Abstract
Global warming and air pollutants are in general major worldwide concerns including for the marine shipping industry. Equipped with new technologies, the onboard DC grid has proven several advantages, including up to 27% reduction in specific fuel consumption with reduced emissions. That can be achieved by installing an optimized variable speed diesel generator. The engine speed is adjusted according to the required power, which allows to always keep the best efficiency of the combustion process. However, it also exposes some changes in the behavior of the structure vibrations. Measurements on an experimental variable speed diesel generator show that vibration increases when trying to slow down the engine for the same load. This behavior is closely related to the resonance in low rev range that usually occurs with general gensets. In other words, we can conclude that the DC grid’s variable speed generator may be beneficial for fuel efficiency, but not for mechanical life and safety. Several measures had been given, of which the alternation of the natural frequency is presented as an economical and efficient solution. The ultimate goal is to maintain operational safety while respecting reduced fuel consumption.
Highlights
In the maritime industry, the DC grid is becoming increasingly more popular and has shown several advantages
The results of calculated root mean square (RMS) velocity vibration values are presented in Table 1 for the test at constant maximum speed of 1800 rpm and Table 2 for test at variable speed mode
Compared to the results obtained, we found that all the vibration levels are below the limit in the test at constant maximum speed mode, but it is not preferable to be in variable speed mode
Summary
The DC grid is becoming increasingly more popular and has shown several advantages. An additional generator for port usage is not required These minimizations can save the carbon footprint up to 30% [2]. The benefits of the DC network are expressed through the best-in-class fault-tolerance It provides a highly controllable power plant suitable for advanced operation and optimization by overriding control. In case the full advantages of all these features are exploited, the specific fuel oil consumption (SFOC) can be improved by up to 27% with reduced emissions [10]. With these high hands, the DC network is gaining ground in a wide range of vessels
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