# Real-Time Circuit Breaker Availability Assessment in the Transmission Network
###### Abstract  
Circuit breakers (CBs) in the transmission network are the basic elements for energy flow control. CB diagnosis represents a decisive action for increasing power system reliability and safety. Their actual availability status and ability to perform major functions can sometimes be difficult to determine. This paper presents a general state estimation model based on fuzzy logic (FL), membership function (MF), and expert knowledge for diagnosis schemes to handle unclear information in the diagnosis procedure. The proposed model uses inputs from the Supervisory Control and Data Acquisition (SCADA) system, data on the position and state of the switch, changes in current in the network element CB (NECB), start or trip action of a protection relay on the NECB, and alarm status of the CB. For the diagnostic system input variables, data from the SCADA system, along with transformer and line protection devices, are used to allow the proper formation of rules and ultimately to determine the diagnostic status of the CB. The proposed method is tested on an authentic test power system, and the outcome results are compared with a previously reported technique. The obtained test results and the comparison prove the efficiency, authenticity, and fast operation feature of the suggested strategy. c 2021 2021 1  
application for the necessary determination of real-time CB availability, and thus only data from the SCADA system and protection devices should be used. Some researchers have engaged in power system fault detection [20; 21; 22; 23; 24; 25; 26], and some have engaged in fault modeling in the power system. Most of the fault detection techniques have exploited artificial intelligence (AI)-based techniques [20; 23; 24; 25], and among them, some methods have performed fault diagnosis using fuzzy logic [27; 28]. This paper tries to address the problems of determining the diagnostic state of high-voltage circuit breakers using fuzzy logic with the help of information from SCADA systems and protection devices in real-time network events, consequently increasing the safety and reliability of the whole power system. The authors provide a new fuzzy logic method and procedure overview for determining the availability of CBs, which can be applied and used in any transmission or distribution network. Expert (authors) knowledge and experience in the field of CB availability examination are used in the entire fuzzy logic implementation process. The availability of each element of the grid, and thereby the system as a whole, could be improved with the CBs state availability assessment. The importance of the presented method is even more significant if implemented in a real-time environment. An adequate selection of faulty network elements, as well as increased security and reliability of the entire power system, is the expected contribution of the presented method. Additionally, keeping a faulty CB in operation in the event of a fault on a network element, and due to the inability of the CB to operate, could lead to nonselective tripping of other network parts. This can significantly reduce the security and reliability of a network element, part of the network, and the power system as a whole. For the calculation of the safety and reliability of the power system to be adequate, it would have to cover countless possible and specified individual cases on a specific part of the network, and the same could not be carried out due to the content, topic, and interests of this paper. We exploit fuzzy MFs to handle the uncertainties of the information used in the diagnosis process and use the expert knowledge of an individual to determine the availability of a CB state to fulfill its function. The required data (including changes in current on the NECB, position and switch state, CB alarm status, and star or trip action of a protection relay on the NECB) are acquired from the SCADA system and system, along with transformer and line protection devices.