Independent System Operators (ISOs) emerged from FERC orders 888 and 889, envisioned as a means of providing open access to the US power transmission network while fostering competition within the wholesale electricity generation market. Each of the ISOs manages competitive bid-based energy and ancillary services markets to determine the most economical energy for dispatch to consumers. Resilience and reliability are also critical considerations for the ISOs, ensuring the network can meet the energy requirements of consumers; however, the cost of delivering this service is another key factor. ISOs guide network investment that not only improves reliability but also enables electricity markets to work as designed, with system upgrades typically selected on the grounds of allowing the ISO to dispatch the most economic energy resources.
While this overarching series of priorities have been in place since the 1990s, there are fundamental forces at play that are changing how these drivers are managed now and in the future. Today, ISOs are facing unprecedented challenges in their operations due to a range of converging factors.
The integration of new distributed renewable generation and the electrification of end-use sectors are creating challenges for ISO operations. For example, one of the biggest recent trends is the increase in the electrification of industry and transportation, including electric vehicles (EVs), electrified heating and cooling, and new growth industries such as data centers and the use of AI, which add significant sources of new demand. There is also evidence of an increasing frequency of extreme weather events and incidents, such as wildfires, that inevitably impact reliability. Late last year, for example, the 18 month-long Interregional Transfer Capability Study (ITCS) by the North American Electric Reliability Corporation (NERC) concluded that the North American system is not only vulnerable to extreme weather but that an additional 35 GW of transfer capability is recommended to reduce the likelihood of energy deficits during extreme conditions. The result of these diverse influences is a renewed focus on grid resilience such that the transmission system can remain reliable even in the face of changing electricity system fundamentals. As a result, many forecasts indicate a worldwide need for huge investments in transmission and distribution assets.
While traditional grid reinforcement remains a cornerstone of long-term planning, escalating capital costs and decade-long lead times necessitate the adoption of more agile, data-driven solutions.
Between 2003 and 2023, U.S. transmission investment nearly tripled, reaching over $27 billion. In 2023 alone, capital investment rose by $2.7 billion, an 11% increase, driven largely by resilience-focused upgrades. However, while at face value the solution to these resilience challenges is to ramp up grid investments, ISOs, and through them the local utilities that are ultimately responsible for grid enhancements, always face issues in allocating limited investment resources to fund all the required grid infrastructure. Developing new assets is not only expensive but it is slow too. It can take a decade or more to gain relevant approvals, secure investment funding, build and commission a new transmission line for example.
These issues are prompting ISOs to seek alternatives that maximise the utility of existing assets.
Transmission grids often have greater capacity than it seems, due to old legacy rules that set the maximum transmission limits. A key factor that can restrict conductor capacity is the line temperature and related factors such as sag, which influences clearance requirements. Excessive temperatures beyond the manufacturer’s specified limits can damage the conductor. Additionally, higher temperatures can cause increased sag between pylons or poles, which may lead to safety hasards and even cause fires if the lines contact tree branches, for example.
While higher ambient temperatures tend to reduce the available transmission capacity, higher wind speeds, which have a cooling effect, can support extra power capacity. However, conventional conductor capacity ratings are based on established safety margins that are historically derived from a conservative approach which considers the worst-case scenario. These safety margins are commonly determined on a broadly seasonal basis using static assumptions on temperature and wind conditions, but which actually bear little resemblance to the true condition of any individual conductor. When combined with accurate weather forecasts and factoring in ambient conditions, a far more accurate rating can be determined though by understanding the actual conditions of a conductor.
Dynamic Line Rating (DLR) is a leading Grid Enhancing Technology (GET) that enables real-time optimisation of transmission capacity. By continuously monitoring conductor temperature, sag, and wind speed, DLR systems calculate actual ampacity under prevailing ambient conditions. This allows operators to apply emergency ratings during post-contingency events, defer capital-intensive upgrades, and alleviate congestion, all while maintaining NERC reliability standards.
Unlike static seasonal ratings DLR reflects the true thermal state of the conductor. This unlocks latent capacity and supports more efficient dispatch of generation resources. Deployment timelines are also significantly shorter: while new transmission lines can take over a decade to complete, DLR systems can be installed and operational in under three months.
Ampacimon’s DLR platform exemplifies this approach. It integrates patented sensor technology with AI-driven analytics and meteorological forecasting to deliver up to 40% additional capacity on existing lines. The system includes autonomous fallback logic to maintain operational continuity in the event of sensor or communication failures. In 2024, Basin Electric Power Cooperative deployed Ampacimon’s DLR on a 75-mile 230 kV line, avoiding the need for a new build and redirecting capital to higher-priority projects.
As Jeremy Severson, Vice President of Transmission at Basin Electric, noted: “The goal is to fully utilise the capability of the transmission system we have in place, maintain reliability, and to minimise congestion on our grid. The utilisation of that existing capacity ultimately helps keep costs low”.
Further value is unlocked through seamless integration with Ambient Adjusted Ratings (AAR) and facility rating systems. These tools provide operators with full-system visibility and real-time capacity insights, enabling faster, more accurate operational decisions and enhancing situational awareness across the network.
DLR is not merely a tactical enhancement, it is a strategic enabler. It supports deferred investment, enhances grid utilisation, and strengthens resilience planning. For ISOs, DLR and complementary technologies represent a scalable, cost-effective, and technically robust pathway to modernising the grid while advancing decarbonisation and protecting ratepayers.
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