Rotor blades of large, modern wind turbines are susceptible to lightning strikes. In order to produce a design that resists lightning strikes, it is crucial to simulate lightning current propagation in the blade components. Since the current in the blade is generated by the superposition of potential and induced electric fields, a coupling exists between electric and magnetic fields which need to be calculated by an imposed integral constraint at each time step. Commercial software packages can deal with such constraints, but it results in time-consuming computations. Therefore, this work aims to develop a numerical methodology able to compute the voltage which drives the lightning current through the structure. In this way, the problem is reformulated as a voltage-driven one which in turn allows a simple subsequent coupling of electrical and magnetic problems. The computation of the voltage waveform was accomplished using the fast Fourier transform and the finite element method (FEM) to compute the structure impedance in the frequency domain. The developed procedure showed high efficiency for a blade subjected to different lightning impulses. It allows a description of the time-dependent lightning current to be given, as well as the distribution of current within the blade conductors.

中文翻译：

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使用傅里叶变换和有限元方法计算风力涡轮机叶片中雷电流分布的有效方法

大型现代风力涡轮机的转子叶片容易遭受雷击。为了产生抗雷击的设计，至关重要的是模拟雷电电流在叶片组件中的传播。由于叶片中的电流是由电势和感应电场的叠加产生的，因此在电场和磁场之间存在耦合，需要在每个时间步长施加积分约束来计算这些耦合。商业软件包可以处理此类约束，但是这会导致耗时的计算。因此，这项工作旨在开发一种数值方法，能够计算驱动雷电流通过结构的电压。通过这种方式，该问题被重新表述为电压驱动的问题，而电压驱动的问题又允许随后简单的电磁问题耦合。电压波形的计算是使用快速傅立叶变换和有限元方法（FEM）在频域中计算结构阻抗来完成的。对于受到不同雷电冲击的叶片，开发的程序显示出很高的效率。它允许描述随时间变化的雷电流，以及叶片导体内电流的分布。对于受到不同雷电冲击的叶片，开发的程序显示出很高的效率。它允许描述随时间变化的雷电流，以及叶片导体内电流的分布。对于受到不同雷电冲击的叶片，开发的程序显示出很高的效率。它允许描述随时间变化的雷电流，以及叶片导体内电流的分布。