Shaft Motor-Generator Design Assessment for Increased Operational Efficiency in Container Ships

Abstract

Fuel costs are the sigle most important driver of marginal costs for commercial marine transportation and account for almost 50% of total voyage costs for typical configurations. Hence, there has developed a desire among operators and manufacturers of all classes of ships to embrace innovative ways to reduce the demand for fuels. This research investigates the fuel consumption of a standard container ship architecture based on different scenarios of operation. The approach is to first model fuel consumption from the main propulsion engines and the auxiliary engines based on standard propulsion modes, with a configuration known as a Power Take Off (PTO) system. These preliminary results are then analyzed to identify opportunities for retrofitting this configuration by utilizing the same engine combination, but augmenting the PTO system into a modernized shaft motor-generator system, or Auxiliary Power System (APS). The APS enables electrification, which can potentially decrease system fuel consumption. Lastly, the potential for these fuel savings is evaluated for multiple scales of the APS.

Control Design of the Brushless Doubly-Fed Machines for Stand-Alone VSCF Ship Shaft Generator Systems

“…However, in sub-synchronous operation, the CW will absorb power from the PW, because 2  is negative from Equ. (2). This means that the directions of the power flow in the PW and CW are the opposite according to Equ.…”

“…The first type adopts a synchronous generator and the power electronic converters require the same power rating as the generator [1], [2]. This means that the system cost is very high.…”

Control design and experimental verification of the brushless doubly‐fed machine for stand‐alone power generation applications

“…When BDFM is used in a stand-alone generation system, PW outputs power at any rotor speed [5]. However, at subsynchronous speed, the CW will absorb power from the PW, because f 2 is negative according to (2), which means that the directions of the power flow in the PW and CW are the opposite. Similarly, at supersynchronous speed, the CW will output power to the load.…”

“…The zeroes and poles of this term are very close and thus can cancel 2 in the denominator of the second term of (15) occupies a small proportion and can be ignored, and then the second term in (15) can be simplified as…”

“…Ship shaft generation systems, which show excellent energy-saving performance, are becoming a research hotspot. The conventional ship shaft generation systems are based on the synchronous generator (SG) or doubly-fed induction machine (DFIM) [1][2][3][4]. In an SG-based ship shaft generation system, the converter requires the same power rating as that of the generator.…”