# Fault Diagnosis System of Power Grid Based on Multi-Data Sources
## 3 Realization of Fault Diagnosis Real-Time Processing System  
Many symbols are involved in this chapter. The main symbols are shown in Table 1. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Symbol (1)** & **Meaning** & **Symbol (1)** & **Meaning** \\ \hline \(V\)_class_ & The class of all electrical elements in power grid & \(NBP\) & The class of near backup protections \\  & The class of partial electrical elements containing & \(P\)\_e_ & \(BP\) & The class of bus protections \\  & transformers, buses, lines and generators in & \(BP\) & The set of the grid’s action protections \\  & power grid & & \(V\_e\)\_e_1 (2) & The initial set of suspicious faulty \(V\_e\) class \\ \(B\)_class_ & The class of circuit breakers in power grid & \(P\)\_e_ & The set of the grid’s action protections \\  & The class of electrical elements other than \(V\_e\) & \(V\_e\)\_e_1 (2) & The initial set of suspicious faulty \(V\_e\) class \\  & class elements and \(B\) class elements & & elements elements \\ \(V\_T\) & The class of transformers & \(V\_e\)\_2 (2) & The set of suspicious faulty \(V\_e\) class elements \\ \(V\_G\) & The class of generators & \(V\_e\)\_3 (2) & The initial set of faulty \(V\_e\) class elements \\ \(V\_L\) & The class of lines & \(V\_e\)\_4 (3) & The set of faulty \(V\_e\) class elements \\ \(V\_B\) & The class of buses & \(V\_e\)\_5 (4) & The set of suspected faulty \(V\_e\) class elements \\ \(G\)_class_ & The class of the power grid network & \(P\_1\) (3) & The set of maloperation protections \\ \(P\)_class_ & The class of protections & \(P\_2\) (3) & The set of refuse-operation protections \\ \(MP\) & The class of main protections & \(P\_3\) (4) & The set of unprocessed protections \\ \(TP\) & The class of transformer protections & \(CB\_1\) (3) & The set of maloperation circuit breakers \\ \(RBP\) & The class of remote backup protections & \(CB\_2\) (3) & The set of refuse-operation circuit breakers \\ \hline \hline \end{tabular}  
* Only the main symbols are listed here. Other symbols (especially symbols used in calculations) are defined in the corresponding sections. All symbols in the main text of this article are expressed in italics. (2) \(V\_e\)_1, \(V\_e\)_2 and \(V\_e\)_3 are defined in detail in Section 3.2. (3) \(V\_e\)_3, \(P\_1\), \(P\_2\), \(CB\_1\) and \(CB\_2\) are defined in detail in Section 3.3.1. (4) \(V\_e\)_5 and \(P\_3\) are defined in detail in Section 3.3.2.  
\end{table} 
Table 1: Table of main symbols. Object-Oriented Information Representation Method of Electrical Elements, Protection Information and Power Grid Network Topology  
In this article, the object-oriented representation method is used to classify and design all electrical elements, protections and network topology in the power grid, as shown in Figure 2.  
In the object-oriented representation method, a subclass inherits all the attributes and methods of its parent class and has its own other attributes, while a single object is an instantiation realization of the subclass. The inheritance performance between parent class and child class preferable shows the relationship between power grid network and various electrical elements. Compared with other representation methods, object-oriented representation of electrical elements, protections and network topology in the power grid has many advantages:  
1. The system is easier to maintain. When the operating status of certain elements or parts of the power grid changes, only one single object or partial module needs to be modified;
2. Code reuse and system development efficiency are improved. Electrical components, their connection relationships and protections in the power grid are abstracted into categories, and logical thinking methods closer to nature are adopted, which can reduce the amount of repetitive code and the amount of follow-up work development;
3. The system functions are easier to expand.