## 3 Simulation Results and Discussion
### Reconfiguration with DGs
#### 3.2.3 Standard IEEE 119-Bus Distribution System  
The distributed generations at buses of 50, 71, and 109 with the capacities of 2.88, 2.97, and 3.11 MW are proposed to be integrated into the standard IEEE 119-bus distribution system, respectively. The minimum voltages for before and after reconfiguration based on three methods are slightly different (i.e., 0.9545 pu vs. 0.9549 pu). The voltage profiles of the system before and after the reconfiguration are illustrated in Figure 11. However, the power losses are reduced considerably from 666.04 to 620.65 kW (SFS), 617.9 kW (SSOE), and 616.8 kW (MSSOE), respectively. The result in Table 6 shows that the power loss reduction is not much different, however, the time consumption of the proposed method is less compared to the existing method. The computation time of MSSOE is 1.2727 s faster than SSOE as provided in the Table 6. Therefore, distributed generators into the system are the key solution for loss reduction in the power system network.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Items** & **Base Case** & **SFS [30]** & **SSOE [4]** & **MSSOE** \\ \hline \multirow{4}{*}{Tie-switches} & 118,119,120,121, & 23,25,34,39,42,50, & 23,25,34,39,42,50, & 23,26,34,39,42,50, \\  & 122,123,124,125, & 58,71,74,95,97,109, & 58,71,74,95,97,109, & 58,71,74,95,97,109, \\  & 130,131,132 & 121,129,130 & 121,129,130 & 121,129,130 \\ \cline{1-1} Power loss (kW) & 1296.57 & 853.6 & 853.6 & 854.03 \\ \cline{1-1} Loss reduction (\%) & N/A & 34.16 & 34.16 & 34.13 \\ \cline{1-1} \cline{2-2} V\({}_{\min}\) (pu) & 0.8688 & 0.9323 & 0.9323 & 0.9323 \\ \cline{1-1} Voltage node & 77 & 111 & 111 & 111 \\ \cline{1-1} Computation time (s) & N/A & N/A & 4.0328 & 2.5256 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Simulation result of reconfiguration for IEEE 119-bus without DGs.  
Figure 7: Single-line diagram of IEEE 119-bus distribution system.  
Figure 8: Voltage profile of IEEE 119-bus before and after the reconfiguration with DGs.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Items** & **Base Case** & **SFS [30]** & **SSOE [4]** & **MSSOE** \\ \hline \multirow{2}{*}{Tie-switches} & 33,34,35,36,36 & 7,8,32,34,37 & 7,9,27,34,36 & 7,9,27,34,36 \\  & 754 (14), & & & 754 (14), \\ \multirow{2}{*}{\(\mathrm{P_{DGs}}\) in kW (placement)} & 1099.4 (24), & & & \\  & 1071.4 (30) & (24), 1071.4 (30) & (24), 1071.4 (30) & 1099.4 (24), \\ \multirow{2}{*}{Power loss (kW)} & 71.46 & 57.7 & 57.7 & 57.7 \\ \multirow{2}{*}{Loss reduction (\%)} & N/A & 19.25 & 19.25 & 19.25 \\ \multirow{2}{*}{\(\mathrm{V_{min}}\) (pu)} & 0.9687 & 0.9717 & 0.9774 & 0.9774 \\ \multirow{2}{*}{\(\mathrm{V_{Voltage}}\) node} & 33 & 33 & 18 & 18 \\ \multirow{2}{*}{Computation time (s)} & N/A & N/A & 0.2313 & 0.1903 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Simulation result of reconfiguration for IEEE 33-bus with DGs.  
Figure 9: Voltage profile of IEEE 33-bus before and after the reconfiguration with DGs.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Items** & **Base Case** & **SFS [30]** & **SSOE [4]** & **MSSOE** \\ \hline \multirow{2}{*}{Tie-switches} & 69,70,71,72,73 & 13,55,64,69,70 & 13,58,64,69,70 & 13,58,64,69,70 \\  & 526,8 (11), & 526.8 (11), & 526.8 (11), & 526.8 (11), \\ \multirow{2}{*}{\(\mathrm{P_{DGs}}\) in kW (placement)} & 3804 (18), & 3804 (18), & 3804 (18), & 3804 (18), \\  & 1719 (61) & 1719 (61) & 1719 (61) & 1719 (61) \\ \multirow{2}{*}{Power loss (kW)} & 69.40 & 39.64 & 39.64 & 39.64 \\ \multirow{2}{*}{Loss reduction (\%)} & N/A & 42.88 & 42.88 & 42.88 \\ \multirow{2}{*}{\(\mathrm{V_{min}}\) (pu)} & 0.9790 & 0.9693 & 0.9693 & 0.9693 \\ \multirow{2}{*}{Voltage node} & 65 & 64 & 64 & 64 \\ \multirow{2}{*}{Computation time (s)} & N/A & N/A & 0.5104 & 0.3813 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Simulation result of reconfiguration for IEEE 69-bus with DGs.