DESIGN AND SIMULATION OF DC MICROGRID FOR ELECTRIC VEHICLE CHARGING STATION (A CASE STUDY HAWASSA CITY)

Abstract

Development of electric vehicle has been established as an effective way to ensure energy security and realize emission reduction. However, the public electric vehicles charging station which is important element of using electric vehicles is not installed in Ethiopia. Therefore design of DC microgrid for charging station is proposed in this paper. In Ethiopia the electric energy infrastructure is not modernized enough and it is really difficult to fully depend on the energy obtained from grids. Thus, it is important to integrate the renewable energy (solar), grids and energy storage. However, the reliability of integration of renewable energy is dependent on the ability of the system to accommodate expected and unexpected changes (in production and consumption) and disturbances, while maintaining quality and continuity of service to the customers. Thus to improve real-time control performance and reduce possible seasonal variation forecasting is proposed for the solar energy used in the system. Thus in this study the author used the metrological data from Hawassa station and used machine learning algorithm for train the model with collected data and python used as programming language to develop forecasting model score system. Python is one of a well known high level programming language in data science.In this thesis, Jupiter notebook is used to write Python codes to develop a solar energy forecasting system.The designed forecasting system can predict the next day irradiance with accuracy of 97.56%. Next MATLAB simulation tool is used to integrate system. The proposed maximum operating voltage of this DC microgrid charging station is 500 Vdc. Power flow management using fuzzy logic controller keeps voltage within expected range with standard voltage deviation 2.2 and improved the response time 1.645 ms. More over the author also investigated the operating costs per year for this design. The operating costs for energy is $43,651per year if you use grid only for charging of EVs. On the other hand if 400 kW of PV and 680 kWh of battery capacity is integrated to the grid it reduce the operating costs to$6,344 /yearwith annualized saving of $37,306.This implies as the hybrid system has investment payback of 3.06 years and an IRR of 32.7%.Thus, clearly the result obtain in this thesis have great potential in future charging station design