000011206 001__ 11206
000011206 005__ 20241022163711.0
000011206 0247_ $$2doi$$a10.24868/11206
000011206 037__ $$aGENERAL
000011206 245__ $$aDC secondary distribution grids on future naval ships: a comparison with conventional AC distribution systems and their safety aspects
000011206 269__ $$a2024-11-06
000011206 336__ $$aConference Proceedings
000011206 520__ $$aMore and more naval ships use energy storage systems for the transition towards zero-emission technologies. Those hybrid ships are gaining ground because of the integration of alternative sources such as methanol engines and fuel cells onboard ships. The generation, storage and propulsion devices are connected to a DC grid to increase energy efficiency. However, smaller consumers and hotel loads throughout the ship are connected via a low-voltage AC distribution grid. 
A DC distribution grid is expected to be more energy efficient, lighter and smaller than a conventional AC distribution grid. Besides, the availability of DC loads and components is increasing, making a DC distribution grid a viable option. This paper aims to quantify the potential benefits of using a DC distribution grid and identify the risks of this new technology.
We compare a conventional AC distribution grid design with an equivalent DC distribution grid design for a typical surface combatant use case. Aspects included are energy efficiency, weight and footprint. Then, this paper delves into the various aspects affected by the choice of earthing, including common-mode voltages and currents, which can lead to electromagnetic interference. Given the presence of multiple power converters in a DC grid, which act as common-mode current sources, it is crucial to focus on mitigating this phenomenon.
We show that a DC distribution grid can save up to 23 tons of weight and 28 square meters of space for the specific use case. The energy losses are expected to be a factor of 2.5 less. Since this is a new technology, it is crucial to thoroughly investigate the consequences of applying DC grids throughout the ship regarding safety and availability. The role that earthing plays is important, especially in combination with the influence of parasitic capacitance and filter capacitors to earth. Various earthing strategies, such as those involving the midpoint or negative terminal of the grid, yield different sets of advantages and disadvantages in terms of safety and availability. Unlike the relatively straightforward choices regarding the earthing strategy of the neutral point in AC grids, determining the best approach for the midpoint of DC grids is less obvious. It will be shown that there is no earthing approach that gives the optimal solution for all investigated aspects.
The adoption of new grid topologies brings about both advantages and risks. This paper elucidates the rationale behind these changes and underscores the importance of considering associated risks, particularly emphasizing the role of earthing. As long as the risks are properly mitigated, a DC distribution grid can be an improvement compared to a conventional AC distribution grid.
000011206 7001_ $$aWikkerink, D$$uRH Marine
000011206 7001_ $$avan der Ven, JK$$uRH Marine
000011206 7001_ $$aMitropoulou, D$$uRH Marine
000011206 773__ $$tConference Proceedings of INEC
000011206 773__ $$jINEC 2024
000011206 8564_ $$uhttps://library.imarest.org/record/11206/files/.pdf$$9c7ca688c-0233-47a5-bf47-f6e34f9d9ab3$$s1662147