Characterization of Gas Turbine Lean Blowout During Frequency Excursions in Power Networks

While gas turbines are popular in power networks due to reduced emissions and economical operation, their frequency response characteristics are substantially different from other conventional generation technologies; hence, gas turbine dynamics may influence system stability during significant frequency excursions. This study characterizes the impact of gas turbine combustor lean blowout (LBO) while considering large frequency excursions and, in particular, during short-circuit faults. Studies have shown that combined-cycle gas turbines are more vulnerable to an LBO condition during short-circuit events when they operate at rated power output. A sensitivity analysis was also carried out against a number of factors influencing the LBO, revealing that generator loading and rate-of-change-of-frequency are the main contributing factors for the LBO. Furthermore, mitigation strategies are also proposed to alleviate the LBO condition during large frequency excursions.