Distribution systems fault analysis considering fault resistance estimation

Fault resistance is a critical component of electric power systems operation due to its stochastic nature. If not considered, this parameter may interfere in fault analysis studies. This paper presents an iterative fault analysis algorithm for unbalanced three-phase distribution systems that considers a fault resistance estimate. The proposed algorithm is composed by two sub-routines, namely the fault resistance and the bus impedance. The fault resistance sub-routine, based on local fault records, estimates the fault resistance. The bus impedance sub-routine, based on the previously estimated fault resistance, estimates the system voltages and currents. Numeric simulations on the IEEE 37-bus distribution system demonstrate the algorithm’s robustness and potential for offline applications, providing additional fault information to Distribution Operation Centers and enhancing the system restoration process.

► An extended bus impedance phase component fault analysis formulation is developed.
► A RF estimate formulation is presented considering distribution system asymmetries.
► Fault resistance estimate is included in fault analysis formulation.
► RF estimates have some dependency to its value and are invariant to fault location.
► Fault analysis accuracy is independent to fault resistance and fault location.