1. A method for operating a gas turbine group, the gas turbine group including a fuel gas supply line and a device for determining fuel gas properties arranged in said fuel gas supply line, the method comprising: determining at least one fuel gas property; feeding the determined fuel gas property to a control system of the gas turbine group; and performing control action on the operation of the gas turbine group dependent on the determined fuel gas property, the control action being performed on at least one selected from the group consisting of the distribution of a fuel gas mass flow between different fuel gas outlet openings, a combustion air supply of burners of the gas turbine group, and the injection of inert media into a gas turbine group working fluid.