ZSI-DVR ELIMINATION OF SHOOT THROUGH PROBLEMS AND DEEP SAG COMPENSATION WITH HFL CONTROLLER

The growth in the use of power electronics has caused 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. The Dynamic Voltage Restorer (DVR) is fast, flexible and efficient solution to voltage sag/swell problem. In this work Z-Source Inverter (ZSI) based DVR will be proposed. 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. ZSI based DVR is controlled by PI controller. PI control scheme suffers from fixed gains, i.e., it cannot adapt itself to the varying parameter and conditions of system. To overcome this drawback this work proposes a fuzzy controller. This is a non linear controller and it can provide a better performance under changing system parameters and operating conditions based on knowledge base and rule base. This work proposes another control method of Hybrid fuzzy-PI which is combination of PI and fuzzy controllers. The control schemes of ZSI based DVR are modelled and simulated in MATLAB/SIMULINK under voltage sags and swells