Coordinated protection of RC-Crowbar and energy storage systems for enhanced low-voltage ride-through in wind turbines

Abstract

With the widespread adoption of doubly-fed induction generators (DFIGs) in power grids, the enhancement of their low-voltage ride-through (LVRT) capability has become critically important for grid stability, especially under conditions of severe voltage sags. This study proposes a coordinated control strategy that integrates an improved RCCrowbar circuit with a hybrid energy storage system (HESS) to enhance DFIG LVRT capability. Unlike conventional crowbars that absorb large reactive power during faults, the improved RC-Crowbar leverages capacitor-based reactive power support to reduce DFIG reactive power demand and accelerate fault current decay. Meanwhile, the HESS provides dynamic voltage support and reactive power compensation, which results in improved DC-link voltage stability and a more optimised power response from the stator and rotor. The performance of the proposed approach was evaluated under diverse grid fault conditions using a DFIG wind turbine model constructed in the MATLAB/Simulink environment to verify its effectiveness. From the simulation results as shown, it means that the RC-Crowbar can reduce the DC-link voltage fluctuations, restrain the rotor overcurrent, and also helps to speed up the recovery. And combined with the HESS, combined with the coordinated protection scheme can also improve and coordinate voltage stability and reduce power oscillation and other improvements, which will further improve the overall DFIG system LVRT performance.