## 6 Conclusions  
In this research an effective heuristic optimization technique called IEPSO was proposed. The aim of this optimization function is to solve three optimization problems. The first problem was to determine optimal DG location. Meanwhile, the second optimization problem was to minimize TPL and VSI with DNR implementation. Finally, the third issue was to get the minimum TPL and better VSI with DNR and DG implementation. Thus, the objective function was formulated to minimize TPL and to improve the VSI. VSI is determined for three load demand levels namely light load, nominal  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Load Levels**} & \multicolumn{4}{c}{**33-Bus System**} & \multicolumn{4}{c}{**69-Bus System**} \\ \cline{2-10}  & \multicolumn{2}{c}{**DNR**} & \multicolumn{2}{c}{**DNR with DG**} & \multicolumn{2}{c}{**DNR with DG**} \\ \cline{2-10}  & **TPL** & **VSI** & **TPL** & **VSI** & **TPL** & **VSI** & **TPL** & **VSI** \\  & **Reduction** & **Improvement** & **Reduction** & **Improvement** & **Reduction** & **Improvement** & **Reduction** & **Improvement** \\  & **(\%)** & **(\%)** & **(\%)** & **(\%)** & **(\%)** & **(\%)** & **(\%)** & **(\%)** & **(\%)** \\ \hline Light Load & 4.16 & 2.62 & 17.98 & 10.34 & 64.69 & 11.34 & 66.19 & 15.54 \\ Nominal Load & 23.26 & 5.21 & 36.33 & 18.16 & 73.06 & 26.14 & 76.28 & 34.39 \\ Heavy Load & 31.36 & 21.14 & 37.73 & 28.22 & 74.95 & 49.03 & 79.26 & 58.41 \\ \hline \hline \end{tabular}
\end{table}
Table 8: Total power losses reduction and VSI improvement for IEPSO technique.  
load, and heavy load with proper optimal DNR and DG sizing. The performance of the proposed technique was compared with other optimization techniques, namely PSO and IPSO. Four case studies on IEEE 33-bus and IEEE 69-bus distribution systems have been conducted to validate the effectiveness of the proposed IEPSO. The optimization results show that, the best achievement is done by IEPSO technique with power losses reduction up to 79.26%, and 58.41% improvement in the voltage stability index. Moreover, IEPSO has the fastest computational time for all load conditions as compared to other algorithms.  
N.F.N., A.F.A.K., E.E.H., M.F.S. and T.K. have done the Methodology, Simulation, Validation, Analysis, and wrote the paper. Conceptualization, N.F.N., A.F.A.K., E.E.H., M.F.S. and T.K.; Methodology, N.F.N., A.F.A.K., E.E.H., M.F.S. and T.K.; Software, N.F.N., A.F.A.K., E.E.H., M.F.S. and T.K., Validation, N.F.N., A.F.A.K., E.E.H., M.F.S. and T.K., and Z.Z.; Formal Analysis, N.F.N., A.F.A.K., E.E.H., M.F.S. and T.K.; Investigation, N.F.N., A.F.A.K., E.E.H., M.F.S. and T.K.; Resources, N.F.N., A.F.A.K., E.E.H., M.F.S. and T.K.; Writing-Original Draft Preparation, N.F.N., A.F.A.K., E.E.H., M.F.S. and T.K.; Writing-Review & Editing, N.F.N., A.F.A.K., E.E.H., M.F.S. and T.K.; Visualization, N.F.N., A.F.A.K., E.E.H., M.F.S. and T.K.; Supervision, N.F.N., A.F.A.K., E.E.H., M.F.S. and T.K.; Project Administration, N.F.N., A.F.A.K., E.E.H., M.F.S. and T.K.; Funding Acquisition, N.F.N., A.F.A.K., E.E.H., M.F.S. and T.K. Funding: This research was partially funded by An-Najah National University and Palestine Ministry of Higher Education grant number ANNU-MoHE-1819-Sc003 and grant number ANNU-1718-Sc0014. Financial support is also received form Palestinian Universities Support Fund, Grant No1458959.  
The authors declare no conflict of interest.