How hydropower can help the grid recover from extreme events
Water is known to have healing qualities, but in the case of hydroelectric power generation, it has the power to stabilize the electric grid in times of crisis. As threats become more common from both nature and human activity, researchers are beginning to understand and measure how hydro, one of the nation's oldest and largest sources of renewable energy, can make the grid more stable.
One study on the topic has now earned top honors at an event focused on infrastructure resiliency. Five Idaho National Laboratory researchers and their partners at Pacific Northwest National Laboratory (PNNL) took "Best Paper" honors at the International Resilience Week conference in mid-October. The researchers examined how hydropower's flexibility can provide stability and resilience in the face of events such as rolling blackouts, hurricanes and earthquakes.
The paper, "A Metric Framework for Evaluating the Resilience Contribution of Hydropower to the Grid," was written by Tim McJunkin (who led the team on resilience metrics), Manisha Maharjan, Shafiul Alam and Thomas Mosier, all of INL's Power & Energy Systems office, Tyler Phillips of the lab's National & Homeland Security directorate, as well as Vishvas Chalishazar and Abhishek Somani of PNNL.
The study was part of a yearlong project funded by the U.S. Department of Energy's Water Power Technologies Office (WPTO). Power systems analysis is part of the office's Hydropower and Water Innovation for a Resilient Electricity System (HydroWIRES) initiative, which aims to clarify hydropower's evolving role as part of a modern grid infrastructure.
The research team evaluated three different configurations of hydropower -- reservoir-based, run-of-river and pumped storage -- looking into how each can support the electric grid during and after extreme events. In addition to natural disasters, they also considered physical and cyberattacks. For each class of hydropower, the team presented each configuration's responses in a new, visual metric that makes comparing different generations of technologies' resilience contributions easier.
The paper offers insights into hydropower's characteristics and how well they match a system's resilience requirements. More importantly, McJunkin said it quantifies capabilities and limitations in a way that allows timely planning and effective response.
"People talk about resilience all the time, but how do you actually quantify that?" he said. To that end, he thinks about the four Rs: resist, respond, recover and restore. Hydropower resources have a great deal of flexibility because of the spinning momentum in the generators, which can slow down any shock that comes from a disturbance in the grid and respond to the frequency changes. But while hydropower has inertia, inertia alone does not give it flexibility. Related to the four Rs, inertia is responsible for resist. Hydro's flexibility comes from having storage and a high ramping rate, also because it is usually not operating at maximum capacity. That gives it the ability to respond, recover and restore.
Winning the best paper award reflects well on the team's innovative perspectives and the growing relationship between INL and PNNL, McJunkin said. INL enjoys a longstanding reputation in resilience research. Since 2008 when INL started Resilience Week, the event has grown and attracts leading minds from around the world to discuss improving the resilience of critical cyber and physical systems from unexpected and malicious threats.
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This year's event, which will be virtual due to the COVID-19 pandemic, is scheduled for Oct. 19-23. More information can be found at https://resilience.inl.gov/resilience-week/.
With natural disasters and human-caused incidents on the rise -- e.g., the hurricane season of 2020 -- resiliency has become a top priority in the first two decades of the 21st century. According to the Federal Emergency Management Agency, disaster declarations between 2005 and 2014 rose 35% compared to the previous decade, costing $106 billion in federal assistance.
The INL/PNNL paper addresses one of the most striking attributes of hydropower in general: its ability to support all of the time frames considered in what's called the DIRE curve. DIRE stands for disturbance and impact resistance evaluation, and the curve expresses the performance of a system at a level that can be considered resilient. With an understanding of capabilities and tradeoffs, stakeholders can make informed decisions to prioritize use of the resources.
McJunkin and his team at INL also developed an open-source software application called Power Distribution Designing for Resilience Application (PowDDeR), designed to capture a power system's capabilities for responding to natural and human-caused disturbances. A link is available at https://github.com/IdahoLabCuttingBoard/PowDDeR.