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Abstract-In this paper a review of common wind turbine systems and wind farm configurations with AC and DC links is presented first, and then a new structure based on HVDC local grid is proposed and compared to the existing structures to show its effectiveness with respect to the older ones. The most important feature of the new structure is its lower cost, while it preserves controllability of the most flexible configurations like DFIG-based wind farms or wind farms with PMSG generators and back-to-back converters. The other feature of the proposed structure is its high efficiency, which is due to the use of direct driven multi-pole synchronous generators.

Excitation Controlled Synchronous Generator-based Wind Turbine (ECSG WT) is a recently proposed wind turbine scheme which has not been fully investigated in detail. This paper is devoted to analyze performance of the ECSG WT scheme and to compare it with two mainstream wind turbine schemes based on electrically excited synchronous generator, i.e. VSC-based full converter wind turbine and diode bridge rectifier-based wind turbine equipped with boost converter on its DC link. The aim of this comparison is to demonstrate great potentials of ECSG WT for being considered in wind industry. To do so, two successful WT schemes at the market which are structurally close to ECSG WT are selected. The comparison includes different technical and economic aspects of the three schemes, assuming DC grid connection for the wind turbines. In addition, another comparison is made between the recently introduced Siemens 2 nd generation DC Grid Access Offshore wind farm and a wind farm with similar structure, but using ECSG WTs. The results of these comparisons declare that ECSG WT scheme has promising characteristics, especially regarding economic, reliability and efficiency aspects.