Introduction  Offshore wind farms are characterized by long distance from shore, high costs of repair due to vessels involved and weather, long maintenance cycles and the fact that daily operations and maintenance is highly dependent on weather and sea state. It is then of vital importance to select a reliable main electrical wiring for reliable operations of offshore wind farms, optimal planning of maintenance and secure finance returns.

  Method  Various design schemes for subsea cables, main transformers, electrical wiring on the high/medium voltage side and major electrical components on the offshore substation have been compared and assessed in this paper through calculating short-circuit currents, modeling and analyzing vibration and various operating scenarios.

  Result  Based on the comparisons and assessments, the main electrical wiring scheme is recommended to use three-winding main transformers, circuit-transformer unit arrangement and cable connection on the low voltage side of transformer for main electrical wiring scheme.

  Conclusion  The design for main electrical wiring scheme for a 400 MW offshore substation is proposed in this paper.