Department of Civil and Environmental Engineering, Catastrophe Modeling Center, ATLSS Engineering Research Center, Lehigh University, Bethlehem, 18015, USA.
Sci Rep. 2023 Mar 10;13(1):3998. doi: 10.1038/s41598-023-30802-w.
During high wind events with dry weather conditions, electric power systems can be the cause of catastrophic wildfires. In particular, conductor-vegetation contact has been recognized as the major ignition cause of utility-related wildfires. There is a urgent need for accurate wildfire risk analysis in support of operational decision making, such as vegetation management or preventive power shutoffs. This work studies the ignition mechanism caused by transmission conductor swaying out to nearby vegetation and resulting in flashover. Specifically, the studied limit state is defined as the conductor encroaching into prescribed minimum vegetation clearance. The stochastic characteristics of the dynamic displacement response of a multi-span transmission line are derived through efficient spectral analysis in the frequency domain. The encroachment probability at a specified location is estimated by solving a classical first-excursion problem. These problems are often addressed using static-equivalent models. However, the results show that the contribution of random wind buffeting to the conductor dynamic displacement is appreciable under turbulent strong winds. Neglecting this random and dynamic component can lead to an erroneous estimation of the risk of ignition. The forecast duration of the strong wind event is an important parameter to determine the risk of ignition. In addition, the encroachment probability is found highly sensitive to vegetation clearance and wind intensity, which highlights the need of high resolution data for these quantities. The proposed methodology offers a potential avenue for accurate and efficient ignition probability prediction, which is an important step in wildfire risk analysis.
在大风干燥天气事件中，电力系统可能是灾难性野火的原因。特别是，导体-植被接触已被认为是与公用事业相关的野火的主要点火原因。需要进行准确的野火风险分析，以支持运营决策，例如植被管理或预防性停电。这项工作研究了输电导线摆动到附近植被并导致闪络的点火机制。具体来说，所研究的极限状态定义为导体侵入规定的最小植被净空。通过在频域中进行有效的谱分析，推导出多跨输电线路动态位移响应的随机特征。通过求解经典的首次穿越问题来估计指定位置的侵入概率。这些问题通常使用静态等效模型来解决。然而，结果表明，在强风湍流中，随机风冲击对导体动态位移的贡献是相当可观的。忽略此随机和动态分量可能会导致点火风险的错误估计。强风事件的预测持续时间是确定点火风险的重要参数。此外，侵入概率对植被净空和风速强度非常敏感，这突出了这些数量的高分辨率数据的必要性。所提出的方法为准确高效的点火概率预测提供了一种潜在途径，这是野火风险分析的重要步骤。
