A comparative study of inverter- and line-side filtering schemes in the dynamic voltage restorer

The filtering scheme in the dynamic voltage restorer can be placed either on the line- or the inverter-side of the series transformer. While the purpose of any of the filtering schemes is for the attenuation of the high-order harmonics due to the inverter switching, the introduction of either of the filtering schemes will incur problems that must be understood and properly handled. Based on the electric circuit theory, the two filtering schemes are examined. Factors considered include the attenuation of harmonic voltages on the load-side of the series transformer, minimization of the inverter rating and the alleviation of other undesirable effects incurred by the filter installation.