On low voltage ride-through and stability of wind energy conversion systems with FACTS devices

This paper provides a comparative study on the low voltage ride-through (LVRT) capacity of wind energy conversion systems (WECSs) under Fixed Speed Induction Generator (FSIG), FSIG with FACTS (Flexible AC Transmission) devices such as Static Synchronous Compensator (STATCOM) or Static Var Compensator (SVC), and Doubly Fed Induction Generator (DFIG). The dynamic operations of the WECSs during grid side voltage sag and various balanced and unbalanced faults are investigated. The simulation results in MATLAB/SimPowerSystems show that a FSIG based wind farm does not have the LVRT capacity due to insufficient reactive power support during disturbances. FACTS devices such as STATCOM or SVC can improve the LVRT capacity of FSIG based WECSs, with STATCOM providing better Var compensating capacity than SVC. DFIG based WECSs has better LVRT capacity and voltage stability due to its real and reactive power control ability. As a result, DFIG based WECS can provide better stability performance to enable the WECS to ride-through severe balanced and unbalanced faults.