Analysis of Transmission Lines With Arrester Termination, Considering the Frequency-Dependence of Grounding Systems

The paper proposes a modeling technique to analyze the response of a transmission line terminated by a lightning arrester connected to a grounding system buried in a lossy ground. In this technique, the transmission line is modeled in the frequency domain with the aid of Baum-Liu-Tesche equations, while the grounding system to which the arrester is connected is treated using a general electromagnetic approach. The electromagnetic approach is based on the solutions to Maxwell´s equations obtained by using the method of moment in the frequency domain. The arrester nonlinearity is included in the frequency-domain analysis using the arithmetic operator method. To examine the performance of the proposed modeling technique, numerical results are presented for a single-conductor transmission line connected to a typical lightning arrester. The results are first compared for a simple grounding configuration of a vertical rod with those obtained using the well-known electromagnetic transient program, showing the validity of the proposed technique. The generality of the technique is then demonstrated by studying the results of a more complex case of a typical grounding grid. It is shown that the early time responses of the lightning overvoltages are affected by the harmonic impedance of the grounding system.