International Journal of Scientific & Engineering Research, Volume 7, Issue 10, October-2016 379 ISSN 2229-5518 IJSER © 2016 http://www.ijser.org Optimal Operational Analysis of Off-Grid Hybrid Renewable Energy System with Multiple Storage Facilities OludamilareB. Adewuyi, OlusolaA. Komolafe Abstract— This paper discussed the benefits of integrating multiple storage facilities into hybrid renewable energy system(HRES) configuration.A scheduling algorithm was developed for a hybrid renewable energy system that consists of wind and solar energy sources, pumped-hydro and battery storage with diesel generator as backup, for a selected site. The sequential quadratic programming (SQP) approach for solving convex non–linear optimization problems was used to determine an adequate and cost- effective capacity for each of the incorporated energy systems. An algorithm for supervisory controller for optimal scheduling of the hybrid renewable energy system was developed and simulated on Matlab. The cost analysis of the hybrid renewable energy system was carried out using the cost per kW of each component for obtaining the total installation cost and the cost of consumed diesel for each of the considered scenarios. These costs were compared with the cost of grid extension and the cost of electricity using the current Nigerian electricity tariff. The results showed that an off-grid energy system that consists of renewable energy sources, with multiple storage facilities, is capable of meeting the energy requirement of the studied site with little or no contribution from the backup diesel generator in most of the considered scenarios. The simulation outcomes showed that renewable energy contribution varies between 17.26% of the total load demand, during weekdays of normal academic period in the dry season and 96.11% of the total load demand, during weekends of holiday periods inthe rainy season. The contribution from storage facilities to the energy contribution from the renewable energy sources was between 9.21% and 29.15% of the total load demand. In terms of the installation cost, supplying electricity from the grid was found to be more economical for a distance of up to 180 km, but the free relatively low or free running cost of the hybrid renewable energy system made it a better option in the long run. Index Terms— Renewable energy technologies (RETs), hybrid renewable energy systems (HRES), pumped - hydro storage system (PHSS), cost of electricity per kW generation, optimtool, sequential quadratic programming (SQP), Supervisory control algorithm. ——————————  —————————— 1 INTRODUCTION Meeting the ever-increasing energy demand in a clean, neat and environmentally friendly manner is one of the major problems facing developing countries. Nigeria has one of the lowest population versus electricity supply profile in the world; a nation with a population of over 150 million people having a power generating capacity of about 4000 MW. Many of the rural areas of Nigeria have not benefited from the use of electricity in the same proportion as the more populated urban areas of the country [1] and a large percentage of the urban areas that are connected to the grid witness, on a daily basis, irregular and unreliable supply of electricity. One approach that has been identified as a means of overcoming this challenge is the adoption of renewable energy technologies. However, solar energy system is not going to function at night; wind turbine will not generate electricity when the wind speed is not sufficient and the water level at the potential hydro sites changes with the season. Nevertheless, one suitable and cost effective way of obtaining the maximum benefits from these absolutely free but intermittent energy resources is through integrating them to produce hybrid energy systems. Economic aspects of the Hybrid Renewable Energy System (HRES) technologies are becoming sufficiently promising for the development of power generation capacity for developing countries [32]. However, it is only recently that significant efforts are being made through research and development, to mobilize theavailable renewable energy resources in hybrid form towardsoptimizing theirbenefits [10], [12], [19]. In this study, the load demand data and the meteorological data for wind speed and solar radiation of the Obafemi Awolowo University main campus were used to optimally design an effective operational strategy for off- grid hybrid renewable energy system for the university community. The target of the design is to ensure efficient utilization of the available renewable resources through storage sufficiency. 2 LITERATURES REVIEW Regions with difficult terrains and topography often have the highest potential for renewable energy technologies (RETs). Hence, countries have embarked on research and development programs that are targeted towards the proper utilization of RETs in either the off-grid or grid-tied _______________________________ • OludamilareB. Adewuyi received B.Tech. degree from Ladoke Akintola University of Technology, Ogbomoso, Nigeria, in 2011 and M.Sc. degree from Obafemi Awolowo University, Ile – Ife, Nigeria, in 2016. He is currently a Ph.D. research student in Power Energy System Control Laboratory in University of the Ryukyus, Okinawa, Japan. E-mail: adewuyiobode@gmail.com . • OlusolaA. Komolafe, Ph.D, is an Associate Professor in the department of Electronic and Electrical Engineering,ObafemiAwolowo University,Ile – Ife, Nigeria. IJSER