The Design Of Marine Diesel Engine Cooling Water Control System Based On H-theory

Marine diesel engine cooling water temperature control system is an important component of the process control system in marine engine room,also one of the important systems in order to ensure marine power plant work in a safety and reliable operating condition. In the meanwhile, the cooling water temperature of the cooling water system directly influences the operational efficiency of main, auxiliary engine as well as the mechanical system. In order to make the cylinder cooling water temperature control more stable,reliable, strong adaptability and has high control accuracy, it is necessary to conduct deep research to the system control method of temperature controller. In current research, most of the engine cooling water temperature control system of marine engine room adopted with traditional PID control, but due to the cooling water temperature control system is a loop closed system, it has the characteristics of nonlinear, time-varying and large delay etc, in addition, the traditional PID in some circumstances are difficult to achieve the ideal controlling effect. For the purpose of improve the management level of marine, reduce operating costs, as well as enhance the operation of marine safety, reliability and economy issues, in the true sense of fulfill engine room with integrated automation technology, it is necessary to take further exploration and research in order to control the application of advanced control technology inside the engine room.This thesis set about from the diesel engine cooling water control system of the ship in construction, in research of the marine diesel engine cooling water system thermodynamic model and temperature control system, analyzed the PID temperature control valve used in the existing vessels; meanwhile go through understanding the robust control theory, using this method of marine diesel engine cooling water temperature control system for the design and simulation analysis of the ∞H controller; go through the processes of simulation found that without parameter perturbation, optimal ∞H controller makes the system stable time is much shorter and have small amplitude than what PID do. When the parameters model generate small perturbation, although the ∞H state feedback control and PID control system can make the system stable, but PID control system significantly decreased the system performance, it proved from the stable of performance in period of time. When perturbation reached to a certain figures, the PID control system is no longer stable, while ∞H system feedback control maintains the system as a good stable condition. Followed by the analysis of engine cooling water temperature control system of mechanical parameters in a certain range can perturbed system output response, and then the simulation results showed that the ∞H controller can make the system return to an equilibrium condition. To sum to up, all evidences demonstrated that ∞H control system compared with PID control system has better robust stability and anti-interference ability.