Dynamic rating of overhead transmission lines over complex terrain using a large-eddy simulation paradigm

Abstract

Dynamic Line Rating (DLR) enables rating of power line conductors using realtime weather conditions. Conductors are typically operated based on a conservative static rating that assumes worst case weather conditions to avoid line sagging to unsafe levels. Static ratings can cause unnecessary congestion on transmission lines. To address this potential issue, a simulation-based dynamic line rating approach is applied to an area with moderately complex terrain. A micro-scale wind solver-accelerated on multiple graphics processing units (GPUs)-is deployed to compute wind speed and direction in the vicinity of powerlines. The wind solver adopts the large-eddy simulation technique and the immersed boundary method with fine spatial resolutions to improve the accuracy of wind field predictions. Statistical analysis of simulated winds compare favorably against wind data collected at multiple weather stations across the testbed area. The simulation data is then used to compute excess transmission capacity that may not be utilized because of a static rating practice. Our results show that the present multi-GPU accelerated simulation-based approach-supported with transient calculation of conductor temperature with high-order schemes-could be used as a non-intrusive smart-grid technology to increase transmission capacity on existing lines.

Evaluating Implementations of the Immersed Boundary Method in the Weather Research and Forecasting Model

“…While Bao et al 2018did not apply eddy-viscosity reconstruction in their original WRF implementation of VR-IB, the present VR-IB implementation applies this reconstruction. A hybrid RANS/LES scheme proposed by Senocak et al (2007) has been used with VR-IB (Senocak et al 2004;Phillips et al 2017;DeLeon et al 2018), and is therefore included as an option here as well. The hybrid scheme works by blending the grid length scale in Eq.…”

“…Although Bao et al (2018) demonstrated good performance of VR-IB for flat terrain with 30 m horizontal grid spacing, such coarse resolution was not used for a case with more complex terrain. Additionally, Phillips et al (2017) used VR-IB to study flow over complex terrain with horizontal and vertical grid spacings of approximately 30 and 4 m, respectively, for the purpose of improving the rating of power lines. However, there is evidence of poorer performance when coarser grids are used with IB methods (see discussion in Chow et al 2019).…”

“…In this approach, Prandtl's mixing length model is applied near the surface, where the model grid is too coarse to adequately resolve turbulence in the LES sense, and then blended with an LES subgrid model aloft. The hybrid RANS/LES scheme has been used to improve VR-IB performance (Senocak et al 2004;Phillips et al 2017;DeLeon et al 2018), but has not yet been tested in WRF or with SR-IB, and will therefore be explored further in this work.…”

“…IB method performance at the coarser resolutions used by many ABL LES studies (e.g., Talbot et al 2012;Nottrott et al 2014;Mazzaro et al 2017;Phillips et al 2017;Muñoz-Esparza et al 2018). Additionally, WRF and other finite-difference codes have a known dependence on the grid aspect ratio a 5 Dx/Dz (Mirocha et al 2010;Ercolani et al 2017;Arthur et al 2019), so IB method performance is also evaluated over a range of a values.…”

Review of Thermal Stress and Condition Monitoring Technologies for Overhead Transmission Lines: Issues and Challenges

“…The temperature and thermal rating may be different in each span due to different atmospheric conditions although the same current loading flows through the lines. The line rating of the conductor was calculated by using available standards and applying real-time data in [67], [68]. The line rating of the conductor is dependent on weather conditions in specific circumstances.…”