Introduction  In order to ensure the safe and reliable operation of offshore wind farm, this paper analyzes the configuration scheme and operation mode of standby diesel generator set under the condition of isolated networks of offshore wind farm.

  Method  Considering the diesel generator capacity accounting, reactive overvoltage, short-circuit current, harmonic analysis and protection setting under the condition of isolated grids of offshore wind farms, the rationality of the standby diesel generator set scheme was verified.

  Result  The results show that the standby diesel generator set with rated capacity of 1.2 MW can meet the load requirements and voltage requirements of offshore wind turbines and offshore wind station under the condition of operation and maintenance, with half of the wind turbines connected to island operation mode and 2 Mvar reactors, also meet the 35 kV submarine cable reactive demand. At the same time, in order to avoid harmonic resonance, diesel generator is not recommended to provide yaw power for the wind turbines. For transformer of diesel generator and grounding transformer for offshore wind station, it is recommended to use recompression and overcurrent as main protection.

  Conclusion  The configuration scheme of this paper provides a solution to the study of the isolated operation mode of offshore wind farms.