Online assessment of fault current considering substation topologies

Changes to the power system, especially the installation of new generation sources and new operating conditions, result in higher fault currents. Circuit breakers, which are previously designed and coordinated for the power systems before the appearances of new generation sources and new operating conditions, may have inadequate fault current interruption capability. This paper discusses those operating conditions that result in interruption capability violations of circuit breakers, based on substation topologies/circuit breaker connections. An online application of fault current assessment is proposed to identify those unsafe operating conditions limited by circuit breaker interruption capabilities. Based on the findings of the paper, this application can give system operators suggestions of remedy actions that eliminate unsafe operating conditions by changing substation topologies. The design of such an online application is described and a MATLAB version is tested on IEEE 14-bus system.