Adaptive vector control for slip energy recovery in doubly-fed wind driven induction generator

Induction generators are increasingly used in wind power generation systems especially for grid connected applications, since the terminal voltage and frequency controls are not required and the reactive power demand can be met by the grid. Wound-rotor induction generators have the advantage of operating as a variable-speed constant-frequency system to maintain maximum power transfer conditions for shaft speed variations over a wide range of wind speed and, hence, to maximize the annual energy production. This can be achieved by the use of a converter cascade between the slip-ring terminals and the utility grid to control the power flow from/to the rotor. In this paper, a simple yet efficient way by which the controller can change its behavior is proposed. The absolute value of the error signal is used to divide the error space into three regions. Each region has its parameters to achieve certain desired dynamic response. It can be shown that by using the proposed adaptive controller, a more accurate control and quicker transient response under various operating conditions is achieved