Assessment of the Effectiveness of Gas Path Diagnostic Schemes

Abstract

A variety of methods can be used for the diagnosis of faults in gas path components of gas turbines. Problems that are common for diagnostic method implementation are the choice of measured quantities, choice of health parameters, and choice of operating conditions for data retrieval. The present paper introduces some general principles for evaluation of the effectiveness of different diagnostic schemes. They encompass criteria proposed in past publications, while they offer additional possibilities for assessment of diagnostic effectiveness in various situations. The method is based on the evaluation of the behavior of linear systems, which are a good approximation of the nonlinear ones for small deviations and employs the concept of system condition number to formulate criteria. The determination of limits for this number for establishing system condition criteria and quantification of observability is examined, on the basis of uncertainty propagation. Sample problems evaluated are: maximizing effectiveness of individual component identification from a multiplicity of available measurements, selection of individual operating points for multipoint applications.