Operation and Control of a Dynamic Voltage Restorer Realized Using Cascaded H-Bridge Converters

The dynamic voltage restorer as a means of series compensation for mitigating the effect of voltage sags has become established as a preferred approach for improving power quality at sensitive load locations. Meanwhile, the cascaded multilevel type of power converter topology has also become a workhorse topology in high power applications. This paper presents the detailed design of a closed loop regulator to maintain the load voltage within acceptable levels in a DVR using cascaded multilevel converters. The paper presents system operation and controller design approaches, verified using computer simulations and a laboratory scale experimental prototype