A system comprising: a gas turbine engine system; a fuel conduit included in the gas turbine engine system; a plurality of sensors disposed in the fuel conduit, said plurality of sensors comprising a fuel composition sensor, a pressure sensor (114, 120), a temperature sensor (116, 122), and/or a flow sensor (118, 124); and a gas turbine controller configured to: receive a plurality of sensor signals from the plurality of sensors disposed in the fuel conduit; execute a gas turbine model by applying the plurality of sensor signals as input to derive a plurality of estimated gas turbine engine parameters; execute a flame holding model by applying the plurality of sensor signals and the plurality of estimated gas turbine engine parameters as input to derive a steam flow to fuel flow ratio that minimizes or eliminates flame holding in a fuel nozzle of the gas turbine engine system; and control delivery of a steam and a fuel based on the steam flow to fuel flow ratio; the system being characterized in that a heat recovery steam generator (HRSG) system is fluidly coupled downstream from the gas turbine system and configured to receive an exhaust from the gas turbine system, and the steam comprises a high pressure steam produced by the HRSG system, an intermediate pressure steam produced by the HRSG system, or a combination thereof; a mixing chamber for mixing the steam and the fuel is located immediately downstream from a first heat exchanger and immediately upstream of a second heat exchanger. a gas turbine engine system; a fuel conduit included in the gas turbine engine system; a plurality of sensors disposed in the fuel conduit, said plurality of sensors comprising a fuel composition sensor, a pressure sensor (114, 120), a temperature sensor (116, 122), and/or a flow sensor (118, 124); and a gas turbine controller configured to: receive a plurality of sensor signals from the plurality of sensors disposed in the fuel conduit; execute a gas turbine model by applying the plurality of sensor signals as input to derive a plurality of estimated gas turbine engine parameters; execute a flame holding model by applying the plurality of sensor signals and the plurality of estimated gas turbine engine parameters as input to derive a steam flow to fuel flow ratio that minimizes or eliminates flame holding in a fuel nozzle of the gas turbine engine system; and control delivery of a steam and a fuel based on the steam flow to fuel flow ratio; the system being characterized in that a heat recovery steam generator (HRSG) system is fluidly coupled downstream from the gas turbine system and configured to receive an exhaust from the gas turbine system, and the steam comprises a high pressure steam produced by the HRSG system, an intermediate pressure steam produced by the HRSG system, or a combination thereof; a mixing chamber for mixing the steam and the fuel is located immediately downstream from a first heat exchanger and immediately upstream of a second heat exchanger. receive a plurality of sensor signals from the plurality of sensors disposed in the fuel conduit; execute a gas turbine model by applying the plurality of sensor signals as input to derive a plurality of estimated gas turbine engine parameters; execute a flame holding model by applying the plurality of sensor signals and the plurality of estimated gas turbine engine parameters as input to derive a steam flow to fuel flow ratio that minimizes or eliminates flame holding in a fuel nozzle of the gas turbine engine system; and control delivery of a steam and a fuel based on the steam flow to fuel flow ratio; the system being characterized in that a heat recovery steam generator (HRSG) system is fluidly coupled downstream from the gas turbine system and configured to receive an exhaust from the gas turbine system, and the steam comprises a high pressure steam produced by the HRSG system, an intermediate pressure steam produced by the HRSG system, or a combination thereof; a mixing chamber for mixing the steam and the fuel is located immediately downstream from a first heat exchanger and immediately upstream of a second heat exchanger.