12 kV 3 Phase, 3 Wire Campus Loop

[LJonesElec]

We are attempting to get the serving Utility's approval for an interconnect agreement for a photovoltaic system installed on a building served by a customer owned 12 kV, 3 Phase, 3 Wire with 1 grounding conductor Campus Loop. The campus is primary metered with the primary meter and (2) customer owned 12 kV interrupter switches located at a remote location on the campus. The service point is on the line side of the customer owned 12 kV interrupter switches. The campus has one (1) large building served by multiply Delta-Wye transformers (12 kV - 480/277Y). In order to receive approval from the utility, the utility is requiring the campus to switch all 12 kV-480/277Y transformers serving a photovoltaic installation via the electrical distribution equipment, i.e. 480/277 volt distribution panelboards from a Delta-Wye to a grounded Wye-grounded Wye transformer. The utility's concern is the contribution from the photovoltaic system to the available fault and high phase voltages. Please note; this presently does not require all Delta-Wye transformers serving the campus to be replaced.

Providing a grounded wye-grounded wye transformer supplied by an ungrounded, medium voltage distribution feeder create any negative issues? Does establishing a ground at the high side of the wye-wye transformer without a neutral conductor to the service point create any issues? I would like to verify the installation of a grounded wye-grounded wye transformer will not negatively impact the campus loop or the electrical distribution equipment served by the same.