Application of distance protection to offshore windfarm with external disturbance

This paper analysed the challenges of the distance protection application at the AC windfarm offshore platform array cables and inter-tie cables. The study cases are based on fault records that were retrieved from an offshore windfarm in which Siemens Energy was the principal contractor. This paper focused on the distance protection stability for the fault ride through requirement of National Grid (NG). Also, during the offshore 66kV earth fault, the distance protection will be impacted by the unbalanced charging current flow due to the zero-sequence path resembling an isolated earth system. At end of this paper the protection logic improvements for this application are discussed.