# Effects of On-Site PV Generation and Residential Demand Response on Distribution System Reliability
## 3 Test and Results
### Case Studies and Results  
In order to validate the effectiveness of the proposed model, four different case studies were conducted in this study as follows:  
* Case-1: LP9 was only considered as load, i.e., PV based generation unit and DR were out of concept. Additionally, it was used as the reference base case for showing the reliability improvement of other cases. * Case-2: PV system was incorporated as DG for backup power supply. * Case-3: In addition to PV based generation unit, 10% demand reduction was also implemented through DR program. * Case-4: In addition to PV based generation unit, 20% demand reduction was also implemented through DR program. In Case-1, PV based generation unit and demand reduction were not taken into consideration, i.e., the load demand of LP9 was supplied by only external grid. Thus, the other case studies could be analyzed thoroughly in terms of reliability improvement based on the reference condition. The feeder reliability indices (SAIFI, SAIDI, ENS) and the load point reliability indices (LPIF, LPID, LPENS) were calculated in MATLAB environment for base case, as indicated in Table 2.  
The feeder reliability indices (SAIFI, SAIDI, ENS) and the load point reliability indices (LPIF, LPID, LPENS) were calculated in MATLAB environment for Case-2, as indicated in Table 3. The impacts of DG power supply can be clearly examined in terms of improvement in indicators, as stated in Table 4. In total, 7.02% and more improvement was achieved in SAIFI and SAIDI indices, while 13.72% was achieved in ENS. On the other hand, higher load reliability indices were obtained for the points near the LP9. For example, LPIF improvement was 17.71% at LP7, while it was 52.10% at LP9. It is worth \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multicolumn{1}{c}{\multirow{2}{*}{**External Network**}} & \multicolumn{2}{c}{**Distribution Transformer**} & \multirow{2}{*}{**Bus and Circuit Breaker**} & \multirow{2}{*}{**Cable**} \\  & & **(34.5/0.4 kV)** & & \\ \hline \(\lambda\) (1/year) & 0.1 & 0.5 & 0.25 & 0.75 \\ \(\mathbf{r}\) (hr/year) & 8.7 & 3 & 4 & 4 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Failure rate and mean time to repair parameters of distribution feeder components. Figure 3: Daily load curve of the distribution feeder for winter. As a result of Case-3 and Case-4, it is seen that this combined structure helped to achieve a significant amount of contributions into the distribution system operation through increasing reliability indices. It is evident that the improvement was achieved even at LP1 point in LPIF, LPID, and LPENS as shown in Figures 4-6, respectively. The results show that the improvements depended on the location of the load points and on the capacity of the transformer. As a conclusion, it can be said that a respectable reliability improvement was achieved with DG availability and effective DR strategies. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multicolumn{2}{c}{**Feeder**} & \multicolumn{2}{c}{**Load Point**} & \multicolumn{10}{c}{**Load Points**} \\ \cline{3-13} \multicolumn{2}{c}{**Reliability**} & \multicolumn{2}{c}{**Reliability**} & \multicolumn{2}{c}{**LP1**} & **LP2** & **LP3** & **LP4** & **LP5** & **LP6** & **LP7** & **LP8** & **LP9** \\ \hline SAIFI (\(\frac{\mathrm{f}}{\mathrm{c-y}}\)) & 5.13 & LPIF (\(\frac{\mathrm{f}}{\mathrm{c-y}}\)) & 2.92 & 3.92 & 4.92 & 5.92 & 6.92 & 7.69 & 6.90 & 5.80 & 5.35 \\ SAIDI (\(\frac{\mathrm{h}}{\mathrm{c-y}}\)) & 20.48 & LPID (\(\frac{\mathrm{h}}{\mathrm{c-y}}\)) & 11.64 & 15.64 & 19.64 & 23.64 & 27.64 & 30.71 & 27.58 & 23.18 & 21.39 \\ ENS (\(\frac{\mathrm{MWs}}{\mathrm{y}}\)) & 48.54 & LPENS (\(\frac{\mathrm{MWs}}{\mathrm{y}}\)) & 1.02 & 16.91 & 3.12 & 8.37 & 2.22 & 2.48 & 7.51 & 5.60 & 3.20 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Calculated reliability indices for Case-4.