What sort of turbine - steam or gas? Makes a bit of difference.
What you are asking for is available commercially but can be quite expensive.
The calculations are not that difficult and can be done in Excel. The hard part is actually getting the correct measurements of the required input values - fuel flow for the turbine, mass flow through the compressor etc.
For my plant, I don't deal in absolutes. I look for changes in trended values from new/overhauled condition (and compare with other trains). For the GTs, I look at fuel demand (from the gas valve position), shaft speeds and EGT - for the compressors, I look at head v speed v mass flow
Bascially what I do is compare the energy consumed by a compressor (head) against energy consumed by the GT driving the compressor to determine the source of a loss of efficiency.
