Abstracts

The power management strategy in a MVDC based power system of an all electric ship (AES) with Hybrid Energy Storage System (HESS) can greatly affect the energy efficiency of the system. In order to maintain the bus voltage of a medium voltage DC (MVDC) shipboard power system within the allowable margin with the operation of different types of loads, the energy storage has become indispensable part of the AES. With the aim of supporting the MVDC shipboard power system, an energy storage management (ESM) system based on Fuzzy Logic (FL) has been proposed and its performance with a Proportional-Integral (PI) control algorithms is compared. In order to support the peak demand and pulsed load, a HESS incorporating high energy density storage (battery), and high power density storage (supercapacitor) are proposed. Based on the analysis of power flow, the load characteristics, the power management objectives, constraints and the ease of implementation in MVDC power system, the battery and super capacitor are considered as the potential storage devices. For energy transfer among the energy storages and the MVDC system, bi-directional DC-DC converters with dual active bridge (DAB) configuration are used. With the changes of the bus voltage and load power demand, the ESM systems provide instantaneous reference powers for charging or discharging of the battery and supercapacitor. The reference powers for the battery and supercapacitor are sent to the respective controllers of the DAB converters. Two power sharing strategies are designed to share power among multiple energy storages. The MVDC shipboard power system with the generators, loads, battery and supercapacitor with DAB converters are modeled in SimPowerSystems. Simulation results are used to make a comparison of performances of the FL and PI controller based ESM systems. Finally, controller hardware-in-the-loop (CHIL) based experimental results are added to demonstrate the effectiveness of the controller. A Thesis submitted to the Department of Electrical and Computer Engineering in partial fulfillment of the requirements for the degree of Master of Science. Spring Semester 2017. April 6, 2017. Md Omar Faruque, Professor Directing Thesis; Simon Y. Foo, Committee Member; Pedro Moss, Committee Member.Advisors/Committee Members: Md Omar Faruque (professor directing thesis), Simon Y. Foo (committee member), Pedro L. Moss (committee member).