Reactive Power Control Design in Doubly Fed Induction Generators for Wind Turbines

The high penetration level of wind power generation in an interconnected electrical network carries new technical challenges regarding system stability. Despite the stochastic nature of the wind, grid reliability has to be guaranteed. In compliance with power companies´ new requirements on wind turbines as regards contribution to voltage regulation, this paper proposes a reactive power controller design for doubly fed induction generator drives. This drive topology enables the control of reactive power independently of the active power flow using both rotor and mains-side inverters. This degree of freedom is used in order to share the reactive powers circulating in the drive system and resulting from the reactive power required in the network. The controllers are designed using well-known linear control techniques in order to present the same dynamics. Furthermore, the proper reactive power share can be used to enhance the drive efficiency. Experimental results show the performance of the proposed reactive power control.