Switching Pattern for Transformer Cascaded Inverter in Dynamic Voltage Restorer Structure

Sensitive loads cannot tolerate voltage sags and swells in power distribution networks and lots of problems are engendered for them. Therefore, different instruments are planned to compensate voltage swells and sags. Between them dynamic voltage restorer (DVR) has found special importance, because it operates better than others for this purpose and restores voltage to its initial value conveniently. A DVR is a power-electronic controller that can protect sensitive loads from disturbances in the supply system. The DVR is installed in series to the network. In this paper 9 level cascaded inverters with cascaded transformers are used in DVR internal circuit, but the difference in magnetic flux in cascading transformers has adverse effects on the plan. Therefore, a new switching pattern is used.