Anti islanding protection for VFDs with active regen

[bacon4life]

Do VFDs with active regen capability typically have any sort of anti-islanding protection? IEEE 1547 specifies that Distributed Energy Resources must trip within 2 seconds, but VFD controlled loads like cranes and elevators can regen for tens of seconds under normal conditions. It seems like there is a risk the VFDs could stay energized for more than 2 seconds during an islanding scenario.

NERC is working on new rules for modeling DER for simulating performance of the Bulk Electric System. So far I have not seen any good proposals for a language to require modeling of flywheel energy storage devices without also requiring modeling of incidental energy storage devices like cranes and elevators. Does anyone have language for a clear distinction?

 

[jraef]

Yes, AFE (Active Front End) drives used for regenerative braking would shut down if the Line side power is lost. Most AFE drives do not have UL 1741 listings (which is what you need for an IEEE 1547 system), so they cannot remain connected to the Line if the power fails. So for that reason, equipment that must rely on braking for safe operations must have a backup braking system.

There ARE a few VFD mfrs that have UL-1741 however, mostly those that make both VFDs for motors and grid tied inverters for Solar PV systems, because they are essentially the same thing. So if you make a grid tied solar inverter, a change in firmware can make it a VFD too.


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