A Common Capacitor Based Three Level STATCOM and Design of DFIG Converter for a Zero-Voltage Fault Ride-Through Capability

 Abstract

The doubly-fed induction generator (DFIG) based wind power conversion system (WECS) is a viable option for meeting increased load power demand. External reactive power sources like STATCOM type FACTS devices can further improve power flow capability and system security margin. This paper proposes a lookup table-based control scheme for the outer control loops of the Rotor Side Converter (RSC) and the Grid Side Converter (GSC) of DFIG, with a three-level STATCOM coordinating the system. The aim is to enhance power flow transfer and dynamic as well as transient stability, mitigate voltage fluctuations, enable DFIG operation during symmetrical and asymmetrical faults, and limit surge currents. The performance of the DFIG system is evaluated by examining winding currents, torque, and rotor speed at varying loads and symmetrical voltage dips. Additionally, zero-voltage fault ride through is investigated for both super-synchronous and sub-synchronous rotor speeds under symmetrical and asymmetrical LG faults. Finally, the DFIG system's performance is analyzed under different phases to ground faults with and without a three-level STATCOM.

Keywords

Doubly-fed induction generator (DFIG), Field oriented control (FOC), Common-capacitor based STATCOM, Voltage compensation, Balanced and unbalanced faults, Zero-voltage fault ride through