Since the first naval ship propelled by a gas turbine engine was operated in 1947, gas turbine engines have been developed rapidly until today. Gas turbine engines in the commercial marine field, however, have not gained as much attention as other fields such as aerospace, power plant industries and naval ship. Recently gas turbine engines have increasingly been utilized as commercial marine engine. The primary reasons are the engine's low weight, low volume, high availability, low first cost, and acceptable operating costs.
The gas turbine engines, in general, are operated in operating points which have the highest TIT(Turbine Inlet Temperature) and CDP(Compressor Discharge Pressure) for thermal efficiency. And when gas turbine engine accelerates and decelerates, that is transient condition, compressor tend to move close to the surge line. If the gas turbine engine is accelerated from design point to other operating point, front stages of compressor are to stall and rear stages to choke. On the contrary when the gas turbine engine is decelerated, rear stages are to stall and front stages to choke. Besides the system parameters of the gas turbine engine, such as time constant and gain etc., get changed remarkably in real operating condition. It means that operators must consider to these operating environment and suitably control fuel flow which is unique control input.
Although in this paper the author merely deals with system parameter change with the exception of transient condition, the conventional controller, such as a PID controller based on fixed parameters, could not guarantee the robustness and good control performance in the aspect of system parameter changes caused by the change of operating condition.
The author, therefore, propose a fuzzy-PID controller which combines PID control and fuzzy technique to obtain the good performance of gas turbine engine speed control system on the whole operating range.
To combine the PID controller with fuzzy logic, at first, the sub-PID controller is designed at each speed mode, whose parameters are optimally adjusted using a RCGA. Then fuzzy "If～Then" rules combine the sub-PID controllers as a consequence part.
Finally, the effectiveness of the proposed fuzzy-PID controller is verified through computer simulation.