Active Power Control of DFIG Wind Turbines for Transient Stability Enhancement

Abstract

This paper proposes an adaptive Dynamic Power Reduction (aDPR) scheme for Type-3 Wind Turbine-Generators (WTGs) to enhance transient stability of synchronous generators (SGs), with benefits of increasing transfer limits on already fully loaded transmission paths. The scheme consists of three components to deal with a fault close to a SG. Initially, the WTG curtails its active power to a predefined level to act as a dynamic brake for the SG. Then the controller monitors the rate of change of frequency to adaptively ramp the WTG back to its original power output while minimizing the WTG pitch and rotor motion. Finally, to reduce the risk of second-swing instability, the converter uses its reactive current to damp SG power swings. The aDPR scheme can be classified as a remedial action scheme and is enabled if its action can ensure transient stability. To demonstrate the effectiveness of aDPR and to benchmark it against other WTG active current and frequency feedback control techniques, a single-machine infinite-bus system with one WTG is utilized. Next, an aDPR enabled WTG is integrated in the NPCC 68-bus system. Finally, the aDPR controller’s ability to prevent transient instability is demonstrated on the two-area system.