Control and dynamic performance of a grid-connected wind turbine with a doubly-fed induction generator.

摘要

The use of wind turbines as a source of renewable energy has seen a resurgence in popularity over the past decade. Unlike the wind turbines with synchronous generators considered in the past, modern doubly-fed induction generators offer the advantage of allowing the turbine to operate at variable rotational speeds which provides for optimal energy capture in low wind regimes. Moreover, the inertia in the blades and connected generator offers a place to temporarily store energy that can be used to help filter electric power fluctuations due to wind turbulence. A thorough understanding of the control and dynamic behavior of these machines is necessary to accurately predict their dynamic performance. In this research, a detailed electromechanical model of a wind turbine with a doubly-fed induction generator was developed, and its generator/turbine control structure was implemented based upon manufacturer's data. A thorough explanation of this control structure is presented, along with the assumptions that were made in order to establish an end-to-end model of the turbine, generator, and overall control system. The output power of the wind turbine at different constant wind speeds, as well as ramp changes in wind speed, was established and used to validate control performance. Subsequently, turbulent effects were included to establish the dynamic behavior during large fluctuations in wind speed. In conjunction with a spatial-temporal wind turbulence model, it is now possible to efficiently and accurately characterize electric power fluctuations in wind farms containing a large number of dispersed wind turbine generators.