Systems and methods of estimating a combustion equivalence ratio in a gas turbine with exhaust gas recirculation

A method, comprising:

• combusting a fuel and an oxidant in a combustor of an exhaust gas recirculation (EGR) gas turbine system that produces electrical power and provides a portion of the electrical power to an electrical grid;
• driving, via a combustion fluid provided by the combustor, a gas turbine, wherein the gas turbine produces a rotative power and an exhaust gas;
• recirculating the exhaust gas into the combustor as a diluent;
• sensing an exhaust flow composition of the exhaust gas;
• sensing a diluent flow composition of the diluent;
• deriving an estimated exhaust mass flow;
• deriving an estimated diluent mass flow;
• deriving a combustion equivalence ratio ΦCOMB based at least in part on the sensed exhaust flow composition the sensed diluent flow composition, the estimated exhaust mass flow, and the estimated diluent mass flow;
• and
• controlling, via one or more processors, one or more parameters of the EGR gas turbine system based at least in part on the combustion equivalence ratio ΦCOMB.

A non-transitory, computer readable medium storing instructions executable by one or more processors, the instructions including:

• instructions, that when executed by the one or more processors, cause the one or more processors to combust a fuel and an oxidant in a combustor of an exhaust gas recirculation (EGR) gas turbine system that produces electrical power and provides a portion of the electrical power to an electrical grid;
• instructions, that when executed by the one or more processors, cause the one or more processors to drive, via a combustion fluid provided by the combustor, a gas turbine, wherein the gas turbine produces a rotative power and an exhaust gas;
• instructions, that when executed by the one or more processors, cause the one or more processors to recirculate the exhaust gas into the combustor as a diluent;
• instructions, that when executed by the one or more processors, cause the one or more processors to sense an exhaust flow composition of the exhaust gas;
• instructions, that when executed by the one or more processors, cause the one or more processors to sense a diluent flow composition of the diluent;
• instructions, that when executed by the one or more processors, cause the one or more processors to derive an estimated exhaust mass flow;
• instructions, that when executed by the one or more processors, cause the one or more processors to derive an estimated diluent mass flow;
• instructions, that when executed by the one or more processors, cause the one or more processors to derive a combustion equivalence ratio ΦCOMB based at least in part on the sensed exhaust flow composition the sensed diluent flow composition, the estimated exhaust mass flow, and the estimated diluent mass flow;
• and
• instructions, that when executed by the one or more processors, cause the one or more processors to control one or more parameters of the EGR gas turbine system based at least in part on the combustion equivalence ratio ΦCOMB.