## 4 Example Analysis
### Multi-Voltage Levels Distribution Network Power Supply Reliability Evaluation Results  
In order to prove the effectiveness of the collaborative evaluation method, under the condition that each section switch is equipped with a sense-control terminal and without considering the fault of the sense-control terminal, the sequential evaluation and collaborative evaluation methods are used to analyze the reliability of the medium and low-voltage distribution network. Taking the load point LP1 on the feeder F1, the load point LP12 on the feeder F3, and the load point LP18 on the feeder F4 as examples, the sequential evaluation and collaborative evaluation methods are used to analyze the power supply reliability of the low-voltage stations supplied by different load points.  
The system reliability indices of specific load points and the overall reliability indices are compared.  
By comparing the results of Table 3, it can be seen that the SAIDI, ASAI, and ENS of each load point calculated by the sequential evaluation method are the same, while the reliability indices calculated by the collaborative evaluation method are different. This is because in the sequential evaluation method, it is necessary to evaluate the reliability of the medium-voltage distribution system. Moreover, the evaluation indices SAIFI and SAIDI of the medium-voltage system are used as the fault frequency and outage time of the 400 V bus of the low-voltage system. Finally, the reliability evaluation of the low-voltage system is completed. The collaborative evaluation method proposed in this paper will calculate the outage frequency and outage time index of each medium-voltage load point and take them as the fault frequency and outage time of the 400 V bus in the low-voltage area of the load point, so the reliability parameters of the 400 V bus of each low-voltage system are different. Compared with the sequential evaluation method, the calculation results of the collaborative evaluation method can better reflect the differences in feeders connected to different low-voltage stations, and then targeted methods can be used to improve the weak links in the power supply. For example, the TUs with tele-control function terminals are installed in the feeder section of the low-voltage station area to improve the reliability of the power supply.  
Figure 8: Structure of a low-voltage distribution system.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Load Points**} & \multicolumn{2}{c}{**SAIDI (h/Household-Year)**} & \multicolumn{2}{c}{**ASAI (\%)**} & \multicolumn{2}{c}{**ASAI (kWh/Year)**} \\ \cline{2-7}  & **Collaborative Assessment** & **Sequential Evaluation** & **Collaborative Assessment** & **Sequential Evaluation** & **Collaborative Assessment** & **Sequential Evaluation** \\ \hline LP1 & 3.5321 & 3.0127 & 99.9533 & 99.9631 & 288.14 & 205.73 \\ \hline LP12 & 3.3759 & 3.0127 & 99.9582 & 99.9631 & 279.31 & 205.73 \\ \hline LP18 & 3.1362 & 3.0127 & 99.9616 & 99.9631 & 243.95 & 205.73 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Comparison of reliability indices of low-voltage station areas with load points.  
By calculating the reliability indices of all low-voltage stations and averaging the reliability indices, the final reliability evaluation results of the medium and low-voltage distribution network are shown in Table 4.  
From the results of Table 4, we can find that compared with the sequential evaluation method, the SAIFI, SAIDI, and ENS calculated by the collaborative evaluation method have increased, while the ASAI has decreased by 0.0015% because the collaborative evaluation method considers the reliability of each distribution transformer area. The results can better reflect the actual operation of the distribution network, and the reliability index is also more valuable.