Gas turbines in mechanical drive applications and operating methods

A method of operating a gas turbine system comprised of a gas turbine and a load driven by said gas turbine, said method comprising:

• mechanically coupling a load to said gas turbine,
• mechanically coupling an electric motor/generator to said load, with said electric motor/generator arranged opposite to said gas turbine with respect to said load,
• generating mechanical power by means of the gas turbine,
• powering the load with the mechanical power generated by the gas turbine,
• when the mechanical power generated by the gas turbine exceeds the mechanical power required to drive the load:
• operating the electric motor/generator in a generator mode;
• transferring excess mechanical power from the gas turbine to the electric motor/generator;
• and converting said excess mechanical power into electric power in the electric motor/generator;
• when the mechanical power generated by the gas turbine is not null and less than the power required to drive the load:
• operating said electric motor/generator in a motor mode;
• electrically powering the electric motor/generator;
• converting electric power into supplemental mechanical power in the electric motor/generator;
• transferring the supplemental mechanical power from the electric motor/generator to the load;
• driving the load with combined power generated by the gas turbine and supplemental mechanical power generated by the electric motor/generator;
• when the mechanical power generated by the gas turbine is null or the gas turbine is turning off:
• disconnecting the gas turbine from the load;
• operating said electric motor/generator in a motor mode;
• converting electric power into mechanical power in the electric motor/generator;
• transferring the mechanical power from the electric motor/generator to the load;
• and
• driving the load with the mechanical power generated by the electric motor/generator.

A system for storing pressure energy in a pipeline for gas, comprising:

• at least one compressor arranged in the pipeline and design to compress said gas in the pipeline,
• a gas turbine configured and arranged for driving said at least one compressor,
• an electric motor/generator electrically connected to an electric power grid,
• a first load coupling connecting the gas turbine to said at least one compressor,
• a second load coupling, connecting said at least one compressor to said electric motor/generator, said electric motor/generator being adapted to function as a generator for converting excess mechanical power from said gas turbine into electrical power and delivering the electrical power to the electric power grid, and as a motor for supplementing driving power to said at least one compressor,
• a disconnecting device to reversibly disconnect said at least one compressor from said gas turbine, so that said at least one compressor can be driven only by said motor/generator;
• wherein said system provides a phase of disconnection of said at least one compressor from said gas turbine, and a subsequent phase of compression of gas in said pipeline by operating said at least one compressor only by said electric motor.