## 5 Results and Discussion
### Results of 33-Bus Radial Distribution 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{4}{*}{Light Load} & Switches & 28, 7, 10, 17, 33 & 24, 10, 18, 8, 7 & 7, 12, 10, 31, 26 \\  & TPL (kW) & 45.9 & 45.4 & 45.1 \\  & VSI min & 0.8622 & 0.8657 & 0.8664 \\  & Voltage profile (p.u.) & 0.9636 & 0.9646 & 0.9646 \\  & Computational time (s) & 30.044280 & 4.545669 & 2.055129 \\ \hline \multirow{4}{*}{Nominal Load} & Switches & 7, 33, 34, 28, 14 & 28, 15, 33, 8, 34 & 9, 13, 33, 6, 26 \\  & TPL (kW) & 167.10 & 158.80 & 155.50 \\  & VSI min & 0.7181 & 0.7216 & 0.7333 \\  & Voltage profile (p.u.) & 0.9206 & 0.9217 & 0.9254 \\  & Computational time (s) & 19.630266 & 1.516081 & 2.216311 \\ \hline \multirow{4}{*}{Heavy Load} & Switches & 33, 10, 7, 21, 28 & 14, 33, 29, 28 & 33, 11, 34, 28, 32 \\  & TPL (kW) & 391.00 & 342.9 & 340.6 \\ \cline{1-1}  & VSI min & 0.6618 & 0.6718 & 0.6763 \\ \cline{1-1}  & Voltage profile (p.u.) & 0.9020 & 0.9054 & 0.9069 \\ \cline{1-1}  & Computational time (s) & 14.352825 & 4.281991 & 3.445760 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Base case at different load conditions for 33-bus 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{4}{*}{Light Load} & Switches & 28, 7, 10, 17, 33 & 24, 10, 18, 8, 7 & 7, 12, 10, 31, 26 \\  & TPL (kW) & 45.9 & 45.4 & 45.1 \\ \cline{1-1}  & VSI min & 0.8622 & 0.8657 & 0.8664 \\ \cline{1-1}  & Voltage profile (p.u.) & 0.9636 & 0.9646 & 0.9646 \\ \cline{1-1}  & Computational time (s) & 30.044280 & 4.545669 & 2.055129 \\ \hline \multirow{4}{*}{Nominal Load} & Switches & 7, 33, 34, 28, 14 & 28, 15, 33, 8, 34 & 9, 13, 33, 6, 26 \\ \cline{1-1}  & TPL (kW) & 167.10 & 158.80 & 155.50 \\ \cline{1-1}  & VSI min & 0.7181 & 0.7216 & 0.7333 \\ \cline{1-1}  & Voltage profile (p.u.) & 0.9206 & 0.9217 & 0.9254 \\ \cline{1-1}  & Computational time (s) & 19.630266 & 1.516081 & 2.216311 \\ \hline \multirow{4}{*}{Heavy Load} & Switches & 33, 10, 7, 21, 28 & 14, 33, 29, 28 & 33, 11, 34, 28, 32 \\ \cline{1-1}  & TPL (kW) & 391.00 & 342.9 & 340.6 \\ \cline{1-1}  & VSI min & 0.6618 & 0.6718 & 0.6763 \\ \cline{1-1}  & Voltage profile (p.u.) & 0.9020 & 0.9054 & 0.9069 \\ \cline{1-1}  & Computational time (s) & 14.352825 & 4.281991 & 3.445760 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The performance of particle swarm optimization (PSO), improved particle swarm optimization (IPSO) and IEPSO for DNR implementation in 33-bus radial distribution system. In addition to that, tor nominal load, IEPSO technique also gave the most reduction with 23.26% in TPL, 5.21% highest VSI, but slightly defeated in computational time compared to IPSO by 0.7 s in nominal load. Finally, for heavy load, IEPSO technique gave the most reduction with 31.36% in TPL, 21.14% highest VSI, the fastest in computational time in heavy load compared to other techniques. As for the DNR with DG placement case, Table 4 summarizes the performances of three optimization techniques in DNR with DG sizing simultaneously for switches, TPL, VSI, voltage profile, DG sizing and computational time at three different load levels. As noted from Table 4, the IEPSO technique gives the best optimal solution with the lowest power losses, improved VSI and computational time as indicated in bold for all load conditions. The increased in load levels, gave results in increasing power losses and decreasing VSI. For light load, IEPSO technique gave the most reduction with 17.98% in TPL, 10.34% highest VSI, the fastest in computational time in light load compared to other techniques.