An Enhanced Dynamic Voltage Restorer using Cascaded Multilevel Inverter

摘要

This paper deals with protection of sensitive loads present in the consumer premises with specially designed enhanced Dynamic Voltage Restorer which applies a sinusoidal voltage in series with supply mains, during any kind of turbulence eg: sag, swell etc. Phase locked loop is used to synchronise the supply between source, injected and load voltages. Cascaded H-bridges are designed for achieving scalability & modularisation. Hysteresis controller is used to trigger the switches of inverter and there by providing good dynamic performance. Particular level of voltage is adopted based on an algorithm which can be easily extended for higher levels of cascaded H-Bridge inverters. Voltage is injected between source and load with the help of transformer connected in series with the supply. Performance & harmonics of the system are analysed for DVR having 3, 5, 7 & 9 levels of voltages by verifying simulation results carried out by using MATLAB tool.