I am working on a power generation plant, the National grid is unstable. National dispatching center always requesting a shut down of our big units (Fr,9E), because they can not control the grid. During my last shift, they requested to shut down two units (around 180 MW) at 1:00 am, then he called to start one of them at 4:30 am.
This is happening all the time. So I am wondering what are the effects of those multiple shutdowns/startups or trips on turbine mechanical parts, turbine life time, and equipment maintenance schedule. If there is a document from OEM, I would highly appreciate sending to me at firstname.lastname@example.org.
GE publishes a document, GER-3960, which states the different methods of assessing the effects of starts, stops and trips on their heavy duty gas turbines. It's a rather large publication, and it tries to cover every Frame turbine they build, so sometimes it can be very difficult to read and find the exact information you are looking for. They also have formulas for the different methods in the publication.
Thermal stresses are the hardest on the hot gas path parts life of any heavy duty gas turbine. They run best when they are started per manufacturer's guidelines and loaded to Base Load and left there for weeks or months at a time, then shut down in an orderly fashion according to manufacturer's guidelines. I have seen many sites extend the time between maintenance outages because they had so few starts/stops and trips--which can save LOTS of money, in addition to receiving more income for the power which is generated in these extended periods.
Many power generators (mostly independent power producers) have negotiated contracts with payments by the grid companies for each and every start/stop. This encourages the grid companies to be judicious about calling for frequent starts and stops.... BUT, those contracts usually have very stiff "penalties" when they call for a unit start and the unit doesn't go on-line in a certain period of time. The knife can cut both ways.
Use your preferred Internet search engine and look for GER-3960. It's a LONG read, and it has a LOT of good information, but for a lot of machines. So, I encourage reading the document slowly and drawing lines through the inapplicable portions of the document so you can concentrate on the applicable portions (based on the machine(s) you are operating).
Hope this helps!