Assessment of the rise in the turbine operation risk due to increased cyclicity of the power unit operation

• Power units have to change the character of their operation from basic to cyclic.
• Cyclic operation causes a drop of life and an increased risk of operation.
• The increased risk is very important for turbines with long time of operation.
• The risk assessment of the cyclic operation of the real steam turbine is shown.
• For the old units that work cyclically, the new maintenance strategy is needed.

The energy market liberalization and the increasing share of renewable energy sources, considered for environmental reasons to be a priority in electricity generation, necessitate a change in the operation strategy of coal-fired power units. Units that have so far operated as basic ones will more and more often have to function as regulation units. This involves a rise in their operation cyclicity and frequent changes in the power output. This paper presents an analysis of the impact of these new methods of operation on changes in the technical risk. A detailed analysis is made of the turbine rotors, whose damage may lead to severe consequences. It is proved that a rise in the operation cyclicity may raise the level of risk related to further operation. The risk growth effect is especially important for power units which have already been operated for a long time and whose components show a relatively large life consumption.