With the increasing demand for peak regulation in power systems, steam turbine units are experiencing higher start-stop frequencies and increasingly complex operating conditions. High-temperature rotor structures (HTRS) are subjected to cyclic thermal-mechanical loads during start-stop cycles, which can easily lead to fatigue and creep damage, seriously threatening the safe and reliable operation of the units. Therefore, accurate assessment of the reliability of HTRS is crucial for guiding unit maintenance and design.
Methods
Damage-driven reliability assessment: Utilizes damage indicators to analyze the failure process of components under cyclic loading and predict the probabilistic evolution of damage accumulation, providing guidance for life monitoring and maintenance planning.
Efficient reliability analysis: Employs Polynomial Chaos Expansion (PCE) surrogate models to improve computational efficiency, making it more convenient for engineering applications. System-level reliability assessment: Considers the correlation between multiple failure modes, enabling more accurate system-level reliability assessment.
Reveals the impact of start-stop frequency on reliability: The study found that frequent start-stops accelerate damage accumulation, posing challenges to meeting the 30-year design life requirement. Identifies key influencing parameters: Sensitivity analysis indicates that the initial rotor temperature and speed rising rate have the most significant impact on reliability, providing valuable insights for optimizing operation and maintenance.
Fig. 2. Results of FEA to steam turbine rotor (a) the applied start-stop curve, (b) stress-time curves of SRG and BGs in one cycle, (c) temperature-time curves of SRG and BGs in one cycle, and (d) fatigue damage to SRG and creep-fatigue damage to BGs in one cycle.
Authors
Editor: Dr. Jun-Jing He
