In the Dynamic AC (DAC) concept, the electrical system is similar to a conventional AC system but designed to operate at variable frequency. DAC adjusts the rotational speed of the diesel generating sets, allowing the system frequency to vary within the specified range. Currently, many ships still run with their generators at a set speed, regardless of the power requirement, creating a surplus of wasted energy. The medium voltage power system in the ship is specially engineered for variable frequency, including component design and system integration. Distribution for the auxiliary and hotel loads is provided by frequency converters or directly from the variable frequency system.

For a large cruise ship, for example, up to 6% (or up to 2000 tons of fuel) of annual savings can be achieved by engine speed optimization. The concept has been created with a simple configuration of electrical system using existing and proven ABB components, which ensures quality and reliability. The concept is new to the commercial maritime industry.

DAC will sit alongside the Onboard DC Grid in ABB’s portfolio of power distribution products that can significantly increase ship fuel efficiency. Whereas the Onboard DC Grid can improve the performance of vessels with a lower power requirement, DAC is aimed at larger ships with power of 20MW or more.