## 5 Results and Discussion
### Results of 33-Bus Radial Distribution System
Meanwhile, for nominal load IEPSO technique gave the most reduction with 36.33% in TPL, 18.16% highest VSI, but slightly defeated for the computational time compared to IPSO by 4.45 s in nominal load level. Finally, for heavy load IEPSO technique gave also the most reduction with 37.73% in TPL, 28.22% highest VSI, the fastest in computational time in heavy load compared to other techniques. As for system's stability, Figures 5 and 6 show some improvement in the stability for all cases, especially with proposed algorithm application on 33-bus test system. Generally, by increasing the load levels, the VSI will decreases. Thus, the stability of the system which leads to voltage collapse form the load demands increase. For comparison purposes, Figure 7 shows a comparison of TPL and VSI for three cases which are base case, DNR without DG and DNR with DG for light, nominal and heavy load condition in 33-bus system. From the figures, it is shown that TPL is slightly reduced with DNR implementation. However, the TPL has a significant reduced when DNR and DG was applied to the system. Moreover, the VSI also improved when DNR and DG are implemented optimally in the system. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Load Levels**} & \multirow{2}{*}{**Parameters**} & \multicolumn{3}{c}{**DNR**} \\ \cline{3-5}  & & **Case 2: PSO** & **Case 3: IPSO** & **Case 4: IEPSO** \\ \hline \multirow{7}{*}{Light Load} & Switches & 8, 3, 10, 22, 14 & 9, 28, 16, 33, 34 & 33, 28, 34, 16, 9 \\  & DG sizing (MW) & 1.0139 & 1.0147 & 1.0087 \\  & TPL (kW) & 39.1 & 38.9 & 38.6 \\  & VSI min & 0.9239 & 0.9316 & 0.9316 \\  & Voltage profile min (p.u.) & 0.9688 & 0.9824 & 0.9824 \\  & Computational time (s) & 14.246903 & 2.682595 & 2.191424 \\ \hline \multirow{7}{*}{Nominal Load} & Switches & 7, 15, 10, 33, 27 & 15, 8, 28, 7, 11 & 10, 33, 25, 3, 22 \\  & DG sizing (MW) & 1.1368 & 1.1162 & 1.1290 \\  & TPL (kW) & 145.1 & 131.3 & 129.0 \\  & VSI min & 0.7861 & 0.8133 & 0.8236 \\  & Voltage profile min (p.u.) & 0.9398 & 0.9497 & 0.9527 \\  & Computational time (s) & 25.102418 & 2.183219 & 6.634950 \\ \hline \multirow{7}{*}{Heavy Load} & Switches & 28, 7, 33, 9, 31 & 12, 15, 28, 8, 6 & 33, 13, 27, 7, 16 \\  & DG sizing (MW) & 1.0041 & 1.0138 & 1.0363 \\ \cline{1-1}  & TPL (kW) & 384.5 & 309.8 & 309.00 \\ \cline{1-1}  & VSI min & 0.6687 & 0.6828 & 0.7159 \\ \cline{1-1}  & Voltage profile min (p.u.) & 0.9015 & 0.9092 & 0.9200 \\ \cline{1-1}  & Computational time (s) & 10.980474 & 2.337904 & 2.254589 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: The performance of PSO, IPSO and IEPSO for DNR with DG sizing implementation in 33-bus radial distribution system. In addition, it is observed that during light load of 33-bus test system, the total power loss obtained from the PSO algorithm (case 2) with DG is 39.1 kW as compared to 45.9 kW without DG resulted to 14.45% TPL reduction. The VSI without DG is 0.8622 which is improved to be 0.9239 p.u. with DG integration. For IPSO algorithm (case 3), the total power loss is 38.9 kW with DG compared to 45.4 kW without DG with 6.5 kW differences, with 13.81% TPL reduction. The VSI without DG is 0.8657 which is improved to be 0.9316 with DG integration. Finally, For IEPSO algorithm (case 4), the total power loss is 38.6 kW with DG compared to 45.1 kW without DG with 6.5 kW differences, with 13.81% TPL reduction. The VSI without DG is only 0.8664 and enhanced to e 0.9316 with DG integration. Figure 5: Voltage stability index for different load levels for DNR in 33-bus test system. Figure 6: Voltage stability index for different load levels for DNR with DG in 33-bus test system. Figure 7: Total power losses and VSI min for DNR without and with DG at light load in 33-bus test system. Similarly, it is observed that at nominal load in 33-bus test system, the total power loss obtained from the PSO algorithm (case 2) with DG is 145.1 kW compared to 167 kW without DG with 22 kW differences, resulted to 10.86% TPL reduction.