Calculation of Losses in Three-Core Submarine Cables for Fractional Frequency Transmission Operation

摘要

Fractional frequency transmission system (FFTS) has been proposed as a promising alternative to both 50/60 Hz HVAC and HVDC technology for offshore wind power applications. The potential advantages of FFTS are mainly the increasing transmission capability and the reduction of power losses. Research so far has focused on the system feasibility and its potential applications to wind power integration. Nevertheless, the issue of current rating and calculating cable losses under fractional frequency transmission operation (FFTO) is not covered adequately in the literature. In this paper, three-core submarine cables under FFTO are investigated. Typical current rating cases of both export and inter-array cables are examined and losses in conductors, sheaths and armor are evaluated. Calculations are made by means of Finite Element Analysis and ElectroMagnetic Transient Program, while results are also compared with the corresponding derived by IEC 60287 standard. Differences with conventional HVAC are discussed, revealing the benefits of FFTS in terms of losses as well as the implications imposed in the magnitude of the generated magnetic field.