In a method of operating a compressor of a gas
turbine, where compressor air sucked in from the environment is cooled down by
evaporation cooling before entering the compressor, before starting operation of the compressor, maximum possible temperature drops which could be achieved by
evaporation cooling are determined dependent on different ambient conditions and / or are provided as a
data set. These temperature drops are correlated with a
compressor map containing
maximum temperature distortions at different ambient conditions and different rotation frequencies of the compressor which have to be met in order to avoid pumping. The
evaporation cooling is then only operated when current ambient condition result in a maximum possible
temperature drop from which a predetermined fraction of between 50% and 100% does not exceed the maximum
distortion which can be taken from the
compressor map for these ambient conditions and the current rotation frequency of the compressor.
Safe operation of the compressor can be achieved without the need or
monitoring temperature distortions in the sucked in air
stream.