Structural Health Monitoring for Conventional Power Plants: Solutions for Operational Challenges

The load follow operation of thermal power plants in the context of the German “Energiewende” is a big challenge for those power plants. In this context TMF/SHM methods gain increasingly in importance. Most existing power plants do not actually work any more according to the load profile which was originally specified. Load monitoring with the potential of optimization of operational modes combined with highly qualified fatigue and creep-fatigue assessment modules is a central concern. A lot of new methods were developed for getting appropriate information about the structural health situation of loaded components and prevent premature damage. In this context, it is essential to process both design load data as well as information of the real operational load situation and combine this with a highly qualified assessment method based on the relevant design codes for conventional power plant components such as EN 12952-3 and EN 13445-3. In the case of thermal power plants both fatigue due to cyclic loading and creep due to high temperatures (and their combination) play an important role. Note that there is a change of dominating damage mechanisms and dominating damage locations (from creep towards low cycle fatigue) due to new (load follow) operating modes. This implies the qualified assessment of fatigue damage respectively combined creep-fatigue phenomena. Due to the detailed knowledge of stress histories, temperatures and the duration of hold times a best forecast can be given. A staged concept is envisaged consisting of a simplified estimation according to conventional design codes (EN 12952-3 / EN 13445-3) and a detailed solution based on the application of a non-linear material model.