Laboratory-scaled STATCOM for unbalanced voltage sag mitigation by decoupled double synchronous reference current controllers

This paper presents implementations of a laboratory-scaled static synchronous compensator (STATCOM) for reactive power compensation for unbalanced voltage sags. In order to attenuate the effects of coupling terms between sequence components, double decoupled synchronous reference frame (DDSRF) current controllers are implemented. Under this framework, adequate decoupling between positive and negative sequence components can be achieved. PSCAD/EMTDC simulator is used to verify implementation results. A 2kVA, 220 V AC, 60 Hz laboratory-scaled STATCOM platform is constructed for evaluating the dynamic performance of the DDSRF-based STATCOM when unbalanced voltage sags occur in a weak grid.