Control Strategies of Power Electronic Converters for MVDC Shipboard Microgrids

Currently, the all-electric ships concept adopting fully electrified propulsion and power system has drawn great attention from the industry and has become a recognized standard for modern cruise liners, because of its architectural flexibility, space-saving and enhanced efficiency. Compared with conventional terrestrial microgrids, a shipboard power system is limited in size and weight, and can be considered as an independent, small-scale and self-sufficient power system. Hence, it has stricter power requirements in system survivability and reliability, power quality, power density, fault treatment and restoration to serve electric propulsion, daily mission loads and pulsed loads on a ship. Nowadays, the medium voltage direct current (MVDC) technology presents a possibility to renew the shipboard power system of large all electric ships. Compared to its medium voltage ac counterpart, MVDC distribution has several advantages. Nevertheless, MVDC microgrids pose some technical challenges regarding shipboard system design, analysis and application development. Reliable, efficient and secure operations of MVDC shipboard microgirds would require a more sophisticated and systematically-developed set of specifications and regulations to facilitate implementation of future shipboard power system design and analysis activities.

In order to achieve a stable MVDC shipboard microgird, this PhD project aims at analyzing the topologies of different kinds of power electronic equipment for shipboard power system, and proposing the advanced control algorithms in both normal and fault conditions for various types of converters, including AC/DC converters connecting diesel generators and MVDC bus, DC/AC converters for propulsion system, and DC/DC converters for connecting LVDC bus, pulse loads, and energy storage system to the MVDC microgrids. Corresponding topology and control methods of converters need to be studied. Due to the special working conditions on ships and the distribution of power conversion equipment, which consists of large numbers of power electronic devices, the shipboard power supply system faces a series of problems, such as the impact of large weight, high cost and fault inevitability. To solve these problems, the topologies, control methods and protection strategies of AC/DC,

DC/AC and DC/DC converters should be improved to guarantee the power density, reliability and survivability of the MVDC power system.

Funding: Self-financing.