Model Based Diagnosis and Supervision of Industrial Gas Turbines
Supervision of performance in gas turbine applications is important in order to
achieve: (i) reliable operations, (ii) low heat stress in components,
(iii) low fuel consumption, and (iv) efficient overhaul and maintenance.
To obtain good diagnosis performance it is important to have tests which are
based on models with high accuracy.
A main contribution of the thesis is a systematic design procedure to construct
a fault detection and isolation (FDI) system which is based on complex nonlinear
models. These models are preliminary used for simulation and performance
evaluations. Thus, is it possible to use these models also in the FDI-system and
which model parts are necessary to consider in the test design?
To fulfill the requirement of an
automated design procedure, a thermodynamic gas turbine package GTLib is
developed. Using the GTLib framework, a gas turbine diagnosis model is
constructed where component deterioration is introduced. In the design of the
test quantities, equations from the developed diagnosis models are carefully
These equations are then used to implement a Constant Gain Extended Kalman
filter (CGEKF) based test quantity. The number of equations and variables which
the test quantity is based on is significantly reduced compared to the
original reference model.
The test quantity is used in the FDI-system to supervise the performance and the
turbine inlet temperature which is used in the controller. An evaluation is
performed using experimental data from a gas turbine site. The case study shows
that the designed FDI-system can be used when the decision about a compressor
wash is taken.
When the FDI-system is augmented with more test quantities it is possible to
diagnose sensor and actuator faults at the same time the performance is
supervised. Slow varying sensor and actuator bias faults are difficult diagnose
since they appear in a similar manner as the performance deterioration, but the
FDI-system has the ability to detect these faults.
Finally, the proposed model based design procedure can be considered when an
FDI-system of an industrial gas turbine is constructed.
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Last updated: 2019-12-02