Reliability Enhancement in Switching Substations Using Fault Current Limiters

Power system equipments are normally designed for a specific system and load situation. This situation could change significantly as a result of the system expansion or aging. Among the system equipments, circuit breakers are more sensitive to the system expansion and they must be able to isolate the faulty components if a fault occurs. As the system load increases in the future, the power network must be expanded. In this situation, either the switching equipments must be replaced in order to be able to respond to the new fault current or the fault current must be limited to the interrupting capability of the existing circuit breakers. Application of fault current limiters (FCL) serves as a promising answer to solve this problem. FCL allows for more reliable configurations without fault current problems. In this paper, the impact of using FCL in switching substations is studied and possible solutions are presented. The study is performed on the conventional double bus-bar arrangement. The study results show the effectiveness of this device in limiting the short circuit current as well as enhancing the load point reliability. Aging is another important factor that increases the failure rate of components and decreases the system reliability as such. Study results show that sensitivity of system parameters to the variation of failure rates and aging effects is reduced by using FCL