Feasibility and optimal operation of micro energy hybrid system (hydro/wind) in the rural valley region

Abstract

Abstract With the increase in the global and local demand for electrical energy, which is necessary for the functioning of several fields such as the economy and agriculture, this study introduces a micro-hydro–wind hybrid system in order to obtain an economic feasibility of the off-grid isolated and renewable energy system. The main objective of this research is to determine the optimum design size for a hydro–wind hybrid energy system that is supposed to meet the demand for the electric load in front of a valley in Algeria called Yesser with variable water flow and wind speeds in three positions. Batteries are supplied to increase the reliability of the system when the performance of the wind turbine energy and the flow rate of the hydro system are evaluated. This system is proposed to reduce financial costs in addition to the possibility of providing interchangeable energy and operating reserves with short start times. The Homer Pro software is used to model the hybrid renewable energy system and to perform the required analysis of the economic side of the system in terms of the valley's flow rate and the wind speed. The average speed of the water flow in Yesser valley is varied between 10 and 24.6 m3/s, and three cases of the valley's flow rate were studied with the maximum and minimum wind speeds: the passage (the transit) with 10 m3/s, the downstream (the estuary) with 19 m3/s and the valley's upstream (the source) with 24.6 m3/s. From the results, it appears that the hydro power was not enough to meet the load demand in the first area (the transit); however, the hydro/wind hybrid system was capable to feed the required load. For the second area (the estuary) the wind power was needed just in summer season, and for the third area (the source) the hydro generator was sufficient to feed the load all the year as the hydro power generated exceeds the load demand. The Homer Pro software calculations prove that the financial cost of the system is inversely proportional with the wind speed, such that the higher the wind speed the lower the cost of the system, the same relationship is for the flow rate speed as we consider the third case the most cost-effective with 61 330.46 USD.