This complex arrangement of distributed power and energy sources, distributed more » impedance and proximity to other sources of power requires sensing of ground faults and proper reaction by the ground-fault protection devices. PV systems are frequently connected to other sources of power or energy storage such as batteries, standby generators, and the utility grid. Leakage currents associated with the PV modules, the interconnected array, wires, surge protection devices and conduit add up and can become large enough to look like a ground-fault. Stray inductance, capacitance and resistance are distributed throughout the system. Installed PV systems always have invisible elements other than those indicated by their electrical schematics. Photovoltaic (PV) power systems, like other electrical systems, may be subject to unexpected ground faults. Unfortunately, this benefit reaches a limit as fuses become smaller and their internal resistance increases to the point of becoming a major element in the fault current circuit. The results of the simulations show that reducing the amperage rating of the protective fuse does increase fault current detection sensitivity without increasing the likelihood of nuisance trips to a degree. The behavior of the array during various ground faults is studied for a range of ground fault fuse sizes to determine if reducing the size of the fuse improves ground fault detection sensitivity. Closed-form analytical approximations for GFPD currents from faults to the grounded current carrying conductor-known as %E2%80%9Cblind spot%E2%80%9D ground faults-are derived to provide greater understanding of the influence of array impedances on fault currents. The derivation of the SPICE model and the results of parametric fault current studies are provided with varying array topologies, fuse sizes, and fault impedances. The numerical simulations were conducted with Simulation Program with Integrated Circuit more » Emphasis (SPICE) using a circuit model of the PV system which included the modules, wiring, switchgear, grounded or ungrounded components, and the inverter. In order to understand the limitations of fuse-based ground fault protection in PV systems, analytical and numerical simulations of different ground faults were performed. Recently the effectiveness of these protection devices has come under question because multiple fires have started when ground faults went undetected. To mitigate these risks, AC-isolated, DC grounded PV systems in the United States use Ground Fault Protection Devices (GFPDs), e.g., fuses, to de-energize the PV system when there is a ground fault.
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Ground faults in photovoltaic (PV) systems pose a fire and shock hazard.