Today’s LiveWire Spotlight looks at a “teachable moment” where manual underfrequency load shedding (UFLS) options were reduced to the point where normally excluded service had to be disconnected to preserve BES reliability.  The situation arose during the February 2021 cold weather event when large-scale generator losses and increased demand forced the activation of manual UFLS in in ERCOT, MISO, and SPP.  The findings led to revisions in ERCOT’s protocols that allow Texas-based TOPs to access load shedding capacity normally reserved for automatic UFLS as long as the 25% minimum is maintained.

Preparatory and system deficiencies that restrict emergency response procedures are top reliability concerns.  Severe penalties may be levied if UFLS options are hindered during an extreme event, and it is found that an Operator did not act upon these Lessons Learned.