FixReF: A control strategy for offshore wind farms with different wind turbine types and diode rectifier HVDC transmission

Abstract

Offshore wind farms built at a long distance from the onshore grid are connected via HVDC-transmission. Future HVDC-systems may connect offshore wind farms via uncontrolled diode rectifiers instead of VSC-HVDC converters. Due to this wind turbine inverters must own a grid forming capability. This paper describes a control strategy that requires only minor changes in the conventional wind turbine inverter control software to form the AC-voltage in the offshore island grid. It is shown that this strategy allows an interconnection of different wind turbine types considering auxiliary power supply and reactive power sharing.