Positive sequence voltage control, full negative sequence cancellation and current limitation for static compensators

This paper presents a control scheme in the stationary reference frame for Static Synchronous Compensators that provides three features: 1) regulation of the positive sequence voltage to the nominal value, 2) full cancellation of the negative sequence voltage, and 3) peak limitation of the injected currents. These features can help improving the performance of these devices under perturbed grid conditions, including low, high and unbalanced voltages. Also, the peak current limiter guarantees both the safe operation of the converter, and a priority-based achievement of the voltage regulation targets, which is of interest during severe perturbations like voltage dips. Experimental results, implementation details and closed-loop analysis are presented to validate the regulation capabilities and to demonstrate the feasibility of the power quality improvement.