Though there is consensus that a large-scale geomagnetic disturbance (GMD) poses a significant risk to the bulk power system, the lack of certainty about how vulnerable the system is to these disturbances results in two competing schools of thought: take steps now to protect the power grid and associated equipment while research is done to strengthen our understanding of potential impacts, or do more analysis before making any investments in the grid.
A panel of experts testifying at FERC’s staff-led reliability technical conference on geomagnetic disturbances of the bulk-power system on April 30 demonstrated this divide, with some arguing for more studies to be performed while others argued for action to be taken.
Though steps could be taken today, more study is needed, according to Frank Koza, the PJM Interconnection’s executive director for support operations.
“Before a transmission asset owner can make an informed decision on the deployment of mitigation measures, more analysis needs to be done,” Koza said, adding that PJM will review and update operations and training based on NERC’s GMD Task Force (GMDTF).
Koza offered four implementation steps to take in the near-term: assessing extra high-voltage (EHV) transformers; implementing specifications of geomagnetically induced currents and new transformers; developing operating procedures; and incorporating GMD impacts into system analysis.
“At the level of today’s knowledge, no one can definitively say whether the above strategy will be sufficient to protect transformers from space weather events,” Koza said. “Conversely, no one can provide sufficient evidence that a large scale investment by asset owners or government would adequately address the risk, let alone meet an appropriate cost benefit ratio given the state of today’s research.”
Numerous studies have been performed, finding the potential effects of a GMD could include widespread voltage collapse and transformer damage that could take months, if not years, to fix. However, harmonious conclusions among those studies have not been reached for two reasons, said Scott Pugh, science and technology directorate for the Department of Homeland Security.
“First, there’s significant scientific uncertainty surrounding the potential magnitude of space weather events, because we don’t know whether limited space weather data collected over the past few centuries accurately reflects the full range of possibilities,” Pugh said. “Second, there is technical uncertainty about whether a worst-case geomagnetic storm would cause bulk power transformers to fail in large numbers, small numbers or not at all.”
Pugh pointed to a 2012 NERC report that largely contradicted other academic and government studies, finding that a major storm would probably cause system voltage collapse and large blackouts, but that it would not take as long to recover from transformer damage, possibly taking a few hours or days as opposed to weeks or even years.
“Without this type of conclusive information, it can be said we are essentially flying blind, hoping that NERC is right and the national academies are wrong,” Pugh said.
Pugh called for a test program to be developed for the transformer fleet, exposing transformers to worst-case levels of induced current to see whether failures occur and the extent to which action should be urgently undertaken.
Mark Lauby, NERC vice president and director of reliability assessment and performance analysis, said that NERC’s GMDTF members “agreed the most likely impact was voltage instability caused by significant loss of reactive power support, simultaneous to a dramatic increase in reactive power demand from transformers.”
John Kappenman, owner of Storm Analysis Consultants, criticized the NERC study, alleging that NERC has been “entirely reluctant” to gather and ask for data from the power industry. “How can we do a serious study lacking any real attempt to gather and investigate evidence?” Kappenman said.
“We essentially have here a situation where a task force report was developed without all of the information that should be contained in that report,” he said. He added that all of the studies have concluded that the risks are serious. “Even without modeling, using simple extrapolations of major power grid data using space weather environments, you can reach the same conclusion,” he said.
Based on historical data and what the industry has gleaned from storms identified from historical evidence, GMDs could be “multiples of times worse,” than the 1989 storm that took out Hydro Québec’s grid in Canada. “Four to 10 times worse is not unrealistic for what we need to be prepared for,” Kappenman speculated.
Ben McConnell, a research scientist and lecturer with the University of Tennessee and retired principal investigator for Oak Ridge National Laboratory’s Power Systems Program for Electric Energy Systems, seconded the need to take action over pursuing more analysis.
“We need to not to do research but to … get something done,” he said. “Adequate and cheap means are known for protecting against the entire range of natural GMDs and manmade [electromagnetic pulses]. … What is lacking is economic incentive and political will.”