Design of a Mode Decoupling STATCOM for Voltage Control of Wind-Driven Induction Generator Systems

This paper presents a systematic approach based on eigenstructure assignment to determine the mode shape and transient response of a STATCOM utilized as an exciter for induction generators (IG). A physical control scheme, including four control loops: ac voltage, dc voltage, ac active current and ac reactive current controllers, is pre-specified for the STATCOM. A synthetic algorithm is proposed to embed these physical control loops in the output feedback path. With appropriate oscillation mode design (eigenstructure) in each state variable, the STATCOM active current and reactive current will no longer be governed by the same mode but driven by new respective modes. The simulation and experimental results demonstrated that under various system disturbances, the proposed mode decoupling STATCOM is effective in regulating IG terminal voltage.