumes the form of power-frequency one the boiler steam pressure as a controlled object can be viewed as a self balancing-absent process. When the DEH control functions as a pure speed regulation, the former represents a self-balancing process. By way of simulations the effect of fuel and load perturbations on the dynamic characteristics of a mono-block thermal power plant unit has been determined when different DEH control modes are used. At the end of the paper presented are the operating modes of the mono-block unit under unstable working conditions or in case of a high frequency of outside perturbations. In sum, the paper has provided some hints of highly practical value for ensuring the safe operation of large-sized mono-block thermal power plants.