Method for operating a gas turbine power plant with cooling of the combustion air

The gas turbine assembly has a cooling system for the combustion air, using a suitable coolant (20,21). At least a part of the air mass flow is cooled before or within the compressor (1,2) so that critical temperatures are not breached at critical points (30-38) e.g. at the outlet from the compressor or at other turbine components. The cooling reduces the air and/or component temperatures below the maximum thermal resistance ability of the turbine component materials. Thermal sensors (40) are at least at one of the critical points, to give measured temperature values (42) to control (41) the coolants.