Dynamic Simulation of a Fuel Cell-Powered Electric-Drive Ship

摘要

This report describes a dynamic simulation model (DSM) of an electrically propelled ship with power provided by four 625 kW fuel cells. The model allows prediction of transient responses, and allows design modifications to be made inexpensively prior to hardware construction. Simulations are performed for extreme acceleration and deceleration maneuvers, and the responses are compared to those of diesel and turbine-powered ships. It is concluded that a fuel cell-powered ship can achieve transient responses comparable to those of conventionally powered vessels. The report documents refinements to the existing DSM model of Fuel Cell Energy (FCE) Corporation's diesel-faded molten carbonate fuel cell module. The DSM is based on principles of mass and energy balance, and incorporates dynamic characteristics of the fuel cell, all balance-of-plant components, the controller, electric bus, AC propulsion motors, shafting and propellers. Recent changes in FCE's design improve the power module's transient response. Rapid accelerations and crash stop maneuvers were simulated. Results showed the need for careful coordination between available power, the torque absorption of the AC motors, and total system load requirements. For crash stops, shaft brakes were used to reduce propeller RPM. Resistance banks, included in the model, can also be used to absorb excess power, and some fuel cell venting may be required. It is shown that a fuel cell-powered ship can achieve starting and stopping distances considered acceptable under current practice.