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By Hannah Davinroy
Figure: Model of Geomagnetic Intensity -
March 1989 Hydro-Quebec Storm
Source: NERC Reliability Assessment: Effects of Geomagnetic Disturbance on the Bulk Power System 2012, http://www.nerc.com/files/2012GMD.pdf
As the reliability of the American electric grid and bulk power electric system is bombarded every day with challenges including a shifting resource mix, the integration of new renewable technologies, and severe weather, the contribution of the Sun in considering reliability has only recently taken a spotlight. Solar storms—in particular, those of the magnitude to cause large coronal mass ejections (CME) of upwards of a billion tons of plasma matter—can cause a rapid change of the alignment of the magnet field of Earth over large geographic distances. The geomagnetic disturbances (GMDs) produced by CMEs—when directed towards the Earth—can also cause magnetic disturbances across the surface of the Earth. These shifts in the magnetosphere can manifest disturbances within the high-voltage power grids around the globe. Geomagnetically induced current (GIC) emerges in the bulk electric system (BES) as a highly magnetizing current and a high harmonic current travel along high-voltage transmission lines and grounded transformers.
Though solar storms and CMEs occur with some frequency, the potentially dramatic impacts to the American BES have not historically been realized. The most often cited event is the GMD-caused collapse of the Hydro-Quebec system in March 1989. Leaving almost six million people without power for nine hours, the 1989 incident pales in comparison with the magnitude of storms in 1921—which disabled telegraph service—and with “the Carrington event” of 1859, which researchers predict would have crippled the BES. Because of the infrequency of events, the projection of the incidence, frequency and magnitude of future storms is highly uncertain. However, as research continues, there is a growing consensus that a “Carrington”-scale storm is inevitable, and that collective action is necessary to protect the national electric infrastructure from extensive damaging impacts. Despite the collaborative resources of national laboratories, regulatory agencies, and industry applied over the last decade to researching and addressing the potential for serious, high-impact GMD events, much information surrounding the impact of their subsequent GIC to the grid is still uncertain. The regulatory challenge is to define equipment and protocol standards with incomplete knowledge of how the threat will propagate throughout the BES—either as a loss of reactive power support increasing voltage instability and power system collapse or as physical damage to BES assets, most commonly transformers.
Though the surging interest in GMD prevention has really occurred in the last 15 years, the technology to prevent GIC is not new. GIC blockers—both in the form of neutral-blocking capacitors and neutral-blocking resistors—have been around since the Hydro-Quebec event in 1989. While hardware solutions are available, they are not widely used due to disagreement on their effectiveness. The other option involves system reconfiguration and operational procedures. Richard Waggel, Electrical Engineer from the Office of Energy Infrastructure Security at the Federal Energy Regulatory Commission, believes that for the grid to be robustly durable during GMD, there must be a balance between operational improvements and hardware installation. Speaking on this balance, he contends, “A lot of people look at reconfiguring the system, but that in itself isn’t a foolproof method. It might be able to buy you something, but against a large-scale GMD event, that’s unlikely to be enough.” One of the largest arguments against the implementation of any sort of technology is cost effectiveness. “What you have to look at is the cost to society to have power outages similar to the Quebec incident in ’89,” Waggel said, “For the billions of dollars lost in those outages, you might think mitigating is a very slight cost in comparison.”
On the other side of the equation is the equation of monitoring of CMEs by satellites. It takes CMEs between 14 hrs and 6 days to reach the surface of the earth. Space weather is monitored very closely by the National Oceanic and Atmospheric Administration as well as NASA. Improved modeling and forecasting have allowed timely distribution to grid operators of information regarding if and when CMEs will impact the earth and their projected magnitude. Waggel praises the importance of monitoring as an instrumental foundation to the overall response strategy, “One thing I’ll say especially about NOAA and space prediction center is they are instrumental in all this, and we wouldn’t be as far along if it weren’t for them.”
Regulatory Jurisdiction over the reliability of the electric grid falls to the Federal Energy Regulatory Commission (FERC). The FERC designated electric reliability organization—the North American Electric Reliability Corporation—submits system-operator voted standards to FERC for approval. In 2013, FERC moved for the first time to require mandatory standards related to GMD. A directive to NERC issued May 13, 2103, Order 779 comprised two major steps toward GMD mitigation. The first was an interim step requiring development of operational procedures—like grid-level monitoring and communication of solar activity—to provide some safeguards to the grid, within 6 months of Order 779. The second stage required NERC to develop a standard that included a system-wide risk assessment and the implementation of a plan that would protect against a “benchmark” event. Part of NERC’s response was to define a “benchmark” GMD event, which they set as the 1-in-100 year event in their submission of standards to FERC in January 2015.
Commissioner Cheryl LaFleur, appointed to the five-member Commission in 2010, arrived to the Commission at about the same time as GMD policy did. “Ten years ago, this wasn’t on most people’s radar, in industry or in government,1 ” she says. Commissioner LaFleur served on the Commission in 2013 when Order 779 was voted on, and she has remained a prominent spokeswoman on the issue. FERC’s first mandatory GMD standard has not been without controversy however. “One reason is that when we attempt to make rules about geomagnetic disturbance we are making requirements about threats that are not fully understood,” explains LaFleur on the issue, “This isn’t simple like directing them to trim trees. Some studies say that GMD would cause high voltage transformers to melt. Others say that the reactive power would cause the system to break apart before transformers were damaged. So we are developing standards while there’s still some unknown information.”
In May 2015, two years after Order 779, FERC issued a Notice of Proposed Rulemaking that proposed to accept some NERC-submitted standards and required revision of others, including the definition of a benchmark event and the timeline for compliance. Comment period for The Notice of Proposed Rulemaking closed in July 2015 and currently is awaiting further action at FERC.
In addition to GMD concerns, the growing threat of Electromagnetic Pulse (EMP)—intentional manipulation of the electric grid often associated with the magnetic pulse caused by a high-altitude nuclear explosion—increases the need for recent standards for GMD mitigation. EMP threats cause concern for national security. Though EMP pulses occur within a much shorter time scale, mitigation for GMD can diffuse some impact of the EMP pulses as well. The addition of GMD standards can potentially create a more robust electric grid, addressing several reliability issues.
Even without the mandatory standards that will emerge from Order 779, many in industry have been addressing system vulnerabilities with voluntary measures for years. According to Commissioner LaFleur, “Most scientists agree that it’s a question of when not if one of these large scale events occur. I don’t want to be the one with the report that the levee would break if the hurricane came when it’s our responsibility to get ready.” The policy addressing GMD has become a forefront of the reliability question, and Order 779 is simply the foundation of grid protection. “I believe the long term solution is building the transformers to have more resistance to GMD up front, not retrofitting equipment,” LaFleur says, “A lot of thought is going into how to design the system so that we have more redundancy if something happens and to mitigate against the effects of cascading outages. I think the future of grid protection is in the way we build and design it.”
Hannah Davinroy is an undergraduate studying physics at Princeton University. She worked as an intern at the Federal Energy Regulatory Commission this summer.
1 Personal interview, October 5, 2015