Jae‐bok Lee, Jun Zou, Mo Li and Sughun Chang
A fast algorithm is proposed to calculate the lightning electromagnetic field over a perfectly conducting earth surface.
Abstract
Purpose
A fast algorithm is proposed to calculate the lightning electromagnetic field over a perfectly conducting earth surface.
Design/methodology/approach
The channel base current is approximated by a number of sub‐domain quadratic functions using the proposed adaptive sampling technique, and the derivative and integral of the channel base current with respect to time can be analytically expressed. With the help of these approximations, the ideal electromagnetic field of the lightning channel can be evaluated along the lightning channel with respect to the height.
Findings
The computational time can be greatly reduced using the proposed approach to evaluate the electromagnetic field of a lightning channel in the time domain.
Originality/value
The adaptive sampling technique is a general‐purposed approach, which can be potentially used in other applications to fit a function with the minimal number of intervals.
Details
Keywords
Jun Zou, Chenglong Zhou, Wenwen Li, Jae-bok Lee and Sughun Chang
The electromagnetic field radiated from a lightning channel is the excitation for analyzing the field-to-transmission line coupling problem. The purpose of this paper is to…
Abstract
Purpose
The electromagnetic field radiated from a lightning channel is the excitation for analyzing the field-to-transmission line coupling problem. The purpose of this paper is to propose a novel efficient approach to evaluate the horizontal electric field of the lightning channel expressed by the generalized Sommerfeld integral.
Design/methodology/approach
The asymptotic integral is extracted from the original one, which actually makes the Sommerfeld integral tail reach its convergence very quickly. To handle the sharp variance around k0, a closed-form integral, which is obtained by replacing the original kernel with an approximated function, is presented in detail. The numerical examples validated the proposed approach in the both frequency and time domain.
Findings
The approach proposed in this paper has been validated by the comparison with results in other papers. The agreement among these results reaches very well, and the approach proposed in this paper is more efficient and easy to implement, especially for the calculation of the tail integral part.
Originality/value
In accordance with the numerical experiments, the proposed approach can be served as a qualified candidate in terms of computational efficiency to evaluate the electromagnetic field generated by the lightning channel.
Details
Keywords
Jun Zou, Jae‐bok Lee, JunJie Li and Sughun Chang
The purpose of this paper is to present an original iterative nodal approach to calculate the fault current distribution on overhead lines.
Abstract
Purpose
The purpose of this paper is to present an original iterative nodal approach to calculate the fault current distribution on overhead lines.
Design/methodology/approach
By changing the mutual couplings among different conductors into the equivalent voltage sources, node voltages are updated iteratively by using conventional nodal analysis with those additional sources until the convergence is achieved.
Findings
The proposed algorithm can handle the complicated topology of a power transmission line and has no difficulties in taking all physical couplings into account. The fault current distribution calculated by this method is in good agreement with those published in the literature. Although the proposed approach is iterative, the CPU time needed is still reasonable compared to the direct solution approach. The memory requirement is low because the coefficient matrix is highly sparse for the nodal analysis of each iteration loop.
Originality/value
The proposed approach can serve as an alternative in calculating the fault current because of its efficiency and ease of implementation.