**4. Discussion**

Transient simulation of nonuniform transmission lines using traditional software (such as ATP in this paper) is a challenging task. This difficulty is due to the fact that the nonuniformities are typically approximated by cascade-connecting several small line segments. Such approximation requires the use of a very small time step in the simulation (at least five times smaller than the traveling time of the line segments [6]), which may translate into excessive simulation times and the saturation of the software's available memory, as was the case in this work. Additionally, the connection of several line segments can introduce errors in the simulation results [2].

In contrast, the proposed method is able to accurately compute transient profiles along nonuniform transmission lines with substantially larger time steps in comparison to ATP, resulting in a better memory usage as expected from the findings reported in [16] with regards to the use of the INLT algorithm. As it can be observed in Figures 7, 10, 11 and 14, the main advantage of the proposed method is the fact that it allows visualizing the voltage and current transient behavior along the line and not only at its ends, which can be advantageous when designing lines with a high level of nonuniformities and cannot be easily done using traditional simulation software.

The precision of the proposed method was validated by comparisons with the results obtained with ATP simulations. In general, there was a very good level of agreemen<sup>t</sup> between the results from both methods, as it can be seen by the mean relative difference presented in Tables 2–4. There is a slight difference in the comparison of results presented in Figure 12 corresponding to the simulation of sequential pole closure. This is attributed to the previously mentioned ATP limitations and the difference in the time step used in each method, which can result in deviations in the operation time of the switch model, leading to the observed variations.

**Table 2.** Mean relative difference of transient voltage in example 3.1.



**Table 3.** Mean relative difference of transient voltage in example 3.2.

**Table 4.** Mean relative difference of transient voltage in example 3.3.

