m. j. khosrowjerdi

Degradation due to the long time operation at the gas turbine may cause a fall in the combustor and compressor efficiency and characteristics, which makes a decrease in total efficiency and, an increase in fuel consumption with growth in the production of the pollutants. These phenomena are not distinguishable by conventional diagnostic systems. Although instrumental protection of gas turbine may be profited by the control system but, it depends to components damage result revealation. So, in this research, a special method using the Multiple Model approach, based on multi-operating points is developed to continuously estimation these kinds of faults, to sustain the major defects in an industrial gas turbine. The object is done by defining the main components health indicator variables. First nonlinear thermodynamic static and dynamic models are constructed and linearized. By a combination of those in a dynamic convex set the alternate adaptive model is developed that, could cover the dynamic of the gas turbine. By decoupling the adaptive filter residuals, estimation of the faults and operating point determination are executed. Finally, the efficiency of the proposed approach is demonstrated in a simulation environment.

A flight control system (FCS) as an example of nonlinear systems should be stabilizing the airplane in healthy and faulty modes with the desired performance. In this paper, first, the nonlinear model of the flight system (FS) is linearized in predefined operating points, and the airplane’s healthy and faulty modes convert to a multi-model system. To eliminate the undesired effect of multi-modeling and the controller robustness that usually causes to mask the faults in FSs, the problem of integrated design of FCS based on active fault detection (AFD) is formulated. The proposed problem concluded to design the optimal auxiliary signal of AFD and a static, fixed, and full-order controller with the capability in reduced-order design. The FCS guarantees to stabilize all of the healthy and faulty models and to satisfy the performance constraints. In the following, to solve the formulated problem, a numerical solution based on the genetic algorithm is proposed. To evaluate the proposed method, two full-order and reduced-ordered controllers are designed for an aircraft in the case of actuator degradation conditions. The simulation results show the ability of the proposed method to meet the control objectives and design the auxiliary signal for AFD.

A novel design approach to construct a fault-tolerant control (FTC) system for a class of nonlinear systems based on a generalized Takagi-Sugeno (GT-S) fuzzy model is proposed. The local rules of the GT-S fuzzy model consist of some multiplicative nonlinear terms. The nonlinear system is affected by actuator faults and unknown disturbances. A state/fault observer is designed and then, a dynamic output feedback scheme is proposed based on the estimated fault and state information. The sufficient conditions for observer and controller design are separately given in terms of linear matrix inequalities (LMIs). It can be shown that the number of LMIs and the computational burden is less than that of similar methods and the effectiveness of the proposed dynamic output feedback FTC approach is verified by proposing simulation results applied to an inverted pendulum system.