By Rich Heidorn Jr.
NERC offered a mostly upbeat report on the long-term health of the nation’s grid Thursday, celebrating results from its first interconnection-wide frequency response studies while highlighting the need to model the increasing volume of distributed resources and supplement variable generation with ramping resources.
The 2018 Long-Term Reliability Assessment, NERC’s 10-year outlook for the North American bulk power system, found that frequency response will remain adequate through 2022 despite the loss of synchronous generators and the increase in inverter-based renewables.
“That gives us some confidence in the resource mix and also the ability to … see whether that performance is degrading out in the future — which is really important, so that if there are issues, you can put [in] policies or build new resources,” said John Moura, director of reliability assessment and system analysis, during a press briefing on the report.
Moura noted that FERC Order 842, issued in February, requires all new resources seeking interconnections be able to provide frequency response, calling the requirement “really, really important for reliability.” (See FERC Finalizes Frequency Response Requirement.)
The report said dynamic stability analysis showed both the Eastern and Western interconnections’ generation “sufficiently supports frequency after simulated disturbances despite reductions in inertia” from the loss of synchronous generation. It said ERCOT has operational procedures to address risks from “degraded inertia.”
“My optimism is not only based on the current mechanisms in place but the ability of the industry to respond and adapt to the changes. And so, while today we don’t have really what I would call excellent frequency response modeling capability, we’ve got pretty good [capability]. We’re able to see it,” Moura said. “And I have confidence that we’ll be able to have that excellent frequency response model in by the time we really need it.”
Load & Reserves
The report predicts North America will see compound annual load growth of only 0.57% for summer and 0.59% for winter, with five areas — New York, New England, the Maritimes, Manitoba and the California-Mexico region (most of California and a northern sliver of Baja California) — expecting reductions in peak demand. The fastest growing regions are ERCOT and the Rocky Mountains region of the Western Electricity Coordinating Council, both projected to grow about 1.8% annually.
The report did identify concerns, noting that ERCOT’s anticipated reserve margins are below targets for the next five years, with MISO and Ontario foreseeing reserve shortfalls beginning in 2023. (See ERCOT Predicts Tight Reserve Margin for 2019.) But it said the shortfalls could be filled by accelerating construction of additional Tier 2 resources — those that have met milestones such as completing feasibility, system impact or facilities studies.
The report includes new probabilistic evaluations — loss-of-load studies that evaluate all hours of the year — which found the California-Mexico assessment area of WECC at risk of 2.3 loss-of-load hours in 2022, with an expected 152 MWh of unserved energy. “These are not significant numbers … but it’s a faint signal that tells us about risk that may not be occurring in the peak hour,” Moura said.
Following Florida, California
The report projects 100 GW of new generation in the next decade, including about 41 GW of gas and 60 GW of solar. ERCOT and the California-Mexico region expect gas generation to contribute more than 60% of on-peak capacity, while Florida expects gas’ share to rise from 70% to 80%.
“When you do have this level of natural gas resources, you have to plan differently,” Moura said. “There are things that, for example, Florida does that other areas may need to do in the future, such as procuring more firm gas … or ensuring we have more dual-fuel capabilities.”
California is leading the way in addressing reliability risks from increasing solar, with CAISO’s three-hour ramping needs hitting a record 14,777 MW last March and expected to rise to 17,000 MW by 2022.
“As solar generation continues to increase in California and elsewhere across North America, system planners should ensure sufficient flexible ramping capacity, including large-scale energy storage,” the report said.
More than 30 GW of new distributed solar PV generation is expected by the end of 2023, with California expected to reach 18 GW of capacity, almost 40% of its projected peak. New Jersey, Massachusetts and New York are projected to each have 3.5 to 4 GW of distributed solar by 2023.
“There’s more [distributed energy resources] coming online faster than we’ve really ever seen any type of resource coming on. … If that’s not represented in models, we’re going to be modeling the system completely inaccurately. And if we don’t have flexibility in our resources, we really won’t be able to meet the challenges of the daily demand curves,” Moura said.
“In areas that may not have a lot of DER, or only starting to get DER, it’s perhaps common for planning studies to negate them or net them out or mostly ignore them. However, as we get a larger penetration of DERs, it’s really important that their characteristics are modeled,” Moura said. “Engineers and planners need to prepare data specifications and data exchanges that are needed now so that we have a better understanding of what the system’s going to look like in the future.”
This fall, NERC created a new working group to guide its efforts: System Planning Impacts of DER (SPIDER).
Among the report’s recommendations was a call for NERC’s Reliability Assessment Subcommittee to lead development of common metrics to assess energy adequacy. “Additional analysis is needed to determine energy sufficiency, particularly during off-peak periods and where energy-limited resources are most prominent.”
Similarly, it urged NERC’s Planning Committee to develop a common framework for assessing fuel disruptions, saying “system planners should identify potential system vulnerabilities that could occur under extreme, but realistic, contingencies and under various future supply portfolios.” The assessments could be used to develop regulations or market mechanisms to promote fuel assurance.
“A common approach for what kind of contingencies to study would be very valuable to the industry,” Moura said.