Cyclic Load Profiles for Offshore Wind Farm Cable Rating

By its nature, the power generated by offshore wind farms varies substantially with time. Despite this fact, the cable systems which connect such wind farms back to the onshore grid are typically sized based on a maximum, continuous current rating. In order to develop techniques by which the sizing of such cable connections might be optimized, this paper presents a method for deriving equivalent cyclic load curves from realistic, time-variant generation data. These cyclic load profiles may be used with the conventional IEC 60853-2 cable rating calculation, allowing the cable to be sized for a more realistic duty cycle. The example calculations presented show that this reduction in conservatism permits the use of smaller cable sizes, helping to drive down project costs. The implications of using such methods are discussed, highlighting the tradeoff between cost and conservatism.