Grey wolf optimization based optimal isolated microgrid with battery and pumped hydro as double storage to limit excess energy

Abstract

This paper proposes a 100 % renewable fraction based isolated microgrid with wind turbine, solar photovoltaic, battery, and pumped hydro storage to minimize the levelized cost of energy (LCOE) considering a) Loss of power supply probability (LOPSP) to enhance reliability and b) Percentage of excess generation (PEG) to limit excess energy (Pex) generation. The reliability assessment is performed considering the outage rate of generating units. Isolated Microgrids with a 100 % renewable fraction generate Pex, a short-duration and infrequent event, adding to system uncertainty. The presence of Pex causes operational and reliability issues, increasing the system cost. Diesel generators are a popular choice to overcome the Pex; however, they cause greenhouse gas (GHG) emissions. The proposed microgrid is simulated on MATLAB for a year using Grey wolf optimization (GWO), Moth flame optimization (MFO), and the Dragonfly algorithm (DA). The GWO algorithm outperforms the other algorithms in terms of accuracy and execution time. The results show that the proposed microgrid restricts the Pex to 4.91 % (Case-I) and 4.95 % (Case-II) of total generation. The LCOE is 0.3588 $/kWh and 0.2491 $/kWh for Case-I and Case-II, respectively, using GWO. With the hybridization of energy storage, GHG emissions are reduced by 82.37 % and 93.15 % for Case-I and Case-II, respectively, compared to grid-supplied. The sensitivity analysis shows that CO2 emissions vary linearly with generation. However, LCOE variation is non-linear due to its significant correlation with energy storage. Thus, the isolated microgrids operate at 100 % renewable fraction with minimum LCOE, Pex, and low GHG emissions.