Control of series active compensator using estimation of the filter capacitor current

In the paper control of series active compensator, particularly dynamic voltage restorer (DVR), is considered. The compensator consists of VSI and an LC filter for smoothing VSI output voltage. Presence of the filter makes control of the compensator more difficult due to dynamics of a second order plant introduced by the filter which results in oscillations during a sudden voltage change. Multiloop controller is able to compensate the effect, however measurement of additional signals is needed. In the paper an estimator of the LC capacitor current is proposed in order to decrease total number of sensor needed for 3-ph DVR controller.