Interfacing of PV System Based on Dual Cascaded Inverter / by Ahmed Samir Hamed Alhafeny ; Supervisors : Prof Dr. Mohamed Abd Al-Raheem Badr, Prof Dr. Mostafa Ibrahim Mohamed Marei.

Thesis (M.Sc.) - Ain Shams University - Faculty of Engineering Department of ELECTRICAL POWER AND MACHINES, 2018.

Includes bibliographical references (82 - 88 p.).

The power electronics converters are coming into wide scale in different fields due to their ability of producing high quality current with low harmonic content, speed and dynamic response for variable change of the load. Power electronics converters provide precise control over wide range of application for electric drive systems, electric traction, ship propulsion and automotive application. In additions, converters are used widely for energy conversion, grid connection, manufacturing, mining and petrochemical. All of these applications require cost reduction, high production rate, high performance and efficiency, which could be served by power electronics systems. This thesis presents an interfacing system of a photovoltaic (PV) array with an electrical grid based on a dual cascaded inverter which consists of main and auxiliary inverters. The PV array is connected to the main inverter through a boost converter for maximum power extraction, while the dc-side of the auxiliary inverter is connected to a capacitor bank. The main and auxiliary inverters are controlled to deliver the harvested maximum power from the PV array to the grid and simultaneously regulating the dc-side voltage of the auxiliary inverter at a constant ratio from the dc-link voltage of the main inverter. Four Hysteresis controllers are proposed for the three-phase currents fed to the grid and the dc-side capacitor voltage of the auxiliary inverter. Two switching control methods are adopted for the dual cascaded inverter: the conventional Hysteresis Current Control (HCC) and the Space Vector Modulation (SVM) based HCC. The later technique offers reduced switching numbers for both inverters compared with the conventional HCC. The system has been also studied during fault / voltage sag condition. A low voltage ride through (LVRT) controller is adopted to fulfill the E.ON grid code requirements. The E.ON grid code ensures that the proposed PV interface system supplies reactive power to the grid according to the value of voltage at the point of common coupling. The proposed dual cascaded inverter for the PV interface system is studied using EMTDC/PSCAD software package. Different test scenarios are conducted under different conditions to evaluate the dynamic behavior of the proposed system. Simulation results show fast dynamic response and accurate performance of the proposed control systems.