Credit: Michael Kappel / Creative Commons

The North American power grid is reliable and resilient despite the growth of variable, renewable energy sources as well as an increasing risk of both cybersecurity and physical threats.

That’s the conclusion of a new report by the North American Electric Reliability Corporation’s (NERC), a not-for-profit regulatory body that oversees reliability of North America’s power system.

“In 2016, there were no reported cyber or physical security incidents that resulted in a loss of load,” the report, released last week, finds. “Nonetheless, grid security, particularly cyber security, is an area where past performance does not predict future risk. Threats continue to increase and are becoming more serious.”

For some, the recent shift in the power grid toward distributed, variable and interconnected power resources has raised concern about maintaining the high level of power quality that North American consumers have come to expect whenever they plug a device into an outlet.

In April, U.S. Energy Secretary Rick Perry directed the Department of Energy to study “critical issues central to protecting the long-term reliability of the electric grid.” In a memo obtained by Bloomberg News, Secretary Perry wrote that “regulatory burdens” and “federal subsidies” have in part diminished coal-fired power generation and which “create acute and chronic problems for maintaining adequate baseload generation and have impacted reliable generators of all types.”

“A reliable and resilient electric system is essential to protecting public health and fostering economic growth and job creation,” Secretary Perry wrote. “Nonetheless, there are significant changes occurring within the electric system that could profoundly affect the economy and even national security, and as such, these changes require further study and investigation.”

The results of the DOE study are expected to be released in the coming weeks.

NERC’s own findings suggest that – for now, at least – the nation’s power system has been largely successful in adapting to new technologies, shifting policies and fickle market forces.

Still, the report makes clear that there is a continued, if not heightened, need for vigilance. Both digital and physical threats to the grid are proliferating and becoming more serious over time, according to NERC.

Improved performance

By some measures, transmission grid performance has improved in recent years. The percent of “protection system misoperations” – essentially, the failure of protective relays, associated communication systems, voltage sensing devices, station batteries and other elements that handle glitches and faults in the power system – have consistently declined for four years. In 2016, the number declined to 8.7 percent, according to NERC, down from 9.5 percent in 2015 and 10.4 percent in 2014.

Resilience to severe weather continues to improve as well, NERC found. In 2016, there were zero days in which the daily severity risk index – which measures stress to the bulk power system – made the top-10 most severe days between 2008 and 2015.

Overall frequency response, which measures the transmission grid’s ability to respond to a sudden loss of power generation or load, has also improved between 2012 and 2016. This is a particularly critical capability as “variable energy resources” (e.g. wind and solar power, whose output is dependent on natural forces) continue to gain prominence on the U.S. power grid.

“The addition of a large number of variable energy resources onto the [Bulk Power System ] has resulted in the need for operational flexibility to accommodate demand while also effectively managing the resource portfolio,” the NERC report reads. “This metric should continue to be monitored as the rapidly changing resource mix presents a potential challenge to frequency response, one of the essential reliability services .”

In 2005, solar and other non-hydroelectric renewables made up just 2 percent of total utility-scale power generation, according to the U.S. Energy Information Administration (EIA). Ten years later, that figure rose to 7 percent, not including distributed solar generation. In March, wind and solar made up 10 percent of U.S. electricity generation for the first time, according to EIA.

NERC’s jurisdiction does not extend to local power distribution systems, but there are signs of progress on that front as well. In Illinois, for example, the state’s two leading utilities have improved reliability while implementing aggressive smart-grid deployment over recent years.

Between 2012 and 2016, ComEd’s outage frequency dropped nearly 34 percent and the duration of outages has been reduced by 48 percent, the company announced in February.

“The smart grid investment has vastly improved the infrastructure of our system,” Terence R. Donnelly, executive vice-president and chief operating officer for ComEd, said in a press release.  “On a daily basis and during storms, our customers are seeing less interruption in their lives and their business operations.”

Renewables helping, not hurting

In anticipation of the forthcoming DOE study, some advocates and analysts have defended the power system’s ability to incorporate rising amounts of variable generation and adapt to the erosion of “baseload” sources like coal and nuclear.

A study by the Analysis Group released this week found that advanced energy technologies were making the grid more – not less – diverse and thus reliable.

“These newer generating resources are also contributing to the varied reliability services — such [as] frequency and voltage management, ramping and load-following capabilities, provision of contingency and replacement reserves, black start capability, and sufficient electricity output to meet demand at all times — that electric grids require to provide electric service to consumers on an around-the-clock basis,” said the study, which received funding from the trade groups the Advanced Energy Economy Institute and the American Wind Energy Association. “As a result, increasing quantities of natural gas and renewable generation are increasing the diversity of the power system and supporting continued reliable operations.”

Other, smaller technological advances – both on-the-horizon and online today – have contributed to a smarter and more reliable grid, advocates say.

“Coordination of demand response, electric vehicle charging, and simple upgrades such as thermostats and efficient lighting reduce the stress on the grid, directly and immediately improving reliability,” Mike Jacobs, senior energy analyst at the Union of Concerned Scientists wrote in a blog post responding to the DOE study. “The utility industry has great potential to improve this sort of interaction with consumers, as well as the game-changing possibilities of battery energy storage.”

David started writing for Midwest Energy News in 2016. His work has also appeared in InsideClimate News, The Atlantic, McClatchy DC and other outlets. Previously, he was the energy editor at The Christian Science Monitor in Boston, where he wrote and edited stories about the global energy transition toward cleaner fuels.