Ship unified electric-power systems

In the last two decades, rapid and radical changes connected with the improvement and application of electrical-propulsion installations (EPIs) have taken place in shipbuilding. The creation of high-power frequency converters, propeller–rudder columns, and the Azipod propulsion equipment has considerably improved the qualitative characteristics of EPIs. Currently, EPIs have found an application in all types of ships. The electric-power systems of electrically driven modern ships are constructed as unified electricpower systems (UEPSs) ensuring power supply both of EPIs and the many power consumers on a ship. This article considers the advantages and drawbacks of three variants of structures of ship UEPSs: a UEPS with a transformer consisting of the EPI widely applicable in ships; a UEPS made by Wartsila Corp., and a UEPS that St. Petersburg State Marine Technical University developed. It is shown that, in all three variants of UEPSs, the quality of supply voltage of propulsion electrical motors and shipboard consumers is about the same. However, the last two variants of UEPSs make it possible to omit transformers in the EPS, which makes it possible to reduce the cost, weight, and dimensions of ship electric equipment, decrease fuel consumption, and free up some onboard space. © 2017, Allerton Press, Inc.