Distributed voltage and frequency control of off-shore wind farms connected with a diode based HVDC link

This paper introduces a new technique for the distributed voltage and frequency control of the local ac-grid in off-shore wind farms based on synchronous generators. The proposed control technique allows the connection of the off-shore wind farm using a diode based HVDC rectifier. The system comprising the wind farm and the diode HVDC rectifier can be operated in current or voltage control mode. Fault response to on-shore voltage sags of up to 80% has been shown to be comparable to that of thyristor rectifiers. PSCAD simulations are used to prove the technical feasibility of the proposed control techniques both in steady state and during transients.