Power quality recorders were placed on ten distribution feeders of the Centerpoint system in 2011. 1381 events were observed in the summers of 2011 through 2013. Many of these events were small voltage changes and single-sample spikes that, while of interest for other purposes, do not relate to the FIDVR phenomenon. A selector based on a voltage-time profile was used to choose events that might be of interest.
Of the 317 events that were selected:
- There is a very broad range of forms of voltage-time profile
- A significant number, but far from all, of the selected events exhibit ramping recovery of voltage over periods as long as 3 seconds
- Relatively few of the ramping voltage recoveries go to voltages significantly higher than the initial voltages
The selection of events is described in the memo, Distribution System Voltage Dip Recordings.
Plots of the voltage dips can be downloaded below.