Phase-Shifted DR Based HVDC Link Dedicated to Filter-Free Distant Offshore Wind Farms

This paper develops a phase-shifted diode rectifier (PSDR) based high voltage DC (PSDR-HVDC) link for distant offshore wind farms (OWFs). By integrating phase-shifted transformers with multiplexed DR units, the proposed topology addresses the harmonic distortion challenges of conventional DR HVDC systems and the prohibitive cost burdens of modular multilevel converter (MMC) based HVDC systems. Accordingly, a harmonic emission model considering commutation overlap is established to reveal the phase-shifting harmonic cancellation mechanism and determine the multiplexing requirements for filter-free operation under steady-state conditions. Furthermore, the steady-state sensitivities of the OWF-integrated system are derived to examine the compatibility of the proposed topology with the P-V/Q-ω droop-based grid-forming control framework. Simulations and scaled-down hardware experiments verify the steady-state harmonic performance and operational feasibility of the PSDR-HVDC topology. A comparative economic evaluation estimates a 34.8% cost reduction for the PSDR-HVDC platform relative to the MMC-HVDC solution, indicating its potential as a cost-effective solution for large-capacity distant offshore wind power sending.