A study of AC link and DC link method for wind power generation connected to electric power system

Abstract

SUMMARYIn this paper, grid-connection of wind power generators was evaluated from the viewpoint of frequency fluctuation. Wind power generation is a power generation method that depends on natural energy, and there is some concern that it may exert a negative influence on electric power quality. As a result, it is necessary to maintain high electric power quality when wind power generation is connected to the grid. The AC link method, the AC-DC link method, and the DC link method are alternatives for grid connection of wind power generators. The model system was constructed with the use of a synchronous generator and an induction generator as wind power generator, and verification experiments were performed. Verification experiments using the various grid-connection methods for each generator were conducted. The steadiest frequency characteristic was obtained in the DC link method. In particular, the stability level was highest in the wind power generation system using the DC link method with a woundrotor induction generator. Generally, induction generators are grid-connected by the AC link method. Therefore, gridconnection of induction generators by the DC link method appears effective from the viewpoint of frequency fluctuation.