Hodge

The Grid’s New Shock Absorber: ‘Droop-e’ Control tames frequency swings and keeps renewable energy flowing smoothly

Daniel Morton — Tue, 09 Dec 2025 16:00:00 +0000

The Grid’s New Shock Absorber: ‘Droop-e’ Control tames frequency swings and keeps renewable energy flowing smoothly Daniel Morton Tue, 12/09/2025 - 09:00

Daniel Morton

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Electricity is crucial to modern life. We rely on being able to plug devices in to the outlet in the wall, flipping a switch, and things working without a problem. But it is not that simple, the power grid, all of the infrastructure that delivers energy from the power plant to your home, is something of a balancing act.

In order for a grid to operate safely, supply must equal demand. The flow of electricity through the grid in the United States flows at a frequency of 60 Hz, if the supply increases more than the demand, the frequency will increase, while if the demand increases, or the supply dips, the frequency decreases. The vast array of hardware that makes up the grid and in electrical devices, such as transformers, motors, or electronics, have been designed to operate at a specific frequency. If the grid is unbalanced, and the frequency changes too much, equipment can be damaged, efficiency is reduced, and it can lead to overheating, system failures, and blackouts. Keeping the grid online, and safe, is a balancing act that requires sophisticated controls systems to make sure that supply always equals demand.

Think of the electric grid like a high-speed train system. In order for the train system to operate effectively all the trains need to maintain consistent speeds and keep to schedule, so passengers are not left waiting on the platform, or miss their trains because they left too early. Traditional power plants are like massive freight trains, that are super heavy and take a long time to speed up or slow down. These massive freight trains provide a kind of inertia to the whole system. They are hard to disrupt, which results in a consistent speed. Renewable energy sources, such as solar and wind, are more like fast, light commuter trains, that can change speed essentially instantly. They lack the inertia of the massive freight trains, but they can change fast. If it were up to just human conductors and train line controllers to regulate how the trains are running, having the freight trains and the commuter trains on the same lines would be near impossible, the difference in speed and inertia would make it really hard to reconcile. This is where advanced computer-driven control systems come into play. In the train analogy the smart predictive system would predictively control the brake and throttle of the commuter trains to ensure a simple constant speed. How would the grid be impacted if we developed a smart control system?

This new report details work led by RASEI Fellow Bri-Mathias Hodge, and discloses a new approach for smart control in the grid. The grid is already full of control systems, with the standard way power generators respond to frequency events being via linear droop control. This would be like a simplistic cruise control for one of the Commuter Trains in the above analogy. If the frequency drops a little, the system increases the power proportionately. The problem with this approach is that it often doesn’t use the inverters full capacity fast enough. The innovation described in this work is an update called Droop-e, a non-linear control based on an exponential function. Think of it like replacing the trains cruise control, which previously had a simple on/off switch, with a smart responsive gas pedal, that can speed up, or slow down, on a curve.

This change, from an on/off control to a responsive curve, has the potential to have significant impacts on the grid. By using the available power reserves more effectively, Droop-e reduces the number of severe power swings in the system, and results in a slower rate of change of frequency (ROCOF), which can buy grid operators valuable time to react to changes in frequency.

The benefits from the ‘shock-absorber’ properties that Droop-e offers could help prevent blackouts before they start, help stabilize the grid and improve integration of renewable energy sources, and create a smarter, more responsive grid, future-proofing systems by replacing the software, and not the hardware, a significant cost saving.

The simulations from this study confirm that this new control approach could improve the stability of grids that include a combination of traditional power plants and renewable energy generators. If a major power plant trips offline, this sophisticated control system activates un-tapped power reserves in batteries and renewables, acting as a hyper responsive shock absorber to protect the entire grid system. For grid operators, it means more time to react. For everyone with devices plugged into a power outlet, it means improved stability, and less equipment damage. It also provides a more effective mechanism to integrate different power sources, improving reliability, security, and affordability.

December 2025

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Exploring Colorado's untapped geothermal energy potential

Daniel Morton — Tue, 21 Oct 2025 14:23:05 +0000

Exploring Colorado's untapped geothermal energy potential Daniel Morton Tue, 10/21/2025 - 08:23

October 2025

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Autonomous grid-forming inverter exponential droop control for improved frequency stability

Daniel Morton — Fri, 26 Sep 2025 00:00:06 +0000

Autonomous grid-forming inverter exponential droop control for improved frequency stability Daniel Morton Thu, 09/25/2025 - 18:00

INTERNATIONAL JOURNAL OF ELECTRICAL POWER AND ENERGY SYSTEMS, 2025, 172, 111160

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RASEI Fellow Bri-Mathias Hodge selected as member of the 25th Excellence in Leadership Cohort

Daniel Morton — Wed, 27 Aug 2025 17:49:27 +0000

RASEI Fellow Bri-Mathias Hodge selected as member of the 25th Excellence in Leadership Cohort Daniel Morton Wed, 08/27/2025 - 11:49

August 2025

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Semi-supervised multi-task learning based framework for power system security assessment

Daniel Morton — Tue, 29 Jul 2025 19:58:02 +0000

Semi-supervised multi-task learning based framework for power system security assessment Daniel Morton Tue, 07/29/2025 - 13:58

INTERNATIONAL JOURNAL OF ELECTRICAL POWER AND ENERGY SYSTEMS, 2025, 170, 110910

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Exploring new frontiers in the renewable energy transition

Daniel Morton — Tue, 27 May 2025 21:35:49 +0000

Exploring new frontiers in the renewable energy transition Daniel Morton Tue, 05/27/2025 - 15:35

Daniel Morton

RASEI Fellow Bri-Mathias Hodge, in collaboration with Shae Frydenlund, are exploring the barriers in the deployment of geothermal energy.

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2025 New Frontiers Grants

Each year the CU Boulder Research and Innovation Office (RIO), awards grants in their New Frontiers Grant Program, an initiative that is designed to foster new, interdisciplinary research at CU Boulder.

In 2025 three projects were selected that seek to improve understanding and address challenges in some of society’s most pressing issues. The teams were chosen through a competitive process that included eight in-person pitches. In all cases the new research strengths, based around interdisciplinary collaboration, expanded CU Boulder opportunities.

RASEI Fellow Bri-Mathias Hodge, in collaboration with Shae Frydenlund from the Center for Asian Studies, was successful in proposing a project exploring the technological and social dimensions of geothermal development in Colorado. It has been identified that geothermal energy is an underutilized resource that could play a significant role in Colorado’s energy future. However, despite abundant resource potential in the state there are many significant yet poorly understood technological and social barriers to the expansion of deployment. This project will support an interdisciplinary team to explore these different perspectives and positions CU Boulder to be a leader in the state in geothermal energy.

May 2025

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RASEI Fellows develop sustainable solutions to address AI increases in energy demand

Daniel Morton — Wed, 16 Apr 2025 20:18:56 +0000

RASEI Fellows develop sustainable solutions to address AI increases in energy demand Daniel Morton Wed, 04/16/2025 - 14:18

April 2025

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Climate Innovation Collaboratory awards $1M to tackle key sustainability challenges

Daniel Morton — Tue, 15 Apr 2025 16:19:12 +0000

Climate Innovation Collaboratory awards $1M to tackle key sustainability challenges Daniel Morton Tue, 04/15/2025 - 10:19

April 2025

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Lunar Power Grid: Network Structure and Spontaneous Synchronization

Daniel Morton — Mon, 07 Apr 2025 19:23:48 +0000

Lunar Power Grid: Network Structure and Spontaneous Synchronization Daniel Morton Mon, 04/07/2025 - 13:23

IEEE ACCESS, 2025, 13, 63120-63128

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RASEI Fellows receive 2024-2025 Deloitte and CIC Research Awards

Daniel Morton — Mon, 11 Nov 2024 21:11:59 +0000

RASEI Fellows receive 2024-2025 Deloitte and CIC Research Awards Daniel Morton Mon, 11/11/2024 - 14:11

Daniel Morton

The Climate Innovation Collaboratory (CIC) was launched as a collaborative venture between CU Boulder and Deloitte, with the goal of translating cutting-edge climate research and data into meaningful climate solutions for businesses, organization, government agencies and communities.

This year three RASEI Fellows were recipients of awards to develop long-term engagements with Deloitte and expand access to critical climate data analytics, research and technology. These projects explore how the renewable energy grid can be built out to offer clean solutions for AI data centers and greater adoption of electric vehicles.

RASEI Fellow Bri-Mathias Hodge is the principal investigator for a project titled “Interconnection Planning for Large Data Centers”. The goal is to develop a system planning tool to automate the initial processes needed for utilities to identify generation expansion, network reinforcement, and asset upgrades to meet the demands of new data centers. This work will help utilities, grid operators, and data center operators to deal with the expansion in the number and energy usage of data centers at the state, regional, and international levels. With the rise of AI, seen as the industrial revolution of the 21^st century, better understanding of how and where to place the data centers that are the engines driving this transformation will be critical.

RASEI Fellow Kyri Baker is the principal investigator for a project titled “Viability of long- and short-duration energy storage for AI Data Centers: Carbon, Cost, and Reliability”. This project combines the benefits of short and long duration energy storage to increase uptime, improve renewable energy utilization, and lower payback periods for AI data centers. By developing an optimization framework for data centers energy storage that leverages price and renewable energy forecasts to co-optimize cost, carbon, and resilience. Creation of a tool that optimizes data energy storage would have significant relevance to commercial and government clients seeking to lower data center consumption.

RASEI Fellow Stephanie Weber is the principal investigator for a project titled “EV Infrastructure and local economic spillovers”. This project seeks to understand both how the construction of public electric vehicle charging infrastructure affects the surrounding areas as well as the tradeoffs associated with prioritizing equity in public charging locations. This will help inform state and national governments in the deployment of EV charging stations, to help incentivize EV adoption, and better understand the non-monetary impact of building EV chargers.

November 2024

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