Fault ridethrough and power quality improvement of Doubly-Fed Induction Generator based wind turbine system during grid fault with Novel Active Crowbar Protection design

Abstract

In this paper a Novel Active Crowbar Protection (NACBP) system is proposed to enhance the Fault-ride through (FRT) capability of Doubly Fed Induction Generator (DFIG) to enrich the power quality of the overall system. The proposed protection scheme is designed with a capacitor in series with the resistor unlike conventional Crowbar (CB) having only resistors. NACBP plays an important role in maintaining the connection of DFIG with the grid during fault to provide continuous power supply to the loads. The capacitor accommodates all the ripples generated in the rotor current and protects the converter as well as the DC-link capacitor. The main objectives of the proposed approach are: minimization of rotor fault currents, maintaining constant dc-link voltage across the converter, reduction in the operation time of the crowbar to avoid disconnection between the DFIG and the Rotor side converter (RSC), improvement in the transient response of terminal voltage, and overall improvement in the dynamic response of the DFIG. These objectives are solved by injecting NACBP design scheme between the rotor of the DFIG and RSC for a very small duration of time during grid disturbances. To validate the proposed scheme, different fault conditions are considered and it is observed that there is significant improvement in the objectives of this work. Simulation results are carried out on 1.7 MVA, DFIG based Wind Energy Conversion System (WECS) using MATLAB/Simulation and are compared without and with the triggering of the proposed scheme.