Before diode rectifier (DR) technology for connecting offshore wind farms (OWFs) to HVdc is deployed, indepth studies are needed to assess the actual capabilities of DRconnected OWFs to contribute to the secure operation of the networks linked to them. This study assesses the capability of such an OWF to provide communication-less frequency support (CLFS) to an onshore ac network. It is shown that the HVdc link's offshore terminal direct voltage can be estimated from measurements at the OWF's

more »

... int of connection with the DR platform. Two different methods are proposed for implementing CLFS in the OWF active power controls. In Method 1, the estimated offshore terminal direct voltage is used for estimating the onshore frequency deviation. In Method 2, the actual offshore terminal direct voltage measurement is used instead. Unique features of the provision of CLFS from OWFs connected to HVdc via DRs are highlighted, and the dynamic and static performance of the CLFS control scheme is compared to that of the communication-based frequency support scheme. To assess the impact of parameter estimation errors on the provision of CLFS, a parametric sensitivity study is presented as well, and recommendations are given to increase accuracy. Index Terms-Diode-rectifier-based HVdc transmission, frequency support, grid-forming wind turbine control, offshore wind energy integration, primary frequency response Authorized licensed use limited to: Danmarks Tekniske Informationscenter. Downloaded on June 30,2020 at 11:28:53 UTC from IEEE Xplore. Restrictions apply.