## 5 Results and Discussion
### Results of 33-Bus Radial Distribution System  
The 33-bus radial distribution system consists of a feeder, 5 tie switches. The total nominal load of this system is 3715 kW and 2300 kVAr. On the other hand, the 69-bus radial distribution system consists of a feeder and involves 5 tie switches. The total nominal load system is 3802 kW and 2695 kVAr. Both systems MVA base has a base power constant, \(S_{base}\) of 100 MVA and base voltage \(V_{base}\) of 12.66 kV. The maximum active output of DG in this study is set at 50% of the connected load. The size of a population for test systems is assumed to be 20, while, the convergence value is taken as 0.0001. The analysis of the results has been divided into three main parts, which are: (i) determination of DG location; (ii) minimization of total power losses (TPL) and VSI improvement with DNR implementation; and (iii) minimization of TPL and VSI improvement with DNR and DG implementation. Three situations have been considered in this study, which are base case, DNR, and DNR with DG. Three load levels are classified into; light, nominal and heavy load in order to evaluate the performance of TPL and VSI respectively. Each situation except for base case has been analyzed among PSO, IPSO and IEPSO algorithms. Initially, the DG location has been set up according to the bus with minimum VSI. The minimum VSI means the most sensitive probability to voltage collapse. The DG is assumed to operate in PQ mode, where the power output is constant. Then, the stability index, \(L\) is calculated to verify the results obtained as shown in Table 1.  
Figure 4: Overall process for distribution network reconfiguration (DNR) and DG sizing. In this research, there are three categories to be analyzed namely base case, DNR and DNR with DG sizing. The analysis is discussed according to three identified load levels as light, nominal and heavy load. Thus, the performances are evaluated among case 1 (base case), case 2 (PSO), case 3 (IPSO) and case 4 (IEPSO). Table 2 shows base case results without reconfiguration and DG placement (case 1). From the table, the VSI values are inversely proportional with TPL for each possibility load levels. In other words, by increasing the load levels, the total loss has significantly increased and the stability is decreased. On the other hand, Table 3 summarizes the performance of three optimization techniques for DNR switches, the TPL, VSI, the minimum bus voltage profile and computational time for these three different load levels. From the result obtained in Table 3, the IEPSO technique provided the best optimal solution with the lowest power losses, improved VSI and less computational time as indicated in bold among all load conditions. From the results, IEPSO technique offered the most completion reduction with 4.16% for TPL, the fastest in computational time, 2.62% highest VSI in light load among others with identified methods. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Test System**} & \multicolumn{3}{c}{**33-Bus Radial Distribution System**} & \multicolumn{3}{c}{**69-Bus Radial Distribution System**} \\ \cline{2-7}  & **0.5 (Light)** & **1.0 (Nominal** & **1.5 (Heavy** & **0.5 (Light)** & **1.0 (Nominal** & **1.5 (Heavy** \\  & **Load)** & **Load)** & **Load)** & **Load)** & **Load)** \\ \hline Stability Index (\(L\)) & 0.0979 & 0.1995 & 0.3056 & 0.0917 & 0.1851 & 0.2979 \\ VSI min Base & 0.8443 & 0.6970 & 0.5583 & 0.8351 & 0.6799 & 0.5321 \\ DG Location & 17 & 17 & 17 & 65 & 65 & 65 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The determination of DG bus location.