Modeling And Simulation Of LNG Carrier Propulsion Control System

Domestic LNG carrier adopts UA-400type steam turbine power plant produced by Kawasaki Heavy Industry, and is equipped with propulsion control system provided by Nabtesco Corporation.There is a great difference between LNG carrier steam turbine power plant and traditional diesel engine propulsion on the control and manipulation. The number of competent marine engineer for LNG carrier is limited at home. Moreover, the gap is increasing annually. Engine room simulator can quickly improve professional skill level of engineers, without practical operation onboard. However, domestic research of the large LNG carrier marine engine simulator has only just begun, thus, the research work of modeling and simulation for propulsion control system need to be speedily developed.Basing above circumstances, relying on LNG carrier engine room simulator research and development project of Dalian Maritime University, this paper carried out an in-depth study of modeling and simulation for LNG carrier propulsion control system. The main achievement and results are summed up as follows:1. This paper established the mathematical model of controlled object, and made the simulation calculation and analysis, which provides a platform for the simulation and debugging of the system. According to the idea of modular modeling method, this paper reasonably divided the main steam turbine propulsion system and respectively established maneuvering valve model, main steam turbine model, reduction gear box and propulsion shafting model and ship-propeller model. This paper successfully used the state space equation to describe the hydraulic servo system of the main control valve hydraulic servo system and reveal its dynamic process. At last, the paper set up each module in order, and made the simulation test under the environment of Mat-lab/Simulink. Both the steady result and dynamic result of simulation test meet the needs of the application.2. On the basis of analyzing LNG carrier propulsion control system deeply, divide it into digital governor unit, logical control unit and safety protection unit, corresponding mathematic model is established respectively, and apply the controlled object model that has been established to conduct the simulation test. The simulation result shows that the model of control system can reflect the actual control process of the main turbine.3. Visual simulation is applied for LNG carrier propulsion control system, LNG carrier propulsion control simulation system is developed by using Visual C#based on VS DotNet platform, as the subsystem of LNG carrier marine engine simulator, it can simulate the start, stop, reversing and other operation and control of main turbine, and communicate with other subsystems and hardware system of simulator.The models of LNG carrier propulsion control system which established in this paper have been applied to the LNG carrier engine room simulator project of Dalian Maritime University. Now, it has stepped into the last stage of system global performance testing and evaluation.