Gas turbine maintenance has historically been performed firstly to keep equipment safe and reliable to operate, and secondly to prevent performance loss. Component replacement plans have often been generic and therefore best suited for one set of ambient conditions and a few pre-defined operation profiles. Continuous development in materials and computerized analysis methods have resulted in much more well understood and robust designs than before, resulting in design induced failure rates dropping to levels where they can be considered as random and unexpected.
While gas turbine designs matured, market conditions changed. Deregulation, consumer energy efficiency improvements, emission reduction requirements and large-scale introduction of renewables have reduced both average electricity price and thus the average amount of gas turbine power needed, but has also increased the variability in demand, resulting in highly unit specific operation profiles. This requires operators to cut unnecessary costs wherever possible and optimize operation and maintenance strategy in a complex environment with a growing number of parameters to consider. Over the past years much focus has been put on cost reduction through extension of maintenance intervals. However, since less maintenance and longer intervals can mean lower reliability and higher degradation, it is not always cost efficient. This paper shows how costs of maintenance, operation, fuel and degradation can be analyzed together, resulting in improved decision support for choosing better operation and maintenance strategies.