Engine controller and methods for controlling emission and power generation system using the same

An engine controller for controlling an emission amount in a gas stream emitted from a power generation system comprising a combustion engine operating at stoichiometric conditions and emitting an exhaust gas stream, an exhaust gas recirculation (EGR) system to recirculate a portion of the exhaust gas stream to the combustion engine, and a three-way catalyst disposed downstream of the combustion engine, the engine controller comprising:

• a memory storing one or more processor-executable routines;
• and
• one or more processors to execute the one or more processor-executable routines which, when executed, cause acts to be performed comprising:
• determining a pre-catalyst emission level in at least one of the one or more processors by measuring at least an EGR set-point value with a pre-catalyst emission sensor disposed upstream of the three-way catalyst, at least one of the one or more processors receiving one or more signals generated by the pre-catalyst emission sensor and using a combustion engine model stored in the memory to correlate at least the EGR set-point value to the pre-catalyst emission level;
• determining a post-catalyst emission level in at least one of the one or more processors using a three-way catalyst model stored in the memory to correlate catalyst properties based on the pre-catalyst emission level to the post-catalyst emission level;
• determining an adjusted post-catalyst emission level in at least one of the one or more processors based on an error corrected form of the post-catalyst emission level;
• determining a difference in at least one of the one or more processors between the post-catalyst emission level and the adjusted post-catalyst emission level and comparing the difference with a threshold value;
• and
• determining, in at least one of the one or more processors, whether the difference between the post-catalyst emission level and the adjusted post-catalyst emission level is greater than the threshold value and maintaining the emission amount in the gas stream below an emission regulatory limit by sending one or more signals from at least one of the one or more processors to adjust an actual value of an engine operating parameter when the difference between the post-catalyst emission level and the adjusted post-catalyst emission level is greater than the threshold value.

A power generation system, comprising:

• a combustion engine operating at stoichiometric conditions and emitting an exhaust gas stream;
• an exhaust gas recirculation (EGR) system to recirculate a portion of the exhaust gas stream to the combustion engine;
• a three-way catalyst disposed downstream of the combustion engine;
• and
• an engine controller operably coupled to the combustion engine to control an emission amount in a gas stream emitted from the power generation system, wherein the engine controller comprises:
• a memory storing one or more processor-executable routines;
• and
• one or more processors to execute the one or more processor-executable routines which, when executed, cause acts to be performed comprising:
• determining a pre-catalyst emission level in at least one of the one or more processors by measuring at least an EGR set-point value with a pre-catalyst emission sensor disposed upstream of the three-way catalyst, at least one of the one or more processors receiving one or more signals generated by the pre-catalyst emission sensor and using a combustion engine model stored in the memory to correlate at least the EGR set-point value to the pre-catalyst emission level;
• determining a post-catalyst emission level in at least one of the one or more processors using a three-way catalyst model stored in the memory to correlate catalyst properties based on the pre-catalyst emission level to the post-catalyst emission level;
• determining an adjusted post-catalyst emission level in at least one of the one or more processors based on an error corrected form of the post-catalyst emission level;
• determining a difference in at least one of the one or more processors between the post-catalyst emission level and the adjusted post-catalyst emission level and comparing the difference with a threshold value;
• and
• determining, in at least one of the one or more processors, whether the difference between the post-catalyst emission level and the adjusted post-catalyst emission level is greater than the threshold value and maintaining the emission amount in the gas stream below an emission regulatory limit by sending one or more signals from at least one of the one or more processors to adjust an actual value of an engine operating parameter when the difference between the post-catalyst emission level and the adjusted post-catalyst emission level is greater than the threshold value.