Modeling and Simulation of Hybrid Electric Ships with AC Power Bus - A Case Study

All-electric ships can provide a significant reduction in fuel consumption, maintenance, and emission as well as improved reliability and responsiveness. Today many electrified ships operate on an AC power bus. Due to the complexity of the system, effective modeling and simulation tools are essential for the design, analysis, optimization and evaluation of the hybrid electric propulsion system. This paper discusses a dynamic model of shipboard AC hybrid power system, which is composed of seven major components: three diesel-generator sets, a battery Energy Storage System (ESS), an AC power sources synchronizer and a bi-directional DC/AC power converter, using a ferry ship as the modeling platform. The power converter is modeled as a nonlinear dynamic average-value model to suit system-level studies. Each of component models is parameterized using data sheet provided information from the manufacturers. A rule-based supervisory controller is proposed to coordinate power sharing among diesel-generator sets and the ESS. Using the acquired load profile of the ferry, simulation results obtained using the introduced modeling tool present power sharing solutions among four power sources in four operation modes with voltage and frequency stabilization of the system AC bus.