Design and optimization of off-Grid Hybrid Renewable Power Plant with storage system for Rural area in Rwanda

Abstract

Rwanda is one of the fastest-growing countries in Africa. The government envisions transitioning the country to 100% electrified by 2024 from which 52% grid-connected and 48% are Off-grid systems. The current offgrid coverage of the country is 13% only. The country is endowed with sufficient renewable energy resources. These resources are mainly micro-hydropower, biomass, and sun which can be used individually or in hybrid form. The application of a hybrid renewable energy system has become an important alternative solution for the rural electrification program. To satisfy the load demand, solar photovoltaic (4kW) and micro-hydro (15kW) energy were considered as the main source of energy to supply electricity to the load and to charge the battery bank when there was excess energy generation. However, either in peak load times or low generation of primary sources storage battery banks could also be discharged. The load has been suggested for residential loads including the deferable load (water pumping). During the design of this power system setup, the simulation and optimization were done based on the load demand, climatic data, the economics of integrated system components, and other parameters in which the total Net Present Cost has to be minimized to select economically feasible and technically capable hybrid power system. Furthermore, to use the power efficiently and economically Fuzzy Logic Controller is also used to control power produced and to take the decision to charge and discharge the battery bank at the necessary time. The decision of fuzzy logic is based on the instructional rule written on it. Well-known licensed HOMER and MATLAB simulating software tools have been used to design optimal off-grid systems and energy management systems respectively. In this thesis, solar PV/micro hydropower/battery bank/converter has been designed, modeled, optimized, and simulated for the rural area of Wimana village among the village of Ruhango District in the Southern Province of Rwanda which has 136 households. Based on the load profile of the data collected for the village was a daily energy consumption of 180.99kWh/day with a peak load demand of 18.56kW. The Net Present Cost and the Cost of Energy for the optimized power system were found to be $78,763.26 and $0.0757/kWh respectively.