Design of a Protected Stand-Alone Photovoltaic System for Uninterrupted Power Supply in Nigerian Hospitals
Keywords:
ETAP, Photovoltaic system, Renewable energy, Stand-alone, Uninterrupted power supplyAbstract
Healthcare delivery service is very crucial and depends to a large extent on reliable, clean and adequate power supply. However, in Nigeria, grid-connected electricity supply has never been reliable, as most Nigerian hospitals depend on alternative gasoline or diesel-powered generating sets, thereby skyrocketing the operating cost of hospitals, causing an increase in patients’ medical bills and an increase in death rates as a result of power outages in essential departments/units with life support gadgets/machines that require uninterrupted power to save lives. This study, therefore, aims to develop a protected and cost-effective stand-alone PV system for uninterrupted power supply in Nigerian hospitals. Solar irradiation and ambient temperature form input data, used for analysis and investigation, which were assessed from the NASA database, while the energy audit data for essential loads of the hospital were obtained using a clamp meter across the 3-phase supply at the various departments. Electrical Transient Analyzer Program (ETAP), version 19.0.1, was used to model and simulate the existing power supply to the hospital and design two networks for essential loads. Placement of capacitor banks on designed networks was carried out to provide reactive power support for a more efficient, stable and reliable network. Thereafter, governing equations were formulated to characterize the study case for improved power supply and size the PV components for both networks. An overcurrent protection scheme was carried out on the networks with a fault inserted at the modular unit (with a lump load of 4.88kVA) and radiology unit (with a lump load of 71.33kVA). Finally, the value engineering approach was adopted for cost savings using the utility bill for the year 2024. The result showed a 138kW of essential loads in RSUTH across fourteen departments, recommending a 180kW(220kVA) capacity protected and cost-effective photovoltaic system with 3 days of autonomy to provide an uninterrupted power supply to essential loads in RSUTH. Capacitor banks of (1 × 45 kVAR) and (1 × 50 kVAR) were adequately sized and placed on the networks, thereby improving the voltage at the buses.
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