Connection of off-shore wind farms using a diode based HVDC link with reduced filter banks

Abstract

This paper shows that it is possible to substantially reduce the rectifier capacitor and filter banks when using diode based HVDC link for the connection of large off-shore wind farms. The considered wind turbines are based on full power power converters. The paper includes a control strategy that allows the wind turbine front-end converters to control the offshore ac-grid voltage and frequency and, at the same time, absorb a substantial amount of the harmonic currents produced by the LC-HVDC rectifier. The proposed control strategy for filter reduction is validated by means of PSCAD simulation, highlighting adequate active, reactive and harmonic current sharing between the wind turbines. Impact on overall efficiency is is also analysed and discussed.