Critical Evaluation of Dual-Speed Grid-Strengthening Synchronous Wind Generators

Abstract

There is no widespread information in the literature on directly connecting synchronous wind turbine generators (WTGs) to the grid. It has been shown, however, that directly connecting synchronous WTGs to the grid has the added benefit of providing the necessary ancillary support, especially grid strength. When evaluating direct grid-connected fixed-speed wind turbine systems (WTSs), it is of critical importance to ensure maximum energy harvesting is achieved. This pursuit gave rise to a novel, pole-changing dual-speed synchronous generator (SG) design for WTS use, in which a new method is considered to determine optimal shaft speed selection, thereby ensuring maximum energy harvesting. This paper further aims to compare the dual-speed and variable-speed WTSs to one another based on drivetrain efficiency and cost analysis regarding onshore wind farms. It therefore evaluates the feasibility of incorporating the widespread integration of dual-speed WTSs into the grid. This paper ascertained that a noticeable decrease in investment is required for a wind farm constructed with dual-speed synchronous direct grid-connected WTSs, with an increase in efficiency and little variation in energy harvesting capabilities.