NERC’S 2017 SUMMER RELIABILITY ASSESSMENT
SHOWS RESERVE MARGINS VARYING IN U.S.
to the bulk power system, as well
as leverage an abundance of must-run hydro resources this summer to
alleviate natural gas constraints in
• The 2017 Summer Reliability Assessment
presents no anticipated impacts to
reliability on the bulk power system
due to the 2017 solar eclipse.
• The first known major loss of util-ity-scale solar resources occurred in
California on August 16, 2016, as the
result of a transmission system disturbance initiated by a fire induced fault.
The solar invertor technology did not
operate as expected and failed to provide frequency ride-through capability.
This event highlights on-going challenges with the interconnection of inver-tor-based technologies to operate reli-ably, and additional steps will be taken
to inform industry, manufacturers, and
planners to ensure they are aware of this
risk to the bulk power system.
NERC is a not-for-profit international regulatory authority whose mission is to assure the reliability of the
bulk power system in North America.
NERC develops and enforces reliability
standards; annually assesses seasonal
and long‐term reliability; monitors the
BPS through system awareness; and
educates, trains, and certifies industry
personnel. NERC’s area of responsibility spans the continental United States,
Canada, and the northern portion of
Baja California in Mexico. NERC’s jurisdiction includes users, owners, and
operators of the BPS, which serve more
than 334 million people.
The North American Electric Reliability
Corp.’s (NERC) recent report finds that
there are enough resources to meet
this summer’s projected peak electricity demand in all areas of the country.
Anticipated reserve margins, the amount
of expected unused electric generating
capacity at the time of peak load, range
from slightly less than 15 percent in
New England to almost 29 percent in
Some findings in the report include:
• Most assessment areas demonstrate
resource adequacy by maintain-
ing sufficient “anticipated resourc-
es” to meet their planning “refer-
ence margin levels” for this sum-
mer. The anticipated reserve margin
for Northeast Power Coordinating
Council (NPCC)-New England falls
to 14.88 percent, which is below
their reference margin level of 15. 10
percent for this summer.
• Relatively large differences between
actual and predicted variable energy
resource outputs can present operational challenges if sufficient flexible resources (dispatchable) are not
available to make up or absorb these
differences in outputs. This is especially challenging for systems that
have a significant level of capacity with operational constraints that
limit their ability to quickly change
their output up or down.
• For the upcoming 2017 summer season, Western Electricity Coordinating
Council (WECC) does not anticipate
any new reliability issues associated
with the Aliso Canyon outage in
Southern California; however, natural gas withdrawal capability is still
limited in the area as a result of this
outage. The California Independent
System Operator (CAISO) continues
to coordinate plans with the impacted gas company to minimize risk