CONTROL OF PHOTOVOLTAIC SYSTEM AND ELECTRIC VEHICLE CHARGING IN HYBRID MODE OPERATION

Abstract

In the last couple of decades, the growing concern in the energy sector is mainly due to continuous depletion of fossil fuels and emission of carbon di oxide which leads to green-house effect. For sustainable management of conventional resources and for minimizing hazardous environmental condition, further research and development is required, in the field of alternate energy sources. Solar powered energy is one of the most widely used non-conventional energy, as it is abundant, inexhaustible, free and clean. One of the major sectors using fossil fuel and natural gas is the transportation sector, hence battery electric vehicle was developed as an alternative to Internal Combustion (IC) engines, for reducing emission of CO2 and to limit the use of fossil fuel. No emission EVs are majorly charged using electricity grid, where the major concentration of fuel mix comes from conventional sources, hence PV powered EV charging is a sustainable option for long term. However, energy supplied by PV system being dependent on various environmental factors such as temperature, irradiance etc. is not fixed. Hence there is a need of integration of PV with electricity grid and other multi-functional operating sources for reliable operation of EV charging. In this work detailed simulation study of hybrid operation of photovoltaic (PV) and electric vehicle (EV) charging system is done. The renewable integrated EV charging infrastructure can be employed in diverse load power requirement scenarios. The overall system uses various converters at each stage, boost converter for harnessing solar PV power, a bi-directional buck-boost converter for EV charging, and a voltage source converter (VSC) with LCL filter for integrating overall system with the grid. The associated controllers for EV charging/discharging and for controlling various power flow mode consist of a controller at bi directional DC to DC and at AC to DC stage. The proposed system contributes towards maximizing energy output from PV system, uninterrupted EV charging, reducing load demand v on grid for enhancing grid performance and using EV as an energy storage system as and when required. Extensive simulation for various power flow modes have been performed to verify the aforementioned claims. Since large scale integration of renewable on main grid can lead to high voltage fluctuation. Hence BESS and on/off grid type inverters can act as a backup to manage black starting, islanding and any fault situation. To avoid system complexity a small sub model is also presented showing power flow management to load during on-grid to off-grid operation. The overall design and simulation work is executed in MATLAB/Simulink software and results are confirmed for various input conditions.