Method to operate a combustor of a gas turbine

A method of operating a combustor of a gas turbine engine, wherein the gas turbine engine comprises a compressor, said combustor, and a turbine,

• wherein said compressor delivers an oxygen containing gas to said combustor, wherein said combustor comprises at least two burners and at least one main combustion chamber downstream of said at least two burners,
• wherein at least two of said at least two burners join commonly into said at least one main combustion chamber to generate combustion gas from burning fuel and said oxygen containing gas,
• wherein one extraction is provided to tap off at least a portion of the oxygen containing gas downstream of said compressor and upstream of said combustor, and wherein said extraction is part of a bypass, wherein said bypass bypasses said combustor and joins into a hot gas path downstream said combustor,
• wherein said extraction comprises a valve to control the portion of the oxygen containing gas to be tapped off, said method comprising:
• monitoring combustion gas temperatures via respective temperature measurements taken at different locations at respectively equal axial flow-distances downstream of the at least two burners of the combustion gas,
• comparing two temperatures of said temperature measurements,
• opening said valve or increasing an opening position of said valve when said comparison reveals that a difference between said two temperatures of said temperature measurements exceeds a temperature difference threshold.