Calculation of Lightning-Induced Overvoltages on Overhead Lines Based on DEPACT Macromodel Using Circuit Simulation Software

One of the simple and accurate methods for calculating the lightning-induced overvoltages is based on the Agrawal et al. held-to-wire model, in which the coupling mechanisms are presented by distributed voltage sources along the lines. There is a difficulty in calculating the lightning-induced overvoltages with the built-in transmission line models or other circuit elements of various circuit simulation software such as the PSCAD/EMTDC, EMTP/ATP, PSpice, etc., as the distributed voltage sources due to the horizontal component of the electric held caused by the lightning channel are in series with the line and not in between two transmission-line segments. In this paper, a simple circuit approach for efficient calculation of the lightning-induced overvoltages using the circuit simulation software is proposed. The delay extraction passive compact circuit (DEPACT) macromodel is applied and the transmission line is divided into a cascade of DEPACT subnetworks which can be represented by a cascade of two lossless transmission lines and a lossy network. By assuming the incident held only couples with the lossless transmission line sections, the distributed equivalent voltage sources due to the horizontal component of the incident electric held can be lumped at the termination of the lines, which makes it convenient for the engineering technologist to calculate the lightning-induced overvoltages in various circuit simulation software. Furthermore, in order to treat the nonlinear element such as metal oxide arrester (MOA) directly, the DEPACT macromodel is improved and the macromodel of multiconductor transmission lines excited by the external electromagnetic held can be solved in the actual phase domain instead of in the modal domain. Compared with the existing method for calculating the lightning-induced overvoltages, the benefit of the proposed algorithm is that it can be used to calculate the transients of the transmission line more efficiently. Considering the PSCAD/EMTDC is a powerful simulation software which providing lots of equipment models in power system, such as transformer, generator, and protection modules et al., an implementation procedure in the PSCAD/EMTDC is provided in this paper, which makes it more convenient for the electrical engineering technologists to analyze the lightning-induced overvoltages problems in the power system. Several numerical calculations of the line transient responses are provided and the CPU time is compared, which indicate the validity and efficiency of the algorithm proposed in the paper. At last, this algorithm is applied to analyze the influence of the ground wire and the MOA on the lightning-induced overvoltages of the overhead lines.