Fast Frequency Response from Offshore Wind Farms Connected to HVDC via Diode Rectifiers

Oscar Saborío-Romano*, Ali Bidadfar, Jayachandra Naidu Sakamuri, Ömer Göksu, Nicolaos Antonio Cutululis

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

104 Downloads (Pure)


Recently proposed as a viable alternative for connecting offshore wind farms (OWFs) to HVDC networks, diode rectifiers have prompted increasing interest from both industry and academia. However, before technical connection requirements for such solutions can be determined, more studies are needed to assess their capabilities to contribute to the secure operation of the networks connected to them.

This study assesses the capability of an OWF to provide frequency support to an onshore AC network, when connected through a HVDC link having a diode-rectifier-based (DR-based) offshore terminal and a voltage-source-converter-based (VSC-based) onshore terminal. The primary focus is fast frequency response (FFR), which contributes to the stabilisation of the onshore AC network during the first stage of large frequency excursions by decreasing the (magnitude of the) rate of change of frequency. The kinetic energy stored in the rotating masses of the wind turbines (WTs) is considered as the main source of additional power/energy for such response during onshore underfrequency events. The WTs areoverloaded (i.e. forced to overproduce) to extract some of that stored kinetic energy when providing FFRduring onshore underfrequency events. A semi-aggregated OWF representation is considered in order to examine the dynamics of each grid-forming wind turbine within a string when providing FFR, while achieving reasonable simulation times.

Simulation results corroborate that the new connection concept (and corresponding changes in WT control) does not have a significant impact on the capability of OWFs to provide FFR to onshore AC networks. That is OWFs connected to HVDC via DR-based offshore terminals can indeed provide FFR, by means of OWF-level active power controls similar to those developed for VSC-HVDC-connected OWFs, while its grid-forming WTs share the reactive power consumption/production and keep the offshore frequency and voltage within their normal operating ranges.
Original languageEnglish
Title of host publicationProceedings of the Cigre Aalborg 2019: International Symposium
Number of pages10
Publication date2019
Publication statusPublished - 2019
EventCigre Aalborg 2019: International Symposium - Aalborg Congress and Culture Centre, Aalborg, Denmark
Duration: 4 Jun 20197 Jun 2019


ConferenceCigre Aalborg 2019: International Symposium
LocationAalborg Congress and Culture Centre
Internet address

Cite this

Saborío-Romano, O., Bidadfar, A., Sakamuri, J. N., Göksu, Ö., & Cutululis, N. A. (2019). Fast Frequency Response from Offshore Wind Farms Connected to HVDC via Diode Rectifiers. In Proceedings of the Cigre Aalborg 2019: International Symposium