On the Effect of Blade Angle on Lightning Strikes to Wind Turbine Blades: Characteristic Impedance and Electrical Parameters

Voltage waves generated by lightning strikes to wind turbines' rotating blades depend on many factors, including the lightning current and the characteristic impedance of the blade stricken by the lightning. Although lightning is more likely to strike a full vertical blade, since the blades are rotating, it may also strike a non-vertical one. In this paper, a formulation for the calculation of the characteristic impedance of slanting conductors is analytically derived and verified based on the experimental data. Then, the electrical parameters of wind turbine blades, as nonuniform transmission lines, are accurately calculated. Numerical studies demonstrated that the blade angle's effect is reduced by increasing the height of the wind turbine.