Hybrid Solar Pv-Gensetbattery Storage Power System For A Remote Offgrid Application: Case Study In Ethiopia
Fissaha, Solomon Gebremariam
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A hybrid power system that consists of PV-array, diesel generator, battery bank (storage device) and convertors has been proposed and discussed to obtain an efficient topology, economic power management strategy (system), and efficient power system with less environmental effect for a typical rural area where electricity has not reached yet. The first work of this thesis was selection of the most efficient topology among the proposed configurations(DC-bus, AC-bus and Mixed-bus topologies) that are connected to different energy sources, DC source (PV-array), AC source (diesel generator) and storage device (battery bank) based on the power output efficiency which delivers to the load demand. Then, depending on the load demand and the solar irradiation considered for typical rural village, all components of the system are sized properly and three different power management strategies where the diesel generator is assisted from the renewable energy and battery bank are considered in order to investigate the best power management strategy by taking into account different criteria such as environmental impact, costs, power losses etc. The selection of the most effective topology is conducted by taking every power source independently and the efficiencies of the system elements then after the output powers are compared by graphs. Depending up on, power balance between the two sides (supply and demand), Genset control and charging/discharging, mathematical modeling is generated for every power management strategy. This different mathematical modeling is modeled using MATLAB/Simulink blocks then, the Simulink models are simulated. Fuel consumption of the system by the generator for different power management strategies and the life-cycle costs of the systems are analyzed by using Microsoft Excel 2010. The cost analysis is analyzed by categorizing into three parties: the capital investment, variable and life-cycle costs. After the output power is compared, it is found that the Mixed-bus configuration is the most efficient topology among the proposed layouts and it is selected for further study. Having Simulink models simulated, the simulation results (power shares of the different energy sources and battery bank, energy stored and power losses) are discussed and it is observed that the results are as per the mathematical modeling in addition to that the battery bank charges and discharges between the limits (lower limit and upper limit) and the demand is supplied from the energy sources and battery bank at each instant of time. The environment effect is associated with fuel consumption of the diesel generator and it is found that the amount of fuel consumption of the system by the generator is different for different power management strategies so that the impact on the environment is also different. After the cost is investigated for each power management strategy, it is noticed that the capital, variable and life-life costs are different for different power management strategies. Even if the capital investment of the renewable energy system (OESPV) is the highest, it is found that OESPV is the most cost effective followed by GAPVB entire the lifetime of the system. Whereas, the Genset system (ODG)) is the most expensive overall the life time of the system due to the continuous fuel supply, replacement and operation and maintenance. In addition to that ODG has high negative impact on the environment.