Application of smart DC-Grid for efficient use of solar photovoltaic system in driving separately excited DC motor: Dynamic performance and techno-economic assessments

Solar energy is one of the solutions to the global threats - climate change, environmental pollution, fossil fuel depletion and high cost of energy - associated with increased energy demand. In this research, the techno-economic feasibility and dynamic performance assessment of a smart solar Photovoltaic (PV) Direct Current grid (DC-grid) powered Separately Excited Direct Current Motor (SEDCM) is presented. The energy mapping was done at Agbani City (6°18.3′N, 7°33.8′E), in Enugu State, Nigeria. Agbani city was identified to have a good amount of solar energy with an annual average solar radiation of 4.67 kWh/m2/d. The dynamic performance assessment of a smart solar PV DC-grid powered SEDCM was conducted with the help of MATLAB/SIMULINK software. The result show that a change in sun intensity affects the photon-generated current and it has effect on the open-circuit voltage of the solar panel. This change in the intensity can be compensated for by the use of a boost converter. The whole system was optimized in HOMER Pro simulation software to assess the techno-economic feasibility of the system. From the techno-economic study, it was observed that the proposed DC-grid PV system is feasible for the generation of electricity to power the SEDCM. The cost of energy was calculated and the categorized result from HOMER Pro shows that the capacity of the DC-grid PV system (35.67 kW) with 120 Surrette S-260 batteries gives the cheapest configuration. This configuration has a cost of energy of 0.11 $/kWh and a Net Present Cost (NPC) value of 0.048 million dollars and was used as optimum system configuration. Comparing the system with the national grid, the proposed DC-grid PV configuration has a cost saving of 35% with 1.679 gCO2~eq/kWh greenhouse gas emission, while the national grid emits a significant amount of greenhouse gas up to 15,104 kg/y.