Diode-Based HVdc Link for the Connection of Large Offshore Wind Farms

Abstract

This paper includes a technical feasibility study on the use of diode-based HVdc links for the connection of large offshore wind farms based on synchronous generators. A technique for the voltage and frequency control of the offshore ac grid is presented. The proposed control technique allows the operation of the rectifier end of the HVdc link in current or voltage control mode. Fault response to onshore voltage sags of up to 80% has been shown to be comparable to that of thyristor-based rectifiers. Moreover, the complete system shows an adequate fault-ride-through operation to solid short circuits at onshore inverter terminals. PSCAD <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">®</sup> simulations are used to prove the technical feasibility of the proposed control techniques both in steady state and during transients.