Fault analysis using continuation power flow and phase coordinates

This paper addresses the problem of fault analysis applied to unbalanced power systems. It is well known that the effectiveness of the classical symmetrical components method of fault analysis is severely impaired when dealing with unbalanced systems, due to couplings that appear between the sequence networks. Simultaneous faults in balanced systems can be solved using symmetrical components, but the derivations are rather cumbersome. Distribution power systems are normally unbalanced. Several proposals have been specifically described to deal with fault analysis on distribution systems, which may include single-phase, two-phase and untransposed three-phase feeders This work discussed a new method to compute fault analysis in unbalanced power systems. The continuation power flow technique has been used to solve the three-phase power flow equations, in which the continuation parameter is the fault impedance. The method was applied to the IEEE 300 busbar system. The importance of load representation was stressed. The method can be very useful as a tool to assess voltage sag conditions on any balanced or unbalanced power system. Additionally, the method can be applied to the study of distribution systems having several power sources such as distributed generation plants.