Impact of Lightning Strike Waveform and Position on Transient Overvoltage in a 500 kV HVAC System

Lightning overvoltage is a major threat to the reliability of power supply in electrical systems. Standard lightning current impulses, such as <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{8}/\mathbf{20}\boldsymbol{\mu}\mathbf{s}$</tex>, are typically used to analyze the system's overvoltage responses, for insulation coordination design of power systems. However, the waveforms of real lightning currents exhibit considerable randomness, resulting in variations of lightning overvoltage induced in the system. In this connection, this paper investigates the lightning overvoltage in a typical 500kV AC power system. By establishing a transient overvoltage simulation model, the transient lightning overvoltage in case of different lightning strike locations and waveforms are studied, the impacts of different factors on the intensity of lightning overvoltage under both shielding failure and back-flashover conditions are obtained. These conclusions are of great significance for elucidating the propagation mechanism of lightning overvoltage in power systems and improving the reliability of power supply.