NERC 2020-2021 Winter Reliability Assessment and Cold Weather Operation of SF6 Circuit Breakers
· NERC 2020-2021 Winter Reliability Assessment
In its 2020–2021 Winter Reliability Assessment , NERC finds sufficient resource capacity is in place across North America to meet winter demand. Noting how extreme weather can challenge grid reliability in specific areas, the assessment closely examines this reliability risk and identifies higher risk areas that are susceptible to emergency operating actions.
· NERC Lessons Learned – Cold Weather Operation of SF6 Circuit Breakers
When a SF6 circuit breaker (CB) hits its critical low pressure, its fault interrupting capability can be compromised. If this occurs across multiple locations, it can place the Bulk Electric System (BES) at additional risk since it weakens the overall topology of the system and can result in more facilities being removed from service to clear a fault. It also means that the contingencies modeled and studied in real-time contingency analysis (RTCA) studies may no longer be accurate, thereby potentially putting the BES in a less secure or unknown state. That condition occurred during the severe cold weather event that hit the upper Midwest region of North America on January 29–30, 2019. This lessons learned report, while primarily focused on TOs/TOPs, provides valuable information for GOs/GOPs that operate SF6 circuit breakers in cold weather conditions.