How was your issue detected?:
I notice my UPS battery backups kicking on and lights dimming everywhere. Did you noticed any other signs of this issue around your home?:
I think it might be when an AC kicks on, but I don’t know for sure.
With the right metrics my guess is you could analyze the NY ISO real-time load interface and predict brownouts, unless of course they behave like CA seems to be doing right now and arbitrarily knock back the voltage based on the grid supply cost rather than actual overload.
@JustinAtSense’s recent response to a similar issue is very informative and worth a read: