INDUCED VOLTAGE ON THE OVERHEAD LINE AT OIL EXPLOITING PORT UNDER LIGHTNING STRIKE

In this paper, a computational model is established for the finite-difference time-domain analyses of induced voltage on the overhead line at oil exploiting port under lightning strike. The MTLL approximate formulation is used to simulate the lightning strike, and convolutional perfectly matched layers are used to truncate the computational domain. A two-step method is established to calculate the coupling to the overhead lines to reduce the huge computational domain of the conventional 3-D FDTD simulation. Parallel implementation is introduced for the second-step calculation to overcome the memory storage limit of a single computer. With this model, the electromagnetic field at the adjacent areas and the induced voltage on the overhead line are studied when lightning strikes an oil derrick. It is demonstrated that the electromagnetic field decreases as the distance from the oil derrick increases, but the vertical field decrease much slower than the horizontal field. It is also shown that the transversely located overhead line will introduce lower voltage than the radially located line. As the length of the overhead line increases, the induced voltage increases and the low-frequency induction is strengthened. The overhead line should be set as low as possible to reduce the induced voltage.