Abstract
Diode rectifiers (DRs) have elicited increasing interest from both industry and academia as a feasible alternative for connecting offshore wind farms (OWFs) to HVDC networks. However, before such technology is deployed, more studies are needed to assess the actual capabilities of DR-connected OWFs to contribute to the secure operation of the networks linked to them. This study assessed the capability of such an OWF to provide support to an onshore AC network by means of (active) power oscillation damping (POD). A semi-aggregated OWF representation was considered in order to examine the dynamics of each grid-forming wind turbine (WT) within a string when providing POD, while achieving reasonable simulation times. Simulation results corroborate that such an OWF can provide POD by means of OWF active power controls similar to those developed for OWFs connected to HVDC via voltage source converters, while its grid-forming WTs share the reactive power consumption/production and keep the offshore voltage frequency and magnitude within their normal operating ranges. Open-loop test results show that such capability can, however, be restricted at operating points corresponding to the lowest and highest values of active power output.
Highlights
Europe’s offshore wind resources cannot be fully exploited without the development of the necessary electrical infrastructure to connect offshore wind farms (OWFs) and onshore networks.Until now, only a few OWFs export their production through HVDC, while the majority are connected via traditional HVAC [1]
Simulation results corroborate that such an OWF can provide power oscillation damping (POD) by means of OWF active power controls similar to those developed for OWFs connected to HVDC via voltage source converters, while its grid-forming wind turbine (WT) share the reactive power consumption/production and keep the offshore voltage frequency and magnitude within their normal operating ranges
Results of the performed dynamic simulations for the different operating conditions corroborate that such an OWF can provide POD by means of OWF active power controls similar to those developed for OWFs connected to HVDC via VSCs, while its grid-forming WTs share the reactive power consumption/production and keep the offshore frequency and voltages within their normal operating ranges
Summary
Europe’s offshore wind resources cannot be fully exploited without the development of the necessary electrical infrastructure to connect offshore wind farms (OWFs) and onshore networks. The present study assessed the actual capability of an OWF to provide POD to an onshore AC network by means of active power modulation, when connected through an HVDC link having a DRbased offshore terminal and a VSC-based onshore terminal. The study examined the compatibility of corresponding higher-level controls previously devised for VSC-HVDC-connected OWFs [17] Through such controls, the OWF modifies its active power output according to the onshore frequency signals directly communicated to it. Results of the performed dynamic simulations for the different operating conditions corroborate that such an OWF can provide POD by means of OWF active power controls similar to those developed for OWFs connected to HVDC via VSCs, while its grid-forming WTs share the reactive power consumption/production and keep the offshore frequency and voltages within their normal operating ranges.
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