A Novel Inversion Method for Lightning Transient Current in Wind Turbine Tower Based on Biaxial Magnetic Field Sensor Array

Measuring the lightning current in the wind turbine tower can help analyze lightning accidents and propose fault prevention strategies. However, due to the large size of the wind turbine tower, the current measurement methods, such as the Rogowski coil and the fiber optic measurement, require the coil to encircle the conductor, which is inconvenient for installation. This article presents a novel method for the lightning current inversion in the wind turbine tower based on the biaxial magnetic field sensor array (BMFSA), which has the advantages of a simple structure, convenient installation, and high measurement accuracy. The wind turbine tower can be considered as a long, straight conductor. According to the Biot-Savart law, the lightning current waveform flowing through the tower can be inverted by the magnetic field waveform. A simulation model of the lightning-struck wind turbine is established. Through this model, the transient magnetic field is acquired, and the optimal installation position of the BMFSA is determined. The feasibility of the inversion method is verified by comparing the results of the inversion current and the simulated current. Furthermore, a coreless BMFSA based on tunnel magnetoresistive (TMR) sensors was developed, and the lightning current measurement verification was conducted using a 1:50 scaled wind turbine model. The experimental results show that the inverted lightning current in the wind turbine tower is basically consistent with the actual measurement results. The measuring relative error is less than 6.08% when the deviation between the center of the TMR sensor and the center of the tower section in the X-and Y-axis directions is kept within +/- 15 mm.