By Rich Heidorn Jr.

NERC on Wednesday called for developing metrics on resilience and urged continued efforts to respond to increased cyber threats and the growth in asynchronous generation.

“By nearly every measure by which we measure reliability … 2018 was one of the most reliable years on record,” Director of Reliability Assessment John Moura said in a press briefing announcing the organization’s revamped State of Reliability report. “While extreme weather events continued to stress transmission, generation and distribution systems, bulk power system reliability was maintained.”

There were no category 3, 4 or 5 events — unintended loss of load or generation of 2,000 MW or more — other than those caused by severe weather: hurricanes Michael and Florence.

“While ongoing performance measures show positive trends in generation, transmission, and protection and control performance, NERC’s 2019 State of Reliability encourages continued vigilance as the evolving resource mix and cyber and physical security threats continue to present critical challenges,” NERC said in announcing the report.

Among its recommendations, the report says “the ERO Enterprise and industry should develop comparative measurements and metrics to understand the different dimensions of resilience (e.g., withstanding the direct impact, managing through the event, recovering from events and preparing for the next event) during the most extreme events and how system performance changes over time.”

Cyber Threats

“Despite continually evolving threats,” no cyber or physical security incidents caused “unauthorized control actions or loss of load” in 2018 NERC said.

However, the lack of incidents “does not mean that the risk of a cybersecurity incident is low,” NERC warned. “The number of cybersecurity vulnerabilities are increasing. Both mandatory and voluntary reporting indicate that distribution-level events are more frequent than those affecting [bulk electric system] equipment.”

The report recommended the ERO continue working with industry to share information and develop responses to cyber and physical security threats, including “resilient system design, consequence-informed planning and operation and practicing response and recovery processes.”

Improved Frequency Response, Despite Inverter Growth

It also said the ERO should continue to develop measures for dealing with the growth of inverter-based resources, including frequency response under low-inertia conditions, contributions of inverter-based resources to essential reliability services and “increasing protection system and restoration complexities.”

Despite the continued growth in inverter-based resources, however, NERC said it saw improved frequency response in all four interconnections (Eastern, Western, Texas and Quebec). Moura said the improvements were the result of manufacturers’ efforts and NERC’s guidance on how to avoid having generator governor response be undermined by other system controls.

He also cited ERCOT’s practice of opening relays to allow load to help maintain frequency. “That can, at times, perform much better than generation,” he said.

NERC also reported that misoperations by protective relays — either tripping when they shouldn’t or failing to trip when they should — rose slightly in 2018 but that the difference was “in the noise” statistically. There has been a significant drop since 2014’s “unacceptable” misoperation rate of 10%, Moura said.

The report noted a continued reliability risk in Texas this summer due to a projected reserves deficit but noted that ERCOT avoided emergencies last year thanks to better than expected performance from its generation fleet.

New Format

The report has been reformatted with less text and more infographics and weighed in at a svelte 89 pages, down from 200 last year.

It is broken into five sections, starting with key statistics (i.e., peak demand, energy, generation capacity, fuel mix) and a chapter summarizing the analyses of 177 events in 2018, including root causes and lessons learned. The report found that design/engineering or management/organization issues were the root of 74% of events in 2018, slightly higher than their share for the five years of 2014-18 (70%).

Reliability Indicators

Chapter 3 covers reliability indicators (energy emergency alerts; planning reserve margins; transmission and generation outages, etc.), and Chapter 4 details the “Severity Risk Index,” which Moura described as a kind of “Dow Jones Index” for comparing performance over years.

2018 did see a spike in Level 3 energy emergency alerts, from six in 2017 (all in the Western Interconnection) to 17 last year (13 in the Eastern Interconnection and four in the West.)

The Eastern Interconnection had the highest number of Level 3 energy emergency alerts — declared when a reliability coordinator or balancing authority expects a capacity or energy deficit and may need assistance from neighbors.

Moura said all but four of the Eastern alerts concerned SaskPower in Saskatchewan, Canada. “Because they’re a lightly coupled system, if they have a couple generator issues, they get into these emergencies more often,” he said. “We’re not incredibly concerned on this one.”

One reliability indicator that NERC rated as red — a statistically significant negative trend — is the weighted effective forced outage rate for conventional (coal, gas, hydro and nuclear) generators.

“The most important metric here is the monthly NERC [rate] compared to the five-year average,” Moura said. “Over the past couple years, we’ve gone a little bit higher. … We do see slight increases in the coal feet forced outage rate, and we also noticed very peaky outages in the gas fleet” in winter.

Long-term Trends

The final chapter, which deals with trends and priority reliability issues, reflects the concerns of NERC’s Reliability Issues Steering Committee. Moura called the chapter a “bridge” to NERC’s Long-Term Reliability Assessments.

The report recommends prioritizing how to ensure resource adequacy in the face of “increasing energy constraints.” Moura said this was a reference to the increasing role of intermittent generation and fuel supply issues, such as winter natural gas shortages in New England.

Despite its acknowledgement of the impact of severe weather on the system, the report does not mention climate change, which many scientists say is causing bigger hurricanes, wildfires and floods.

Moura said it is difficult to attribute any individual weather event to climate change. “The potential for climate change and how that affects [system planning] … will more likely be in our forward-looking assessments like our Long-Term Reliability Assessment,” he said.