Modelagem e controle de microturbina a gás do tipo split-shaft. / Modeling and control of slip-shaft gas microturbine.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2010

RESUMO

The objective of the present work is the development of the model of a split-shaft micro gas turbine with feed back control system. A bibliographical review of the works on control of gas turbines indicated that there are very few works dealing this type of gas turbines. The model was developed starting from the basic geometry of the turbine and applying the fundamentals of thermodynamics, newtonian mechanics and fluid mechanics. The components, materials and controls which can be used in a split-shaft turbine are described. The model is simulated firstly without control and later with control. The results showed that, for the uncontrolled model, typical phenomena which may happen in this type of system are seen such as temperature peaks, influence of one turbine on the other and fuel injection variation due to combustion chamber pressure variation amongst others. For the controlled model, the controls PI, PID, PI-D, I-PD and PI-PD with negative feedback are tested. The parameters choice of each control is determined by the ITAE method within an interval for each parameter. The PI-D control was chosen for its best performance and simplicity. The control made the peak temperatures lower than the uncontrolled system and the electricity generator rotation error was kept under 1% with respect to the reference value. A modeling is done for a lubrification system following the same principles of the split-shaft turbine modeling. Conservation laws of mechanics and fluid mechanics are used, such as momentum conservation and energy conservation equations (pressure loss). The model is simulated firstly without control and later with control. For the uncontrolled model, the effects on increasing the head loss in one branch of the system and the effects for a step reference was showed. These effects are the variations of system losses and the flow variation in the system branches. For the controlled model, the PI and PI-D controls with negative feedback were tested. The parameters choice of each control is determined by the ITAE method within an interval for each parameter. The PI control was chosen because the performance difference was not significant and the derivative part could turn the error bigger due to the way the system was modelled. The process variable was controlled and the effects on the variation head loss in one of the system branches was observed. The models have many simple parts; each one can be replaced by a more complex one if necessary. Thus, the present modeling may be used as guide for future improvements.

ASSUNTO(S)

controle pid pid control turbina split-shaft split-shaft turbine simulation modeling modelagem simulação

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