# Fault Diagnosis System of Power Grid Based on Multi-Data Sources
## 3 Realization of Fault Diagnosis Real-Time Processing System
### Fault Diagnosis and Information Missing Analysis
#### 3.3.2 Information Missing Analysis Based on Classification of Action Protections  
When a \(V\_e\) class element in the power grid fails, protections on both sides (or multiple sides) of the element should act together to disconnect related circuit breakers to remove the faulty element. However, in practical engineering, the protection action information and circuit breaker tripping information are often lost. In this circumstance, the dispatching center may only receive accident-level information of one side (or more sides, but less than the number of adjacency list edges of the element). The purpose of circuit breaker tripping controlled by protection action is to remove a faulty \(V\_e\) class element. The reverse reasoning Petri net used in the fault pre-diagnosis process in Section 3.2 is logically calculated from the purpose of circuit breaker tripping and protection action. The mapped reverse reasoning Petri net cannot work when the protection action and circuit breaker tripping information on the protection information tree of suspicious faulty elements are incomplete. Although it is impossible to determine the potential faulty elements related to the missing part of the information, some suspected faulty elements can be speculated by classifying the known protection action information. It is defined that the protections whose action information can be used to diagnose suspicious faulty elements (namely, the protection action whose purpose is to remove one or more elements in \(V\_e3\)) as the processed protections and other action protections are regarded as unprocessed protections. **Definition 3**. : _Protection processing value: SP. SP is an attribute of protection class to classify action protections. The calculation method of SP has been given in Step 4 of Algorithm 3. When the protection processing value SP of a protection is \(n\), it means that the protection has participated in the fault diagnosis calculation of \(n\)\(V\_e\) elements in \(V\_e3\). Therefore, when the protection processing value SP of a protection is no less than 1, it represents that the protection is a processed protection. The protection processing values of unprocessed protections are equal to the initial value 0._  
The information between the processed protections and the untreated protections do not interfere with each other, so the original power grid network can be decomposed into two parts: the network with only the processed protections and the network with only the untreated protections. The fault diagnosis result of the original power grid is the superposition of the two diagnosis results. The fault diagnosis of the network with only processed protection is completed in Sections 3.2 and 3.3.1, while the fault diagnosis of the network with only unprocessed protection needs to be completed by the batch processing system. The following is Algorithm 4 to complete the logic process described in this section. ```
Input: the power grid network: \(G\) and the set of the grid action protections: \(P^{*}\). Output: the set of unprocessed protections: \(P\_3\) and the set of suspected faulty \(V\_e\) class elements: \(V\_e5\). The specific steps of the algorithm are as follows: Step (1) input \(G\) and \(P^{*}\); Step (2) Traversing \(P^{*}\), selecting the protections whose protection processing value (\(SP\)) is 0 to form \(P\_3\) (If \(P\_3\) is an empty set, no partial information loss occurs. The following steps are not carried out. ); Step (3) Reconstructing power grid network \(G1\). Only the topological connection of elements in \(G\) is retained, all \(V\_e\) class elements in \(G1\) are initialized. The breaking and closing states (\(S\)) of circuit breakers related to protections in \(P\_3\) are retained, and the other circuit breakers are initialized. Step (4) Invoke Algorithm 2, namely Search_FaultV_e (\(G1\), \(P\_3\), \(V\_G1e1\), \(V\_G1e2\)), to generate the initial set (\(V\_G1e1\)) of the suspicious faulty \(V\_e\) elements of \(G1\), which is used as the set (\(V\_e5\)) of suspected faulty elements of \(G\).