Digital Simulation Of Simultaneous Unbalances Involving Open And Faulted Conductors

A method for digitally simulating a three phase power system which is subjected to a fault at one location with blown fuses or open conductors at another location is described. The method is applicable when the simultaneous unbalances are on opposite sides of a delta-wye transformer. Employing symmetrical component theory, it is shown that the sequence networks can be connected with a common neutral bus when simulating a fault or open conductor(s). The interconnected sequence networks are represented by node voltage and constraint equations so that solutions for different conditions are easily obtained. Two different techniques were programmed for solving the equations and they are discussed in terms of the number of operations and computer running time. The method also can be used to simulate other types of shunt and series simultaneous unbalances if the sequence constraint equations are known at each unbalance point.