Earlier this evening, there was a Transmission-level fault that occurred at approximately 7pm. The following is a waveform captured at 22kV incomer (monitored at L-N), located in the city area.
Here, it suggests that there was a Single-phase fault (L2) and that it originated upstream at higher voltage levels. There were reports of voltage dips from other PQ monitors in other transmission blocks as well.
Update: Suspected fault originated from Genco facilities in the west.