Array Coil Design and Experimental Verification for Separation of Tower Grounding Pulsed Eddy Current Excitation and Response Magnetic Field Signals

Transmission line towers play an important role in power transmission, and the assessment of transmission line tower grounding by pulsed eddy current detection technology is conducive to the safe and reliable operation of power transmission. Aiming at the problem that the primary and secondary magnetic fields of the traditional pulsed eddy current transmitting coil structure overlap, resulting in the loss of shallow information, this paper first discusses the loss of shallow information caused by the aliasing of the magnetic field under the non-zero current shutdown effect, and then analyzes the traditional weak magnetic field coupling separation principle, and proposes the array coil structure of this paper based on the magnetic field vector destructive separation principle. Subsequently, the corresponding finite element simulation model was established, and the magnetic field distribution, magnetic field size, induced voltage, and mutual inductance coefficient of the array coil and the traditional center loop structure at the receiving coil were compared in the static field. In the transient field, the response signal of the array coil structure with or without the grounding body and the receiving coil is equidistant was simulated. The simulation results show that, under the same excitation, the vector coil array structure can greatly reduce the mutual inductance coefficient between the excitation and transmitting coils, reduce the influence of the primary magnetic field of the excitation coil on the receiving coil, and avoid the loss of shallow information. Finally, experimental tests were carried out on different tower grounding bodies. The experimental results at different measuring points prove that the array coil structure proposed in this paper can separate well the magnetic field generated by the excitation signal, improve the effective resolution time, avoid the loss of shallow information, and improve the operational stability of power transmission systems.