ABSTRACT
Generally protection systems are designed for the traditional radial circuit formation. Additional concern is attributed to the bidirectional power flows, increased fault levels, safety, voltage swells, fluctuations and transients, equipment ratings, and autoreclosing. Substation metering schemes must be designed to provide monitoring of true loading on circuits and transformers. Overload is not allowed on equipment. Special protection tripping schemes are not allowed, which could provide more flexible transformer loading. When a photovoltaic system is mounted on the roof of a residential dwelling, National Electric Code requirements dictate the installation of ground-fault protection devices. Ground-fault detection and interruption circuitry perform ground-fault current detection, fault current isolation, and solar power load isolation by shutting down the inverter. This technology is currently going through a developmental process, and it is expected to become a mandatory requirement in future installations. Islanding is not encouraged unless it is purposefully conducted.
