## 4 Discussion  
The simulation results confirmed the acceptable accuracy of the proposed algorithm. Eight working modes of current and forecasted/estimated load of the Baltic power system were explored in detail. The most accurate combinations of critical lines were determined by using our approach based on the combined list. Since the load level in all eight variants \begin{table}
\begin{tabular}{c c c c c c} \hline Range of relative load & \textgreater{}60\% & \textgreater{}70\% & \textgreater{}80\% & \textgreater{}90\% & \textgreater{}100\% \\ \hline Number of combinations & 1035 & 410 & 48 & 10 & 5 \\ \hline Determined with the Sn & 29 & 13 & 9 & 6 & 3 \\ \hline Determined with the LF & 43 & 17 & 7 & 3 & 3 \\ \hline Determined with the Ratio & 43 & 17 & 7 & 3 & 3 \\ \hline Determined with the combined (10\%) set & 109 & 45 & 13 & 8 & 3 \\ \hline \end{tabular}
\end{table} 
Table 10: Combined (10%) set and individual criteria results based on a system load of 6.5 GW. \begin{table}
\begin{tabular}{c c c c c c} \hline Range of relative load & \textgreater{}60\% & \textgreater{}70\% & \textgreater{}80\% & \textgreater{}90\% & \textgreater{}100\% \\ \hline Number of combinations & 1035 & 410 & 48 & 10 & 5 \\ \hline Determined with the Sn & 130 & 73 & 20 & 7 & 3 \\ \hline Determined with the LF & 372 & 107 & 28 & 8 & 5 \\ \hline Determined with the Ratio & 243 & 98 & 24 & 8 & 5 \\ \hline Determined with the combined (30\%) set & 551 & 243 & 39 & 10 & 5 \\ \hline \end{tabular}
\end{table} 
Table 12: Combined (30%) set and individual criteria results based on a system load of 6.5 GW. \begin{table}
\begin{tabular}{c c c c c c} \hline Range of relative load & \textgreater{}60\% & \textgreater{}70\% & \textgreater{}80\% & \textgreater{}90\% & \textgreater{}100\% \\ \hline Number of combinations & 1035 & 410 & 48 & 10 & 5 \\ \hline Determined with the Sn & 130 & 73 & 20 & 7 & 3 \\ \hline Determined with the LF & 372 & 107 & 28 & 8 & 5 \\ \hline Determined with the Ratio & 243 & 98 & 24 & 8 & 5 \\ \hline Determined with the combined (30\%) set & 551 & 243 & 39 & 10 & 5 \\ \hline \end{tabular}
\end{table} 
Table 11: Combined (20%) set and individual criteria results based on a system load of 6.5 GW. was highly variable, the N-2 simulation results varied accordingly. The maximum load level after the loss of two lines was varying from summer min mode--64.1% (system load 5 GW) to winter max mode--114.8% (system load 6.5 GW). In this study, it was found that the most accurate results were obtained when using the combined (30%) set, but the number of combinations in the case of this list is largest, with on average 905 combinations depending on the duplication of lines. Using this set, 87.5% out of 10 and 75% out of 20 most loaded operational lines were identified correctly. The shorter set--combined (20%) is slightly less accurate--81.5% out of 10 and 68.3% out of 20 most loaded operational lines, but the number of combinations is significantly lower, on average--428. The shortest set--combined (10%) is the most inaccurate, because 40% out of 10 and 27.5% out of 20 most loaded operational lines were identified correctly. When examining individual combinations in more detail, it was found that some power lines appear more than one time on different lists, i.e., disconnection of the mentioned lines has the greatest influence on the overloading of operational lines, which depends on the network topology, generators, and load distribution in the electricity transmission network. Based on the results of our study, the most rational solution (offering the best accuracy to computational demand ratio) is to use a threshold of 20%. The 30% combined lists provide slightly better results, but the number of combinations is two times higher (in comparison to the case of the 20% combined lists), which results in the double calculation time of the contingency combinations. This is especially important for identifying critical power transmission lines when planning daily or hourly work modes.