# Fault Diagnosis System of Power Grid Based on Multi-Data Sources
## 5 Example Analysis
### Time-Consuming Test and Analysis  
In order to verify the computational efficiency of the system, a time-consuming test is carried out in this article, which is shown in Figure 12.  
It can be seen from Figure 12 that the work and data acquisition of the three subsystems are in parallel operation and do not interfere with each other. The initialization of a real-time processing system takes a long time. If the grid topology is stored in the system in advance, this part of time can be reduced. However, pre-initialization may take up a lot of stored space. Since the quasi-real-time processing system needs to wait for diagnostic results of the real-time processing system, pre-initialization can also help improve efficiency in fault trace. The batch processing system needs to wait for the transmission and scheduling of fault recording wave data, and its reasoning process does not take a short time. However, under ideal conditions, the faulty elements can be diagnosed in about 2.9 s after the fault, the fault tracking process can be completed in about 4.2 s, and the detailed fault diagnosis report can be completed in about 5.0 s. It meets the actual needs of the power system. Time-consuming tests are also carried out with different fault examples on different power grid systems, and the results are shown in Table 12. \begin{table}
\begin{tabular}{l c c c} \hline \hline  & **n-1** (1) & **n-2** & **n-3** \\ \hline IEEE 14 bus system & 2.71 s (2) & 3.04 s & 3.38 s \\ IEEE 30 bus system & 2.73 s & 3.06 s & 3.40 s \\ IEEE 69 bus system & 2.76 s & 3.09 s & 3.44 s \\ IEEE 118 bus system & 2.80 s & 3.14 s & 3.51 s \\ IEEE 300 bus system & 2.87 s & 3.25 s & 3.64 s \\
2746 bus system & 3.41 s & 3.82 s & 4.17 s \\ \hline \hline \end{tabular} (1) n-1 scenario represents the scenario where only one \(V\_e\) class element fails in the power grid. n-2 scenario represents the scenario where two \(V\_e\) class elements of the power grid fail at the same time. n-3 scenario represents the scenario where three \(V\_e\) class elements of the power grid fail at the same time. (2) The time in the table represents the time from initialization of the real-time processing subsystem to completion of the entire fault diagnosis system.  
\end{table} 
Table 12: Time-consuming tests of different fault examples on different systems. Figure 12: System time-consuming test. It can be seen from Table 12 that this fault diagnosis system not only performs well when dealing with relatively simple power systems (IEEE 14 bus system and IEEE 30 bus system) but also maintains a high efficiency when dealing with more complex power systems with a large number of buses. The topological relationship of the entire power grid is only involved in the initialization of the real-time processing system. The subsequent fault diagnosis and tracking link will not search the entire power grid, and its operating efficiency has little to do with the complexity of the power grid system. Therefore, the time consumed by this fault diagnosis system only slightly increases with the increase in the complexity of the power system being processed, and this fault diagnosis system can still maintain high computational efficiency. However, as the number of simultaneous faulty elements increases, the time-consuming time of this fault diagnosis system increases a lot. This is essentially because the number of circulations required in fault diagnosis and tracking link increases at the rate that is a multiple of the increasing number of simultaneous faulty elements. However, in actual engineering applications, there are usually only one or two faulty elements at the same time. This problem will not bring a big reduction in computational efficiency. This paper also makes a transverse comparison between this fault diagnosis system and related technologies, and the results are shown in Table A1 in Appendix A.