Modeling and control system design of a marine condensing system

Rapid and frequent load changes bring a number of challenges to the control system of a marine condenser. However, few studies have been published in this area. In this paper, a whole condensing system, which includes condenser, ejector, cooling water pump and its driving turbine, was modeled based on three conservation laws. Propulsion steam turbine was also modeled to simulate the load changes. A proportional integral (PI) controller was developed to regulate the condenser pressure. Opening signal of the governing valve of the propulsion turbine was added to the controller as a feed forward signal, and to improve the performance further, fuzzy algorithm was adopted to tune the gains of PI controller. Numerical experiments were conducted to study the dynamic behavior and the control performance of the condensing system. The simulation results show that employing the valve opening signal of main turbine as feed forward signal and tuning the gains of conventional PI controller by fuzzy logic are both effectual approaches to enhance the control performance. The former is good at reducing maximum overshooting while the latter is good at decreasing settling time. The combination of these two methods can improve the performance of simple PI controller further.