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Effects of short and long term storage systems on size determination of renewable energy systems in micro-grids

Al-Ghussain, Loiy
Energy resources and global warming are two of the most important concerns for the whole world, where the necessity of finding clean and cheap energy resources have high priority nowadays. Renewable Energy Systems (RES), such as PV power plants and wind turbines, have the ability to meet the demand of the world; however, the energy generation of these kind of systems does not fully match with the electrical energy demand. Having a diversity of RESs with Energy Storage System (ESS) will increase the matching between the energy generation and the energy demand. The purpose of this thesis is to determine the sizes of different Renewable Energy Micro-Grid (REMG) systems with four main ESS scenarios with and without taking the ESS depth of discharge (DOD) into consideration; (1) without ESS, (2) with short term ESS-batteries, (3) with long term ESS-Pumped Hydro Storage (PHS), (4) with hybrid short and long term ESSs- batteries and PHS- for a university campus on a Mediterranean island in order to achieve the maximum yearly RES fraction () with Cost of Electricity (COE) equal or lower than the local grid tariff. Moreover, this study aims to determine the optimal ESS sizing methodologies with different RESs in order to achieve this goal. In addition, a sensitivity analysis of the models is carried out to determine the sensitivity of the RESs to the fluctuation of meteorological data in addition to the variation in the demand. Moreover, the effect of the integration of different ESS scenarios on the COE, , demand supply fraction (DSF) and the feasible sizes of PV, wind, PV/wind hybrid systems is studied in addition to the effect of the DOD of the ESS on these parameters. The results indicate that the PV/wind hybrid system with 4.19 MW PV, 8 MW wind and 89.51 MWh PHS has the highest - 88.04%- among the other RESs while the PV/wind hybrid system with 3.44 MW PV, 8 MW wind, 833 kWh battery and 89.51 MWh PHS has the highest DSF- 80.74%- with COE equal to the grid tariff. Moreover, the results indicate that the integration of ESS affects the economic and technical parameter of the RES where these effects vary based on the RES type, ESS type and RES capacity. Furthermore, the results show that the DOD of the ESS is a vital parameter that affects the optimal ESS sizing methodologies and the economic and technical parameters of the RES.