Estimation of steady-state unbalanced system conditions combining conventional power flow and fault analysis software

In real three-phase power systems, the voltages and currents are not fully symmetrical. A method has been developed to estimate the effects of slight unbalanced network conditions for steady-state operation. A conventional power flow is followed by a linear incremental calculation using a three-phase model of the network. The unbalanced condition is handled like a multiple unbalanced fault. The process is illustrated for the case of a transformer bank with nonidentical single phase units. The results show the effects of different transformer reactances and different voltage ratios, respectively.