| Transmission & distribution
Dotted red line is solar generation (Caribbean). Horizontal red line is static rating. Purple line is DLR, showing increased acceptable solar generation and therefore reduced curtailment. Source: EDF
One alternative to huge investments in bolstering grid infrastructure by either reconductoring existing transmission corridors or building entirely new transmission lines is to use the existing assets in a smarter, more efficient and effective way with the application of grid enhancing technologies. By deploying novel technology, additional network capacity can often be quickly found at a fraction of the cost.
Grid enhancing, not grid building One of the most attractive grid enhancing technologies is known as dynamic line rating (DLR), which can be used to more accurately establish safety margins for conductors. In many jurisdictions, the capacity margins for any cable span are highly conservative and are based on a worst-case scenario model designed to ensure reliability in all weathers. These margins are based largely on factors such as ambient temperatures. Broadly, the higher the temperature of a conductor the more susceptible it is to sag, which reduces clearance, potentially allowing energised lines to arc and also to come into contact with objects such as trees or vehicles. Such sagging
is particularly significant in the context of solar power given that higher solar irradiation implies both higher ambient temperatures and a simultaneous increase in the power generated. The outcome under conventional static line ratings, which are generally set on a seasonal basis, is that just as solar capacity peaks, the line ratings needed to export that power to end users are falling to a minimum. Instead, with its far more sophisticated approach, DLR can not only take into account the solar radiation and the temperature of the conductor but also other factors, such as the wind, which has a cooling effect. More detailed and granular analysis allows the net outcome of all these cumulative influences to be included to generate a far more accurate assessment of a conductor’s real time condition and thus maintain all safety considerations while still allowing a conductor to potentially carry substantially more power.
Ampacimon, for example, deploys a patented sensor technology to generate accurate data from individual conductors or sections of the network, giving an unprecedented level of detail in real time. Fitted with accelerometers, the sensors are
powered using induction from the conductor current. They measure the wind speed as well as the conductor vibration frequency and by analysis of the vibration spectrum they can be used to accurately estimate the sag and the perpendicular wind speed at the conductor. Wind behaviour is complex and it can be subject to major variation on a micro-terrain basis. However, while even minor errors in estimates of the conditions can potentially have a major impact on power line ratings, by taking a physical measurement on the specific conductor span, accuracy in assessing actual conditions is dramatically improved. These measured data are also coupled with accurate weather forecasting to present an assessment of likely wind characteristics, overall conductor condition and accurate predictions of the capacity for many hours ahead. The probabilistic machine learning methods deployed in the Ampacimon model are used to overcome many of the shortcomings that forecasting models present, especially at low wind speeds. With its accurate forecasting and a wealth of hard data, Ampacimon’s DLR system can allow power lines to transport as much as 40% more power in comparison with operations under the standard static line rating regime.
The real-world benefits of DLR Already widely deployed in Europe and America, in a recent year-long project in Japan, a DLR system from Ampacimon was installed on a transmission line span crossing a large river. This line connected high power photovoltaic facilities and the study observed the behaviour of the currents, conductor temperatures, wind speeds and dynamic ampacities using real time data gathered from the Ampacimon sensors deployed on the conductor. The analysis was conducted over a one-year period and it was confirmed that at no point did the conductor temperature reach the maximum allowable 90°C. At most, the conductor was pushed up to 75°C during the course of the trial while often carrying currents that exceeded the static rating by 100 A. This substantial improvement in carrying capacity was achieved in real time without relying on the predictive elements of the Ampacimon solution and thus delivered a highly accurate method of maximising current carrying capacity.
Sensor installed on a conductor. Source: Ampacimon
Simulations were also performed to assess how much energy the DLR system could save by reducing PV curtailment on the assumption of a gradual increase in the output of PV plants connected to the transmission line. This analysis confirmed that adding an additional 20 MW of PV would result in a total of 40 hours’ worth of curtailment when using DLR. In comparison, relying on the static line rating would result in curtailments for a total of 576 hours. The number of hours of curtailment would therefore be reduced by 93% using real time DLR. Clearly then, a DLR system can significantly increase PV power output by reducing the need for curtailment. Grids usually have more physical capacity available when real world and real time conditions are carefully considered.
www.modernpowersystems.com | March 2026 | 39
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