Improving Transient Stability of Dual Stator-Winding Induction Generator-Based Wind Farms by Slip Frequency Control

This article studies improving rotor-speed stability of dual stator-windings induction generators (DWIG)-based wind turbines during a severe fault in the power system. A novel instantaneous slip frequency control (ISFC) with a supplementary control loop containing braking resistors (BRs) is introduced. The ISFC drive technique is selected primarily for its fast-dynamic performance. An active power feed-forward loop in this drive technique can adequately regulate the generator's slip restricting reactive power consumption. The supplementary control loop includes a mechanism that can bring sufficient braking resistance into the circuit to keep the slip's optimal value according to the wind speed. At first, the proposed DWIG-based wind turbine equipped with the ISFC drive technique is described. Then the factors affecting the rotor speed stability are analyzed, and the improved ISFC is proposed. The topology and the proposed drive technique are simulated in MATLAB/Simulink platform and experimented with a scaled 1.2-kW prototype. Both simulation and experimental results demonstrate the significant impact of the proposed method.