Realization of an AC-link pulse width modulated shunt converter for STATCOM applications

This paper presents the topological realization, dynamic modeling, and control strategy of an ac-link based static synchronous compensator (STATCOM). The topology is realized using an ac-link capacitor bank, a three-phase single-pole double-throw vector switching matrix converter, and a coupling transformer. Having a direct ac-ac converter allows for the elimination of the dc capacitor and for adopting a simple modulation strategy based on dc duty cycles. The paper includes details on the filter components design and proposes a PI-based control strategy. The architecture is validated via detailed computer simulations using the Matlab-Simulink mathematical software package. Results suggests the architecture is able to control the bus voltage to a desired set point and is immune to disturbances. Spectral analysis also indicates the waveforms are compliant with the standard IEEE Std. 519.