Transient operating conditions of steam-turbine power units can considerably affect their operating performances. First of all, this emerges in an increase of the operating expenses because of additional fuel expenditures at the transients themselves. Secondly, they entail an increase in the unit’s heat-rate during the subsequent stationary operating conditions because of damages caused by or tied with the transients. Apart from additional fuel costs, the transients have a significant impact on the turbine’s reliability. Equipment failures and forced outages are commonly more probable during the transients, and the equipment lifetime declines due to low-cycle fatigue of the most thermally stressed high-temperature components. The quantitative measure of all these factors to a great degree depends on the operation quality, and the influence of all the above factors can be reduced with the use of advanced on-line informative support for the operator during the transients. The operator should be continuously provided with obvious graphic information about the current temperature and thermal-stress states of the turbine and admissible changes of its operating conditions that can be done without sacrifice of reliability. More often than not, the acting diagrams for the transients can be additionally optimized by way of combined digital solution of direct and reverse unsteady heat conduction problems for so-called “critical” (most thermally stressed) design elements of the turbine. Of significance is also post-operating analysis of the transients to reveal the operator’s errors and prevent their repetition. All these notions refer to both the fossil-fuel and nuclear powerplants. An accumulated experience at different steam-turbine power units proved high effectiveness of these approaches. The developed solutions can be adapted to other equipment types with regard to their design and operation features.

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