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.