Design and analysis of the inverter-side filter used in the dynamic voltage restorer

The role of the inverter-side filter used in the dynamic voltage restorer (DVR) is examined. Using circuit analysis method, it is shown that the selection of the filter parameters can affect the DVR inverter rating. Furthermore, with the DVR filter-series injection transformer combination, the loading effect of the filter on the restorer and the primary supply system has been quantified under normal as well as voltage sag conditions. A systematic filter design method is then proposed, the primary objective of which is to achieve specific harmonic performance while ensuring that the DVR inverter rating and the loading effect are minimized. Illustrative examples are also included.