By Eric Barendsen
Scientists call it “Solar Cycle 25,” and WAPA is getting ready for it. According to a recent NASA press release, researchers believe that the sun passed its cyclical minimum of solar activity in December 2019, and a new period of potential solar outbursts has begun.
Space weather, predominantly affected by varying solar activity, such as solar flares, can have dramatic impacts on Earth, including on the electrical transmission system.
WAPA recognizes the unique risks that space weather poses to its transmission assets and its customers and is taking proactive steps to remain resilient in the face of an unpredictable sun.
Space weather events can cause geomagnetic disturbances, or GMDs, in the Earth’s magnetic field that induce electric currents in grounded transmission equipment. These geomagnetically induced currents, or GICs, can cause physical damage to transformers and protection systems, as well as stress the transmission system’s ability to compensate for abnormal, widespread voltage dips that can compromise electrical service delivery to customers.
“GMD is a tough scientific and engineering challenge,” said Electrical Engineer Chris Colson. “Solar storms are impossible for earthlings to predict, but we have observed the sun’s ability to disrupt our modern electric power system, most significantly during the October 2003 ‘dark Halloween’ solar storm, and earlier during the March 1989 ‘Quebec blackout’ event.”
In both cases, tens of thousands of customers lost power and millions of dollars’ worth of equipment was damaged. Major solar storms, referred to as Carrington-level events after a record-setting 1859 geomagnetic disturbance, occur regularly.
“We need to be prepared,” Colson said. “The last Carrington-level solar storm occurred in July 2012 and, thanks to Earth’s orbital position at the time, missed us by a mere nine days.”
WAPA has been involved in preparing for and mitigating possible GMD effects since the beginning of the 21st century. By partnering with the Electric Power Research Institute’s SUNBURST program, which collects diverse GMD-related data across the U.S., WAPA is contributing to a body of industry data that can help scientists model GICs, forecast when they will happen and develop ways to protect the grid.
The National Oceanic and Atmospheric Administration’s Space Weather Prediction Center uses observations from geostationary satellites along with complex mathematical models to develop short-term forecasts of geomagnetic effects on Earth, similar to the way in which terrestrial weather forecasts are made.
The scientific research that SUNBURST has contributed has helped utilities better understand the nature of geomagnetically-induced impacts to the power system and employ the SWPC forecasts to prepare for solar storms.
“While the electric power industry has known about GMD effects for decades, only recently have high-fidelity tools become available that allow us to simulate and assess the effects on the interconnected transmission system,” said Colson. “These tools along with real-time monitoring give us on Earth a fighting chance to protect the integrity of the power system during solar storms.”
Upper Great Plains is particularly susceptible to GMDs due to being farther north than the other WAPA regions. Because of the potential damage that can be caused by these currents and the persistent risk that UGP faces, WAPA has developed a GIC-monitoring system to alert system operators and gather data ahead of and during GMD events.
“Given our northern footprint and the makeup of the transmission we operate, it was clear that UGP had the strongest vulnerability, and we needed a cost-effective approach to provide GIC operational awareness,” said Transmission Planning Manager Gayle Nansel. “This approach puts WAPA in a well-positioned place as we advance our insight into planning and operating reliably during these solar disturbances.”
Severe space weather events can cause the Earth’s magnetic field to wobble on a massive scale, leading to GICs flowing through power transformers as currents that are undetectable with conventional transmission system instrumentation.
The UGP monitoring system detects these rapidly changing currents directly at the point where the power transformer ties into the grounding system of WAPA’s substation, giving the control center operators instant awareness of voltage dips and other threats to transmission system equipment.
UGP conceived, designed and implemented this GIC-monitoring solution with the primary objective of providing real-time situational awareness of GMD impacts on the transmission system to control center operators. UGP has equipped two substations to gather data on GICs to better inform dispatchers of the timing, magnitude and location of these events.
The monitoring device is a highly sensitive current transformer installed in the neutral section of an extra-high-voltage transformer. This sends a GIC measurement, accurate to one-tenth of an amp, to the supervisory control and data acquisition system that operators use to run the grid. If an induced current beyond a set limit begins to travel through the transformer, the system operator is notified.
The Southwest Power Pool Reliability Coordinator also monitors for unusual activity and will send a GMD alert to any affected control centers.
“That alert, combined with the GIC-monitoring device outputs, will allow the system operator to see in real time if the GMD is directly affecting the power system and take appropriate actions according to our operating procedure,” said Power System Dispatcher Seth Bury.
Armed with the best information, transmission system dispatchers can take immediate action to prevent equipment from overheating, preserve operating service margins and continue to ensure reliable service to customers.
The system also assists UGP in complying with North American Electric Reliability Corporation standards and annual NERC GMD Section 1600 data requests. Based on the success of the initial GIC-monitoring deployment, WAPA intends to widen the network for the benefit of the organization’s other regions, as well as its neighbors and partners.
In developing the in-house system, WAPA used as many existing communication and control assets as possible to minimize costs. Given the modest implementation and operating costs to date, the WAPA solution will yield approximately $300,000 over 10 years in avoided costs—compared to the next-least-expensive alternative—for just a handful of installations. As the WAPA network of monitoring equipment grows, so will the cost savings.
This proactive capability demonstrates an immediate and relevant benefit to WAPA’s transmission customers and helps the organization continue to lead the way in responding to emerging challenges in the energy frontier.
“Having a cost-effective way to provide this important information to our system operators is just one example of how our employees strive to ensure our customers get the biggest bang for their dollar,” said Acting Senior Vice President and Upper Great Plains Regional Manager Lloyd Linke.
Note: Barendsen is a public affairs specialist.
This split image shows the difference between an active sun during solar maximum and a quiet sun during solar minimum. December 2019 marked the beginning of Solar Cycle 25 and the sun’s activity will once again ramp up until solar maximum, predicted for 2025. (Photo courtesy of the National Aeronautics and Space Administration Solar Dynamics Observatory)