Monitorability Analysis for a Gas Turbine Using Structural Analysis

: This paper studies the monitorability of a gas turbine in a combined cycle power plant with respect to sensors fault. The analysis is carried on using the structural analysis where the structurally relations between known and unknown variables are obtained from a nonlinear complex dynamic model described by 37 equations with twelve sensors. The structure decomposition in just-constrained and over-constrained subsets allows a separation of the monitorability analysis in two parts and a reduction in the dimension of the structure from which the causal incidence matched matrices and the redundancy relations are obtained. The analysis concludes that all the turbine variables can be evaluated from measurements and control actions in normal conditions and this capability is only robust with respect to fault in two sensors. Moreover, the monitorability of the structure can be recovered for a set of three sensors fault by redundancy. However, the capability to compute all variables of the structure is destroyed if one of a set of seven sensors is not reliable even some of them are in the over-constrained subsystem. From the just-constrained subsystem one identifies that the plant components without redundancy are associated to the variables of the proper gas turbine.