Research On Intelligent Control For Marine Power Systems

The use of gas turbines and diesel engines for driving power generators is very important in the design of military and commercial shipping vessels. The power system comprises all units necessary to supply the vessel with power. These include the power generation and distribution systems, which are divided into; a power generation plant with prime mover and synchronous generators to supply common load with low-level speed and voltage controller, usually Proportional integral derivative (PID Controllers).The efficiency and electric-power output of gas turbines and diesel engines varie according to the ambient temperature, fuel types and rotation speed. The amount of these variations greatly affects the electricity production, fuel consumption and plant performance.For this purpose, in the first part, this thesis describes the effect of ambient temperature and fuel types of the output power and efficiency in gas turbine, and shows how the efficiency varies according to the ambient temperature and fuel types. From the result we observed that there is variation in output power and efficiency for a gas turbine as a function of ambient temperature and fuels types.In the second part, first a fuzzy logic control algorithm is used to estimate the PID coefficients in order to handle such uncertainties to produce a better control performance. Simulation tests were established using MATLAB program. The simulation results show that the response is still slow with insignificant overshoots when the conventional PID controller is applied on the system. However, when self-tuning fuzzy PID controllers were applied to the system, there is a significantly faster response without overshoot. Secondly, two specific soft-computing techniques, fuzzy logic controller and genetic algorithm, are used to design and tune the PID controller to get an output with better dynamic and static performance. The response of the system became faster using the genetic algorithm and this resulted in a faster and more robust output of the PID controller.Lastly, the excitation system of the mentioned generator included proportional integral controller (PI). Proportional integral derivative (PID) controller was added instead of PI controller to avoid the problems mentioned previously. These problems include the aging of the control element, feedback signal and load increase/decrease problems. Before the PID controller was added, first the frequency response of the automatic voltage regulator (AVR) was simulated by the MATLAB program for different gain parameters. Then the PID controller was added to the AVR and simulations with different inputs disturbances and responses were compared. Results were compared for the system using root locus methods before and after adding the PID Controller. From the results, we conclude that the overall system response was improved with the addition of the PID controller. In addition, self tuning fuzzy PID controller is developed to improve the performance of automated voltage regulation of a synchronous generator. The controller is designed based on the mathematical model of the system which is estimated by using System Identification technique. Simulation was carried out using MATLAB to get the output response of the system to a step input.