Shaft Generator System Design and Ship Operation Improvement Involving SFOC Minimization, Electric Grid Conditioning, and Auxiliary Propulsion

This paper investigates the design and application of an improved shaft generator (SHG) system for an actual Ro-Ro ship, comprising a permanent magnet synchronous generator (PMSG) and a back-to-back converter. The system can operate both in generator and motoring mode, providing active power and ancillary services to the ship's grid, and driving the main shaft under emergency conditions, respectively. Although the literature in the design and optimization of the individual components is vast, the subsystems and their interactions should be studied in tandem in order to accurately evaluate the benefits of implementing such solutions in real-world applications. This paper begins by investigating and improving the design of subsystems, i.e., machine and power converter control, and then evaluates system operation under various conditions. A conventional high-speed salient-pole synchronous generator and a low-speed direct-driven PMSG are investigated. These are then geometrically optimized, based on the specified operating characteristics. Controller design is optimized, and system operation is evaluated under steady-state and transient modes. It is demonstrated that the proposed SHG can provide important grid services, act as an emergency thrust mechanism and lead to a 3% reduction in fuel consumption for a typical voyage compared with a conventional SHG system.