ABSTRACTThe growth in the use of power electronics has increase space a greater awareness of power quality. Voltage sags, swells, harmonics can cause equipment to fail, mis-operate or shut down, as well as create huge current imbalances which could blow fuses or trip breakers. These effects can be very expensive for the customer, ranging from minor quality variations to production downtime and equipment damage. Sensitivity industrial loads, critical commercial operations, Utility distribution networks affected from these different types of outages and service interruptions and which results in financial losses. The Dynamic Voltage Restorer (DVR) is fast, flexible and efficient solution to voltage sag problem. The DVR is a power electronic based device that provides three-phase controllable voltage source, whose voltage vector (magnitude and angle) adds to the source voltage during sag event, to restore the load voltage to pre-sag conditions. The DVR is designed for protecting the whole plant with loads in the range of some MVA. The DVR can restore the load voltage within few milliseconds. Configurations and control schemes for the DVR varies depending upon the nature and characteristics of the load to be protected. In this project Z-source inverter (ZSI) based DVR is proposed to enhance the voltage restoration property of the system. The ZSI uses an LC impedance grid to couple power source to inverter circuit and prepares the possibility of voltage buck and boost by short circuiting the inverter legs. This project presents different cases of fault conditions using the Matlab/Simulink/Sim-Power software environment with the Z-source inverter based Dynamic Voltage Restorer scheme with fuzzy controller for effective voltage compensation, in rush current conditions and transmission line loss reduction.

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