Hourly Dynamic Line Ratings for Existing Transmission Across the Contiguous United States (Preliminary)

This dataset provides estimated hourly dynamic line ratings for ~84,000 transmission lines across the contiguous United States from 2007-2013. The calculation methods are described in the presentation linked below, and the associated open-source Python code repository is linked in the Resources section below.

Abbreviations used in filenames and descriptions are:
- SLR: static line ratings
- ALR: ambient-temperature-adjusted line ratings
- NLR: ambient-temperature- and day/night-irradiance-adjusted line ratings
- CLR: ambient-temperature- and clear-sky-irradiance-adjusted line ratings
- ILR: ambient-temperature- and measured-irradiance-adjusted line ratings
- DLR: full dynamic line ratings (including air temperature/pressure, wind speed/direction, and measured irradiance)

Transmission lines are referenced by their ID in the Homeland Infrastructure Foundation-Level Data (HIFLD) on Transmission Lines (linked in Resources section). Time indices are in UTC. The data files contain ratios between modeled hourly ratings and modeled static ratings. Columns are indexed by HIFLD ID; rows are indexed by hourly timestamps from 2007-2013 (UTC). A data directory is also included in the Resources section.

The SLR files contain modeled static ratings (the denominator of the ratios in the files described above) in amps. As described in the presentation linked in the Resources section below, SLR calculations assume an ambient air temperature of 40 C, air pressure of 101 kPa, wind speed of 2 feet per second (0.61 m/s) perpendicular to the conductor, global horizontal irradiance of 1000 W/m^2, and conductor absorptivity and emissivity of 0.8. Conductor assumptions are Linnet for ~69 kV and below, Condor for ~115 kV, Martin for ~230 kV, and Cardinal for ~345 kV and above.

Caveats and Limitations
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Results are sensitive to the weather data used. Validation studies on the WIND Toolkit and NSRDB are available at:
- King, J. et al. "Validation of Power Output for the WIND Toolkit", 2014 (https://www.nrel.gov/docs/fy14osti/61714.pdf)
- Draxl, C. et al. "Overview and Meteorological Validation of the Wind Integration National Dataset Toolkit", 2015 (https://www.nrel.gov/docs/fy15osti/61740.pdf)
- Sengupta, M. et al. "Validation of the National Solar Radiation Database (NSRDB) (2005-2012)", 2015 (https://www.nrel.gov/docs/fy15osti/64981.pdf)
- Habte, A. et al. "Evaluation of the National Solar Radiation Database (NSRDB Version 2): 1998-2015", 2017 (https://www.nrel.gov/docs/fy17osti/67722.pdf)

More work is required to determine how well ratings calculated from NSRDB and WIND Toolkit data reflect the actual ratings observed by installed sensors (such as sag or tension monitors). In general, ratings calculated from modeled weather data are not a substitute for direct sensor data.

Assuming a single representative conductor type (ACSR of a single diameter) for each voltage level is an important simplification; reported line ratings at a given voltage level can vary widely.

HIFLD line routes are primarily based on imagery instead of exact construction data and may have errors.

We use historical weather data directly; calculated line ratings are thus more indicative of real-time ratings than forecasted ratings

本数据集提供了2007至2013年间美国大陆约84,000条输电线路的每小时动态线评级估计值。计算方法详述于下述链接的演示文稿中，相关开源Python代码库可在下述资源部分找到。

文件名和描述中使用的缩写如下：
- SLR：静态线评级
- ALR：环境温度调整后的线评级
- NLR：环境温度、昼夜辐照度调整后的线评级
- CLR：环境温度、晴空辐照度调整后的线评级
- ILR：环境温度、实测辐照度调整后的线评级
- DLR：完整动态线评级（包括空气温度/压力、风速/风向以及实测辐照度）

输电线路通过其在Homeland Infrastructure Foundation-Level Data（HIFLD）中的ID进行引用，位于输电线路部分（下述资源部分提供链接）。时间索引采用协调世界时（UTC）。数据文件包含模拟每小时评级与模拟静态评级之间的比率。列索引由HIFLD ID决定；行索引由2007至2013年（UTC）的每小时时间戳决定。在资源部分还包含一个数据目录。

SLR文件包含模拟静态评级（上述文件中比率的分母），单位为安培。如资源部分下述链接的演示文稿所述，SLR的计算假设环境空气温度为40摄氏度，空气压力为101千帕，风速为每秒2英尺（0.61米/秒），垂直于导体，全球水平辐照度为1000瓦/平方米，导体吸收率和发射率为0.8。导体假设为：约69千伏及以下为Linnet，约115千伏为Condor，约230千伏为Martin，约345千伏及以上为Cardinal。

注意事项与局限性：
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结果对所使用的气象数据敏感。关于WIND Toolkit和NSRDB的验证研究可在以下文献中找到：
- King, J. 等人. "WIND Toolkit功率输出的验证