Diagnosis of Gas Turbine Operating Conditions by Means of the Inverse Cycle Calculation

This paper presents a method for the analysis of gas turbine operating state, which uses the Cycle-Deck developed by gas turbine manufacturers and the measurements taken by means of the standard machine instrumentation. The gas turbine operating condition analysis is performed "adapting" the characteristic geometric and perfomiance parameters (i.e., characteristic flow passage areas and efficiencies of the compressor and turbine, combustor efficiency, etc ), used as inputs by the Cycle-Deck, until the computed estimates of the measurable parameters agree with the values measured on the gas turbine. This is done by minimizing an objective function built as the sum of the squared residuals between the computed and measured values of the same parameters. The analysis of the variations between computed and expected values of the characteristic parameters allows the localization of inefficient operations due to deterioration and faults.