Automatic combustion control for a gas turbine
View Patent ↗A method of controlling a gas turbine engine to provide protection against damaging pressure transients in the combustion process and to ensure compliance with emission requirements. Pressure fluctuations are monitored in a plurality of frequency ranges, and unacceptable pressure transients in different frequency ranges trigger different corrective actions. Unacceptable pressure transients in low and intermediate frequency ranges trigger a change in the pilot fuel fraction of a dual-mode combustor, while unacceptable pressure transients in a high frequency range trigger immediate power reduction in the engine. A control system for a gas turbine engine includes a plurality of timers for defining consecutive time periods for alternate monitoring of pressure transients and not monitoring pressure transients. Corrective action is taken only if unacceptable pressure transients are detected in each of the monitored time periods. As the combustion process is slowly adjusted to optimize emissions, the system will respond rapidly to an indication of an unacceptable dynamic condition.
1. A gas turbine power generation apparatus comprising:
a compressor for providing a flow of compressed air;
a fuel supply for providing a flow of combustible fuel;
a combustor for burning the fuel in the compressed air to form a flow of combustion gas;
a turbine for expanding the combustion gas and for generating mechanical power;
a sensor for generating a signal responsive to pressure transients in the combustion gas;
a signal processor for determining the spectral components of the signal;
a controller for executing logic for comparing the spectral components of a first frequency range to a first allowable value and the spectral components of a second frequency range extending higher than the first frequency range to a second allowable value to identify unacceptable pressure transients; and
logic executable by the controller for implementing a first corrective action in response to an unacceptable pressure transient in the first frequency range and for implementing a second corrective action different than the first corrective action in response to an unacceptable pressure transient in the second frequency range.
2. The apparatus of claim 1 , further comprising a timing mechanism associated with the controller for defining a plurality of time periods for use in identifying the unacceptable pressure transients.