Electromagnetic Transient Distributed Parameter Modeling of UHV Transmission Line Lightning Shielding Failure Based on Adaptive Finite Element Method

Abstract

In the existing UHV (Ultra High Voltage) transmission line lightning shielding failure modeling, due to the inability to perform high-precision dynamic grid control on the electromagnetic field mutation area, key physical quantities such as electric field and current density in the transient propagation process have insufficient spatial resolution and error accumulation problems, which affects the model's ability to resolve the shielding failure response in time and space. This paper introduced a posteriori error-driven adaptive finite element modeling method, which embedded the grid error control mechanism into the distributed parameter modeling process of lightning shielding. During the modeling process, the physical field is distributed in the space in the form of a continuous function, and the conductor electrical parameters, field strength vector and charge density are spatially coupled and solved inside each unit, reflecting the continuous propagation characteristics of electromagnetic behavior at the structural scale. Firstly, this paper used the three-dimensional Maxwell equations to establish a multi-conductor transmission channel model, and performs time integration in the Newmark-β format. Secondly, the discrete error distribution is locally calibrated by the residual error estimator. It combines unit encryption with least squares field value projection for adaptive grid adjustment, and finally iteratively solves the transient electric field and current vector distribution in each time step. In the experimental simulation, the adaptive finite element model with a threshold of 1e-4 achieved an accurate analysis of the maximum electric field strength of 550kV/m in the lightning strike area, and the lightning current response at the top of the tower reached a peak of 28.5kA at 0.60μs. The electric field error in the key area of the scheme with an error threshold of 1e-2 dropped from the initial 0.2 to within 0.003, and the total simulation time of the modeling was controlled within 53.0 seconds. The results show that this method significantly optimizes the modeling calculation efficiency and the analytical ability of lightning transient evolution while ensuring physical accuracy, providing a more reliable numerical tool for UHV lightning protection design and evaluation.