Modeling and control of a marine diesel engine driving a synchronous machine and a propeller

In some designs of power systems for marine vessels, large-size or medium-size Diesel engine(s) is(are) used to drive one synchronous machine to generate electricity, and the main propeller, simultaneously, through a gear box. Such systems are subject to disturbances that may affect performance and fuel consumption. The most important disturbances occur due to the propeller torque, and load demand on the electric network. In this work, a simplified state-space model is suggested for such systems based on well known models of each component. The model considers the dynamics of the shaft, Diesel engine, and synchronous machine with the propeller in their simplest models. The output voltage and torque coefficient were modeled as uncertain parameters. Then, exploiting feedback linearization, two controllers were suggested for the proposed model to regulate the rotational speed of the shaft. Firstly, by pole placement. The second is a robust controller by mixed H₂/H_∞ synthesis. The results of the simulations of the proposed controller are presented and compared.