Method for operating a power plant

Method for operating a power station having a turbine shafting comprising a gas turbine, having an output greater than 100 MW, and a generator that is driven directly by the gas turbine and that generates alternating current at an operating frequency, whose output is connected to an electrical grid with a given grid frequency (F), an electronic decoupling apparatus is arranged between the generator and the grid, the decoupling apparatus is a frequency converter in the form of a matrix converter and decouples the operating frequency from the grid frequency (F), the method comprising:

• adjusting a mechanical rotational speed (nmech) of the gas turbine in a controlled way in the event of temporary over-frequency or under-frequency events in the electrical grid, wherein the matrix converter comprises a plurality of controllable, bidirectional switches that are arranged in an (m x n) matrix and, controlled by a controller, connect m inputs selectively to n outputs, where m is greater than n and where a first device for determining the polarity of the currents in the inputs are provided and a second device for determining the polarity of the voltages between the inputs are provided, and wherein the first and second devices are connected to the controller by signal lines.

Method for operating a power station having a turbine shafting, a gas turbine having a rotor and a generator having a rotor, the turbine shafting comprising the gas turbine rotor and the generator rotor that is driven directly by the gas turbine and that generates alternating current at an operating frequency, whose output is connected to an electrical grid with a given grid frequency (F), an electronic decoupling apparatus is arranged between the generator and the grid, the decoupling apparatus decouples the operating frequency from the grid frequency (F), the method comprising:

• adjusting a mechanical speed (nmech) of the gas turbine in a controlled way in the event of temporary over-frequency or under-frequency events in the electrical grid wherein in the event of frequency changes in the electrical grid, the mechanical rotational speed (nmech) of the gas turbine is changed up to a first limit with a first ratio to the change in the grid frequency (F), the speed is changed starting at the first limit up to a second limit with a second ratio to the change in the grid frequency (F), and the speed is kept constant starting at the second limit independent of the grid frequency (F).