Fast Current Control Strategy of PWM Inverter used for STATCOM

The Advanced Static VAR Compensator (STATCOM) uses a high power self-commutating inverter to draw reactive current from a transmission line. The STATCOM is based on the principle that a self-commutating static inverter can be connected between three-phase AC power lines and an energy-storage device, such as an inductor or capacitor, and controlled to draw mainly reactive current from the lines. This report deals with the modelling and control of an STATCOM system with self controlled DC bus which employs a three phase PWM voltage source inverter. The STATCOM system is modelled using the d-q transform and employs a programmed PWM voltage wave shaping pattern to simplify the logic software and hardware requirements. The inverter system can compensate leading and lagging reactive power supplied by the load connected to the supply. This model is used to design an efficient control strategy based on the control of the Magnitude and phase angle of the switching pattern. Simulated results obtained with MATLAB are also presented