Novel Energisation Method for Offshore Wind Farms Connected to HVdc via Diode Rectifiers

Abstract

Recently put forward as a feasible alternative for connecting OWFs to HVdc networks, diode rectifiers (DRs) have elicited growing interest from both academia and industry. Energisation of such OWFs is, however, not straightforward. The present study constitutes a proof of concept for the application of a novel energisation method to the case of an OWF connected to HVdc via DRs. The proposed method provides a robust and reliable alternative with minimal additional hardware, i.e. short additional dc cables connecting the dc bus bar of the energising WT to the HVdc link, and corresponding dc disconnectors at the cable terminals and at the DR dc terminals. This can be easily extended to more WTs in the OWF, increasing reliability by providing redundancy. The simulation results indicate that the proposed method is a suitable alternative for energising OWFs connected to HVdc via DRs.<br><br>The manuscript has been accepted for presentation in the 45th Annual Conference of the IEEE Industrial Electronics Society (IECON 2019).

Energisation Method For Offshore Wind Farms Connected To HVdc Via Diode Rectifiers

“…Other solutions avoid the need for additional long submarine cables by introducing additional power conversion equipment offshore to effectively bypass the DRs during energisation [4], [6]. In pursuit of increasing reliability and lowering costs and environmental impact, a new energisation method has been proposed in [20] for the case of an OWF connected to an onshore ac network through an HVdc link having a DR-based offshore terminal and a full-bridge-VSC-based onshore terminal. During energisation, auxiliary power is provided from the shore through the HVdc link and the dc bus bar of one or more WTs.…”

“…This work extends the assessment in [20] to include coinciding auxiliary loads with active and reactive power components and a semi-aggregated OWF model, in which every WT in the string containing the energising WT is represented individually. An additional sequence of simulation events is considered following the initial sequence, in which the OWF is energised with the proposed method.…”