A PI plus passivity-based control of a wind energy conversion system enabled with a solid-state transformer

In this paper, we propose a new control scheme for a wind energy conversion system connected to a solid-state transformer-enabled distribution microgrid. The system consists of a wind turbine, a permanent magnet synchronous generator, a rectifier and a load which is connected to the distribution grid dc bus. The scheme combines a classical PI placed, in a nested-loop configuration, with a passivity-based controller. Guaranteeing stability and endowed with disturbance rejection properties, the controller regulates the wind turbine angular velocity to a desired value - in particular, the set-point is selected such that the maximum power from the wind is extracted - maximising the generator efficiency. The fast response of the closed-loop system makes possible to operate under fast-changing wind speed conditions. To assess and validate the controller performance and robustness under parameter variations, realistic simulations comparing our proposal with a classical PI scheme are included.