New framework identifies true heatwave-caused grid faults, debunks overestimation

A new academic paper from Andrea Mazza and Haoke Wu, published on arXiv (2606.31210), tackles a critical problem for urban power grids: how to tell which summer faults are truly caused by heatwaves versus those from ageing, mechanical defects, soil contamination, or operational constraints. Indiscriminately blaming heatwaves overestimates system vulnerability and leads to poor asset management decisions. The authors propose a systematic framework using the Excess Heat Factor index to characterize heatwave events, then apply a covariance-based attribution criterion to statistically separate faults due to thermal stress from independent causes. A time-delay model further estimates the lag between heatwave onset and fault occurrence by maximizing normalized covariance between hourly temperature and shifted fault-duration series.

Applied to six years of operational data from a real medium-voltage distribution network, the results show that due-to-heatwave faults constitute a significant but variable proportion of total summer faults, underscoring the non-negligible impact of heatwaves on grid reliability. The analysis also confirms that time-between-failures distributions depart significantly from the exponential assumption, which has direct implications for the applicability of Poisson-based reliability models in systems subject to recurrent heatwave stress. This work provides utilities with a data-driven method to more accurately attribute fault causes, enabling targeted investments in grid hardening and maintenance.