ABSTRACT
Distributed photovoltaic grid transformers (DPV-GTs) are used in the pad-mount, station, substation, and grounding transformer applications. Thus these transformers require all security measures to be provided for safety in public areas. Islanding can be extremely dangerous to utility workers, who may not realize that a circuit is still powered, and it may prevent automatic re-connection of devices. The latter thus prevents the control of the utility on the operations of such local distributed generating systems. An inverter continuously monitors the condition of the grid and in the event of grid failure it automatically switches to off-grid supply within seconds. The solar system is then resynchronized with the grid within a few minutes after restoration of the grid. In extremely cold conditions where temperature can fall below zero, the grid and solar ties can fail and cause a direct current over-voltage condition.
