Multi-path overvoltage analysis and fault traceability from lightning strikes on box-type transformers in mountainous wind farms

The power collector systems in mountainous wind farms are particularly vulnerable to lightning strike risks due to multiple contributing factors, such as their high altitude, complex terrain configuration, and extensive transmission corridor layout. Box-type transformers, which serve as a critical interface between wind turbines and the power collector system, are susceptible to multiple lightning strike paths and complex electromagnetic phenomena. This inherent complexity presents substantial challenges for the rapid and accurate identification of lightning fault sources. Consequently, there is an urgent need for a comprehensive analysis of lightning overvoltage propagation characteristics under multi-path conditions. This paper first establishes an electrical model for the wind farm power collector system and investigates how variations in system parameters influence its electrical performance. Subsequently, we analyze the overvoltage propagation characteristics of lightning current through three distinct propagation paths. A comparison of these characteristics is conducted, resulting in the proposal of a multi-path feature synthesis criterion for lightning strike traceability. Finally, a simulation based on the actual operation of a wind farm in Hebei is presented to validate the results. The findings reveal the propagation characteristics of lightning overvoltages in box-type transformers under different paths, providing theoretical support for lightning strike traceability and fault analysis.